1 # SOME DESCRIPTIVE TITLE
2 # Copyright (C) YEAR Red Hat Inc.
3 # This file is distributed under the same license as the libguestfs package.
4 # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
9 "Project-Id-Version: libguestfs 1.9.17\n"
10 "Report-Msgid-Bugs-To: libguestfs@redhat.com\n"
11 "POT-Creation-Date: 2011-04-05 20:38+0200\n"
12 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
13 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
14 "Language-Team: LANGUAGE <LL@li.org>\n"
17 "Content-Type: text/plain; charset=UTF-8\n"
18 "Content-Transfer-Encoding: 8bit\n"
21 #: ../src/guestfs.pod:3 ../fish/guestfish.pod:3 ../test-tool/libguestfs-test-tool.pod:3 ../fuse/guestmount.pod:3 ../tools/virt-edit.pl:32 ../tools/virt-win-reg.pl:35 ../tools/virt-resize.pl:40 ../tools/virt-list-filesystems.pl:30 ../tools/virt-tar.pl:31 ../tools/virt-make-fs.pl:35 ../tools/virt-list-partitions.pl:30
26 #: ../src/guestfs.pod:5
27 msgid "guestfs - Library for accessing and modifying virtual machine images"
31 #: ../src/guestfs.pod:7 ../fish/guestfish.pod:7 ../test-tool/libguestfs-test-tool.pod:7 ../fuse/guestmount.pod:7 ../tools/virt-edit.pl:36 ../tools/virt-win-reg.pl:39 ../tools/virt-resize.pl:44 ../tools/virt-list-filesystems.pl:34 ../tools/virt-tar.pl:35 ../tools/virt-make-fs.pl:39 ../tools/virt-list-partitions.pl:34
36 #: ../src/guestfs.pod:9
39 " #include <guestfs.h>\n"
44 #: ../src/guestfs.pod:11
47 " guestfs_h *g = guestfs_create ();\n"
48 " guestfs_add_drive (g, \"guest.img\");\n"
49 " guestfs_launch (g);\n"
50 " guestfs_mount (g, \"/dev/sda1\", \"/\");\n"
51 " guestfs_touch (g, \"/hello\");\n"
52 " guestfs_umount (g, \"/\");\n"
53 " guestfs_close (g);\n"
58 #: ../src/guestfs.pod:19
61 " cc prog.c -o prog -lguestfs\n"
63 " cc prog.c -o prog `pkg-config libguestfs --cflags --libs`\n"
68 #: ../src/guestfs.pod:23 ../fish/guestfish.pod:30 ../test-tool/libguestfs-test-tool.pod:11 ../fuse/guestmount.pod:20 ../tools/virt-edit.pl:50 ../tools/virt-win-reg.pl:63 ../tools/virt-resize.pl:50 ../tools/virt-list-filesystems.pl:40 ../tools/virt-tar.pl:77 ../tools/virt-make-fs.pl:47 ../tools/virt-list-partitions.pl:40
73 #: ../src/guestfs.pod:25
75 "Libguestfs is a library for accessing and modifying guest disk images. "
76 "Amongst the things this is good for: making batch configuration changes to "
77 "guests, getting disk used/free statistics (see also: virt-df), migrating "
78 "between virtualization systems (see also: virt-p2v), performing partial "
79 "backups, performing partial guest clones, cloning guests and changing "
80 "registry/UUID/hostname info, and much else besides."
84 #: ../src/guestfs.pod:33
86 "Libguestfs uses Linux kernel and qemu code, and can access any type of guest "
87 "filesystem that Linux and qemu can, including but not limited to: ext2/3/4, "
88 "btrfs, FAT and NTFS, LVM, many different disk partition schemes, qcow, "
93 #: ../src/guestfs.pod:38
95 "Libguestfs provides ways to enumerate guest storage (eg. partitions, LVs, "
96 "what filesystem is in each LV, etc.). It can also run commands in the "
97 "context of the guest. Also you can access filesystems over FUSE."
101 #: ../src/guestfs.pod:43
103 "Libguestfs is a library that can be linked with C and C++ management "
104 "programs (or management programs written in OCaml, Perl, Python, Ruby, Java, "
105 "PHP, Haskell or C#). You can also use it from shell scripts or the command "
110 #: ../src/guestfs.pod:48
112 "You don't need to be root to use libguestfs, although obviously you do need "
113 "enough permissions to access the disk images."
117 #: ../src/guestfs.pod:51
119 "Libguestfs is a large API because it can do many things. For a gentle "
120 "introduction, please read the L</API OVERVIEW> section next."
124 #: ../src/guestfs.pod:54
126 "There are also some example programs in the L<guestfs-examples(3)> manual "
131 #: ../src/guestfs.pod:57
136 #: ../src/guestfs.pod:59
138 "This section provides a gentler overview of the libguestfs API. We also try "
139 "to group API calls together, where that may not be obvious from reading "
140 "about the individual calls in the main section of this manual."
144 #: ../src/guestfs.pod:64
149 #: ../src/guestfs.pod:66
151 "Before you can use libguestfs calls, you have to create a handle. Then you "
152 "must add at least one disk image to the handle, followed by launching the "
153 "handle, then performing whatever operations you want, and finally closing "
154 "the handle. By convention we use the single letter C<g> for the name of the "
155 "handle variable, although of course you can use any name you want."
159 #: ../src/guestfs.pod:73
160 msgid "The general structure of all libguestfs-using programs looks like this:"
164 #: ../src/guestfs.pod:76
167 " guestfs_h *g = guestfs_create ();\n"
172 #: ../src/guestfs.pod:78
175 " /* Call guestfs_add_drive additional times if there are\n"
176 " * multiple disk images.\n"
178 " guestfs_add_drive (g, \"guest.img\");\n"
183 #: ../src/guestfs.pod:83
186 " /* Most manipulation calls won't work until you've launched\n"
187 " * the handle 'g'. You have to do this _after_ adding drives\n"
188 " * and _before_ other commands.\n"
190 " guestfs_launch (g);\n"
195 #: ../src/guestfs.pod:89
198 " /* Now you can examine what partitions, LVs etc are available.\n"
200 " char **partitions = guestfs_list_partitions (g);\n"
201 " char **logvols = guestfs_lvs (g);\n"
206 #: ../src/guestfs.pod:94
209 " /* To access a filesystem in the image, you must mount it.\n"
211 " guestfs_mount (g, \"/dev/sda1\", \"/\");\n"
216 #: ../src/guestfs.pod:98
219 " /* Now you can perform filesystem actions on the guest\n"
222 " guestfs_touch (g, \"/hello\");\n"
227 #: ../src/guestfs.pod:103
230 " /* This is only needed for libguestfs < 1.5.24. Since then\n"
231 " * it is done automatically when you close the handle. See\n"
232 " * discussion of autosync in this page.\n"
234 " guestfs_sync (g);\n"
239 #: ../src/guestfs.pod:109
242 " /* Close the handle 'g'. */\n"
243 " guestfs_close (g);\n"
248 #: ../src/guestfs.pod:112
250 "The code above doesn't include any error checking. In real code you should "
251 "check return values carefully for errors. In general all functions that "
252 "return integers return C<-1> on error, and all functions that return "
253 "pointers return C<NULL> on error. See section L</ERROR HANDLING> below for "
254 "how to handle errors, and consult the documentation for each function call "
255 "below to see precisely how they return error indications. See "
256 "L<guestfs-examples(3)> for fully worked examples."
260 #: ../src/guestfs.pod:121
265 #: ../src/guestfs.pod:123
267 "The image filename (C<\"guest.img\"> in the example above) could be a disk "
268 "image from a virtual machine, a L<dd(1)> copy of a physical hard disk, an "
269 "actual block device, or simply an empty file of zeroes that you have created "
270 "through L<posix_fallocate(3)>. Libguestfs lets you do useful things to all "
275 #: ../src/guestfs.pod:129
277 "The call you should use in modern code for adding drives is "
278 "L</guestfs_add_drive_opts>. To add a disk image, allowing writes, and "
279 "specifying that the format is raw, do:"
283 #: ../src/guestfs.pod:133
286 " guestfs_add_drive_opts (g, filename,\n"
287 " GUESTFS_ADD_DRIVE_OPTS_FORMAT, \"raw\",\n"
293 #: ../src/guestfs.pod:137
294 msgid "You can add a disk read-only using:"
298 #: ../src/guestfs.pod:139
301 " guestfs_add_drive_opts (g, filename,\n"
302 " GUESTFS_ADD_DRIVE_OPTS_FORMAT, \"raw\",\n"
303 " GUESTFS_ADD_DRIVE_OPTS_READONLY, 1,\n"
309 #: ../src/guestfs.pod:144
311 "or by calling the older function L</guestfs_add_drive_ro>. In either case "
312 "libguestfs won't modify the file."
316 #: ../src/guestfs.pod:147
318 "Be extremely cautious if the disk image is in use, eg. if it is being used "
319 "by a virtual machine. Adding it read-write will almost certainly cause disk "
320 "corruption, but adding it read-only is safe."
324 #: ../src/guestfs.pod:151
326 "You must add at least one disk image, and you may add multiple disk images. "
327 "In the API, the disk images are usually referred to as C</dev/sda> (for the "
328 "first one you added), C</dev/sdb> (for the second one you added), etc."
332 #: ../src/guestfs.pod:156
334 "Once L</guestfs_launch> has been called you cannot add any more images. You "
335 "can call L</guestfs_list_devices> to get a list of the device names, in the "
336 "order that you added them. See also L</BLOCK DEVICE NAMING> below."
340 #: ../src/guestfs.pod:161
345 #: ../src/guestfs.pod:163
347 "Before you can read or write files, create directories and so on in a disk "
348 "image that contains filesystems, you have to mount those filesystems using "
349 "L</guestfs_mount_options> or L</guestfs_mount_ro>. If you already know that "
350 "a disk image contains (for example) one partition with a filesystem on that "
351 "partition, then you can mount it directly:"
355 #: ../src/guestfs.pod:170
358 " guestfs_mount_options (g, \"\", \"/dev/sda1\", \"/\");\n"
363 #: ../src/guestfs.pod:172
365 "where C</dev/sda1> means literally the first partition (C<1>) of the first "
366 "disk image that we added (C</dev/sda>). If the disk contains Linux LVM2 "
367 "logical volumes you could refer to those instead (eg. C</dev/VG/LV>). Note "
368 "that these are libguestfs virtual devices, and are nothing to do with host "
373 #: ../src/guestfs.pod:178
375 "If you are given a disk image and you don't know what it contains then you "
376 "have to find out. Libguestfs can do that too: use "
377 "L</guestfs_list_partitions> and L</guestfs_lvs> to list possible partitions "
378 "and LVs, and either try mounting each to see what is mountable, or else "
379 "examine them with L</guestfs_vfs_type> or L</guestfs_file>. To list just "
380 "filesystems, use L</guestfs_list_filesystems>."
384 #: ../src/guestfs.pod:186
386 "Libguestfs also has a set of APIs for inspection of unknown disk images (see "
387 "L</INSPECTION> below). But you might find it easier to look at higher level "
388 "programs built on top of libguestfs, in particular L<virt-inspector(1)>."
392 #: ../src/guestfs.pod:191
394 "To mount a filesystem read-only, use L</guestfs_mount_ro>. There are "
395 "several other variations of the C<guestfs_mount_*> call."
399 #: ../src/guestfs.pod:194
400 msgid "FILESYSTEM ACCESS AND MODIFICATION"
404 #: ../src/guestfs.pod:196
406 "The majority of the libguestfs API consists of fairly low-level calls for "
407 "accessing and modifying the files, directories, symlinks etc on mounted "
408 "filesystems. There are over a hundred such calls which you can find listed "
409 "in detail below in this man page, and we don't even pretend to cover them "
410 "all in this overview."
414 #: ../src/guestfs.pod:202
416 "Specify filenames as full paths, starting with C<\"/\"> and including the "
421 #: ../src/guestfs.pod:205
423 "For example, if you mounted a filesystem at C<\"/\"> and you want to read "
424 "the file called C<\"etc/passwd\"> then you could do:"
428 #: ../src/guestfs.pod:208
431 " char *data = guestfs_cat (g, \"/etc/passwd\");\n"
436 #: ../src/guestfs.pod:210
438 "This would return C<data> as a newly allocated buffer containing the full "
439 "content of that file (with some conditions: see also L</DOWNLOADING> below), "
440 "or C<NULL> if there was an error."
444 #: ../src/guestfs.pod:214
446 "As another example, to create a top-level directory on that filesystem "
447 "called C<\"var\"> you would do:"
451 #: ../src/guestfs.pod:217
454 " guestfs_mkdir (g, \"/var\");\n"
459 #: ../src/guestfs.pod:219
460 msgid "To create a symlink you could do:"
464 #: ../src/guestfs.pod:221
467 " guestfs_ln_s (g, \"/etc/init.d/portmap\",\n"
468 " \"/etc/rc3.d/S30portmap\");\n"
473 #: ../src/guestfs.pod:224
475 "Libguestfs will reject attempts to use relative paths and there is no "
476 "concept of a current working directory."
480 #: ../src/guestfs.pod:227
482 "Libguestfs can return errors in many situations: for example if the "
483 "filesystem isn't writable, or if a file or directory that you requested "
484 "doesn't exist. If you are using the C API (documented here) you have to "
485 "check for those error conditions after each call. (Other language bindings "
486 "turn these errors into exceptions)."
490 #: ../src/guestfs.pod:233
492 "File writes are affected by the per-handle umask, set by calling "
493 "L</guestfs_umask> and defaulting to 022. See L</UMASK>."
497 #: ../src/guestfs.pod:236
502 #: ../src/guestfs.pod:238
504 "Libguestfs contains API calls to read, create and modify partition tables on "
509 #: ../src/guestfs.pod:241
511 "In the common case where you want to create a single partition covering the "
512 "whole disk, you should use the L</guestfs_part_disk> call:"
516 #: ../src/guestfs.pod:245
519 " const char *parttype = \"mbr\";\n"
520 " if (disk_is_larger_than_2TB)\n"
521 " parttype = \"gpt\";\n"
522 " guestfs_part_disk (g, \"/dev/sda\", parttype);\n"
527 #: ../src/guestfs.pod:250
529 "Obviously this effectively wipes anything that was on that disk image "
534 #: ../src/guestfs.pod:253
539 #: ../src/guestfs.pod:255
541 "Libguestfs provides access to a large part of the LVM2 API, such as "
542 "L</guestfs_lvcreate> and L</guestfs_vgremove>. It won't make much sense "
543 "unless you familiarize yourself with the concepts of physical volumes, "
544 "volume groups and logical volumes."
548 #: ../src/guestfs.pod:260
550 "This author strongly recommends reading the LVM HOWTO, online at "
551 "L<http://tldp.org/HOWTO/LVM-HOWTO/>."
555 #: ../src/guestfs.pod:263
560 #: ../src/guestfs.pod:265
562 "Use L</guestfs_cat> to download small, text only files. This call is "
563 "limited to files which are less than 2 MB and which cannot contain any ASCII "
564 "NUL (C<\\0>) characters. However the API is very simple to use."
568 #: ../src/guestfs.pod:269
570 "L</guestfs_read_file> can be used to read files which contain arbitrary 8 "
571 "bit data, since it returns a (pointer, size) pair. However it is still "
572 "limited to \"small\" files, less than 2 MB."
576 #: ../src/guestfs.pod:273
578 "L</guestfs_download> can be used to download any file, with no limits on "
579 "content or size (even files larger than 4 GB)."
