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 1.9.3\n"
10 "Report-Msgid-Bugs-To: libguestfs@redhat.com\n"
11 "POT-Creation-Date: 2011-01-11 21:54+0000\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:1011 ../src/guestfs.pod:1015 ../src/guestfs.pod:1019 ../src/guestfs.pod:1024 ../src/guestfs.pod:1032 ../src/guestfs.pod:1051 ../src/guestfs.pod:1059 ../src/guestfs.pod:1081 ../src/guestfs.pod:1085 ../src/guestfs.pod:1089 ../src/guestfs.pod:1093 ../src/guestfs.pod:1097 ../src/guestfs.pod:1101 ../src/guestfs.pod:1583 ../src/guestfs.pod:1588 ../src/guestfs.pod:1592 ../src/guestfs.pod:1702 ../src/guestfs.pod:1707 ../src/guestfs.pod:1711 ../src/guestfs.pod:2063 ../src/guestfs.pod:2069 ../src/guestfs.pod:2074 ../src/guestfs.pod:2080 ../src/guestfs.pod:2544 ../src/guestfs.pod:2548 ../src/guestfs.pod:2552 ../src/guestfs.pod:2556 ../src/guestfs-actions.pod:15 ../src/guestfs-actions.pod:22 ../src/guestfs-actions.pod:569 ../src/guestfs-actions.pod:577 ../src/guestfs-actions.pod:584 ../src/guestfs-actions.pod:591 ../src/guestfs-actions.pod:1587 ../src/guestfs-actions.pod:1591 ../src/guestfs-actions.pod:1595 ../src/guestfs-actions.pod:1599 ../src/guestfs-actions.pod:1607 ../src/guestfs-actions.pod:1611 ../src/guestfs-actions.pod:1615 ../src/guestfs-actions.pod:1625 ../src/guestfs-actions.pod:1629 ../src/guestfs-actions.pod:1633 ../src/guestfs-actions.pod:1771 ../src/guestfs-actions.pod:1775 ../src/guestfs-actions.pod:1780 ../src/guestfs-actions.pod:1785 ../src/guestfs-actions.pod:1846 ../src/guestfs-actions.pod:1850 ../src/guestfs-actions.pod:1855 ../fish/guestfish.pod:427 ../fish/guestfish.pod:431 ../fish/guestfish.pod:435 ../fish/guestfish.pod:439 ../fish/guestfish-actions.pod:13 ../fish/guestfish-actions.pod:20 ../fish/guestfish-actions.pod:373 ../fish/guestfish-actions.pod:381 ../fish/guestfish-actions.pod:388 ../fish/guestfish-actions.pod:395 ../fish/guestfish-actions.pod:1065 ../fish/guestfish-actions.pod:1069 ../fish/guestfish-actions.pod:1073 ../fish/guestfish-actions.pod:1077 ../fish/guestfish-actions.pod:1085 ../fish/guestfish-actions.pod:1089 ../fish/guestfish-actions.pod:1093 ../fish/guestfish-actions.pod:1103 ../fish/guestfish-actions.pod:1107 ../fish/guestfish-actions.pod:1111 ../fish/guestfish-actions.pod:1201 ../fish/guestfish-actions.pod:1205 ../fish/guestfish-actions.pod:1210 ../fish/guestfish-actions.pod:1215 ../fish/guestfish-actions.pod:1257 ../fish/guestfish-actions.pod:1261 ../fish/guestfish-actions.pod:1266 ../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:1204 ../src/guestfs.pod:1335 ../src/guestfs.pod:2108
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:1208 ../src/guestfs.pod:1339 ../src/guestfs.pod:2133
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:1345
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:720
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. (These APIs used to be in a separate Perl-only "
1112 "library called L<Sys::Guestfs::Lib(3)> but since version 1.5.3 the most "
1113 "frequently used part of this library has been rewritten in C and moved into "
1118 #: ../src/guestfs.pod:558
1120 "Add all disks belonging to the unknown virtual machine and call "
1121 "L</guestfs_launch> in the usual way."
1125 #: ../src/guestfs.pod:561
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:570
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:576
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:583
1161 " /boot => /dev/sda1\n"
1162 " / => /dev/vg_guest/lv_root\n"
1163 " /usr => /dev/vg_guest/lv_usr\n"
1168 #: ../src/guestfs.pod:587
1170 "The caller can then make calls to L</guestfs_mount_options> to mount the "
1171 "filesystems as suggested."
1175 #: ../src/guestfs.pod:590
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:594
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:598
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:602
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:611
1213 msgid "SPECIAL CONSIDERATIONS FOR WINDOWS GUESTS"
1217 #: ../src/guestfs.pod:613
1219 "Libguestfs can mount NTFS partitions. It does this using the "
1220 "L<http://www.ntfs-3g.org/> driver."
1224 #: ../src/guestfs.pod:616
1225 msgid "DRIVE LETTERS AND PATHS"
1229 #: ../src/guestfs.pod:618
1231 "DOS and Windows still use drive letters, and the filesystems are always "
1232 "treated as case insensitive by Windows itself, and therefore you might find "
1233 "a Windows configuration file referring to a path like "
1234 "C<c:\\windows\\system32>. When the filesystem is mounted in libguestfs, "
1235 "that directory might be referred to as C</WINDOWS/System32>."
1239 #: ../src/guestfs.pod:624
1241 "Drive letter mappings are outside the scope of libguestfs. You have to use "
1242 "libguestfs to read the appropriate Windows Registry and configuration files, "
1243 "to determine yourself how drives are mapped (see also L<hivex(3)> and "
1244 "L<virt-inspector(1)>)."
1248 #: ../src/guestfs.pod:629
1250 "Replacing backslash characters with forward slash characters is also outside "
1251 "the scope of libguestfs, but something that you can easily do."
1255 #: ../src/guestfs.pod:632
1257 "Where we can help is in resolving the case insensitivity of paths. For "
1258 "this, call L</guestfs_case_sensitive_path>."
1262 #: ../src/guestfs.pod:635
1263 msgid "ACCESSING THE WINDOWS REGISTRY"
1267 #: ../src/guestfs.pod:637
1269 "Libguestfs also provides some help for decoding Windows Registry \"hive\" "
1270 "files, through the library C<hivex> which is part of the libguestfs project "
1271 "although ships as a separate tarball. You have to locate and download the "
1272 "hive file(s) yourself, and then pass them to C<hivex> functions. See also "
1273 "the programs L<hivexml(1)>, L<hivexsh(1)>, L<hivexregedit(1)> and "
1274 "L<virt-win-reg(1)> for more help on this issue."
1278 #: ../src/guestfs.pod:645
1279 msgid "SYMLINKS ON NTFS-3G FILESYSTEMS"
1283 #: ../src/guestfs.pod:647
1285 "Ntfs-3g tries to rewrite \"Junction Points\" and NTFS \"symbolic links\" to "
1286 "provide something which looks like a Linux symlink. The way it tries to do "
1287 "the rewriting is described here:"
1291 #: ../src/guestfs.pod:651
1292 msgid "L<http://www.tuxera.com/community/ntfs-3g-advanced/junction-points-and-symbolic-links/>"
1296 #: ../src/guestfs.pod:653
1298 "The essential problem is that ntfs-3g simply does not have enough "
1299 "information to do a correct job. NTFS links can contain drive letters and "
1300 "references to external device GUIDs that ntfs-3g has no way of resolving. "
1301 "It is almost certainly the case that libguestfs callers should ignore what "
1302 "ntfs-3g does (ie. don't use L</guestfs_readlink> on NTFS volumes)."
1306 #: ../src/guestfs.pod:660
1308 "Instead if you encounter a symbolic link on an ntfs-3g filesystem, use "
1309 "L</guestfs_lgetxattr> to read the C<system.ntfs_reparse_data> extended "
1310 "attribute, and read the raw reparse data from that (you can find the format "
1311 "documented in various places around the web)."
1315 #: ../src/guestfs.pod:665
1316 msgid "EXTENDED ATTRIBUTES ON NTFS-3G FILESYSTEMS"
1320 #: ../src/guestfs.pod:667
1322 "There are other useful extended attributes that can be read from ntfs-3g "
1323 "filesystems (using L</guestfs_getxattr>). See:"
1327 #: ../src/guestfs.pod:670
1328 msgid "L<http://www.tuxera.com/community/ntfs-3g-advanced/extended-attributes/>"
1332 #: ../src/guestfs.pod:672
1333 msgid "USING LIBGUESTFS WITH OTHER PROGRAMMING LANGUAGES"
1337 #: ../src/guestfs.pod:674
1339 "Although we don't want to discourage you from using the C API, we will "
1340 "mention here that the same API is also available in other languages."