583 #: ../src/guestfs.pod:276
584 msgid "To download multiple files, see L</guestfs_tar_out> and L</guestfs_tgz_out>."
588 #: ../src/guestfs.pod:279
593 #: ../src/guestfs.pod:281
595 "It's often the case that you want to write a file or files to the disk "
600 #: ../src/guestfs.pod:284
602 "To write a small file with fixed content, use L</guestfs_write>. To create "
603 "a file of all zeroes, use L</guestfs_truncate_size> (sparse) or "
604 "L</guestfs_fallocate64> (with all disk blocks allocated). There are a "
605 "variety of other functions for creating test files, for example "
606 "L</guestfs_fill> and L</guestfs_fill_pattern>."
610 #: ../src/guestfs.pod:290
612 "To upload a single file, use L</guestfs_upload>. This call has no limits on "
613 "file content or size (even files larger than 4 GB)."
617 #: ../src/guestfs.pod:293
618 msgid "To upload multiple files, see L</guestfs_tar_in> and L</guestfs_tgz_in>."
622 #: ../src/guestfs.pod:295
624 "However the fastest way to upload I<large numbers of arbitrary files> is to "
625 "turn them into a squashfs or CD ISO (see L<mksquashfs(8)> and "
626 "L<mkisofs(8)>), then attach this using L</guestfs_add_drive_ro>. If you add "
627 "the drive in a predictable way (eg. adding it last after all other drives) "
628 "then you can get the device name from L</guestfs_list_devices> and mount it "
629 "directly using L</guestfs_mount_ro>. Note that squashfs images are "
630 "sometimes non-portable between kernel versions, and they don't support "
631 "labels or UUIDs. If you want to pre-build an image or you need to mount it "
632 "using a label or UUID, use an ISO image instead."
636 #: ../src/guestfs.pod:306
641 #: ../src/guestfs.pod:308
643 "There are various different commands for copying between files and devices "
644 "and in and out of the guest filesystem. These are summarised in the table "
649 #: ../src/guestfs.pod:314
650 msgid "B<file> to B<file>"
654 #: ../src/guestfs.pod:316
656 "Use L</guestfs_cp> to copy a single file, or L</guestfs_cp_a> to copy "
657 "directories recursively."
661 #: ../src/guestfs.pod:319
662 msgid "B<file or device> to B<file or device>"
666 #: ../src/guestfs.pod:321
668 "Use L</guestfs_dd> which efficiently uses L<dd(1)> to copy between files and "
669 "devices in the guest."
673 #: ../src/guestfs.pod:324
674 msgid "Example: duplicate the contents of an LV:"
678 #: ../src/guestfs.pod:326
681 " guestfs_dd (g, \"/dev/VG/Original\", \"/dev/VG/Copy\");\n"
686 #: ../src/guestfs.pod:328
688 "The destination (C</dev/VG/Copy>) must be at least as large as the source "
689 "(C</dev/VG/Original>). To copy less than the whole source device, use "
690 "L</guestfs_copy_size>."
694 #: ../src/guestfs.pod:332
695 msgid "B<file on the host> to B<file or device>"
699 #: ../src/guestfs.pod:334
700 msgid "Use L</guestfs_upload>. See L</UPLOADING> above."
704 #: ../src/guestfs.pod:336
705 msgid "B<file or device> to B<file on the host>"
709 #: ../src/guestfs.pod:338
710 msgid "Use L</guestfs_download>. See L</DOWNLOADING> above."
714 #: ../src/guestfs.pod:342
715 msgid "UPLOADING AND DOWNLOADING TO PIPES AND FILE DESCRIPTORS"
719 #: ../src/guestfs.pod:344
721 "Calls like L</guestfs_upload>, L</guestfs_download>, L</guestfs_tar_in>, "
722 "L</guestfs_tar_out> etc appear to only take filenames as arguments, so it "
723 "appears you can only upload and download to files. However many Un*x-like "
724 "hosts let you use the special device files C</dev/stdin>, C</dev/stdout>, "
725 "C</dev/stderr> and C</dev/fd/N> to read and write from stdin, stdout, "
726 "stderr, and arbitrary file descriptor N."
730 #: ../src/guestfs.pod:352
731 msgid "For example, L<virt-cat(1)> writes its output to stdout by doing:"
735 #: ../src/guestfs.pod:355
738 " guestfs_download (g, filename, \"/dev/stdout\");\n"
743 #: ../src/guestfs.pod:357
744 msgid "and you can write tar output to a pipe C<fd> by doing:"
748 #: ../src/guestfs.pod:359
752 " snprintf (devfd, sizeof devfd, \"/dev/fd/%d\", fd);\n"
753 " guestfs_tar_out (g, \"/\", devfd);\n"
758 #: ../src/guestfs.pod:363
759 msgid "LISTING FILES"
763 #: ../src/guestfs.pod:365
765 "L</guestfs_ll> is just designed for humans to read (mainly when using the "
766 "L<guestfish(1)>-equivalent command C<ll>)."
770 #: ../src/guestfs.pod:368
772 "L</guestfs_ls> is a quick way to get a list of files in a directory from "
773 "programs, as a flat list of strings."
777 #: ../src/guestfs.pod:371
779 "L</guestfs_readdir> is a programmatic way to get a list of files in a "
780 "directory, plus additional information about each one. It is more "
781 "equivalent to using the L<readdir(3)> call on a local filesystem."
785 #: ../src/guestfs.pod:375
787 "L</guestfs_find> and L</guestfs_find0> can be used to recursively list "
792 #: ../src/guestfs.pod:378
793 msgid "RUNNING COMMANDS"
797 #: ../src/guestfs.pod:380
799 "Although libguestfs is primarily an API for manipulating files inside guest "
800 "images, we also provide some limited facilities for running commands inside "
805 #: ../src/guestfs.pod:384
806 msgid "There are many limitations to this:"
810 #: ../src/guestfs.pod:388 ../src/guestfs.pod:393 ../src/guestfs.pod:398 ../src/guestfs.pod:402 ../src/guestfs.pod:407 ../src/guestfs.pod:411 ../src/guestfs.pod:416 ../src/guestfs.pod:421 ../src/guestfs.pod:1088 ../src/guestfs.pod:1092 ../src/guestfs.pod:1096 ../src/guestfs.pod:1101 ../src/guestfs.pod:1109 ../src/guestfs.pod:1128 ../src/guestfs.pod:1136 ../src/guestfs.pod:1158 ../src/guestfs.pod:1162 ../src/guestfs.pod:1166 ../src/guestfs.pod:1170 ../src/guestfs.pod:1174 ../src/guestfs.pod:1178 ../src/guestfs.pod:1660 ../src/guestfs.pod:1665 ../src/guestfs.pod:1669 ../src/guestfs.pod:1770 ../src/guestfs.pod:1775 ../src/guestfs.pod:1779 ../src/guestfs.pod:1789 ../src/guestfs.pod:2023 ../src/guestfs.pod:2028 ../src/guestfs.pod:2034 ../src/guestfs.pod:2042 ../src/guestfs.pod:2396 ../src/guestfs.pod:2402 ../src/guestfs.pod:2407 ../src/guestfs.pod:2413 ../src/guestfs.pod:2878 ../src/guestfs.pod:2882 ../src/guestfs.pod:2886 ../src/guestfs.pod:2890 ../src/guestfs-actions.pod:15 ../src/guestfs-actions.pod:22 ../src/guestfs-actions.pod:577 ../src/guestfs-actions.pod:585 ../src/guestfs-actions.pod:592 ../src/guestfs-actions.pod:599 ../src/guestfs-actions.pod:1600 ../src/guestfs-actions.pod:1604 ../src/guestfs-actions.pod:1608 ../src/guestfs-actions.pod:1612 ../src/guestfs-actions.pod:1620 ../src/guestfs-actions.pod:1624 ../src/guestfs-actions.pod:1628 ../src/guestfs-actions.pod:1638 ../src/guestfs-actions.pod:1642 ../src/guestfs-actions.pod:1646 ../src/guestfs-actions.pod:1784 ../src/guestfs-actions.pod:1788 ../src/guestfs-actions.pod:1793 ../src/guestfs-actions.pod:1798 ../src/guestfs-actions.pod:1859 ../src/guestfs-actions.pod:1863 ../src/guestfs-actions.pod:1868 ../fish/guestfish.pod:443 ../fish/guestfish.pod:447 ../fish/guestfish.pod:451 ../fish/guestfish.pod:455 ../fish/guestfish-actions.pod:13 ../fish/guestfish-actions.pod:20 ../fish/guestfish-actions.pod:380 ../fish/guestfish-actions.pod:388 ../fish/guestfish-actions.pod:395 ../fish/guestfish-actions.pod:402 ../fish/guestfish-actions.pod:1072 ../fish/guestfish-actions.pod:1076 ../fish/guestfish-actions.pod:1080 ../fish/guestfish-actions.pod:1084 ../fish/guestfish-actions.pod:1092 ../fish/guestfish-actions.pod:1096 ../fish/guestfish-actions.pod:1100 ../fish/guestfish-actions.pod:1110 ../fish/guestfish-actions.pod:1114 ../fish/guestfish-actions.pod:1118 ../fish/guestfish-actions.pod:1208 ../fish/guestfish-actions.pod:1212 ../fish/guestfish-actions.pod:1217 ../fish/guestfish-actions.pod:1222 ../fish/guestfish-actions.pod:1264 ../fish/guestfish-actions.pod:1268 ../fish/guestfish-actions.pod:1273 ../tools/virt-edit.pl:351 ../tools/virt-edit.pl:356 ../tools/virt-edit.pl:361 ../tools/virt-edit.pl:372 ../tools/virt-edit.pl:376 ../tools/virt-win-reg.pl:536 ../tools/virt-win-reg.pl:542 ../tools/virt-win-reg.pl:548 ../tools/virt-resize.pl:345 ../tools/virt-resize.pl:350 ../tools/virt-resize.pl:360
815 #: ../src/guestfs.pod:390
817 "The kernel version that the command runs under will be different from what "
822 #: ../src/guestfs.pod:395
824 "If the command needs to communicate with daemons, then most likely they "
829 #: ../src/guestfs.pod:400
830 msgid "The command will be running in limited memory."
834 #: ../src/guestfs.pod:404
836 "The network may not be available unless you enable it (see "
837 "L</guestfs_set_network>)."
841 #: ../src/guestfs.pod:409
842 msgid "Only supports Linux guests (not Windows, BSD, etc)."
846 #: ../src/guestfs.pod:413
847 msgid "Architecture limitations (eg. won't work for a PPC guest on an X86 host)."
851 #: ../src/guestfs.pod:418
853 "For SELinux guests, you may need to enable SELinux and load policy first. "
854 "See L</SELINUX> in this manpage."
858 #: ../src/guestfs.pod:423
860 "I<Security:> It is not safe to run commands from untrusted, possibly "
861 "malicious guests. These commands may attempt to exploit your program by "
862 "sending unexpected output. They could also try to exploit the Linux kernel "
863 "or qemu provided by the libguestfs appliance. They could use the network "
864 "provided by the libguestfs appliance to bypass ordinary network partitions "
865 "and firewalls. They could use the elevated privileges or different SELinux "
866 "context of your program to their advantage."
870 #: ../src/guestfs.pod:432
872 "A secure alternative is to use libguestfs to install a \"firstboot\" script "
873 "(a script which runs when the guest next boots normally), and to have this "
874 "script run the commands you want in the normal context of the running guest, "
875 "network security and so on. For information about other security issues, "
880 #: ../src/guestfs.pod:440
882 "The two main API calls to run commands are L</guestfs_command> and "
883 "L</guestfs_sh> (there are also variations)."
887 #: ../src/guestfs.pod:443
889 "The difference is that L</guestfs_sh> runs commands using the shell, so any "
890 "shell globs, redirections, etc will work."
894 #: ../src/guestfs.pod:446
895 msgid "CONFIGURATION FILES"
899 #: ../src/guestfs.pod:448
901 "To read and write configuration files in Linux guest filesystems, we "
902 "strongly recommend using Augeas. For example, Augeas understands how to "
903 "read and write, say, a Linux shadow password file or X.org configuration "
904 "file, and so avoids you having to write that code."
908 #: ../src/guestfs.pod:453
910 "The main Augeas calls are bound through the C<guestfs_aug_*> APIs. We don't "
911 "document Augeas itself here because there is excellent documentation on the "
912 "L<http://augeas.net/> website."
916 #: ../src/guestfs.pod:457
918 "If you don't want to use Augeas (you fool!) then try calling "
919 "L</guestfs_read_lines> to get the file as a list of lines which you can "
924 #: ../src/guestfs.pod:461
929 #: ../src/guestfs.pod:463
931 "We support SELinux guests. To ensure that labeling happens correctly in "
932 "SELinux guests, you need to enable SELinux and load the guest's policy:"
936 #: ../src/guestfs.pod:469 ../src/guestfs.pod:1281 ../src/guestfs.pod:1412 ../src/guestfs.pod:2441
941 #: ../src/guestfs.pod:471
942 msgid "Before launching, do:"
946 #: ../src/guestfs.pod:473
949 " guestfs_set_selinux (g, 1);\n"
954 #: ../src/guestfs.pod:475 ../src/guestfs.pod:1285 ../src/guestfs.pod:1416 ../src/guestfs.pod:2466
959 #: ../src/guestfs.pod:477
961 "After mounting the guest's filesystem(s), load the policy. This is best "
962 "done by running the L<load_policy(8)> command in the guest itself:"
966 #: ../src/guestfs.pod:481
969 " guestfs_sh (g, \"/usr/sbin/load_policy\");\n"
974 #: ../src/guestfs.pod:483
976 "(Older versions of C<load_policy> require you to specify the name of the "
981 #: ../src/guestfs.pod:486 ../src/guestfs.pod:1422
986 #: ../src/guestfs.pod:488
988 "Optionally, set the security context for the API. The correct security "
989 "context to use can only be known by inspecting the guest. As an example:"
993 #: ../src/guestfs.pod:492
996 " guestfs_setcon (g, \"unconfined_u:unconfined_r:unconfined_t:s0\");\n"
1001 #: ../src/guestfs.pod:496
1002 msgid "This will work for running commands and editing existing files."
1006 #: ../src/guestfs.pod:498
1008 "When new files are created, you may need to label them explicitly, for "
1009 "example by running the external command C<restorecon pathname>."
1013 #: ../src/guestfs.pod:502
1018 #: ../src/guestfs.pod:504
1020 "Certain calls are affected by the current file mode creation mask (the "
1021 "\"umask\"). In particular ones which create files or directories, such as "
1022 "L</guestfs_touch>, L</guestfs_mknod> or L</guestfs_mkdir>. This affects "
1023 "either the default mode that the file is created with or modifies the mode "
1028 #: ../src/guestfs.pod:510
1030 "The default umask is C<022>, so files are created with modes such as C<0644> "
1031 "and directories with C<0755>."
1035 #: ../src/guestfs.pod:513
1037 "There are two ways to avoid being affected by umask. Either set umask to 0 "
1038 "(call C<guestfs_umask (g, 0)> early after launching). Or call "
1039 "L</guestfs_chmod> after creating each file or directory."
1043 #: ../src/guestfs.pod:517
1044 msgid "For more information about umask, see L<umask(2)>."
1048 #: ../src/guestfs.pod:519 ../fish/guestfish.pod:765
1049 msgid "ENCRYPTED DISKS"
1053 #: ../src/guestfs.pod:521
1055 "Libguestfs allows you to access Linux guests which have been encrypted using "
1056 "whole disk encryption that conforms to the Linux Unified Key Setup (LUKS) "
1057 "standard. This includes nearly all whole disk encryption systems used by "
1058 "modern Linux guests."
1062 #: ../src/guestfs.pod:527
1064 "Use L</guestfs_vfs_type> to identify LUKS-encrypted block devices (it "
1065 "returns the string C<crypto_LUKS>)."
1069 #: ../src/guestfs.pod:530
1071 "Then open these devices by calling L</guestfs_luks_open>. Obviously you "
1072 "will require the passphrase!"
1076 #: ../src/guestfs.pod:533
1078 "Opening a LUKS device creates a new device mapper device called "
1079 "C</dev/mapper/mapname> (where C<mapname> is the string you supply to "
1080 "L</guestfs_luks_open>). Reads and writes to this mapper device are "
1081 "decrypted from and encrypted to the underlying block device respectively."
1085 #: ../src/guestfs.pod:539
1087 "LVM volume groups on the device can be made visible by calling "
1088 "L</guestfs_vgscan> followed by L</guestfs_vg_activate_all>. The logical "
1089 "volume(s) can now be mounted in the usual way."
1093 #: ../src/guestfs.pod:543
1095 "Use the reverse process to close a LUKS device. Unmount any logical volumes "
1096 "on it, deactivate the volume groups by caling C<guestfs_vg_activate (g, 0, "
1097 "[\"/dev/VG\"])>. Then close the mapper device by calling "
1098 "L</guestfs_luks_close> on the C</dev/mapper/mapname> device (I<not> the "
1099 "underlying encrypted block device)."
1103 #: ../src/guestfs.pod:550
1108 #: ../src/guestfs.pod:552
1110 "Libguestfs has APIs for inspecting an unknown disk image to find out if it "
1111 "contains operating systems, an install CD or a live CD. (These APIs used to "
1112 "be in a separate Perl-only library called L<Sys::Guestfs::Lib(3)> but since "
1113 "version 1.5.3 the most frequently used part of this library has been "
1114 "rewritten in C and moved into the core code)."
1118 #: ../src/guestfs.pod:559
1120 "Add all disks belonging to the unknown virtual machine and call "
1121 "L</guestfs_launch> in the usual way."
1125 #: ../src/guestfs.pod:562
1127 "Then call L</guestfs_inspect_os>. This function uses other libguestfs calls "
1128 "and certain heuristics, and returns a list of operating systems that were "
1129 "found. An empty list means none were found. A single element is the root "
1130 "filesystem of the operating system. For dual- or multi-boot guests, "
1131 "multiple roots can be returned, each one corresponding to a separate "
1132 "operating system. (Multi-boot virtual machines are extremely rare in the "
1133 "world of virtualization, but since this scenario can happen, we have built "
1134 "libguestfs to deal with it.)"
1138 #: ../src/guestfs.pod:571
1140 "For each root, you can then call various C<guestfs_inspect_get_*> functions "
1141 "to get additional details about that operating system. For example, call "
1142 "L</guestfs_inspect_get_type> to return the string C<windows> or C<linux> for "
1143 "Windows and Linux-based operating systems respectively."
1147 #: ../src/guestfs.pod:577
1149 "Un*x-like and Linux-based operating systems usually consist of several "
1150 "filesystems which are mounted at boot time (for example, a separate boot "
1151 "partition mounted on C</boot>). The inspection rules are able to detect how "
1152 "filesystems correspond to mount points. Call "
1153 "C<guestfs_inspect_get_mountpoints> to get this mapping. It might return a "
1154 "hash table like this example:"
1158 #: ../src/guestfs.pod:584
1161 " /boot => /dev/sda1\n"
1162 " / => /dev/vg_guest/lv_root\n"
1163 " /usr => /dev/vg_guest/lv_usr\n"
1168 #: ../src/guestfs.pod:588
1170 "The caller can then make calls to L</guestfs_mount_options> to mount the "
1171 "filesystems as suggested."
1175 #: ../src/guestfs.pod:591
1177 "Be careful to mount filesystems in the right order (eg. C</> before "
1178 "C</usr>). Sorting the keys of the hash by length, shortest first, should "
1183 #: ../src/guestfs.pod:595
1185 "Inspection currently only works for some common operating systems. "
1186 "Contributors are welcome to send patches for other operating systems that we "
1187 "currently cannot detect."
1191 #: ../src/guestfs.pod:599
1193 "Encrypted disks must be opened before inspection. See L</ENCRYPTED DISKS> "
1194 "for more details. The L</guestfs_inspect_os> function just ignores any "
1195 "encrypted devices."
1199 #: ../src/guestfs.pod:603
1201 "A note on the implementation: The call L</guestfs_inspect_os> performs "
1202 "inspection and caches the results in the guest handle. Subsequent calls to "
1203 "C<guestfs_inspect_get_*> return this cached information, but I<do not> "
1204 "re-read the disks. If you change the content of the guest disks, you can "
1205 "redo inspection by calling L</guestfs_inspect_os> again. "
1206 "(L</guestfs_inspect_list_applications> works a little differently from the "
1207 "other calls and does read the disks. See documentation for that function "
1212 #: ../src/guestfs.pod:612
1213 msgid "INSPECTING INSTALL DISKS"
1217 #: ../src/guestfs.pod:614
1219 "Libguestfs (since 1.9.4) can detect some install disks, install CDs, live "
1224 #: ../src/guestfs.pod:617
1226 "Call L</guestfs_inspect_get_format> to return the format of the operating "
1227 "system, which currently can be C<installed> (a regular operating system) or "
1228 "C<installer> (some sort of install disk)."
1232 #: ../src/guestfs.pod:621
1234 "Further information is available about the operating system that can be "
1235 "installed using the regular inspection APIs like "
1236 "L</guestfs_inspect_get_product_name>, L</guestfs_inspect_get_major_version> "
1241 #: ../src/guestfs.pod:626
1243 "Some additional information specific to installer disks is also available "
1244 "from the L</guestfs_inspect_is_live>, L</guestfs_inspect_is_netinst> and "
1245 "L</guestfs_inspect_is_multipart> calls."
1249 #: ../src/guestfs.pod:631
1250 msgid "SPECIAL CONSIDERATIONS FOR WINDOWS GUESTS"
1254 #: ../src/guestfs.pod:633
1256 "Libguestfs can mount NTFS partitions. It does this using the "
1257 "L<http://www.ntfs-3g.org/> driver."
1261 #: ../src/guestfs.pod:636
1262 msgid "DRIVE LETTERS AND PATHS"
1266 #: ../src/guestfs.pod:638
1268 "DOS and Windows still use drive letters, and the filesystems are always "
1269 "treated as case insensitive by Windows itself, and therefore you might find "
1270 "a Windows configuration file referring to a path like "
1271 "C<c:\\windows\\system32>. When the filesystem is mounted in libguestfs, "
1272 "that directory might be referred to as C</WINDOWS/System32>."
1276 #: ../src/guestfs.pod:644
1278 "Drive letter mappings are outside the scope of libguestfs. You have to use "
1279 "libguestfs to read the appropriate Windows Registry and configuration files, "
1280 "to determine yourself how drives are mapped (see also L<hivex(3)> and "
1281 "L<virt-inspector(1)>)."
1285 #: ../src/guestfs.pod:649
1287 "Replacing backslash characters with forward slash characters is also outside "
1288 "the scope of libguestfs, but something that you can easily do."
1292 #: ../src/guestfs.pod:652
1294 "Where we can help is in resolving the case insensitivity of paths. For "
1295 "this, call L</guestfs_case_sensitive_path>."
1299 #: ../src/guestfs.pod:655
1300 msgid "ACCESSING THE WINDOWS REGISTRY"
1304 #: ../src/guestfs.pod:657
1306 "Libguestfs also provides some help for decoding Windows Registry \"hive\" "
1307 "files, through the library C<hivex> which is part of the libguestfs project "
1308 "although ships as a separate tarball. You have to locate and download the "
1309 "hive file(s) yourself, and then pass them to C<hivex> functions. See also "
1310 "the programs L<hivexml(1)>, L<hivexsh(1)>, L<hivexregedit(1)> and "
1311 "L<virt-win-reg(1)> for more help on this issue."
1315 #: ../src/guestfs.pod:665
1316 msgid "SYMLINKS ON NTFS-3G FILESYSTEMS"
1320 #: ../src/guestfs.pod:667
1322 "Ntfs-3g tries to rewrite \"Junction Points\" and NTFS \"symbolic links\" to "
1323 "provide something which looks like a Linux symlink. The way it tries to do "
1324 "the rewriting is described here:"
1328 #: ../src/guestfs.pod:671
1329 msgid "L<http://www.tuxera.com/community/ntfs-3g-advanced/junction-points-and-symbolic-links/>"
1333 #: ../src/guestfs.pod:673
1335 "The essential problem is that ntfs-3g simply does not have enough "
1336 "information to do a correct job. NTFS links can contain drive letters and "
1337 "references to external device GUIDs that ntfs-3g has no way of resolving. "
1338 "It is almost certainly the case that libguestfs callers should ignore what "
1339 "ntfs-3g does (ie. don't use L</guestfs_readlink> on NTFS volumes)."
1343 #: ../src/guestfs.pod:680
1345 "Instead if you encounter a symbolic link on an ntfs-3g filesystem, use "
1346 "L</guestfs_lgetxattr> to read the C<system.ntfs_reparse_data> extended "
1347 "attribute, and read the raw reparse data from that (you can find the format "
1348 "documented in various places around the web)."
1352 #: ../src/guestfs.pod:685
1353 msgid "EXTENDED ATTRIBUTES ON NTFS-3G FILESYSTEMS"
1357 #: ../src/guestfs.pod:687
1359 "There are other useful extended attributes that can be read from ntfs-3g "
1360 "filesystems (using L</guestfs_getxattr>). See:"
1364 #: ../src/guestfs.pod:690
1365 msgid "L<http://www.tuxera.com/community/ntfs-3g-advanced/extended-attributes/>"
1369 #: ../src/guestfs.pod:692
1370 msgid "USING LIBGUESTFS WITH OTHER PROGRAMMING LANGUAGES"
1374 #: ../src/guestfs.pod:694
1376 "Although we don't want to discourage you from using the C API, we will "
1377 "mention here that the same API is also available in other languages."
1381 #: ../src/guestfs.pod:697
1383 "The API is broadly identical in all supported languages. This means that "
1384 "the C call C<guestfs_add_drive_ro(g,file)> is C<$g-E<gt>add_drive_ro($file)> "
1385 "in Perl, C<g.add_drive_ro(file)> in Python, and C<g#add_drive_ro file> in "
1386 "OCaml. In other words, a straightforward, predictable isomorphism between "
1391 #: ../src/guestfs.pod:703
1393 "Error messages are automatically transformed into exceptions if the language "
1398 #: ../src/guestfs.pod:706
1400 "We don't try to \"object orientify\" parts of the API in OO languages, "
1401 "although contributors are welcome to write higher level APIs above what we "
1402 "provide in their favourite languages if they wish."
1406 #: ../src/guestfs.pod:712
1411 #: ../src/guestfs.pod:714
1413 "You can use the I<guestfs.h> header file from C++ programs. The C++ API is "
1414 "identical to the C API. C++ classes and exceptions are not used."
1418 #: ../src/guestfs.pod:718
1423 #: ../src/guestfs.pod:720
1425 "The C# bindings are highly experimental. Please read the warnings at the "
1426 "top of C<csharp/Libguestfs.cs>."
1430 #: ../src/guestfs.pod:723
1435 #: ../src/guestfs.pod:725
1437 "This is the only language binding that is working but incomplete. Only "
1438 "calls which return simple integers have been bound in Haskell, and we are "
1439 "looking for help to complete this binding."
1443 #: ../src/guestfs.pod:729
1448 #: ../src/guestfs.pod:731
1450 "Full documentation is contained in the Javadoc which is distributed with "
1455 #: ../src/guestfs.pod:734
1460 #: ../src/guestfs.pod:736
1461 msgid "See L<guestfs-ocaml(3)>."
1465 #: ../src/guestfs.pod:738
1470 #: ../src/guestfs.pod:740
1471 msgid "See L<guestfs-perl(3)> and L<Sys::Guestfs(3)>."
1475 #: ../src/guestfs.pod:742
1480 #: ../src/guestfs.pod:744
1482 "For documentation see C<README-PHP> supplied with libguestfs sources or in "
1483 "the php-libguestfs package for your distribution."
1487 #: ../src/guestfs.pod:747
1488 msgid "The PHP binding only works correctly on 64 bit machines."
1492 #: ../src/guestfs.pod:749
1497 #: ../src/guestfs.pod:751
1498 msgid "See L<guestfs-python(3)>."
1502 #: ../src/guestfs.pod:753
1507 #: ../src/guestfs.pod:755
1508 msgid "See L<guestfs-ruby(3)>."
1512 #: ../src/guestfs.pod:757
1513 msgid "B<shell scripts>"
1517 #: ../src/guestfs.pod:759
1518 msgid "See L<guestfish(1)>."
1522 #: ../src/guestfs.pod:763
1523 msgid "LIBGUESTFS GOTCHAS"
1527 #: ../src/guestfs.pod:765
1529 "L<http://en.wikipedia.org/wiki/Gotcha_(programming)>: \"A feature of a "
1530 "system [...] that works in the way it is documented but is counterintuitive "
1531 "and almost invites mistakes.\""
1535 #: ../src/guestfs.pod:769
1537 "Since we developed libguestfs and the associated tools, there are several "
1538 "things we would have designed differently, but are now stuck with for "
1539 "backwards compatibility or other reasons. If there is ever a libguestfs 2.0 "
1540 "release, you can expect these to change. Beware of them."
1544 #: ../src/guestfs.pod:777
1545 msgid "Autosync / forgetting to sync."
1549 #: ../src/guestfs.pod:779
1551 "When modifying a filesystem from C or another language, you B<must> unmount "
1552 "all filesystems and call L</guestfs_sync> explicitly before you close the "
1553 "libguestfs handle. You can also call:"
1557 #: ../src/guestfs.pod:783
1560 " guestfs_set_autosync (g, 1);\n"
1565 #: ../src/guestfs.pod:785
1567 "to have the unmount/sync done automatically for you when the handle 'g' is "
1568 "closed. (This feature is called \"autosync\", L</guestfs_set_autosync> "
1573 #: ../src/guestfs.pod:789
1575 "If you forget to do this, then it is entirely possible that your changes "
1576 "won't be written out, or will be partially written, or (very rarely) that "
1577 "you'll get disk corruption."
1581 #: ../src/guestfs.pod:793
1583 "Note that in L<guestfish(3)> autosync is the default. So quick and dirty "
1584 "guestfish scripts that forget to sync will work just fine, which can make "
1585 "this very puzzling if you are trying to debug a problem."
1589 #: ../src/guestfs.pod:797
1591 "Update: Autosync is enabled by default for all API users starting from "
1592 "libguestfs 1.5.24."
1596 #: ../src/guestfs.pod:800
1597 msgid "Mount option C<-o sync> should not be the default."
1601 #: ../src/guestfs.pod:802
1603 "If you use L</guestfs_mount>, then C<-o sync,noatime> are added implicitly. "
1604 "However C<-o sync> does not add any reliability benefit, but does have a "
1605 "very large performance impact."
1609 #: ../src/guestfs.pod:806
1611 "The work around is to use L</guestfs_mount_options> and set the mount "
1612 "options that you actually want to use."