1344 #: ../src/guestfs.pod:677
1346 "The API is broadly identical in all supported languages. This means that "
1347 "the C call C<guestfs_add_drive_ro(g,file)> is C<$g-E<gt>add_drive_ro($file)> "
1348 "in Perl, C<g.add_drive_ro(file)> in Python, and C<g#add_drive_ro file> in "
1349 "OCaml. In other words, a straightforward, predictable isomorphism between "
1354 #: ../src/guestfs.pod:683
1356 "Error messages are automatically transformed into exceptions if the language "
1361 #: ../src/guestfs.pod:686
1363 "We don't try to \"object orientify\" parts of the API in OO languages, "
1364 "although contributors are welcome to write higher level APIs above what we "
1365 "provide in their favourite languages if they wish."
1369 #: ../src/guestfs.pod:692
1374 #: ../src/guestfs.pod:694
1376 "You can use the I<guestfs.h> header file from C++ programs. The C++ API is "
1377 "identical to the C API. C++ classes and exceptions are not used."
1381 #: ../src/guestfs.pod:698
1386 #: ../src/guestfs.pod:700
1388 "The C# bindings are highly experimental. Please read the warnings at the "
1389 "top of C<csharp/Libguestfs.cs>."
1393 #: ../src/guestfs.pod:703
1398 #: ../src/guestfs.pod:705
1400 "This is the only language binding that is working but incomplete. Only "
1401 "calls which return simple integers have been bound in Haskell, and we are "
1402 "looking for help to complete this binding."
1406 #: ../src/guestfs.pod:709
1411 #: ../src/guestfs.pod:711
1413 "Full documentation is contained in the Javadoc which is distributed with "
1418 #: ../src/guestfs.pod:714
1423 #: ../src/guestfs.pod:716
1424 msgid "See L<guestfs-ocaml(3)>."
1428 #: ../src/guestfs.pod:718
1433 #: ../src/guestfs.pod:720
1434 msgid "See L<Sys::Guestfs(3)>."
1438 #: ../src/guestfs.pod:722
1443 #: ../src/guestfs.pod:724
1445 "For documentation see C<README-PHP> supplied with libguestfs sources or in "
1446 "the php-libguestfs package for your distribution."
1450 #: ../src/guestfs.pod:727
1451 msgid "The PHP binding only works correctly on 64 bit machines."
1455 #: ../src/guestfs.pod:729
1460 #: ../src/guestfs.pod:731
1461 msgid "See L<guestfs-python(3)>."
1465 #: ../src/guestfs.pod:733
1470 #: ../src/guestfs.pod:735
1471 msgid "See L<guestfs-ruby(3)>."
1475 #: ../src/guestfs.pod:737
1476 msgid "B<shell scripts>"
1480 #: ../src/guestfs.pod:739
1481 msgid "See L<guestfish(1)>."
1485 #: ../src/guestfs.pod:743
1486 msgid "LIBGUESTFS GOTCHAS"
1490 #: ../src/guestfs.pod:745
1492 "L<http://en.wikipedia.org/wiki/Gotcha_(programming)>: \"A feature of a "
1493 "system [...] that works in the way it is documented but is counterintuitive "
1494 "and almost invites mistakes.\""
1498 #: ../src/guestfs.pod:749
1500 "Since we developed libguestfs and the associated tools, there are several "
1501 "things we would have designed differently, but are now stuck with for "
1502 "backwards compatibility or other reasons. If there is ever a libguestfs 2.0 "
1503 "release, you can expect these to change. Beware of them."
1507 #: ../src/guestfs.pod:757
1508 msgid "Autosync / forgetting to sync."
1512 #: ../src/guestfs.pod:759
1514 "When modifying a filesystem from C or another language, you B<must> unmount "
1515 "all filesystems and call L</guestfs_sync> explicitly before you close the "
1516 "libguestfs handle. You can also call:"
1520 #: ../src/guestfs.pod:763
1523 " guestfs_set_autosync (g, 1);\n"
1528 #: ../src/guestfs.pod:765
1530 "to have the unmount/sync done automatically for you when the handle 'g' is "
1531 "closed. (This feature is called \"autosync\", L</guestfs_set_autosync> "
1536 #: ../src/guestfs.pod:769
1538 "If you forget to do this, then it is entirely possible that your changes "
1539 "won't be written out, or will be partially written, or (very rarely) that "
1540 "you'll get disk corruption."
1544 #: ../src/guestfs.pod:773
1546 "Note that in L<guestfish(3)> autosync is the default. So quick and dirty "
1547 "guestfish scripts that forget to sync will work just fine, which can make "
1548 "this very puzzling if you are trying to debug a problem."
1552 #: ../src/guestfs.pod:777
1554 "Update: Autosync is enabled by default for all API users starting from "
1555 "libguestfs 1.5.24."
1559 #: ../src/guestfs.pod:780
1560 msgid "Mount option C<-o sync> should not be the default."
1564 #: ../src/guestfs.pod:782
1566 "If you use L</guestfs_mount>, then C<-o sync,noatime> are added implicitly. "
1567 "However C<-o sync> does not add any reliability benefit, but does have a "
1568 "very large performance impact."
1572 #: ../src/guestfs.pod:786
1574 "The work around is to use L</guestfs_mount_options> and set the mount "
1575 "options that you actually want to use."
1579 #: ../src/guestfs.pod:789
1580 msgid "Read-only should be the default."
1584 #: ../src/guestfs.pod:791
1586 "In L<guestfish(3)>, I<--ro> should be the default, and you should have to "
1587 "specify I<--rw> if you want to make changes to the image."
1591 #: ../src/guestfs.pod:794
1592 msgid "This would reduce the potential to corrupt live VM images."
1596 #: ../src/guestfs.pod:796
1598 "Note that many filesystems change the disk when you just mount and unmount, "
1599 "even if you didn't perform any writes. You need to use "
1600 "L</guestfs_add_drive_ro> to guarantee that the disk is not changed."
1604 #: ../src/guestfs.pod:800
1605 msgid "guestfish command line is hard to use."
1609 #: ../src/guestfs.pod:802
1611 "C<guestfish disk.img> doesn't do what people expect (open C<disk.img> for "
1612 "examination). It tries to run a guestfish command C<disk.img> which doesn't "
1613 "exist, so it fails. In earlier versions of guestfish the error message was "
1614 "also unintuitive, but we have corrected this since. Like the Bourne shell, "
1615 "we should have used C<guestfish -c command> to run commands."
1619 #: ../src/guestfs.pod:809
1620 msgid "guestfish megabyte modifiers don't work right on all commands"
1624 #: ../src/guestfs.pod:811
1626 "In recent guestfish you can use C<1M> to mean 1 megabyte (and similarly for "
1627 "other modifiers). What guestfish actually does is to multiply the number "
1628 "part by the modifier part and pass the result to the C API. However this "
1629 "doesn't work for a few APIs which aren't expecting bytes, but are already "
1630 "expecting some other unit (eg. megabytes)."
1634 #: ../src/guestfs.pod:818
1635 msgid "The most common is L</guestfs_lvcreate>. The guestfish command:"
1639 #: ../src/guestfs.pod:820
1642 " lvcreate LV VG 100M\n"
1647 #: ../src/guestfs.pod:822
1649 "does not do what you might expect. Instead because L</guestfs_lvcreate> is "
1650 "already expecting megabytes, this tries to create a 100 I<terabyte> (100 "
1651 "megabytes * megabytes) logical volume. The error message you get from this "
1652 "is also a little obscure."
1656 #: ../src/guestfs.pod:827
1658 "This could be fixed in the generator by specially marking parameters and "
1659 "return values which take bytes or other units."
1663 #: ../src/guestfs.pod:830
1664 msgid "Ambiguity between devices and paths"
1668 #: ../src/guestfs.pod:832
1670 "There is a subtle ambiguity in the API between a device name "
1671 "(eg. C</dev/sdb2>) and a similar pathname. A file might just happen to be "
1672 "called C<sdb2> in the directory C</dev> (consider some non-Unix VM image)."