1616 #: ../src/guestfs.pod:809
1617 msgid "Read-only should be the default."
1621 #: ../src/guestfs.pod:811
1623 "In L<guestfish(3)>, I<--ro> should be the default, and you should have to "
1624 "specify I<--rw> if you want to make changes to the image."
1628 #: ../src/guestfs.pod:814
1629 msgid "This would reduce the potential to corrupt live VM images."
1633 #: ../src/guestfs.pod:816
1635 "Note that many filesystems change the disk when you just mount and unmount, "
1636 "even if you didn't perform any writes. You need to use "
1637 "L</guestfs_add_drive_ro> to guarantee that the disk is not changed."
1641 #: ../src/guestfs.pod:820
1642 msgid "guestfish command line is hard to use."
1646 #: ../src/guestfs.pod:822
1648 "C<guestfish disk.img> doesn't do what people expect (open C<disk.img> for "
1649 "examination). It tries to run a guestfish command C<disk.img> which doesn't "
1650 "exist, so it fails. In earlier versions of guestfish the error message was "
1651 "also unintuitive, but we have corrected this since. Like the Bourne shell, "
1652 "we should have used C<guestfish -c command> to run commands."
1656 #: ../src/guestfs.pod:829
1657 msgid "guestfish megabyte modifiers don't work right on all commands"
1661 #: ../src/guestfs.pod:831
1663 "In recent guestfish you can use C<1M> to mean 1 megabyte (and similarly for "
1664 "other modifiers). What guestfish actually does is to multiply the number "
1665 "part by the modifier part and pass the result to the C API. However this "
1666 "doesn't work for a few APIs which aren't expecting bytes, but are already "
1667 "expecting some other unit (eg. megabytes)."
1671 #: ../src/guestfs.pod:838
1672 msgid "The most common is L</guestfs_lvcreate>. The guestfish command:"
1676 #: ../src/guestfs.pod:840
1679 " lvcreate LV VG 100M\n"
1684 #: ../src/guestfs.pod:842
1686 "does not do what you might expect. Instead because L</guestfs_lvcreate> is "
1687 "already expecting megabytes, this tries to create a 100 I<terabyte> (100 "
1688 "megabytes * megabytes) logical volume. The error message you get from this "
1689 "is also a little obscure."
1693 #: ../src/guestfs.pod:847
1695 "This could be fixed in the generator by specially marking parameters and "
1696 "return values which take bytes or other units."
1700 #: ../src/guestfs.pod:850
1701 msgid "Ambiguity between devices and paths"
1705 #: ../src/guestfs.pod:852
1707 "There is a subtle ambiguity in the API between a device name "
1708 "(eg. C</dev/sdb2>) and a similar pathname. A file might just happen to be "
1709 "called C<sdb2> in the directory C</dev> (consider some non-Unix VM image)."
1713 #: ../src/guestfs.pod:857
1715 "In the current API we usually resolve this ambiguity by having two separate "
1716 "calls, for example L</guestfs_checksum> and L</guestfs_checksum_device>. "
1717 "Some API calls are ambiguous and (incorrectly) resolve the problem by "
1718 "detecting if the path supplied begins with C</dev/>."
1722 #: ../src/guestfs.pod:863
1724 "To avoid both the ambiguity and the need to duplicate some calls, we could "
1725 "make paths/devices into structured names. One way to do this would be to "
1726 "use a notation like grub (C<hd(0,0)>), although nobody really likes this "
1727 "aspect of grub. Another way would be to use a structured type, equivalent "
1728 "to this OCaml type:"
1732 #: ../src/guestfs.pod:869
1735 " type path = Path of string | Device of int | Partition of int * int\n"
1740 #: ../src/guestfs.pod:871
1741 msgid "which would allow you to pass arguments like:"
1745 #: ../src/guestfs.pod:873
1748 " Path \"/foo/bar\"\n"
1749 " Device 1 (* /dev/sdb, or perhaps /dev/sda *)\n"
1750 " Partition (1, 2) (* /dev/sdb2 (or is it /dev/sda2 or /dev/sdb3?) *)\n"
1751 " Path \"/dev/sdb2\" (* not a device *)\n"
1756 #: ../src/guestfs.pod:878
1758 "As you can see there are still problems to resolve even with this "
1759 "representation. Also consider how it might work in guestfish."
1763 #: ../src/guestfs.pod:883
1764 msgid "PROTOCOL LIMITS"
1768 #: ../src/guestfs.pod:885
1770 "Internally libguestfs uses a message-based protocol to pass API calls and "
1771 "their responses to and from a small \"appliance\" (see L</INTERNALS> for "
1772 "plenty more detail about this). The maximum message size used by the "
1773 "protocol is slightly less than 4 MB. For some API calls you may need to be "
1774 "aware of this limit. The API calls which may be affected are individually "
1775 "documented, with a link back to this section of the documentation."
1779 #: ../src/guestfs.pod:893
1781 "A simple call such as L</guestfs_cat> returns its result (the file data) in "
1782 "a simple string. Because this string is at some point internally encoded as "
1783 "a message, the maximum size that it can return is slightly under 4 MB. If "
1784 "the requested file is larger than this then you will get an error."
1788 #: ../src/guestfs.pod:899
1790 "In order to transfer large files into and out of the guest filesystem, you "
1791 "need to use particular calls that support this. The sections L</UPLOADING> "
1792 "and L</DOWNLOADING> document how to do this."
1796 #: ../src/guestfs.pod:903
1798 "You might also consider mounting the disk image using our FUSE filesystem "
1799 "support (L<guestmount(1)>)."
1803 #: ../src/guestfs.pod:906
1804 msgid "KEYS AND PASSPHRASES"
1808 #: ../src/guestfs.pod:908
1810 "Certain libguestfs calls take a parameter that contains sensitive key "
1811 "material, passed in as a C string."
1815 #: ../src/guestfs.pod:911
1817 "In the future we would hope to change the libguestfs implementation so that "
1818 "keys are L<mlock(2)>-ed into physical RAM, and thus can never end up in "
1819 "swap. However this is I<not> done at the moment, because of the complexity "
1820 "of such an implementation."
1824 #: ../src/guestfs.pod:916
1826 "Therefore you should be aware that any key parameter you pass to libguestfs "
1827 "might end up being written out to the swap partition. If this is a concern, "
1828 "scrub the swap partition or don't use libguestfs on encrypted devices."
1832 #: ../src/guestfs.pod:921
1833 msgid "MULTIPLE HANDLES AND MULTIPLE THREADS"
1837 #: ../src/guestfs.pod:923
1839 "All high-level libguestfs actions are synchronous. If you want to use "
1840 "libguestfs asynchronously then you must create a thread."
1844 #: ../src/guestfs.pod:926
1846 "Only use the handle from a single thread. Either use the handle exclusively "
1847 "from one thread, or provide your own mutex so that two threads cannot issue "
1848 "calls on the same handle at the same time."
1852 #: ../src/guestfs.pod:930
1854 "See the graphical program guestfs-browser for one possible architecture for "
1855 "multithreaded programs using libvirt and libguestfs."
1859 #: ../src/guestfs.pod:933
1864 #: ../src/guestfs.pod:935
1866 "Libguestfs needs a supermin appliance, which it finds by looking along an "
1871 #: ../src/guestfs.pod:938
1873 "By default it looks for these in the directory C<$libdir/guestfs> "
1874 "(eg. C</usr/local/lib/guestfs> or C</usr/lib64/guestfs>)."
1878 #: ../src/guestfs.pod:941
1880 "Use L</guestfs_set_path> or set the environment variable L</LIBGUESTFS_PATH> "
1881 "to change the directories that libguestfs will search in. The value is a "
1882 "colon-separated list of paths. The current directory is I<not> searched "
1883 "unless the path contains an empty element or C<.>. For example "
1884 "C<LIBGUESTFS_PATH=:/usr/lib/guestfs> would search the current directory and "
1885 "then C</usr/lib/guestfs>."
1889 #: ../src/guestfs.pod:948
1890 msgid "QEMU WRAPPERS"
1894 #: ../src/guestfs.pod:950
1896 "If you want to compile your own qemu, run qemu from a non-standard location, "
1897 "or pass extra arguments to qemu, then you can write a shell-script wrapper "
1902 #: ../src/guestfs.pod:954
1904 "There is one important rule to remember: you I<must C<exec qemu>> as the "
1905 "last command in the shell script (so that qemu replaces the shell and "
1906 "becomes the direct child of the libguestfs-using program). If you don't do "
1907 "this, then the qemu process won't be cleaned up correctly."
1911 #: ../src/guestfs.pod:959
1913 "Here is an example of a wrapper, where I have built my own copy of qemu from "
1918 #: ../src/guestfs.pod:962
1922 " qemudir=/home/rjones/d/qemu\n"
1923 " exec $qemudir/x86_64-softmmu/qemu-system-x86_64 -L $qemudir/pc-bios "
1929 #: ../src/guestfs.pod:966
1931 "Save this script as C</tmp/qemu.wrapper> (or wherever), C<chmod +x>, and "
1932 "then use it by setting the LIBGUESTFS_QEMU environment variable. For "
1937 #: ../src/guestfs.pod:970
1940 " LIBGUESTFS_QEMU=/tmp/qemu.wrapper guestfish\n"
1945 #: ../src/guestfs.pod:972
1947 "Note that libguestfs also calls qemu with the -help and -version options in "
1948 "order to determine features."
1952 #: ../src/guestfs.pod:975
1953 msgid "ATTACHING TO RUNNING DAEMONS"
1957 #: ../src/guestfs.pod:977
1959 "I<Note (1):> This is B<highly experimental> and has a tendency to eat "
1960 "babies. Use with caution."
1964 #: ../src/guestfs.pod:980
1966 "I<Note (2):> This section explains how to attach to a running daemon from a "
1967 "low level perspective. For most users, simply using virt tools such as "
1968 "L<guestfish(1)> with the I<--live> option will \"just work\"."
1972 #: ../src/guestfs.pod:984
1973 msgid "Using guestfs_set_attach_method"
1977 #: ../src/guestfs.pod:986
1979 "By calling L</guestfs_set_attach_method> you can change how the library "
1980 "connects to the C<guestfsd> daemon in L</guestfs_launch> (read "
1981 "L</ARCHITECTURE> for some background)."
1985 #: ../src/guestfs.pod:990
1987 "The normal attach method is C<appliance>, where a small appliance is created "
1988 "containing the daemon, and then the library connects to this."
1992 #: ../src/guestfs.pod:993
1994 "Setting attach method to C<unix:I<path>> (where I<path> is the path of a "
1995 "Unix domain socket) causes L</guestfs_launch> to connect to an existing "
1996 "daemon over the Unix domain socket."
2000 #: ../src/guestfs.pod:997
2002 "The normal use for this is to connect to a running virtual machine that "
2003 "contains a C<guestfsd> daemon, and send commands so you can read and write "
2004 "files inside the live virtual machine."
2008 #: ../src/guestfs.pod:1001
2009 msgid "Using guestfs_add_domain with live flag"
2013 #: ../src/guestfs.pod:1003
2015 "L</guestfs_add_domain> provides some help for getting the correct attach "
2016 "method. If you pass the C<live> option to this function, then (if the "
2017 "virtual machine is running) it will examine the libvirt XML looking for a "
2018 "virtio-serial channel to connect to:"
2022 #: ../src/guestfs.pod:1009
2029 " <channel type='unix'>\n"
2030 " <source mode='bind' path='/path/to/socket'/>\n"
2031 " <target type='virtio' name='org.libguestfs.channel.0'/>\n"
2040 #: ../src/guestfs.pod:1021
2042 "L</guestfs_add_domain> extracts C</path/to/socket> and sets the attach "
2043 "method to C<unix:/path/to/socket>."
2047 #: ../src/guestfs.pod:1024
2049 "Some of the libguestfs tools (including guestfish) support a I<--live> "
2050 "option which is passed through to L</guestfs_add_domain> thus allowing you "
2051 "to attach to and modify live virtual machines."
2055 #: ../src/guestfs.pod:1028
2057 "The virtual machine needs to have been set up beforehand so that it has the "
2058 "virtio-serial channel and so that guestfsd is running inside it."
2062 #: ../src/guestfs.pod:1032
2063 msgid "ABI GUARANTEE"
2067 #: ../src/guestfs.pod:1034
2069 "We guarantee the libguestfs ABI (binary interface), for public, high-level "
2070 "actions as outlined in this section. Although we will deprecate some "
2071 "actions, for example if they get replaced by newer calls, we will keep the "
2072 "old actions forever. This allows you the developer to program in confidence "
2073 "against the libguestfs API."
2077 #: ../src/guestfs.pod:1040
2078 msgid "BLOCK DEVICE NAMING"
2082 #: ../src/guestfs.pod:1042
2084 "In the kernel there is now quite a profusion of schemata for naming block "
2085 "devices (in this context, by I<block device> I mean a physical or virtual "
2086 "hard drive). The original Linux IDE driver used names starting with "
2087 "C</dev/hd*>. SCSI devices have historically used a different naming scheme, "
2088 "C</dev/sd*>. When the Linux kernel I<libata> driver became a popular "
2089 "replacement for the old IDE driver (particularly for SATA devices) those "
2090 "devices also used the C</dev/sd*> scheme. Additionally we now have virtual "
2091 "machines with paravirtualized drivers. This has created several different "
2092 "naming systems, such as C</dev/vd*> for virtio disks and C</dev/xvd*> for "
2097 #: ../src/guestfs.pod:1054
2099 "As discussed above, libguestfs uses a qemu appliance running an embedded "
2100 "Linux kernel to access block devices. We can run a variety of appliances "
2101 "based on a variety of Linux kernels."
2105 #: ../src/guestfs.pod:1058
2107 "This causes a problem for libguestfs because many API calls use device or "
2108 "partition names. Working scripts and the recipe (example) scripts that we "
2109 "make available over the internet could fail if the naming scheme changes."
2113 #: ../src/guestfs.pod:1063
2115 "Therefore libguestfs defines C</dev/sd*> as the I<standard naming scheme>. "
2116 "Internally C</dev/sd*> names are translated, if necessary, to other names as "
2117 "required. For example, under RHEL 5 which uses the C</dev/hd*> scheme, any "
2118 "device parameter C</dev/sda2> is translated to C</dev/hda2> transparently."
2122 #: ../src/guestfs.pod:1069
2124 "Note that this I<only> applies to parameters. The L</guestfs_list_devices>, "
2125 "L</guestfs_list_partitions> and similar calls return the true names of the "
2126 "devices and partitions as known to the appliance."
2130 #: ../src/guestfs.pod:1074
2131 msgid "ALGORITHM FOR BLOCK DEVICE NAME TRANSLATION"
2135 #: ../src/guestfs.pod:1076
2137 "Usually this translation is transparent. However in some (very rare) cases "
2138 "you may need to know the exact algorithm. Such cases include where you use "
2139 "L</guestfs_config> to add a mixture of virtio and IDE devices to the "
2140 "qemu-based appliance, so have a mixture of C</dev/sd*> and C</dev/vd*> "
2145 #: ../src/guestfs.pod:1082
2147 "The algorithm is applied only to I<parameters> which are known to be either "
2148 "device or partition names. Return values from functions such as "
2149 "L</guestfs_list_devices> are never changed."
2153 #: ../src/guestfs.pod:1090
2154 msgid "Is the string a parameter which is a device or partition name?"
2158 #: ../src/guestfs.pod:1094
2159 msgid "Does the string begin with C</dev/sd>?"
2163 #: ../src/guestfs.pod:1098
2165 "Does the named device exist? If so, we use that device. However if I<not> "
2166 "then we continue with this algorithm."
2170 #: ../src/guestfs.pod:1103
2171 msgid "Replace initial C</dev/sd> string with C</dev/hd>."
2175 #: ../src/guestfs.pod:1105
2176 msgid "For example, change C</dev/sda2> to C</dev/hda2>."
2180 #: ../src/guestfs.pod:1107
2181 msgid "If that named device exists, use it. If not, continue."
2185 #: ../src/guestfs.pod:1111
2186 msgid "Replace initial C</dev/sd> string with C</dev/vd>."
2190 #: ../src/guestfs.pod:1113
2191 msgid "If that named device exists, use it. If not, return an error."
2195 #: ../src/guestfs.pod:1117
2196 msgid "PORTABILITY CONCERNS WITH BLOCK DEVICE NAMING"
2200 #: ../src/guestfs.pod:1119
2202 "Although the standard naming scheme and automatic translation is useful for "
2203 "simple programs and guestfish scripts, for larger programs it is best not to "
2204 "rely on this mechanism."
2208 #: ../src/guestfs.pod:1123
2210 "Where possible for maximum future portability programs using libguestfs "
2211 "should use these future-proof techniques:"
2215 #: ../src/guestfs.pod:1130
2217 "Use L</guestfs_list_devices> or L</guestfs_list_partitions> to list actual "
2218 "device names, and then use those names directly."
2222 #: ../src/guestfs.pod:1133
2223 msgid "Since those device names exist by definition, they will never be translated."
2227 #: ../src/guestfs.pod:1138
2229 "Use higher level ways to identify filesystems, such as LVM names, UUIDs and "
2230 "filesystem labels."
2234 #: ../src/guestfs.pod:1143
2239 #: ../src/guestfs.pod:1145
2241 "This section discusses security implications of using libguestfs, "
2242 "particularly with untrusted or malicious guests or disk images."
2246 #: ../src/guestfs.pod:1148
2247 msgid "GENERAL SECURITY CONSIDERATIONS"
2251 #: ../src/guestfs.pod:1150
2253 "Be careful with any files or data that you download from a guest (by "
2254 "\"download\" we mean not just the L</guestfs_download> command but any "
2255 "command that reads files, filenames, directories or anything else from a "
2256 "disk image). An attacker could manipulate the data to fool your program "
2257 "into doing the wrong thing. Consider cases such as:"
2261 #: ../src/guestfs.pod:1160
2262 msgid "the data (file etc) not being present"
2266 #: ../src/guestfs.pod:1164
2267 msgid "being present but empty"
2271 #: ../src/guestfs.pod:1168
2272 msgid "being much larger than normal"
2276 #: ../src/guestfs.pod:1172
2277 msgid "containing arbitrary 8 bit data"
2281 #: ../src/guestfs.pod:1176
2282 msgid "being in an unexpected character encoding"
2286 #: ../src/guestfs.pod:1180
2287 msgid "containing homoglyphs."
2291 #: ../src/guestfs.pod:1184
2292 msgid "SECURITY OF MOUNTING FILESYSTEMS"
2296 #: ../src/guestfs.pod:1186
2298 "When you mount a filesystem under Linux, mistakes in the kernel filesystem "
2299 "(VFS) module can sometimes be escalated into exploits by deliberately "
2300 "creating a malicious, malformed filesystem. These exploits are very severe "
2301 "for two reasons. Firstly there are very many filesystem drivers in the "
2302 "kernel, and many of them are infrequently used and not much developer "
2303 "attention has been paid to the code. Linux userspace helps potential "
2304 "crackers by detecting the filesystem type and automatically choosing the "
2305 "right VFS driver, even if that filesystem type is obscure or unexpected for "
2306 "the administrator. Secondly, a kernel-level exploit is like a local root "
2307 "exploit (worse in some ways), giving immediate and total access to the "
2308 "system right down to the hardware level."
2312 #: ../src/guestfs.pod:1199
2314 "That explains why you should never mount a filesystem from an untrusted "
2315 "guest on your host kernel. How about libguestfs? We run a Linux kernel "
2316 "inside a qemu virtual machine, usually running as a non-root user. The "
2317 "attacker would need to write a filesystem which first exploited the kernel, "
2318 "and then exploited either qemu virtualization (eg. a faulty qemu driver) or "
2319 "the libguestfs protocol, and finally to be as serious as the host kernel "
2320 "exploit it would need to escalate its privileges to root. This multi-step "
2321 "escalation, performed by a static piece of data, is thought to be extremely "
2322 "hard to do, although we never say 'never' about security issues."
2326 #: ../src/guestfs.pod:1210
2328 "In any case callers can reduce the attack surface by forcing the filesystem "
2329 "type when mounting (use L</guestfs_mount_vfs>)."
2333 #: ../src/guestfs.pod:1213
2334 msgid "PROTOCOL SECURITY"
2338 #: ../src/guestfs.pod:1215
2340 "The protocol is designed to be secure, being based on RFC 4506 (XDR) with a "
2341 "defined upper message size. However a program that uses libguestfs must "
2342 "also take care - for example you can write a program that downloads a binary "
2343 "from a disk image and executes it locally, and no amount of protocol "
2344 "security will save you from the consequences."
2348 #: ../src/guestfs.pod:1221
2349 msgid "INSPECTION SECURITY"
2353 #: ../src/guestfs.pod:1223
2355 "Parts of the inspection API (see L</INSPECTION>) return untrusted strings "
2356 "directly from the guest, and these could contain any 8 bit data. Callers "
2357 "should be careful to escape these before printing them to a structured file "
2358 "(for example, use HTML escaping if creating a web page)."
2362 #: ../src/guestfs.pod:1229
2364 "Guest configuration may be altered in unusual ways by the administrator of "
2365 "the virtual machine, and may not reflect reality (particularly for untrusted "
2366 "or actively malicious guests). For example we parse the hostname from "
2367 "configuration files like C</etc/sysconfig/network> that we find in the "
2368 "guest, but the guest administrator can easily manipulate these files to "
2369 "provide the wrong hostname."
2373 #: ../src/guestfs.pod:1237
2375 "The inspection API parses guest configuration using two external libraries: "
2376 "Augeas (Linux configuration) and hivex (Windows Registry). Both are "
2377 "designed to be robust in the face of malicious data, although denial of "
2378 "service attacks are still possible, for example with oversized configuration "
2383 #: ../src/guestfs.pod:1243
2384 msgid "RUNNING UNTRUSTED GUEST COMMANDS"
2388 #: ../src/guestfs.pod:1245
2390 "Be very cautious about running commands from the guest. By running a "
2391 "command in the guest, you are giving CPU time to a binary that you do not "
2392 "control, under the same user account as the library, albeit wrapped in qemu "
2393 "virtualization. More information and alternatives can be found in the "
2394 "section L</RUNNING COMMANDS>."
2398 #: ../src/guestfs.pod:1251
2399 msgid "CVE-2010-3851"
2403 #: ../src/guestfs.pod:1253
2404 msgid "https://bugzilla.redhat.com/642934"
2408 #: ../src/guestfs.pod:1255
2410 "This security bug concerns the automatic disk format detection that qemu "
2411 "does on disk images."
2415 #: ../src/guestfs.pod:1258
2417 "A raw disk image is just the raw bytes, there is no header. Other disk "
2418 "images like qcow2 contain a special header. Qemu deals with this by looking "
2419 "for one of the known headers, and if none is found then assuming the disk "
2420 "image must be raw."
2424 #: ../src/guestfs.pod:1263
2426 "This allows a guest which has been given a raw disk image to write some "
2427 "other header. At next boot (or when the disk image is accessed by "
2428 "libguestfs) qemu would do autodetection and think the disk image format was, "
2429 "say, qcow2 based on the header written by the guest."
2433 #: ../src/guestfs.pod:1268
2435 "This in itself would not be a problem, but qcow2 offers many features, one "
2436 "of which is to allow a disk image to refer to another image (called the "
2437 "\"backing disk\"). It does this by placing the path to the backing disk "
2438 "into the qcow2 header. This path is not validated and could point to any "
2439 "host file (eg. \"/etc/passwd\"). The backing disk is then exposed through "
2440 "\"holes\" in the qcow2 disk image, which of course is completely under the "
2441 "control of the attacker."
2445 #: ../src/guestfs.pod:1276
2446 msgid "In libguestfs this is rather hard to exploit except under two circumstances:"
2450 #: ../src/guestfs.pod:1283
2451 msgid "You have enabled the network or have opened the disk in write mode."
2455 #: ../src/guestfs.pod:1287
2457 "You are also running untrusted code from the guest (see L</RUNNING "
2462 #: ../src/guestfs.pod:1292
2464 "The way to avoid this is to specify the expected disk format when adding "
2465 "disks (the optional C<format> option to L</guestfs_add_drive_opts>). You "
2466 "should always do this if the disk is raw format, and it's a good idea for "
2471 #: ../src/guestfs.pod:1297
2473 "For disks added from libvirt using calls like L</guestfs_add_domain>, the "
2474 "format is fetched from libvirt and passed through."
2478 #: ../src/guestfs.pod:1300
2480 "For libguestfs tools, use the I<--format> command line parameter as "
2485 #: ../src/guestfs.pod:1303
2486 msgid "CONNECTION MANAGEMENT"
2490 #: ../src/guestfs.pod:1305
2495 #: ../src/guestfs.pod:1307
2497 "C<guestfs_h> is the opaque type representing a connection handle. Create a "
2498 "handle by calling L</guestfs_create>. Call L</guestfs_close> to free the "
2499 "handle and release all resources used."
2503 #: ../src/guestfs.pod:1311
2505 "For information on using multiple handles and threads, see the section "
2506 "L</MULTIPLE HANDLES AND MULTIPLE THREADS> below."
2510 #: ../src/guestfs.pod:1314
2511 msgid "guestfs_create"
2515 #: ../src/guestfs.pod:1316
2518 " guestfs_h *guestfs_create (void);\n"
2523 #: ../src/guestfs.pod:1318
2524 msgid "Create a connection handle."
2528 #: ../src/guestfs.pod:1320
2530 "You have to call L</guestfs_add_drive_opts> (or one of the equivalent calls) "
2531 "on the handle at least once."
2535 #: ../src/guestfs.pod:1323
2537 "This function returns a non-NULL pointer to a handle on success or NULL on "
2542 #: ../src/guestfs.pod:1326
2543 msgid "After configuring the handle, you have to call L</guestfs_launch>."
2547 #: ../src/guestfs.pod:1328
2549 "You may also want to configure error handling for the handle. See L</ERROR "
2550 "HANDLING> section below."
2554 #: ../src/guestfs.pod:1331
2555 msgid "guestfs_close"
2559 #: ../src/guestfs.pod:1333
2562 " void guestfs_close (guestfs_h *g);\n"
2567 #: ../src/guestfs.pod:1335
2568 msgid "This closes the connection handle and frees up all resources used."
2572 #: ../src/guestfs.pod:1337
2573 msgid "ERROR HANDLING"
2577 #: ../src/guestfs.pod:1339
2579 "API functions can return errors. For example, almost all functions that "
2580 "return C<int> will return C<-1> to indicate an error."
2584 #: ../src/guestfs.pod:1342
2586 "Additional information is available for errors: an error message string and "
2587 "optionally an error number (errno) if the thing that failed was a system "
2592 #: ../src/guestfs.pod:1346
2594 "You can get at the additional information about the last error on the handle "
2595 "by calling L</guestfs_last_error>, L</guestfs_last_errno>, and/or by setting "
2596 "up an error handler with L</guestfs_set_error_handler>."
2600 #: ../src/guestfs.pod:1351
2602 "When the handle is created, a default error handler is installed which "
2603 "prints the error message string to C<stderr>. For small short-running "
2604 "command line programs it is sufficient to do:"
2608 #: ../src/guestfs.pod:1355
2611 " if (guestfs_launch (g) == -1)\n"
2612 " exit (EXIT_FAILURE);\n"
2617 #: ../src/guestfs.pod:1358
2619 "since the default error handler will ensure that an error message has been "
2620 "printed to C<stderr> before the program exits."
2624 #: ../src/guestfs.pod:1361
2626 "For other programs the caller will almost certainly want to install an "
2627 "alternate error handler or do error handling in-line like this:"
2631 #: ../src/guestfs.pod:1364
2634 " g = guestfs_create ();\n"
2639 #: ../src/guestfs.pod:1366
2642 " /* This disables the default behaviour of printing errors\n"
2644 " guestfs_set_error_handler (g, NULL, NULL);\n"
2649 #: ../src/guestfs.pod:1370
2652 " if (guestfs_launch (g) == -1) {\n"
2653 " /* Examine the error message and print it etc. */\n"
2654 " char *msg = guestfs_last_error (g);\n"
2655 " int errnum = guestfs_last_errno (g);\n"
2656 " fprintf (stderr, \"%s\\n\", msg);\n"
2663 #: ../src/guestfs.pod:1378
2665 "Out of memory errors are handled differently. The default action is to call "
2666 "L<abort(3)>. If this is undesirable, then you can set a handler using "
2667 "L</guestfs_set_out_of_memory_handler>."
2671 #: ../src/guestfs.pod:1382
2673 "L</guestfs_create> returns C<NULL> if the handle cannot be created, and "
2674 "because there is no handle if this happens there is no way to get additional "
2675 "error information. However L</guestfs_create> is supposed to be a "
2676 "lightweight operation which can only fail because of insufficient memory (it "
2677 "returns NULL in this case)."
2681 #: ../src/guestfs.pod:1388
2682 msgid "guestfs_last_error"
2686 #: ../src/guestfs.pod:1390
2689 " const char *guestfs_last_error (guestfs_h *g);\n"
2694 #: ../src/guestfs.pod:1392
2696 "This returns the last error message that happened on C<g>. If there has not "
2697 "been an error since the handle was created, then this returns C<NULL>."
2701 #: ../src/guestfs.pod:1396
2703 "The lifetime of the returned string is until the next error occurs, or "
2704 "L</guestfs_close> is called."
2708 #: ../src/guestfs.pod:1399
2709 msgid "guestfs_last_errno"
2713 #: ../src/guestfs.pod:1401
2716 " int guestfs_last_errno (guestfs_h *g);\n"
2721 #: ../src/guestfs.pod:1403
2722 msgid "This returns the last error number (errno) that happened on C<g>."
2726 #: ../src/guestfs.pod:1405
2727 msgid "If successful, an errno integer not equal to zero is returned."
2731 #: ../src/guestfs.pod:1407
2732 msgid "If no error, this returns 0. This call can return 0 in three situations:"
2736 #: ../src/guestfs.pod:1414
2737 msgid "There has not been any error on the handle."
2741 #: ../src/guestfs.pod:1418
2743 "There has been an error but the errno was meaningless. This corresponds to "
2744 "the case where the error did not come from a failed system call, but for "
2745 "some other reason."
2749 #: ../src/guestfs.pod:1424
2751 "There was an error from a failed system call, but for some reason the errno "
2752 "was not captured and returned. This usually indicates a bug in libguestfs."
2756 #: ../src/guestfs.pod:1430
2758 "Libguestfs tries to convert the errno from inside the applicance into a "
2759 "corresponding errno for the caller (not entirely trivial: the appliance "
2760 "might be running a completely different operating system from the library "
2761 "and error numbers are not standardized across Un*xen). If this could not be "
2762 "done, then the error is translated to C<EINVAL>. In practice this should "
2763 "only happen in very rare circumstances."