1676 #: ../src/guestfs.pod:837
1678 "In the current API we usually resolve this ambiguity by having two separate "
1679 "calls, for example L</guestfs_checksum> and L</guestfs_checksum_device>. "
1680 "Some API calls are ambiguous and (incorrectly) resolve the problem by "
1681 "detecting if the path supplied begins with C</dev/>."
1685 #: ../src/guestfs.pod:843
1687 "To avoid both the ambiguity and the need to duplicate some calls, we could "
1688 "make paths/devices into structured names. One way to do this would be to "
1689 "use a notation like grub (C<hd(0,0)>), although nobody really likes this "
1690 "aspect of grub. Another way would be to use a structured type, equivalent "
1691 "to this OCaml type:"
1695 #: ../src/guestfs.pod:849
1698 " type path = Path of string | Device of int | Partition of int * int\n"
1703 #: ../src/guestfs.pod:851
1704 msgid "which would allow you to pass arguments like:"
1708 #: ../src/guestfs.pod:853
1711 " Path \"/foo/bar\"\n"
1712 " Device 1 (* /dev/sdb, or perhaps /dev/sda *)\n"
1713 " Partition (1, 2) (* /dev/sdb2 (or is it /dev/sda2 or /dev/sdb3?) *)\n"
1714 " Path \"/dev/sdb2\" (* not a device *)\n"
1719 #: ../src/guestfs.pod:858
1721 "As you can see there are still problems to resolve even with this "
1722 "representation. Also consider how it might work in guestfish."
1726 #: ../src/guestfs.pod:863
1727 msgid "PROTOCOL LIMITS"
1731 #: ../src/guestfs.pod:865
1733 "Internally libguestfs uses a message-based protocol to pass API calls and "
1734 "their responses to and from a small \"appliance\" (see L</INTERNALS> for "
1735 "plenty more detail about this). The maximum message size used by the "
1736 "protocol is slightly less than 4 MB. For some API calls you may need to be "
1737 "aware of this limit. The API calls which may be affected are individually "
1738 "documented, with a link back to this section of the documentation."
1742 #: ../src/guestfs.pod:873
1744 "A simple call such as L</guestfs_cat> returns its result (the file data) in "
1745 "a simple string. Because this string is at some point internally encoded as "
1746 "a message, the maximum size that it can return is slightly under 4 MB. If "
1747 "the requested file is larger than this then you will get an error."
1751 #: ../src/guestfs.pod:879
1753 "In order to transfer large files into and out of the guest filesystem, you "
1754 "need to use particular calls that support this. The sections L</UPLOADING> "
1755 "and L</DOWNLOADING> document how to do this."
1759 #: ../src/guestfs.pod:883
1761 "You might also consider mounting the disk image using our FUSE filesystem "
1762 "support (L<guestmount(1)>)."
1766 #: ../src/guestfs.pod:886
1767 msgid "KEYS AND PASSPHRASES"
1771 #: ../src/guestfs.pod:888
1773 "Certain libguestfs calls take a parameter that contains sensitive key "
1774 "material, passed in as a C string."
1778 #: ../src/guestfs.pod:891
1780 "In the future we would hope to change the libguestfs implementation so that "
1781 "keys are L<mlock(2)>-ed into physical RAM, and thus can never end up in "
1782 "swap. However this is I<not> done at the moment, because of the complexity "
1783 "of such an implementation."
1787 #: ../src/guestfs.pod:896
1789 "Therefore you should be aware that any key parameter you pass to libguestfs "
1790 "might end up being written out to the swap partition. If this is a concern, "
1791 "scrub the swap partition or don't use libguestfs on encrypted devices."
1795 #: ../src/guestfs.pod:901
1796 msgid "MULTIPLE HANDLES AND MULTIPLE THREADS"
1800 #: ../src/guestfs.pod:903
1802 "All high-level libguestfs actions are synchronous. If you want to use "
1803 "libguestfs asynchronously then you must create a thread."
1807 #: ../src/guestfs.pod:906
1809 "Only use the handle from a single thread. Either use the handle exclusively "
1810 "from one thread, or provide your own mutex so that two threads cannot issue "
1811 "calls on the same handle at the same time."
1815 #: ../src/guestfs.pod:910
1817 "See the graphical program guestfs-browser for one possible architecture for "
1818 "multithreaded programs using libvirt and libguestfs."
1822 #: ../src/guestfs.pod:913
1827 #: ../src/guestfs.pod:915
1829 "Libguestfs needs a kernel and initrd.img, which it finds by looking along an "
1834 #: ../src/guestfs.pod:918
1836 "By default it looks for these in the directory C<$libdir/guestfs> "
1837 "(eg. C</usr/local/lib/guestfs> or C</usr/lib64/guestfs>)."
1841 #: ../src/guestfs.pod:921
1843 "Use L</guestfs_set_path> or set the environment variable L</LIBGUESTFS_PATH> "
1844 "to change the directories that libguestfs will search in. The value is a "
1845 "colon-separated list of paths. The current directory is I<not> searched "
1846 "unless the path contains an empty element or C<.>. For example "
1847 "C<LIBGUESTFS_PATH=:/usr/lib/guestfs> would search the current directory and "
1848 "then C</usr/lib/guestfs>."
1852 #: ../src/guestfs.pod:928
1853 msgid "QEMU WRAPPERS"
1857 #: ../src/guestfs.pod:930
1859 "If you want to compile your own qemu, run qemu from a non-standard location, "
1860 "or pass extra arguments to qemu, then you can write a shell-script wrapper "
1865 #: ../src/guestfs.pod:934
1867 "There is one important rule to remember: you I<must C<exec qemu>> as the "
1868 "last command in the shell script (so that qemu replaces the shell and "
1869 "becomes the direct child of the libguestfs-using program). If you don't do "
1870 "this, then the qemu process won't be cleaned up correctly."
1874 #: ../src/guestfs.pod:939
1876 "Here is an example of a wrapper, where I have built my own copy of qemu from "
1881 #: ../src/guestfs.pod:942
1885 " qemudir=/home/rjones/d/qemu\n"
1886 " exec $qemudir/x86_64-softmmu/qemu-system-x86_64 -L $qemudir/pc-bios "
1892 #: ../src/guestfs.pod:946
1894 "Save this script as C</tmp/qemu.wrapper> (or wherever), C<chmod +x>, and "
1895 "then use it by setting the LIBGUESTFS_QEMU environment variable. For "
1900 #: ../src/guestfs.pod:950
1903 " LIBGUESTFS_QEMU=/tmp/qemu.wrapper guestfish\n"
1908 #: ../src/guestfs.pod:952
1910 "Note that libguestfs also calls qemu with the -help and -version options in "
1911 "order to determine features."
1915 #: ../src/guestfs.pod:955
1916 msgid "ABI GUARANTEE"
1920 #: ../src/guestfs.pod:957
1922 "We guarantee the libguestfs ABI (binary interface), for public, high-level "
1923 "actions as outlined in this section. Although we will deprecate some "
1924 "actions, for example if they get replaced by newer calls, we will keep the "
1925 "old actions forever. This allows you the developer to program in confidence "
1926 "against the libguestfs API."
1930 #: ../src/guestfs.pod:963
1931 msgid "BLOCK DEVICE NAMING"
1935 #: ../src/guestfs.pod:965
1937 "In the kernel there is now quite a profusion of schemata for naming block "
1938 "devices (in this context, by I<block device> I mean a physical or virtual "
1939 "hard drive). The original Linux IDE driver used names starting with "
1940 "C</dev/hd*>. SCSI devices have historically used a different naming scheme, "
1941 "C</dev/sd*>. When the Linux kernel I<libata> driver became a popular "
1942 "replacement for the old IDE driver (particularly for SATA devices) those "
1943 "devices also used the C</dev/sd*> scheme. Additionally we now have virtual "
1944 "machines with paravirtualized drivers. This has created several different "
1945 "naming systems, such as C</dev/vd*> for virtio disks and C</dev/xvd*> for "
1950 #: ../src/guestfs.pod:977
1952 "As discussed above, libguestfs uses a qemu appliance running an embedded "
1953 "Linux kernel to access block devices. We can run a variety of appliances "
1954 "based on a variety of Linux kernels."
1958 #: ../src/guestfs.pod:981
1960 "This causes a problem for libguestfs because many API calls use device or "
1961 "partition names. Working scripts and the recipe (example) scripts that we "
1962 "make available over the internet could fail if the naming scheme changes."