2767 #: ../src/guestfs.pod:1438
2768 msgid "guestfs_set_error_handler"
2772 #: ../src/guestfs.pod:1440
2775 " typedef void (*guestfs_error_handler_cb) (guestfs_h *g,\n"
2777 " const char *msg);\n"
2778 " void guestfs_set_error_handler (guestfs_h *g,\n"
2779 " guestfs_error_handler_cb cb,\n"
2785 #: ../src/guestfs.pod:1447
2787 "The callback C<cb> will be called if there is an error. The parameters "
2788 "passed to the callback are an opaque data pointer and the error message "
2793 #: ../src/guestfs.pod:1451
2795 "C<errno> is not passed to the callback. To get that the callback must call "
2796 "L</guestfs_last_errno>."
2800 #: ../src/guestfs.pod:1454
2802 "Note that the message string C<msg> is freed as soon as the callback "
2803 "function returns, so if you want to stash it somewhere you must make your "
2808 #: ../src/guestfs.pod:1458
2809 msgid "The default handler prints messages on C<stderr>."
2813 #: ../src/guestfs.pod:1460
2814 msgid "If you set C<cb> to C<NULL> then I<no> handler is called."
2818 #: ../src/guestfs.pod:1462
2819 msgid "guestfs_get_error_handler"
2823 #: ../src/guestfs.pod:1464
2826 " guestfs_error_handler_cb guestfs_get_error_handler (guestfs_h *g,\n"
2827 " void **opaque_rtn);\n"
2832 #: ../src/guestfs.pod:1467
2833 msgid "Returns the current error handler callback."
2837 #: ../src/guestfs.pod:1469
2838 msgid "guestfs_set_out_of_memory_handler"
2842 #: ../src/guestfs.pod:1471
2845 " typedef void (*guestfs_abort_cb) (void);\n"
2846 " int guestfs_set_out_of_memory_handler (guestfs_h *g,\n"
2847 " guestfs_abort_cb);\n"
2852 #: ../src/guestfs.pod:1475
2854 "The callback C<cb> will be called if there is an out of memory situation. "
2855 "I<Note this callback must not return>."
2859 #: ../src/guestfs.pod:1478
2860 msgid "The default is to call L<abort(3)>."
2864 #: ../src/guestfs.pod:1480
2865 msgid "You cannot set C<cb> to C<NULL>. You can't ignore out of memory situations."
2869 #: ../src/guestfs.pod:1483
2870 msgid "guestfs_get_out_of_memory_handler"
2874 #: ../src/guestfs.pod:1485
2877 " guestfs_abort_fn guestfs_get_out_of_memory_handler (guestfs_h *g);\n"
2882 #: ../src/guestfs.pod:1487
2883 msgid "This returns the current out of memory handler."
2887 #: ../src/guestfs.pod:1489
2892 #: ../src/guestfs.pod:1491 ../fish/guestfish.pod:1003
2897 #: ../src/guestfs.pod:1493
2902 #: ../src/guestfs.pod:1495
2907 #: ../src/guestfs.pod:1497
2908 msgid "AVAILABILITY"
2912 #: ../src/guestfs.pod:1499
2913 msgid "GROUPS OF FUNCTIONALITY IN THE APPLIANCE"
2917 #: ../src/guestfs.pod:1501
2919 "Using L</guestfs_available> you can test availability of the following "
2920 "groups of functions. This test queries the appliance to see if the "
2921 "appliance you are currently using supports the functionality."
2925 #: ../src/guestfs.pod:1506
2926 msgid "@AVAILABILITY@"
2930 #: ../src/guestfs.pod:1508
2931 msgid "GUESTFISH supported COMMAND"
2935 #: ../src/guestfs.pod:1510
2937 "In L<guestfish(3)> there is a handy interactive command C<supported> which "
2938 "prints out the available groups and whether they are supported by this build "
2939 "of libguestfs. Note however that you have to do C<run> first."
2943 #: ../src/guestfs.pod:1515
2944 msgid "SINGLE CALLS AT COMPILE TIME"
2948 #: ../src/guestfs.pod:1517
2950 "Since version 1.5.8, C<E<lt>guestfs.hE<gt>> defines symbols for each C API "
2951 "function, such as:"
2955 #: ../src/guestfs.pod:1520
2958 " #define LIBGUESTFS_HAVE_DD 1\n"
2963 #: ../src/guestfs.pod:1522
2964 msgid "if L</guestfs_dd> is available."
2968 #: ../src/guestfs.pod:1524
2970 "Before version 1.5.8, if you needed to test whether a single libguestfs "
2971 "function is available at compile time, we recommended using build tools such "
2972 "as autoconf or cmake. For example in autotools you could use:"
2976 #: ../src/guestfs.pod:1529
2979 " AC_CHECK_LIB([guestfs],[guestfs_create])\n"
2980 " AC_CHECK_FUNCS([guestfs_dd])\n"
2985 #: ../src/guestfs.pod:1532
2987 "which would result in C<HAVE_GUESTFS_DD> being either defined or not defined "
2992 #: ../src/guestfs.pod:1535
2993 msgid "SINGLE CALLS AT RUN TIME"
2997 #: ../src/guestfs.pod:1537
2999 "Testing at compile time doesn't guarantee that a function really exists in "
3000 "the library. The reason is that you might be dynamically linked against a "
3001 "previous I<libguestfs.so> (dynamic library) which doesn't have the call. "
3002 "This situation unfortunately results in a segmentation fault, which is a "
3003 "shortcoming of the C dynamic linking system itself."
3007 #: ../src/guestfs.pod:1544
3009 "You can use L<dlopen(3)> to test if a function is available at run time, as "
3010 "in this example program (note that you still need the compile time check as "
3015 #: ../src/guestfs.pod:1548
3018 " #include <stdio.h>\n"
3019 " #include <stdlib.h>\n"
3020 " #include <unistd.h>\n"
3021 " #include <dlfcn.h>\n"
3022 " #include <guestfs.h>\n"
3027 #: ../src/guestfs.pod:1554
3032 " #ifdef LIBGUESTFS_HAVE_DD\n"
3034 " int has_function;\n"
3039 #: ../src/guestfs.pod:1560
3042 " /* Test if the function guestfs_dd is really available. */\n"
3043 " dl = dlopen (NULL, RTLD_LAZY);\n"
3045 " fprintf (stderr, \"dlopen: %s\\n\", dlerror ());\n"
3046 " exit (EXIT_FAILURE);\n"
3048 " has_function = dlsym (dl, \"guestfs_dd\") != NULL;\n"
3054 #: ../src/guestfs.pod:1569
3057 " if (!has_function)\n"
3058 " printf (\"this libguestfs.so does NOT have guestfs_dd function\\n\");\n"
3060 " printf (\"this libguestfs.so has guestfs_dd function\\n\");\n"
3061 " /* Now it's safe to call\n"
3062 " guestfs_dd (g, \"foo\", \"bar\");\n"
3066 " printf (\"guestfs_dd function was not found at compile time\\n\");\n"
3073 #: ../src/guestfs.pod:1582
3075 "You may think the above is an awful lot of hassle, and it is. There are "
3076 "other ways outside of the C linking system to ensure that this kind of "
3077 "incompatibility never arises, such as using package versioning:"
3081 #: ../src/guestfs.pod:1587
3084 " Requires: libguestfs >= 1.0.80\n"
3089 #: ../src/guestfs.pod:1589
3090 msgid "CALLS WITH OPTIONAL ARGUMENTS"
3094 #: ../src/guestfs.pod:1591
3096 "A recent feature of the API is the introduction of calls which take optional "
3097 "arguments. In C these are declared 3 ways. The main way is as a call which "
3098 "takes variable arguments (ie. C<...>), as in this example:"
3102 #: ../src/guestfs.pod:1596
3105 " int guestfs_add_drive_opts (guestfs_h *g, const char *filename, ...);\n"
3110 #: ../src/guestfs.pod:1598
3112 "Call this with a list of optional arguments, terminated by C<-1>. So to "
3113 "call with no optional arguments specified:"
3117 #: ../src/guestfs.pod:1601
3120 " guestfs_add_drive_opts (g, filename, -1);\n"
3125 #: ../src/guestfs.pod:1603
3126 msgid "With a single optional argument:"
3130 #: ../src/guestfs.pod:1605
3133 " guestfs_add_drive_opts (g, filename,\n"
3134 " GUESTFS_ADD_DRIVE_OPTS_FORMAT, \"qcow2\",\n"
3140 #: ../src/guestfs.pod:1609
3145 #: ../src/guestfs.pod:1611
3148 " guestfs_add_drive_opts (g, filename,\n"
3149 " GUESTFS_ADD_DRIVE_OPTS_FORMAT, \"qcow2\",\n"
3150 " GUESTFS_ADD_DRIVE_OPTS_READONLY, 1,\n"
3156 #: ../src/guestfs.pod:1616
3158 "and so forth. Don't forget the terminating C<-1> otherwise Bad Things will "
3163 #: ../src/guestfs.pod:1619
3164 msgid "USING va_list FOR OPTIONAL ARGUMENTS"
3168 #: ../src/guestfs.pod:1621
3170 "The second variant has the same name with the suffix C<_va>, which works the "
3171 "same way but takes a C<va_list>. See the C manual for details. For the "
3172 "example function, this is declared:"
3176 #: ../src/guestfs.pod:1625
3179 " int guestfs_add_drive_opts_va (guestfs_h *g, const char *filename,\n"
3185 #: ../src/guestfs.pod:1628
3186 msgid "CONSTRUCTING OPTIONAL ARGUMENTS"
3190 #: ../src/guestfs.pod:1630
3192 "The third variant is useful where you need to construct these calls. You "
3193 "pass in a structure where you fill in the optional fields. The structure "
3194 "has a bitmask as the first element which you must set to indicate which "
3195 "fields you have filled in. For our example function the structure and call "
3200 #: ../src/guestfs.pod:1636
3203 " struct guestfs_add_drive_opts_argv {\n"
3204 " uint64_t bitmask;\n"
3206 " const char *format;\n"
3209 " int guestfs_add_drive_opts_argv (guestfs_h *g, const char *filename,\n"
3210 " const struct guestfs_add_drive_opts_argv *optargs);\n"
3215 #: ../src/guestfs.pod:1645
3216 msgid "You could call it like this:"
3220 #: ../src/guestfs.pod:1647
3223 " struct guestfs_add_drive_opts_argv optargs = {\n"
3224 " .bitmask = GUESTFS_ADD_DRIVE_OPTS_READONLY_BITMASK |\n"
3225 " GUESTFS_ADD_DRIVE_OPTS_FORMAT_BITMASK,\n"
3227 " .format = \"qcow2\"\n"
3233 #: ../src/guestfs.pod:1654
3236 " guestfs_add_drive_opts_argv (g, filename, &optargs);\n"
3241 #: ../src/guestfs.pod:1656 ../src/guestfs-actions.pod:11 ../src/guestfs-actions.pod:1855 ../fish/guestfish-actions.pod:9 ../fish/guestfish-actions.pod:1260 ../tools/virt-win-reg.pl:532
3246 #: ../src/guestfs.pod:1662
3247 msgid "The C<_BITMASK> suffix on each option name when specifying the bitmask."
3251 #: ../src/guestfs.pod:1667
3252 msgid "You do not need to fill in all fields of the structure."
3256 #: ../src/guestfs.pod:1671
3258 "There must be a one-to-one correspondence between fields of the structure "
3259 "that are filled in, and bits set in the bitmask."
3263 #: ../src/guestfs.pod:1676
3264 msgid "OPTIONAL ARGUMENTS IN OTHER LANGUAGES"
3268 #: ../src/guestfs.pod:1678
3270 "In other languages, optional arguments are expressed in the way that is "
3271 "natural for that language. We refer you to the language-specific "
3272 "documentation for more details on that."
3276 #: ../src/guestfs.pod:1682
3277 msgid "For guestfish, see L<guestfish(1)/OPTIONAL ARGUMENTS>."
3281 #: ../src/guestfs.pod:1684
3282 msgid "SETTING CALLBACKS TO HANDLE EVENTS"
3286 #: ../src/guestfs.pod:1686
3288 "B<Note:> This section documents the generic event mechanism introduced in "
3289 "libguestfs 1.10, which you should use in new code if possible. The old "
3290 "functions C<guestfs_set_log_message_callback>, "
3291 "C<guestfs_set_subprocess_quit_callback>, "
3292 "C<guestfs_set_launch_done_callback>, C<guestfs_set_close_callback> and "
3293 "C<guestfs_set_progress_callback> are no longer documented in this manual "
3298 #: ../src/guestfs.pod:1694
3300 "Handles generate events when certain things happen, such as log messages "
3301 "being generated, progress messages during long-running operations, or the "
3302 "handle being closed. The API calls described below let you register a "
3303 "callback to be called when events happen. You can register multiple "
3304 "callbacks (for the same, different or overlapping sets of events), and "
3305 "individually remove callbacks. If callbacks are not removed, then they "
3306 "remain in force until the handle is closed."
3310 #: ../src/guestfs.pod:1702
3312 "In the current implementation, events are only generated synchronously: that "
3313 "means that events (and hence callbacks) can only happen while you are in the "
3314 "middle of making another libguestfs call. The callback is called in the "
3319 #: ../src/guestfs.pod:1707
3321 "Events may contain a payload, usually nothing (void), an array of 64 bit "
3322 "unsigned integers, or a message buffer. Payloads are discussed later on."
3326 #: ../src/guestfs.pod:1711
3327 msgid "CLASSES OF EVENTS"
3331 #: ../src/guestfs.pod:1715
3332 msgid "GUESTFS_EVENT_CLOSE (payload type: void)"
3336 #: ../src/guestfs.pod:1718
3338 "The callback function will be called while the handle is being closed "
3339 "(synchronously from L</guestfs_close>)."
3343 #: ../src/guestfs.pod:1721
3345 "Note that libguestfs installs an L<atexit(3)> handler to try to clean up "
3346 "handles that are open when the program exits. This means that this callback "
3347 "might be called indirectly from L<exit(3)>, which can cause unexpected "
3348 "problems in higher-level languages (eg. if your HLL interpreter has already "
3349 "been cleaned up by the time this is called, and if your callback then jumps "
3350 "into some HLL function)."
3354 #: ../src/guestfs.pod:1728
3356 "If no callback is registered: the handle is closed without any callback "
3361 #: ../src/guestfs.pod:1731
3362 msgid "GUESTFS_EVENT_SUBPROCESS_QUIT (payload type: void)"
3366 #: ../src/guestfs.pod:1734
3368 "The callback function will be called when the child process quits, either "
3369 "asynchronously or if killed by L</guestfs_kill_subprocess>. (This "
3370 "corresponds to a transition from any state to the CONFIG state)."
3374 #: ../src/guestfs.pod:1738 ../src/guestfs.pod:1747
3375 msgid "If no callback is registered: the event is ignored."
3379 #: ../src/guestfs.pod:1740
3380 msgid "GUESTFS_EVENT_LAUNCH_DONE (payload type: void)"
3384 #: ../src/guestfs.pod:1743
3386 "The callback function will be called when the child process becomes ready "
3387 "first time after it has been launched. (This corresponds to a transition "
3388 "from LAUNCHING to the READY state)."
3392 #: ../src/guestfs.pod:1749
3393 msgid "GUESTFS_EVENT_PROGRESS (payload type: array of 4 x uint64_t)"
3397 #: ../src/guestfs.pod:1752
3399 "Some long-running operations can generate progress messages. If this "
3400 "callback is registered, then it will be called each time a progress message "
3401 "is generated (usually two seconds after the operation started, and three "
3402 "times per second thereafter until it completes, although the frequency may "
3403 "change in future versions)."
3407 #: ../src/guestfs.pod:1758
3409 "The callback receives in the payload four unsigned 64 bit numbers which are "
3410 "(in order): C<proc_nr>, C<serial>, C<position>, C<total>."
3414 #: ../src/guestfs.pod:1761
3416 "The units of C<total> are not defined, although for some operations C<total> "
3417 "may relate in some way to the amount of data to be transferred (eg. in bytes "
3418 "or megabytes), and C<position> may be the portion which has been "
3423 #: ../src/guestfs.pod:1766
3424 msgid "The only defined and stable parts of the API are:"
3428 #: ../src/guestfs.pod:1772
3430 "The callback can display to the user some type of progress bar or indicator "
3431 "which shows the ratio of C<position>:C<total>."
3435 #: ../src/guestfs.pod:1777
3436 msgid "0 E<lt>= C<position> E<lt>= C<total>"
3440 #: ../src/guestfs.pod:1781
3442 "If any progress notification is sent during a call, then a final progress "
3443 "notification is always sent when C<position> = C<total> (I<unless> the call "
3444 "fails with an error)."
3448 #: ../src/guestfs.pod:1785
3450 "This is to simplify caller code, so callers can easily set the progress "
3451 "indicator to \"100%\" at the end of the operation, without requiring special "
3452 "code to detect this case."
3456 #: ../src/guestfs.pod:1791
3458 "For some calls we are unable to estimate the progress of the call, but we "
3459 "can still generate progress messages to indicate activity. This is known as "
3460 "\"pulse mode\", and is directly supported by certain progress bar "
3461 "implementations (eg. GtkProgressBar)."
3465 #: ../src/guestfs.pod:1796
3467 "For these calls, zero or more progress messages are generated with "
3468 "C<position = 0> and C<total = 1>, followed by a final message with "
3469 "C<position = total = 1>."
3473 #: ../src/guestfs.pod:1800
3475 "As noted above, if the call fails with an error then the final message may "
3480 #: ../src/guestfs.pod:1805
3482 "The callback also receives the procedure number (C<proc_nr>) and serial "
3483 "number (C<serial>) of the call. These are only useful for debugging "
3484 "protocol issues, and the callback can normally ignore them. The callback "
3485 "may want to print these numbers in error messages or debugging messages."
3489 #: ../src/guestfs.pod:1811
3490 msgid "If no callback is registered: progress messages are discarded."
3494 #: ../src/guestfs.pod:1813
3495 msgid "GUESTFS_EVENT_APPLIANCE (payload type: message buffer)"
3499 #: ../src/guestfs.pod:1816
3501 "The callback function is called whenever a log message is generated by qemu, "
3502 "the appliance kernel, guestfsd (daemon), or utility programs."
3506 #: ../src/guestfs.pod:1819
3508 "If the verbose flag (L</guestfs_set_verbose>) is set before launch "
3509 "(L</guestfs_launch>) then additional debug messages are generated."
3513 #: ../src/guestfs.pod:1822 ../src/guestfs.pod:1836
3515 "If no callback is registered: the messages are discarded unless the verbose "
3516 "flag is set in which case they are sent to stderr. You can override the "
3517 "printing of verbose messages to stderr by setting up a callback."
3521 #: ../src/guestfs.pod:1827
3522 msgid "GUESTFS_EVENT_LIBRARY (payload type: message buffer)"
3526 #: ../src/guestfs.pod:1830
3528 "The callback function is called whenever a log message is generated by the "
3529 "library part of libguestfs."
3533 #: ../src/guestfs.pod:1833
3535 "If the verbose flag (L</guestfs_set_verbose>) is set then additional debug "
3536 "messages are generated."
3540 #: ../src/guestfs.pod:1841
3541 msgid "GUESTFS_EVENT_TRACE (payload type: message buffer)"
3545 #: ../src/guestfs.pod:1844
3547 "The callback function is called whenever a trace message is generated. This "
3548 "only applies if the trace flag (L</guestfs_set_trace>) is set."
3552 #: ../src/guestfs.pod:1847
3554 "If no callback is registered: the messages are sent to stderr. You can "
3555 "override the printing of trace messages to stderr by setting up a callback."
3559 #: ../src/guestfs.pod:1853
3560 msgid "guestfs_set_event_callback"
3564 #: ../src/guestfs.pod:1855
3567 " int guestfs_set_event_callback (guestfs_h *g,\n"
3568 " guestfs_event_callback cb,\n"
3569 " uint64_t event_bitmask,\n"
3576 #: ../src/guestfs.pod:1861
3578 "This function registers a callback (C<cb>) for all event classes in the "
3583 #: ../src/guestfs.pod:1864
3585 "For example, to register for all log message events, you could call this "
3586 "function with the bitmask C<GUESTFS_EVENT_APPLIANCE|GUESTFS_EVENT_LIBRARY>. "
3587 "To register a single callback for all possible classes of events, use "
3588 "C<GUESTFS_EVENT_ALL>."
3592 #: ../src/guestfs.pod:1870
3593 msgid "C<flags> should always be passed as 0."
3597 #: ../src/guestfs.pod:1872
3599 "C<opaque> is an opaque pointer which is passed to the callback. You can use "
3600 "it for any purpose."
3604 #: ../src/guestfs.pod:1875
3606 "The return value is the event handle (an integer) which you can use to "
3607 "delete the callback (see below)."
3611 #: ../src/guestfs.pod:1878
3613 "If there is an error, this function returns C<-1>, and sets the error in the "
3614 "handle in the usual way (see L</guestfs_last_error> etc.)"
3618 #: ../src/guestfs.pod:1881
3620 "Callbacks remain in effect until they are deleted, or until the handle is "
3625 #: ../src/guestfs.pod:1884
3627 "In the case where multiple callbacks are registered for a particular event "
3628 "class, all of the callbacks are called. The order in which multiple "
3629 "callbacks are called is not defined."
3633 #: ../src/guestfs.pod:1888
3634 msgid "guestfs_delete_event_callback"
3638 #: ../src/guestfs.pod:1890
3641 " void guestfs_delete_event_callback (guestfs_h *g, int event_handle);\n"
3646 #: ../src/guestfs.pod:1892
3648 "Delete a callback that was previously registered. C<event_handle> should be "
3649 "the integer that was returned by a previous call to "
3650 "C<guestfs_set_event_callback> on the same handle."
3654 #: ../src/guestfs.pod:1896
3655 msgid "guestfs_event_callback"
3659 #: ../src/guestfs.pod:1898
3662 " typedef void (*guestfs_event_callback) (\n"
3665 " uint64_t event,\n"
3666 " int event_handle,\n"
3668 " const char *buf, size_t buf_len,\n"
3669 " const uint64_t *array, size_t array_len);\n"
3674 #: ../src/guestfs.pod:1907
3675 msgid "This is the type of the event callback function that you have to provide."
3679 #: ../src/guestfs.pod:1910
3681 "The basic parameters are: the handle (C<g>), the opaque user pointer "
3682 "(C<opaque>), the event class (eg. C<GUESTFS_EVENT_PROGRESS>), the event "
3683 "handle, and C<flags> which in the current API you should ignore."
3687 #: ../src/guestfs.pod:1914
3689 "The remaining parameters contain the event payload (if any). Each event may "
3690 "contain a payload, which usually relates to the event class, but for future "
3691 "proofing your code should be written to handle any payload for any event "
3696 #: ../src/guestfs.pod:1919
3698 "C<buf> and C<buf_len> contain a message buffer (if C<buf_len == 0>, then "
3699 "there is no message buffer). Note that this message buffer can contain "
3700 "arbitrary 8 bit data, including NUL bytes."
3704 #: ../src/guestfs.pod:1923
3706 "C<array> and C<array_len> is an array of 64 bit unsigned integers. At the "
3707 "moment this is only used for progress messages."
3711 #: ../src/guestfs.pod:1926
3712 msgid "EXAMPLE: CAPTURING LOG MESSAGES"
3716 #: ../src/guestfs.pod:1928
3718 "One motivation for the generic event API was to allow GUI programs to "
3719 "capture debug and other messages. In libguestfs E<le> 1.8 these were sent "
3720 "unconditionally to C<stderr>."
3724 #: ../src/guestfs.pod:1932
3726 "Events associated with log messages are: C<GUESTFS_EVENT_LIBRARY>, "
3727 "C<GUESTFS_EVENT_APPLIANCE> and C<GUESTFS_EVENT_TRACE>. (Note that error "
3728 "messages are not events; you must capture error messages separately)."
3732 #: ../src/guestfs.pod:1937
3734 "Programs have to set up a callback to capture the classes of events of "
3739 #: ../src/guestfs.pod:1940
3743 " guestfs_set_event_callback\n"
3744 " (g, message_callback,\n"
3745 " GUESTFS_EVENT_LIBRARY|GUESTFS_EVENT_APPLIANCE|\n"
3746 " GUESTFS_EVENT_TRACE,\n"
3747 " 0, NULL) == -1)\n"
3748 " if (eh == -1) {\n"
3749 " // handle error in the usual way\n"
3755 #: ../src/guestfs.pod:1950
3757 "The callback can then direct messages to the appropriate place. In this "
3758 "example, messages are directed to syslog:"
3762 #: ../src/guestfs.pod:1953
3766 " message_callback (\n"
3769 " uint64_t event,\n"
3770 " int event_handle,\n"
3772 " const char *buf, size_t buf_len,\n"
3773 " const uint64_t *array, size_t array_len)\n"
3775 " const int priority = LOG_USER|LOG_INFO;\n"
3776 " if (buf_len > 0)\n"
3777 " syslog (priority, \"event 0x%lx: %s\", event, buf);\n"
3783 #: ../src/guestfs.pod:1968
3784 msgid "PRIVATE DATA AREA"
3788 #: ../src/guestfs.pod:1970
3790 "You can attach named pieces of private data to the libguestfs handle, fetch "
3791 "them by name, and walk over them, for the lifetime of the handle. This is "
3792 "called the private data area and is only available from the C API."
3796 #: ../src/guestfs.pod:1975
3797 msgid "To attach a named piece of data, use the following call:"
3801 #: ../src/guestfs.pod:1977
3804 " void guestfs_set_private (guestfs_h *g, const char *key, void *data);\n"
3809 #: ../src/guestfs.pod:1979
3811 "C<key> is the name to associate with this data, and C<data> is an arbitrary "
3812 "pointer (which can be C<NULL>). Any previous item with the same name is "
3817 #: ../src/guestfs.pod:1983
3819 "You can use any C<key> you want, but names beginning with an underscore "
3820 "character are reserved for internal libguestfs purposes (for implementing "
3821 "language bindings). It is recommended to prefix the name with some unique "
3822 "string to avoid collisions with other users."
3826 #: ../src/guestfs.pod:1988
3827 msgid "To retrieve the pointer, use:"
3831 #: ../src/guestfs.pod:1990
3834 " void *guestfs_get_private (guestfs_h *g, const char *key);\n"
3839 #: ../src/guestfs.pod:1992
3841 "This function returns C<NULL> if either no data is found associated with "
3842 "C<key>, or if the user previously set the C<key>'s C<data> pointer to "
3847 #: ../src/guestfs.pod:1996
3849 "Libguestfs does not try to look at or interpret the C<data> pointer in any "
3850 "way. As far as libguestfs is concerned, it need not be a valid pointer at "
3851 "all. In particular, libguestfs does I<not> try to free the data when the "
3852 "handle is closed. If the data must be freed, then the caller must either "
3853 "free it before calling L</guestfs_close> or must set up a close callback to "
3854 "do it (see L</GUESTFS_EVENT_CLOSE>)."
3858 #: ../src/guestfs.pod:2003
3859 msgid "To walk over all entries, use these two functions:"
3863 #: ../src/guestfs.pod:2005
3866 " void *guestfs_first_private (guestfs_h *g, const char **key_rtn);\n"
3871 #: ../src/guestfs.pod:2007
3874 " void *guestfs_next_private (guestfs_h *g, const char **key_rtn);\n"
3879 #: ../src/guestfs.pod:2009
3881 "C<guestfs_first_private> returns the first key, pointer pair (\"first\" does "
3882 "not have any particular meaning -- keys are not returned in any defined "
3883 "order). A pointer to the key is returned in C<*key_rtn> and the "
3884 "corresponding data pointer is returned from the function. C<NULL> is "
3885 "returned if there are no keys stored in the handle."
3889 #: ../src/guestfs.pod:2015
3891 "C<guestfs_next_private> returns the next key, pointer pair. The return "
3892 "value of this function is also C<NULL> is there are no further entries to "
3897 #: ../src/guestfs.pod:2019
3898 msgid "Notes about walking over entries:"
3902 #: ../src/guestfs.pod:2025
3903 msgid "You must not call C<guestfs_set_private> while walking over the entries."
3907 #: ../src/guestfs.pod:2030
3909 "The handle maintains an internal iterator which is reset when you call "
3910 "C<guestfs_first_private>. This internal iterator is invalidated when you "
3911 "call C<guestfs_set_private>."
3915 #: ../src/guestfs.pod:2036
3916 msgid "If you have set the data pointer associated with a key to C<NULL>, ie:"
3920 #: ../src/guestfs.pod:2038
3923 " guestfs_set_private (g, key, NULL);\n"
3928 #: ../src/guestfs.pod:2040
3929 msgid "then that C<key> is not returned when walking."
3933 #: ../src/guestfs.pod:2044
3935 "C<*key_rtn> is only valid until the next call to C<guestfs_first_private>, "
3936 "C<guestfs_next_private> or C<guestfs_set_private>."
3940 #: ../src/guestfs.pod:2050
3942 "The following example code shows how to print all keys and data pointers "
3943 "that are associated with the handle C<g>:"
3947 #: ../src/guestfs.pod:2053
3950 " const char *key;\n"
3951 " void *data = guestfs_first_private (g, &key);\n"
3952 " while (data != NULL)\n"
3954 " printf (\"key = %s, data = %p\\n\", key, data);\n"
3955 " data = guestfs_next_private (g, &key);\n"
3961 #: ../src/guestfs.pod:2061
3963 "More commonly you are only interested in keys that begin with an "
3964 "application-specific prefix C<foo_>. Modify the loop like so:"
3968 #: ../src/guestfs.pod:2064
3971 " const char *key;\n"
3972 " void *data = guestfs_first_private (g, &key);\n"
3973 " while (data != NULL)\n"
3975 " if (strncmp (key, \"foo_\", strlen (\"foo_\")) == 0)\n"
3976 " printf (\"key = %s, data = %p\\n\", key, data);\n"
3977 " data = guestfs_next_private (g, &key);\n"
3983 #: ../src/guestfs.pod:2073
3985 "If you need to modify keys while walking, then you have to jump back to the "
3986 "beginning of the loop. For example, to delete all keys prefixed with "
3991 #: ../src/guestfs.pod:2077
3994 " const char *key;\n"
3997 " data = guestfs_first_private (g, &key);\n"
3998 " while (data != NULL)\n"
4000 " if (strncmp (key, \"foo_\", strlen (\"foo_\")) == 0)\n"
4002 " guestfs_set_private (g, key, NULL);\n"
4003 " /* note that 'key' pointer is now invalid, and so is\n"
4004 " the internal iterator */\n"
4007 " data = guestfs_next_private (g, &key);\n"
4013 #: ../src/guestfs.pod:2093
4015 "Note that the above loop is guaranteed to terminate because the keys are "
4016 "being deleted, but other manipulations of keys within the loop might not "
4017 "terminate unless you also maintain an indication of which keys have been "
4022 #: ../src/guestfs.pod:2098 ../src/guestfs.pod:2103
4027 #: ../src/guestfs.pod:2100
4029 "<!-- old anchor for the next section --> <a "
4030 "name=\"state_machine_and_low_level_event_api\"/>"
4034 #: ../src/guestfs.pod:2105
4035 msgid "ARCHITECTURE"
4039 #: ../src/guestfs.pod:2107
4041 "Internally, libguestfs is implemented by running an appliance (a special "
4042 "type of small virtual machine) using L<qemu(1)>. Qemu runs as a child "
4043 "process of the main program."