1966 #: ../src/guestfs.pod:986
1968 "Therefore libguestfs defines C</dev/sd*> as the I<standard naming scheme>. "
1969 "Internally C</dev/sd*> names are translated, if necessary, to other names as "
1970 "required. For example, under RHEL 5 which uses the C</dev/hd*> scheme, any "
1971 "device parameter C</dev/sda2> is translated to C</dev/hda2> transparently."
1975 #: ../src/guestfs.pod:992
1977 "Note that this I<only> applies to parameters. The L</guestfs_list_devices>, "
1978 "L</guestfs_list_partitions> and similar calls return the true names of the "
1979 "devices and partitions as known to the appliance."
1983 #: ../src/guestfs.pod:997
1984 msgid "ALGORITHM FOR BLOCK DEVICE NAME TRANSLATION"
1988 #: ../src/guestfs.pod:999
1990 "Usually this translation is transparent. However in some (very rare) cases "
1991 "you may need to know the exact algorithm. Such cases include where you use "
1992 "L</guestfs_config> to add a mixture of virtio and IDE devices to the "
1993 "qemu-based appliance, so have a mixture of C</dev/sd*> and C</dev/vd*> "
1998 #: ../src/guestfs.pod:1005
2000 "The algorithm is applied only to I<parameters> which are known to be either "
2001 "device or partition names. Return values from functions such as "
2002 "L</guestfs_list_devices> are never changed."
2006 #: ../src/guestfs.pod:1013
2007 msgid "Is the string a parameter which is a device or partition name?"
2011 #: ../src/guestfs.pod:1017
2012 msgid "Does the string begin with C</dev/sd>?"
2016 #: ../src/guestfs.pod:1021
2018 "Does the named device exist? If so, we use that device. However if I<not> "
2019 "then we continue with this algorithm."
2023 #: ../src/guestfs.pod:1026
2024 msgid "Replace initial C</dev/sd> string with C</dev/hd>."
2028 #: ../src/guestfs.pod:1028
2029 msgid "For example, change C</dev/sda2> to C</dev/hda2>."
2033 #: ../src/guestfs.pod:1030
2034 msgid "If that named device exists, use it. If not, continue."
2038 #: ../src/guestfs.pod:1034
2039 msgid "Replace initial C</dev/sd> string with C</dev/vd>."
2043 #: ../src/guestfs.pod:1036
2044 msgid "If that named device exists, use it. If not, return an error."
2048 #: ../src/guestfs.pod:1040
2049 msgid "PORTABILITY CONCERNS WITH BLOCK DEVICE NAMING"
2053 #: ../src/guestfs.pod:1042
2055 "Although the standard naming scheme and automatic translation is useful for "
2056 "simple programs and guestfish scripts, for larger programs it is best not to "
2057 "rely on this mechanism."
2061 #: ../src/guestfs.pod:1046
2063 "Where possible for maximum future portability programs using libguestfs "
2064 "should use these future-proof techniques:"
2068 #: ../src/guestfs.pod:1053
2070 "Use L</guestfs_list_devices> or L</guestfs_list_partitions> to list actual "
2071 "device names, and then use those names directly."
2075 #: ../src/guestfs.pod:1056
2076 msgid "Since those device names exist by definition, they will never be translated."
2080 #: ../src/guestfs.pod:1061
2082 "Use higher level ways to identify filesystems, such as LVM names, UUIDs and "
2083 "filesystem labels."
2087 #: ../src/guestfs.pod:1066
2092 #: ../src/guestfs.pod:1068
2094 "This section discusses security implications of using libguestfs, "
2095 "particularly with untrusted or malicious guests or disk images."
2099 #: ../src/guestfs.pod:1071
2100 msgid "GENERAL SECURITY CONSIDERATIONS"
2104 #: ../src/guestfs.pod:1073
2106 "Be careful with any files or data that you download from a guest (by "
2107 "\"download\" we mean not just the L</guestfs_download> command but any "
2108 "command that reads files, filenames, directories or anything else from a "
2109 "disk image). An attacker could manipulate the data to fool your program "
2110 "into doing the wrong thing. Consider cases such as:"
2114 #: ../src/guestfs.pod:1083
2115 msgid "the data (file etc) not being present"
2119 #: ../src/guestfs.pod:1087
2120 msgid "being present but empty"
2124 #: ../src/guestfs.pod:1091
2125 msgid "being much larger than normal"
2129 #: ../src/guestfs.pod:1095
2130 msgid "containing arbitrary 8 bit data"
2134 #: ../src/guestfs.pod:1099
2135 msgid "being in an unexpected character encoding"
2139 #: ../src/guestfs.pod:1103
2140 msgid "containing homoglyphs."
2144 #: ../src/guestfs.pod:1107
2145 msgid "SECURITY OF MOUNTING FILESYSTEMS"
2149 #: ../src/guestfs.pod:1109
2151 "When you mount a filesystem under Linux, mistakes in the kernel filesystem "
2152 "(VFS) module can sometimes be escalated into exploits by deliberately "
2153 "creating a malicious, malformed filesystem. These exploits are very severe "
2154 "for two reasons. Firstly there are very many filesystem drivers in the "
2155 "kernel, and many of them are infrequently used and not much developer "
2156 "attention has been paid to the code. Linux userspace helps potential "
2157 "crackers by detecting the filesystem type and automatically choosing the "
2158 "right VFS driver, even if that filesystem type is obscure or unexpected for "
2159 "the administrator. Secondly, a kernel-level exploit is like a local root "
2160 "exploit (worse in some ways), giving immediate and total access to the "
2161 "system right down to the hardware level."
2165 #: ../src/guestfs.pod:1122
2167 "That explains why you should never mount a filesystem from an untrusted "
2168 "guest on your host kernel. How about libguestfs? We run a Linux kernel "
2169 "inside a qemu virtual machine, usually running as a non-root user. The "
2170 "attacker would need to write a filesystem which first exploited the kernel, "
2171 "and then exploited either qemu virtualization (eg. a faulty qemu driver) or "
2172 "the libguestfs protocol, and finally to be as serious as the host kernel "
2173 "exploit it would need to escalate its privileges to root. This multi-step "
2174 "escalation, performed by a static piece of data, is thought to be extremely "
2175 "hard to do, although we never say 'never' about security issues."
2179 #: ../src/guestfs.pod:1133
2181 "In any case callers can reduce the attack surface by forcing the filesystem "
2182 "type when mounting (use L</guestfs_mount_vfs>)."
2186 #: ../src/guestfs.pod:1136
2187 msgid "PROTOCOL SECURITY"
2191 #: ../src/guestfs.pod:1138
2193 "The protocol is designed to be secure, being based on RFC 4506 (XDR) with a "
2194 "defined upper message size. However a program that uses libguestfs must "
2195 "also take care - for example you can write a program that downloads a binary "
2196 "from a disk image and executes it locally, and no amount of protocol "
2197 "security will save you from the consequences."
2201 #: ../src/guestfs.pod:1144
2202 msgid "INSPECTION SECURITY"
2206 #: ../src/guestfs.pod:1146
2208 "Parts of the inspection API (see L</INSPECTION>) return untrusted strings "
2209 "directly from the guest, and these could contain any 8 bit data. Callers "
2210 "should be careful to escape these before printing them to a structured file "
2211 "(for example, use HTML escaping if creating a web page)."
2215 #: ../src/guestfs.pod:1152
2217 "Guest configuration may be altered in unusual ways by the administrator of "
2218 "the virtual machine, and may not reflect reality (particularly for untrusted "
2219 "or actively malicious guests). For example we parse the hostname from "
2220 "configuration files like C</etc/sysconfig/network> that we find in the "
2221 "guest, but the guest administrator can easily manipulate these files to "
2222 "provide the wrong hostname."
2226 #: ../src/guestfs.pod:1160
2228 "The inspection API parses guest configuration using two external libraries: "
2229 "Augeas (Linux configuration) and hivex (Windows Registry). Both are "
2230 "designed to be robust in the face of malicious data, although denial of "
2231 "service attacks are still possible, for example with oversized configuration "
2236 #: ../src/guestfs.pod:1166
2237 msgid "RUNNING UNTRUSTED GUEST COMMANDS"
2241 #: ../src/guestfs.pod:1168
2243 "Be very cautious about running commands from the guest. By running a "
2244 "command in the guest, you are giving CPU time to a binary that you do not "
2245 "control, under the same user account as the library, albeit wrapped in qemu "
2246 "virtualization. More information and alternatives can be found in the "
2247 "section L</RUNNING COMMANDS>."
2251 #: ../src/guestfs.pod:1174
2252 msgid "CVE-2010-3851"
2256 #: ../src/guestfs.pod:1176
2257 msgid "https://bugzilla.redhat.com/642934"
2261 #: ../src/guestfs.pod:1178
2263 "This security bug concerns the automatic disk format detection that qemu "
2264 "does on disk images."
2268 #: ../src/guestfs.pod:1181
2270 "A raw disk image is just the raw bytes, there is no header. Other disk "
2271 "images like qcow2 contain a special header. Qemu deals with this by looking "
2272 "for one of the known headers, and if none is found then assuming the disk "
2273 "image must be raw."
2277 #: ../src/guestfs.pod:1186
2279 "This allows a guest which has been given a raw disk image to write some "
2280 "other header. At next boot (or when the disk image is accessed by "
2281 "libguestfs) qemu would do autodetection and think the disk image format was, "
2282 "say, qcow2 based on the header written by the guest."
2286 #: ../src/guestfs.pod:1191
2288 "This in itself would not be a problem, but qcow2 offers many features, one "
2289 "of which is to allow a disk image to refer to another image (called the "
2290 "\"backing disk\"). It does this by placing the path to the backing disk "
2291 "into the qcow2 header. This path is not validated and could point to any "
2292 "host file (eg. \"/etc/passwd\"). The backing disk is then exposed through "
2293 "\"holes\" in the qcow2 disk image, which of course is completely under the "
2294 "control of the attacker."
2298 #: ../src/guestfs.pod:1199
2299 msgid "In libguestfs this is rather hard to exploit except under two circumstances:"
2303 #: ../src/guestfs.pod:1206
2304 msgid "You have enabled the network or have opened the disk in write mode."
2308 #: ../src/guestfs.pod:1210
2310 "You are also running untrusted code from the guest (see L</RUNNING "
2315 #: ../src/guestfs.pod:1215
2317 "The way to avoid this is to specify the expected disk format when adding "
2318 "disks (the optional C<format> option to L</guestfs_add_drive_opts>). You "
2319 "should always do this if the disk is raw format, and it's a good idea for "
2324 #: ../src/guestfs.pod:1220
2326 "For disks added from libvirt using calls like L</guestfs_add_domain>, the "
2327 "format is fetched from libvirt and passed through."
2331 #: ../src/guestfs.pod:1223
2333 "For libguestfs tools, use the I<--format> command line parameter as "
2338 #: ../src/guestfs.pod:1226
2339 msgid "CONNECTION MANAGEMENT"
2343 #: ../src/guestfs.pod:1228
2348 #: ../src/guestfs.pod:1230
2350 "C<guestfs_h> is the opaque type representing a connection handle. Create a "
2351 "handle by calling L</guestfs_create>. Call L</guestfs_close> to free the "
2352 "handle and release all resources used."
2356 #: ../src/guestfs.pod:1234
2358 "For information on using multiple handles and threads, see the section "
2359 "L</MULTIPLE HANDLES AND MULTIPLE THREADS> below."
2363 #: ../src/guestfs.pod:1237
2364 msgid "guestfs_create"
2368 #: ../src/guestfs.pod:1239
2371 " guestfs_h *guestfs_create (void);\n"
2376 #: ../src/guestfs.pod:1241
2377 msgid "Create a connection handle."
2381 #: ../src/guestfs.pod:1243
2383 "You have to call L</guestfs_add_drive_opts> (or one of the equivalent calls) "
2384 "on the handle at least once."
2388 #: ../src/guestfs.pod:1246
2390 "This function returns a non-NULL pointer to a handle on success or NULL on "
2395 #: ../src/guestfs.pod:1249
2396 msgid "After configuring the handle, you have to call L</guestfs_launch>."
2400 #: ../src/guestfs.pod:1251
2402 "You may also want to configure error handling for the handle. See L</ERROR "
2403 "HANDLING> section below."
2407 #: ../src/guestfs.pod:1254
2408 msgid "guestfs_close"
2412 #: ../src/guestfs.pod:1256
2415 " void guestfs_close (guestfs_h *g);\n"
2420 #: ../src/guestfs.pod:1258
2421 msgid "This closes the connection handle and frees up all resources used."
2425 #: ../src/guestfs.pod:1260
2426 msgid "ERROR HANDLING"
2430 #: ../src/guestfs.pod:1262
2432 "API functions can return errors. For example, almost all functions that "
2433 "return C<int> will return C<-1> to indicate an error."
2437 #: ../src/guestfs.pod:1265
2439 "Additional information is available for errors: an error message string and "
2440 "optionally an error number (errno) if the thing that failed was a system "
2445 #: ../src/guestfs.pod:1269
2447 "You can get at the additional information about the last error on the handle "
2448 "by calling L</guestfs_last_error>, L</guestfs_last_errno>, and/or by setting "
2449 "up an error handler with L</guestfs_set_error_handler>."
2453 #: ../src/guestfs.pod:1274
2455 "When the handle is created, a default error handler is installed which "
2456 "prints the error message string to C<stderr>. For small short-running "
2457 "command line programs it is sufficient to do:"
2461 #: ../src/guestfs.pod:1278
2464 " if (guestfs_launch (g) == -1)\n"
2465 " exit (EXIT_FAILURE);\n"
2470 #: ../src/guestfs.pod:1281
2472 "since the default error handler will ensure that an error message has been "
2473 "printed to C<stderr> before the program exits."
2477 #: ../src/guestfs.pod:1284
2479 "For other programs the caller will almost certainly want to install an "
2480 "alternate error handler or do error handling in-line like this:"
2484 #: ../src/guestfs.pod:1287
2487 " g = guestfs_create ();\n"
2492 #: ../src/guestfs.pod:1289
2495 " /* This disables the default behaviour of printing errors\n"
2497 " guestfs_set_error_handler (g, NULL, NULL);\n"
2502 #: ../src/guestfs.pod:1293
2505 " if (guestfs_launch (g) == -1) {\n"
2506 " /* Examine the error message and print it etc. */\n"
2507 " char *msg = guestfs_last_error (g);\n"
2508 " int errnum = guestfs_last_errno (g);\n"
2509 " fprintf (stderr, \"%s\\n\", msg);\n"
2516 #: ../src/guestfs.pod:1301
2518 "Out of memory errors are handled differently. The default action is to call "
2519 "L<abort(3)>. If this is undesirable, then you can set a handler using "
2520 "L</guestfs_set_out_of_memory_handler>."
2524 #: ../src/guestfs.pod:1305
2526 "L</guestfs_create> returns C<NULL> if the handle cannot be created, and "
2527 "because there is no handle if this happens there is no way to get additional "
2528 "error information. However L</guestfs_create> is supposed to be a "
2529 "lightweight operation which can only fail because of insufficient memory (it "
2530 "returns NULL in this case)."
2534 #: ../src/guestfs.pod:1311
2535 msgid "guestfs_last_error"
2539 #: ../src/guestfs.pod:1313
2542 " const char *guestfs_last_error (guestfs_h *g);\n"
2547 #: ../src/guestfs.pod:1315
2549 "This returns the last error message that happened on C<g>. If there has not "
2550 "been an error since the handle was created, then this returns C<NULL>."
2554 #: ../src/guestfs.pod:1319
2556 "The lifetime of the returned string is until the next error occurs, or "
2557 "L</guestfs_close> is called."
2561 #: ../src/guestfs.pod:1322
2562 msgid "guestfs_last_errno"
2566 #: ../src/guestfs.pod:1324
2569 " int guestfs_last_errno (guestfs_h *g);\n"
2574 #: ../src/guestfs.pod:1326
2575 msgid "This returns the last error number (errno) that happened on C<g>."
2579 #: ../src/guestfs.pod:1328
2580 msgid "If successful, an errno integer not equal to zero is returned."
2584 #: ../src/guestfs.pod:1330
2585 msgid "If no error, this returns 0. This call can return 0 in three situations:"
2589 #: ../src/guestfs.pod:1337
2590 msgid "There has not been any error on the handle."
2594 #: ../src/guestfs.pod:1341
2596 "There has been an error but the errno was meaningless. This corresponds to "
2597 "the case where the error did not come from a failed system call, but for "
2598 "some other reason."