4047 #: ../src/guestfs.pod:2111
4050 " ___________________\n"
4052 " | main program |\n"
4054 " | | child process / appliance\n"
4055 " | | __________________________\n"
4057 " +-------------------+ RPC | +-----------------+ |\n"
4058 " | libguestfs <--------------------> guestfsd | |\n"
4059 " | | | +-----------------+ |\n"
4060 " \\___________________/ | | Linux kernel | |\n"
4061 " | +--^--------------+ |\n"
4062 " \\_________|________________/\n"
4068 " \\______________/\n"
4073 #: ../src/guestfs.pod:2131
4075 "The library, linked to the main program, creates the child process and hence "
4076 "the appliance in the L</guestfs_launch> function."
4080 #: ../src/guestfs.pod:2134
4082 "Inside the appliance is a Linux kernel and a complete stack of userspace "
4083 "tools (such as LVM and ext2 programs) and a small controlling daemon called "
4084 "L</guestfsd>. The library talks to L</guestfsd> using remote procedure "
4085 "calls (RPC). There is a mostly one-to-one correspondence between libguestfs "
4086 "API calls and RPC calls to the daemon. Lastly the disk image(s) are "
4087 "attached to the qemu process which translates device access by the "
4088 "appliance's Linux kernel into accesses to the image."
4092 #: ../src/guestfs.pod:2143
4094 "A common misunderstanding is that the appliance \"is\" the virtual machine. "
4095 "Although the disk image you are attached to might also be used by some "
4096 "virtual machine, libguestfs doesn't know or care about this. (But you will "
4097 "care if both libguestfs's qemu process and your virtual machine are trying "
4098 "to update the disk image at the same time, since these usually results in "
4099 "massive disk corruption)."
4103 #: ../src/guestfs.pod:2150
4104 msgid "STATE MACHINE"
4108 #: ../src/guestfs.pod:2152
4109 msgid "libguestfs uses a state machine to model the child process:"
4113 #: ../src/guestfs.pod:2154
4125 " / | \\ \\ guestfs_launch\n"
4126 " / | _\\__V______\n"
4128 " / | | LAUNCHING |\n"
4129 " / | \\___________/\n"
4131 " / | guestfs_launch\n"
4133 " ______ / __|____V\n"
4134 " / \\ ------> / \\\n"
4135 " | BUSY | | READY |\n"
4136 " \\______/ <------ \\________/\n"
4141 #: ../src/guestfs.pod:2176
4143 "The normal transitions are (1) CONFIG (when the handle is created, but there "
4144 "is no child process), (2) LAUNCHING (when the child process is booting up), "
4145 "(3) alternating between READY and BUSY as commands are issued to, and "
4146 "carried out by, the child process."
4150 #: ../src/guestfs.pod:2181
4152 "The guest may be killed by L</guestfs_kill_subprocess>, or may die "
4153 "asynchronously at any time (eg. due to some internal error), and that causes "
4154 "the state to transition back to CONFIG."
4158 #: ../src/guestfs.pod:2185
4160 "Configuration commands for qemu such as L</guestfs_add_drive> can only be "
4161 "issued when in the CONFIG state."
4165 #: ../src/guestfs.pod:2188
4167 "The API offers one call that goes from CONFIG through LAUNCHING to READY. "
4168 "L</guestfs_launch> blocks until the child process is READY to accept "
4169 "commands (or until some failure or timeout). L</guestfs_launch> internally "
4170 "moves the state from CONFIG to LAUNCHING while it is running."
4174 #: ../src/guestfs.pod:2194
4176 "API actions such as L</guestfs_mount> can only be issued when in the READY "
4177 "state. These API calls block waiting for the command to be carried out "
4178 "(ie. the state to transition to BUSY and then back to READY). There are no "
4179 "non-blocking versions, and no way to issue more than one command per handle "
4184 #: ../src/guestfs.pod:2200
4186 "Finally, the child process sends asynchronous messages back to the main "
4187 "program, such as kernel log messages. You can register a callback to "
4188 "receive these messages."
4192 #: ../src/guestfs.pod:2204
4197 #: ../src/guestfs.pod:2206
4198 msgid "COMMUNICATION PROTOCOL"
4202 #: ../src/guestfs.pod:2208
4204 "Don't rely on using this protocol directly. This section documents how it "
4205 "currently works, but it may change at any time."
4209 #: ../src/guestfs.pod:2211
4211 "The protocol used to talk between the library and the daemon running inside "
4212 "the qemu virtual machine is a simple RPC mechanism built on top of XDR (RFC "
4213 "1014, RFC 1832, RFC 4506)."
4217 #: ../src/guestfs.pod:2215
4219 "The detailed format of structures is in C<src/guestfs_protocol.x> (note: "
4220 "this file is automatically generated)."
4224 #: ../src/guestfs.pod:2218
4226 "There are two broad cases, ordinary functions that don't have any C<FileIn> "
4227 "and C<FileOut> parameters, which are handled with very simple request/reply "
4228 "messages. Then there are functions that have any C<FileIn> or C<FileOut> "
4229 "parameters, which use the same request and reply messages, but they may also "
4230 "be followed by files sent using a chunked encoding."
4234 #: ../src/guestfs.pod:2225
4235 msgid "ORDINARY FUNCTIONS (NO FILEIN/FILEOUT PARAMS)"
4239 #: ../src/guestfs.pod:2227
4240 msgid "For ordinary functions, the request message is:"
4244 #: ../src/guestfs.pod:2229
4247 " total length (header + arguments,\n"
4248 " but not including the length word itself)\n"
4249 " struct guestfs_message_header (encoded as XDR)\n"
4250 " struct guestfs_<foo>_args (encoded as XDR)\n"
4255 #: ../src/guestfs.pod:2234
4257 "The total length field allows the daemon to allocate a fixed size buffer "
4258 "into which it slurps the rest of the message. As a result, the total length "
4259 "is limited to C<GUESTFS_MESSAGE_MAX> bytes (currently 4MB), which means the "
4260 "effective size of any request is limited to somewhere under this size."
4264 #: ../src/guestfs.pod:2240
4266 "Note also that many functions don't take any arguments, in which case the "
4267 "C<guestfs_I<foo>_args> is completely omitted."
4271 #: ../src/guestfs.pod:2243
4273 "The header contains the procedure number (C<guestfs_proc>) which is how the "
4274 "receiver knows what type of args structure to expect, or none at all."
4278 #: ../src/guestfs.pod:2247
4280 "For functions that take optional arguments, the optional arguments are "
4281 "encoded in the C<guestfs_I<foo>_args> structure in the same way as ordinary "
4282 "arguments. A bitmask in the header indicates which optional arguments are "
4283 "meaningful. The bitmask is also checked to see if it contains bits set "
4284 "which the daemon does not know about (eg. if more optional arguments were "
4285 "added in a later version of the library), and this causes the call to be "
4290 #: ../src/guestfs.pod:2255
4291 msgid "The reply message for ordinary functions is:"
4295 #: ../src/guestfs.pod:2257
4298 " total length (header + ret,\n"
4299 " but not including the length word itself)\n"
4300 " struct guestfs_message_header (encoded as XDR)\n"
4301 " struct guestfs_<foo>_ret (encoded as XDR)\n"
4306 #: ../src/guestfs.pod:2262
4308 "As above the C<guestfs_I<foo>_ret> structure may be completely omitted for "
4309 "functions that return no formal return values."
4313 #: ../src/guestfs.pod:2265
4314 msgid "As above the total length of the reply is limited to C<GUESTFS_MESSAGE_MAX>."
4318 #: ../src/guestfs.pod:2268
4320 "In the case of an error, a flag is set in the header, and the reply message "
4321 "is slightly changed:"
4325 #: ../src/guestfs.pod:2271
4328 " total length (header + error,\n"
4329 " but not including the length word itself)\n"
4330 " struct guestfs_message_header (encoded as XDR)\n"
4331 " struct guestfs_message_error (encoded as XDR)\n"
4336 #: ../src/guestfs.pod:2276
4338 "The C<guestfs_message_error> structure contains the error message as a "
4343 #: ../src/guestfs.pod:2279
4344 msgid "FUNCTIONS THAT HAVE FILEIN PARAMETERS"
4348 #: ../src/guestfs.pod:2281
4350 "A C<FileIn> parameter indicates that we transfer a file I<into> the guest. "
4351 "The normal request message is sent (see above). However this is followed by "
4352 "a sequence of file chunks."
4356 #: ../src/guestfs.pod:2285
4359 " total length (header + arguments,\n"
4360 " but not including the length word itself,\n"
4361 " and not including the chunks)\n"
4362 " struct guestfs_message_header (encoded as XDR)\n"
4363 " struct guestfs_<foo>_args (encoded as XDR)\n"
4364 " sequence of chunks for FileIn param #0\n"
4365 " sequence of chunks for FileIn param #1 etc.\n"
4370 #: ../src/guestfs.pod:2293
4371 msgid "The \"sequence of chunks\" is:"
4375 #: ../src/guestfs.pod:2295
4378 " length of chunk (not including length word itself)\n"
4379 " struct guestfs_chunk (encoded as XDR)\n"
4380 " length of chunk\n"
4381 " struct guestfs_chunk (encoded as XDR)\n"
4383 " length of chunk\n"
4384 " struct guestfs_chunk (with data.data_len == 0)\n"
4389 #: ../src/guestfs.pod:2303
4391 "The final chunk has the C<data_len> field set to zero. Additionally a flag "
4392 "is set in the final chunk to indicate either successful completion or early "
4397 #: ../src/guestfs.pod:2307
4399 "At time of writing there are no functions that have more than one FileIn "
4400 "parameter. However this is (theoretically) supported, by sending the "
4401 "sequence of chunks for each FileIn parameter one after another (from left to "
4406 #: ../src/guestfs.pod:2312
4408 "Both the library (sender) I<and> the daemon (receiver) may cancel the "
4409 "transfer. The library does this by sending a chunk with a special flag set "
4410 "to indicate cancellation. When the daemon sees this, it cancels the whole "
4411 "RPC, does I<not> send any reply, and goes back to reading the next request."
4415 #: ../src/guestfs.pod:2318
4417 "The daemon may also cancel. It does this by writing a special word "
4418 "C<GUESTFS_CANCEL_FLAG> to the socket. The library listens for this during "
4419 "the transfer, and if it gets it, it will cancel the transfer (it sends a "
4420 "cancel chunk). The special word is chosen so that even if cancellation "
4421 "happens right at the end of the transfer (after the library has finished "
4422 "writing and has started listening for the reply), the \"spurious\" cancel "
4423 "flag will not be confused with the reply message."
4427 #: ../src/guestfs.pod:2327
4429 "This protocol allows the transfer of arbitrary sized files (no 32 bit "
4430 "limit), and also files where the size is not known in advance (eg. from "
4431 "pipes or sockets). However the chunks are rather small "
4432 "(C<GUESTFS_MAX_CHUNK_SIZE>), so that neither the library nor the daemon need "
4433 "to keep much in memory."
4437 #: ../src/guestfs.pod:2333
4438 msgid "FUNCTIONS THAT HAVE FILEOUT PARAMETERS"
4442 #: ../src/guestfs.pod:2335
4444 "The protocol for FileOut parameters is exactly the same as for FileIn "
4445 "parameters, but with the roles of daemon and library reversed."
4449 #: ../src/guestfs.pod:2338
4452 " total length (header + ret,\n"
4453 " but not including the length word itself,\n"
4454 " and not including the chunks)\n"
4455 " struct guestfs_message_header (encoded as XDR)\n"
4456 " struct guestfs_<foo>_ret (encoded as XDR)\n"
4457 " sequence of chunks for FileOut param #0\n"
4458 " sequence of chunks for FileOut param #1 etc.\n"
4463 #: ../src/guestfs.pod:2346
4464 msgid "INITIAL MESSAGE"
4468 #: ../src/guestfs.pod:2348
4470 "When the daemon launches it sends an initial word (C<GUESTFS_LAUNCH_FLAG>) "
4471 "which indicates that the guest and daemon is alive. This is what "
4472 "L</guestfs_launch> waits for."
4476 #: ../src/guestfs.pod:2352
4477 msgid "PROGRESS NOTIFICATION MESSAGES"
4481 #: ../src/guestfs.pod:2354
4483 "The daemon may send progress notification messages at any time. These are "
4484 "distinguished by the normal length word being replaced by "
4485 "C<GUESTFS_PROGRESS_FLAG>, followed by a fixed size progress message."
4489 #: ../src/guestfs.pod:2358
4491 "The library turns them into progress callbacks (see "
4492 "L</GUESTFS_EVENT_PROGRESS>) if there is a callback registered, or discards "
4497 #: ../src/guestfs.pod:2362
4499 "The daemon self-limits the frequency of progress messages it sends (see "
4500 "C<daemon/proto.c:notify_progress>). Not all calls generate progress "
4505 #: ../src/guestfs.pod:2366
4506 msgid "LIBGUESTFS VERSION NUMBERS"
4510 #: ../src/guestfs.pod:2368
4512 "Since April 2010, libguestfs has started to make separate development and "
4513 "stable releases, along with corresponding branches in our git repository. "
4514 "These separate releases can be identified by version number:"
4518 #: ../src/guestfs.pod:2373
4521 " even numbers for stable: 1.2.x, 1.4.x, ...\n"
4522 " .-------- odd numbers for development: 1.3.x, 1.5.x, ...\n"
4528 " | `-------- sub-version\n"
4530 " `------ always '1' because we don't change the ABI\n"
4535 #: ../src/guestfs.pod:2384
4536 msgid "Thus \"1.3.5\" is the 5th update to the development branch \"1.3\"."
4540 #: ../src/guestfs.pod:2386
4542 "As time passes we cherry pick fixes from the development branch and backport "
4543 "those into the stable branch, the effect being that the stable branch should "
4544 "get more stable and less buggy over time. So the stable releases are ideal "
4545 "for people who don't need new features but would just like the software to "
4550 #: ../src/guestfs.pod:2392
4551 msgid "Our criteria for backporting changes are:"
4555 #: ../src/guestfs.pod:2398
4557 "Documentation changes which don't affect any code are backported unless the "
4558 "documentation refers to a future feature which is not in stable."
4562 #: ../src/guestfs.pod:2404
4564 "Bug fixes which are not controversial, fix obvious problems, and have been "
4565 "well tested are backported."
4569 #: ../src/guestfs.pod:2409
4571 "Simple rearrangements of code which shouldn't affect how it works get "
4572 "backported. This is so that the code in the two branches doesn't get too "
4573 "far out of step, allowing us to backport future fixes more easily.&q