2602 #: ../src/guestfs.pod:1347
2604 "There was an error from a failed system call, but for some reason the errno "
2605 "was not captured and returned. This usually indicates a bug in libguestfs."
2609 #: ../src/guestfs.pod:1353
2611 "Libguestfs tries to convert the errno from inside the applicance into a "
2612 "corresponding errno for the caller (not entirely trivial: the appliance "
2613 "might be running a completely different operating system from the library "
2614 "and error numbers are not standardized across Un*xen). If this could not be "
2615 "done, then the error is translated to C<EINVAL>. In practice this should "
2616 "only happen in very rare circumstances."
2620 #: ../src/guestfs.pod:1361
2621 msgid "guestfs_set_error_handler"
2625 #: ../src/guestfs.pod:1363
2628 " typedef void (*guestfs_error_handler_cb) (guestfs_h *g,\n"
2630 " const char *msg);\n"
2631 " void guestfs_set_error_handler (guestfs_h *g,\n"
2632 " guestfs_error_handler_cb cb,\n"
2638 #: ../src/guestfs.pod:1370
2640 "The callback C<cb> will be called if there is an error. The parameters "
2641 "passed to the callback are an opaque data pointer and the error message "
2646 #: ../src/guestfs.pod:1374
2648 "C<errno> is not passed to the callback. To get that the callback must call "
2649 "L</guestfs_last_errno>."
2653 #: ../src/guestfs.pod:1377
2655 "Note that the message string C<msg> is freed as soon as the callback "
2656 "function returns, so if you want to stash it somewhere you must make your "
2661 #: ../src/guestfs.pod:1381
2662 msgid "The default handler prints messages on C<stderr>."
2666 #: ../src/guestfs.pod:1383
2667 msgid "If you set C<cb> to C<NULL> then I<no> handler is called."
2671 #: ../src/guestfs.pod:1385
2672 msgid "guestfs_get_error_handler"
2676 #: ../src/guestfs.pod:1387
2679 " guestfs_error_handler_cb guestfs_get_error_handler (guestfs_h *g,\n"
2680 " void **opaque_rtn);\n"
2685 #: ../src/guestfs.pod:1390
2686 msgid "Returns the current error handler callback."
2690 #: ../src/guestfs.pod:1392
2691 msgid "guestfs_set_out_of_memory_handler"
2695 #: ../src/guestfs.pod:1394
2698 " typedef void (*guestfs_abort_cb) (void);\n"
2699 " int guestfs_set_out_of_memory_handler (guestfs_h *g,\n"
2700 " guestfs_abort_cb);\n"
2705 #: ../src/guestfs.pod:1398
2707 "The callback C<cb> will be called if there is an out of memory situation. "
2708 "I<Note this callback must not return>."
2712 #: ../src/guestfs.pod:1401
2713 msgid "The default is to call L<abort(3)>."
2717 #: ../src/guestfs.pod:1403
2718 msgid "You cannot set C<cb> to C<NULL>. You can't ignore out of memory situations."
2722 #: ../src/guestfs.pod:1406
2723 msgid "guestfs_get_out_of_memory_handler"
2727 #: ../src/guestfs.pod:1408
2730 " guestfs_abort_fn guestfs_get_out_of_memory_handler (guestfs_h *g);\n"
2735 #: ../src/guestfs.pod:1410
2736 msgid "This returns the current out of memory handler."
2740 #: ../src/guestfs.pod:1412
2745 #: ../src/guestfs.pod:1414 ../fish/guestfish.pod:958
2750 #: ../src/guestfs.pod:1416
2755 #: ../src/guestfs.pod:1418
2760 #: ../src/guestfs.pod:1420
2761 msgid "AVAILABILITY"
2765 #: ../src/guestfs.pod:1422
2766 msgid "GROUPS OF FUNCTIONALITY IN THE APPLIANCE"
2770 #: ../src/guestfs.pod:1424
2772 "Using L</guestfs_available> you can test availability of the following "
2773 "groups of functions. This test queries the appliance to see if the "
2774 "appliance you are currently using supports the functionality."
2778 #: ../src/guestfs.pod:1429
2779 msgid "@AVAILABILITY@"
2783 #: ../src/guestfs.pod:1431
2784 msgid "GUESTFISH supported COMMAND"
2788 #: ../src/guestfs.pod:1433
2790 "In L<guestfish(3)> there is a handy interactive command C<supported> which "
2791 "prints out the available groups and whether they are supported by this build "
2792 "of libguestfs. Note however that you have to do C<run> first."
2796 #: ../src/guestfs.pod:1438
2797 msgid "SINGLE CALLS AT COMPILE TIME"
2801 #: ../src/guestfs.pod:1440
2803 "Since version 1.5.8, C<E<lt>guestfs.hE<gt>> defines symbols for each C API "
2804 "function, such as:"
2808 #: ../src/guestfs.pod:1443
2811 " #define LIBGUESTFS_HAVE_DD 1\n"
2816 #: ../src/guestfs.pod:1445
2817 msgid "if L</guestfs_dd> is available."
2821 #: ../src/guestfs.pod:1447
2823 "Before version 1.5.8, if you needed to test whether a single libguestfs "
2824 "function is available at compile time, we recommended using build tools such "
2825 "as autoconf or cmake. For example in autotools you could use:"
2829 #: ../src/guestfs.pod:1452
2832 " AC_CHECK_LIB([guestfs],[guestfs_create])\n"
2833 " AC_CHECK_FUNCS([guestfs_dd])\n"
2838 #: ../src/guestfs.pod:1455
2840 "which would result in C<HAVE_GUESTFS_DD> being either defined or not defined "
2845 #: ../src/guestfs.pod:1458
2846 msgid "SINGLE CALLS AT RUN TIME"
2850 #: ../src/guestfs.pod:1460
2852 "Testing at compile time doesn't guarantee that a function really exists in "
2853 "the library. The reason is that you might be dynamically linked against a "
2854 "previous I<libguestfs.so> (dynamic library) which doesn't have the call. "
2855 "This situation unfortunately results in a segmentation fault, which is a "
2856 "shortcoming of the C dynamic linking system itself."
2860 #: ../src/guestfs.pod:1467
2862 "You can use L<dlopen(3)> to test if a function is available at run time, as "
2863 "in this example program (note that you still need the compile time check as "
2868 #: ../src/guestfs.pod:1471
2871 " #include <stdio.h>\n"
2872 " #include <stdlib.h>\n"
2873 " #include <unistd.h>\n"
2874 " #include <dlfcn.h>\n"
2875 " #include <guestfs.h>\n"
2880 #: ../src/guestfs.pod:1477
2885 " #ifdef LIBGUESTFS_HAVE_DD\n"
2887 " int has_function;\n"
2892 #: ../src/guestfs.pod:1483
2895 " /* Test if the function guestfs_dd is really available. */\n"
2896 " dl = dlopen (NULL, RTLD_LAZY);\n"
2898 " fprintf (stderr, \"dlopen: %s\\n\", dlerror ());\n"
2899 " exit (EXIT_FAILURE);\n"
2901 " has_function = dlsym (dl, \"guestfs_dd\") != NULL;\n"
2907 #: ../src/guestfs.pod:1492
2910 " if (!has_function)\n"
2911 " printf (\"this libguestfs.so does NOT have guestfs_dd function\\n\");\n"
2913 " printf (\"this libguestfs.so has guestfs_dd function\\n\");\n"
2914 " /* Now it's safe to call\n"
2915 " guestfs_dd (g, \"foo\", \"bar\");\n"
2919 " printf (\"guestfs_dd function was not found at compile time\\n\");\n"
2926 #: ../src/guestfs.pod:1505
2928 "You may think the above is an awful lot of hassle, and it is. There are "
2929 "other ways outside of the C linking system to ensure that this kind of "
2930 "incompatibility never arises, such as using package versioning:"
2934 #: ../src/guestfs.pod:1510
2937 " Requires: libguestfs >= 1.0.80\n"
2942 #: ../src/guestfs.pod:1512
2943 msgid "CALLS WITH OPTIONAL ARGUMENTS"
2947 #: ../src/guestfs.pod:1514
2949 "A recent feature of the API is the introduction of calls which take optional "
2950 "arguments. In C these are declared 3 ways. The main way is as a call which "
2951 "takes variable arguments (ie. C<...>), as in this example:"
2955 #: ../src/guestfs.pod:1519
2958 " int guestfs_add_drive_opts (guestfs_h *g, const char *filename, ...);\n"
2963 #: ../src/guestfs.pod:1521
2965 "Call this with a list of optional arguments, terminated by C<-1>. So to "
2966 "call with no optional arguments specified:"
2970 #: ../src/guestfs.pod:1524
2973 " guestfs_add_drive_opts (g, filename, -1);\n"
2978 #: ../src/guestfs.pod:1526
2979 msgid "With a single optional argument:"
2983 #: ../src/guestfs.pod:1528
2986 " guestfs_add_drive_opts (g, filename,\n"
2987 " GUESTFS_ADD_DRIVE_OPTS_FORMAT, \"qcow2\",\n"
2993 #: ../src/guestfs.pod:1532
2998 #: ../src/guestfs.pod:1534
3001 " guestfs_add_drive_opts (g, filename,\n"
3002 " GUESTFS_ADD_DRIVE_OPTS_FORMAT, \"qcow2\",\n"
3003 " GUESTFS_ADD_DRIVE_OPTS_READONLY, 1,\n"
3009 #: ../src/guestfs.pod:1539
3011 "and so forth. Don't forget the terminating C<-1> otherwise Bad Things will "
3016 #: ../src/guestfs.pod:1542
3017 msgid "USING va_list FOR OPTIONAL ARGUMENTS"
3021 #: ../src/guestfs.pod:1544
3023 "The second variant has the same name with the suffix C<_va>, which works the "
3024 "same way but takes a C<va_list>. See the C manual for details. For the "
3025 "example function, this is declared:"
3029 #: ../src/guestfs.pod:1548
3032 " int guestfs_add_drive_opts_va (guestfs_h *g, const char *filename,\n"
3038 #: ../src/guestfs.pod:1551
3039 msgid "CONSTRUCTING OPTIONAL ARGUMENTS"
3043 #: ../src/guestfs.pod:1553
3045 "The third variant is useful where you need to construct these calls. You "
3046 "pass in a structure where you fill in the optional fields. The structure "
3047 "has a bitmask as the first element which you must set to indicate which "
3048 "fields you have filled in. For our example function the structure and call "
3053 #: ../src/guestfs.pod:1559
3056 " struct guestfs_add_drive_opts_argv {\n"
3057 " uint64_t bitmask;\n"
3059 " const char *format;\n"
3062 " int guestfs_add_drive_opts_argv (guestfs_h *g, const char *filename,\n"
3063 " const struct guestfs_add_drive_opts_argv *optargs);\n"
3068 #: ../src/guestfs.pod:1568
3069 msgid "You could call it like this:"
3073 #: ../src/guestfs.pod:1570
3076 " struct guestfs_add_drive_opts_argv optargs = {\n"
3077 " .bitmask = GUESTFS_ADD_DRIVE_OPTS_READONLY_BITMASK |\n"
3078 " GUESTFS_ADD_DRIVE_OPTS_FORMAT_BITMASK,\n"
3080 " .format = \"qcow2\"\n"
3086 #: ../src/guestfs.pod:1577
3089 " guestfs_add_drive_opts_argv (g, filename, &optargs);\n"
3094 #: ../src/guestfs.pod:1579 ../src/guestfs-actions.pod:11 ../src/guestfs-actions.pod:1842 ../fish/guestfish-actions.pod:9 ../fish/guestfish-actions.pod:1253 ../tools/virt-win-reg.pl:532
3099 #: ../src/guestfs.pod:1585
3100 msgid "The C<_BITMASK> suffix on each option name when specifying the bitmask."
3104 #: ../src/guestfs.pod:1590
3105 msgid "You do not need to fill in all fields of the structure."
3109 #: ../src/guestfs.pod:1594
3111 "There must be a one-to-one correspondence between fields of the structure "
3112 "that are filled in, and bits set in the bitmask."
3116 #: ../src/guestfs.pod:1599
3117 msgid "OPTIONAL ARGUMENTS IN OTHER LANGUAGES"
3121 #: ../src/guestfs.pod:1601
3123 "In other languages, optional arguments are expressed in the way that is "
3124 "natural for that language. We refer you to the language-specific "
3125 "documentation for more details on that."
3129 #: ../src/guestfs.pod:1605
3130 msgid "For guestfish, see L<guestfish(1)/OPTIONAL ARGUMENTS>."
3134 #: ../src/guestfs.pod:1607
3135 msgid "SETTING CALLBACKS TO HANDLE EVENTS"
3139 #: ../src/guestfs.pod:1609
3141 "The child process generates events in some situations. Current events "
3142 "include: receiving a log message, the child process exits."
3146 #: ../src/guestfs.pod:1612
3148 "Use the C<guestfs_set_*_callback> functions to set a callback for different "
3153 #: ../src/guestfs.pod:1615
3155 "Only I<one callback of each type> can be registered for each handle. "
3156 "Calling C<guestfs_set_*_callback> again overwrites the previous callback of "
3157 "that type. Cancel all callbacks of this type by calling this function with "
3158 "C<cb> set to C<NULL>."
3162 #: ../src/guestfs.pod:1620
3163 msgid "guestfs_set_log_message_callback"
3167 #: ../src/guestfs.pod:1622
3170 " typedef void (*guestfs_log_message_cb) (guestfs_h *g, void *opaque,\n"
3171 " char *buf, int len);\n"
3172 " void guestfs_set_log_message_callback (guestfs_h *g,\n"
3173 " guestfs_log_message_cb cb,\n"
3179 #: ../src/guestfs.pod:1628
3181 "The callback function C<cb> will be called whenever qemu or the guest writes "
3182 "anything to the console."
3186 #: ../src/guestfs.pod:1631
3187 msgid "Use this function to capture kernel messages and similar."
3191 #: ../src/guestfs.pod:1633
3193 "Normally there is no log message handler, and log messages are just "
3198 #: ../src/guestfs.pod:1636
3199 msgid "guestfs_set_subprocess_quit_callback"
3203 #: ../src/guestfs.pod:1638
3206 " typedef void (*guestfs_subprocess_quit_cb) (guestfs_h *g, void *opaque);\n"
3207 " void guestfs_set_subprocess_quit_callback (guestfs_h *g,\n"
3208 " guestfs_subprocess_quit_cb cb,\n"
3214 #: ../src/guestfs.pod:1643
3216 "The callback function C<cb> will be called when the child process quits, "
3217 "either asynchronously or if killed by L</guestfs_kill_subprocess>. (This "
3218 "corresponds to a transition from any state to the CONFIG state)."
3222 #: ../src/guestfs.pod:1648
3223 msgid "guestfs_set_launch_done_callback"
3227 #: ../src/guestfs.pod:1650
3230 " typedef void (*guestfs_launch_done_cb) (guestfs_h *g, void *opaque);\n"
3231 " void guestfs_set_launch_done_callback (guestfs_h *g,\n"
3232 " guestfs_launch_done_cb cb,\n"
3238 #: ../src/guestfs.pod:1655
3240 "The callback function C<cb> will be called when the child process becomes "
3241 "ready first time after it has been launched. (This corresponds to a "
3242 "transition from LAUNCHING to the READY state)."
3246 #: ../src/guestfs.pod:1659
3247 msgid "guestfs_set_close_callback"
3251 #: ../src/guestfs.pod:1661
3254 " typedef void (*guestfs_close_cb) (guestfs_h *g, void *opaque);\n"
3255 " void guestfs_set_close_callback (guestfs_h *g,\n"
3256 " guestfs_close_cb cb,\n"
3262 #: ../src/guestfs.pod:1666
3264 "The callback function C<cb> will be called while the handle is being closed "
3265 "(synchronously from L</guestfs_close>)."
3269 #: ../src/guestfs.pod:1669
3271 "Note that libguestfs installs an L<atexit(3)> handler to try to clean up "
3272 "handles that are open when the program exits. This means that this callback "
3273 "might be called indirectly from L<exit(3)>, which can cause unexpected "
3274 "problems in higher-level languages (eg. if your HLL interpreter has already "
3275 "been cleaned up by the time this is called, and if your callback then jumps "
3276 "into some HLL function)."
3280 #: ../src/guestfs.pod:1677
3281 msgid "guestfs_set_progress_callback"
3285 #: ../src/guestfs.pod:1679
3288 " typedef void (*guestfs_progress_cb) (guestfs_h *g, void *opaque,\n"
3289 " int proc_nr, int serial,\n"
3290 " uint64_t position, uint64_t total);\n"
3291 " void guestfs_set_progress_callback (guestfs_h *g,\n"
3292 " guestfs_progress_cb cb,\n"
3298 #: ../src/guestfs.pod:1686
3300 "Some long-running operations can generate progress messages. If this "
3301 "callback is registered, then it will be called each time a progress message "
3302 "is generated (usually two seconds after the operation started, and three "
3303 "times per second thereafter until it completes, although the frequency may "
3304 "change in future versions)."
3308 #: ../src/guestfs.pod:1692
3310 "The callback receives two numbers: C<position> and C<total>. The units of "
3311 "C<total> are not defined, although for some operations C<total> may relate "
3312 "in some way to the amount of data to be transferred (eg. in bytes or "
3313 "megabytes), and C<position> may be the portion which has been transferred."
3317 #: ../src/guestfs.pod:1698
3318 msgid "The only defined and stable parts of the API are:"
3322 #: ../src/guestfs.pod:1704
3324 "The callback can display to the user some type of progress bar or indicator "
3325 "which shows the ratio of C<position>:C<total>."
3329 #: ../src/guestfs.pod:1709
3330 msgid "0 E<lt>= C<position> E<lt>= C<total>"
3334 #: ../src/guestfs.pod:1713
3336 "If any progress notification is sent during a call, then a final progress "
3337 "notification is always sent when C<position> = C<total>."
3341 #: ../src/guestfs.pod:1716
3343 "This is to simplify caller code, so callers can easily set the progress "
3344 "indicator to \"100%\" at the end of the operation, without requiring special "
3345 "code to detect this case."
3349 #: ../src/guestfs.pod:1722
3351 "The callback also receives the procedure number and serial number of the "
3352 "call. These are only useful for debugging protocol issues, and the callback "
3353 "can normally ignore them. The callback may want to print these numbers in "
3354 "error messages or debugging messages."
3358 #: ../src/guestfs.pod:1727
3359 msgid "PRIVATE DATA AREA"
3363 #: ../src/guestfs.pod:1729
3365 "You can attach named pieces of private data to the libguestfs handle, and "
3366 "fetch them by name for the lifetime of the handle. This is called the "
3367 "private data area and is only available from the C API."
3371 #: ../src/guestfs.pod:1733
3372 msgid "To attach a named piece of data, use the following call:"
3376 #: ../src/guestfs.pod:1735
3379 " void guestfs_set_private (guestfs_h *g, const char *key, void *data);\n"
3384 #: ../src/guestfs.pod:1737
3386 "C<key> is the name to associate with this data, and C<data> is an arbitrary "
3387 "pointer (which can be C<NULL>). Any previous item with the same name is "
3392 #: ../src/guestfs.pod:1741
3394 "You can use any C<key> you want, but names beginning with an underscore "
3395 "character are reserved for internal libguestfs purposes (for implementing "
3396 "language bindings). It is recommended to prefix the name with some unique "
3397 "string to avoid collisions with other users."
3401 #: ../src/guestfs.pod:1746
3402 msgid "To retrieve the pointer, use:"
3406 #: ../src/guestfs.pod:1748
3409 " void *guestfs_get_private (guestfs_h *g, const char *key);\n"
3414 #: ../src/guestfs.pod:1750
3416 "This function returns C<NULL> if either no data is found associated with "
3417 "C<key>, or if the user previously set the C<key>'s C<data> pointer to "
3422 #: ../src/guestfs.pod:1754
3424 "Libguestfs does not try to look at or interpret the C<data> pointer in any "
3425 "way. As far as libguestfs is concerned, it need not be a valid pointer at "
3426 "all. In particular, libguestfs does I<not> try to free the data when the "
3427 "handle is closed. If the data must be freed, then the caller must either "
3428 "free it before calling L</guestfs_close> or must set up a close callback to "
3429 "do it (see L</guestfs_set_close_callback>, and note that only one callback "
3430 "can be registered for a handle)."
3434 #: ../src/guestfs.pod:1762
3436 "The private data area is implemented using a hash table, and should be "
3437 "reasonably efficient for moderate numbers of keys."
3441 #: ../src/guestfs.pod:1765 ../src/guestfs.pod:1770
3446 #: ../src/guestfs.pod:1767
3448 "<!-- old anchor for the next section --> <a "
3449 "name=\"state_machine_and_low_level_event_api\"/>"
3453 #: ../src/guestfs.pod:1772
3454 msgid "ARCHITECTURE"
3458 #: ../src/guestfs.pod:1774
3460 "Internally, libguestfs is implemented by running an appliance (a special "
3461 "type of small virtual machine) using L<qemu(1)>. Qemu runs as a child "
3462 "process of the main program."
3466 #: ../src/guestfs.pod:1778
3469 " ___________________\n"
3471 " | main program |\n"
3473 " | | child process / appliance\n"
3474 " | | __________________________\n"
3476 " +-------------------+ RPC | +-----------------+ |\n"
3477 " | libguestfs <--------------------> guestfsd | |\n"
3478 " | | | +-----------------+ |\n"
3479 " \\___________________/ | | Linux kernel | |\n"
3480 " | +--^--------------+ |\n"
3481 " \\_________|________________/\n"
3487 " \\______________/\n"
3492 #: ../src/guestfs.pod:1798
3494 "The library, linked to the main program, creates the child process and hence "
3495 "the appliance in the L</guestfs_launch> function."
3499 #: ../src/guestfs.pod:1801
3501 "Inside the appliance is a Linux kernel and a complete stack of userspace "
3502 "tools (such as LVM and ext2 programs) and a small controlling daemon called "
3503 "L</guestfsd>. The library talks to L</guestfsd> using remote procedure "
3504 "calls (RPC). There is a mostly one-to-one correspondence between libguestfs "
3505 "API calls and RPC calls to the daemon. Lastly the disk image(s) are "
3506 "attached to the qemu process which translates device access by the "
3507 "appliance's Linux kernel into accesses to the image."
3511 #: ../src/guestfs.pod:1810
3513 "A common misunderstanding is that the appliance \"is\" the virtual machine. "
3514 "Although the disk image you are attached to might also be used by some "
3515 "virtual machine, libguestfs doesn't know or care about this. (But you will "
3516 "care if both libguestfs's qemu process and your virtual machine are trying "
3517 "to update the disk image at the same time, since these usually results in "
3518 "massive disk corruption)."
3522 #: ../src/guestfs.pod:1817
3523 msgid "STATE MACHINE"
3527 #: ../src/guestfs.pod:1819
3528 msgid "libguestfs uses a state machine to model the child process:"
3532 #: ../src/guestfs.pod:1821
3544 " / | \\ \\ guestfs_launch\n"
3545 " / | _\\__V______\n"
3547 " / | | LAUNCHING |\n"
3548 " / | \\___________/\n"
3550 " / | guestfs_launch\n"
3552 " ______ / __|____V\n"
3553 " / \\ ------> / \\\n"
3554 " | BUSY | | READY |\n"
3555 " \\______/ <------ \\________/\n"
3560 #: ../src/guestfs.pod:1843
3562 "The normal transitions are (1) CONFIG (when the handle is created, but there "
3563 "is no child process), (2) LAUNCHING (when the child process is booting up), "
3564 "(3) alternating between READY and BUSY as commands are issued to, and "
3565 "carried out by, the child process."
3569 #: ../src/guestfs.pod:1848
3571 "The guest may be killed by L</guestfs_kill_subprocess>, or may die "
3572 "asynchronously at any time (eg. due to some internal error), and that causes "
3573 "the state to transition back to CONFIG."
3577 #: ../src/guestfs.pod:1852
3579 "Configuration commands for qemu such as L</guestfs_add_drive> can only be "
3580 "issued when in the CONFIG state."
3584 #: ../src/guestfs.pod:1855
3586 "The API offers one call that goes from CONFIG through LAUNCHING to READY. "
3587 "L</guestfs_launch> blocks until the child process is READY to accept "
3588 "commands (or until some failure or timeout). L</guestfs_launch> internally "
3589 "moves the state from CONFIG to LAUNCHING while it is running."
3593 #: ../src/guestfs.pod:1861
3595 "API actions such as L</guestfs_mount> can only be issued when in the READY "
3596 "state. These API calls block waiting for the command to be carried out "
3597 "(ie. the state to transition to BUSY and then back to READY). There are no "
3598 "non-blocking versions, and no way to issue more than one command per handle "
3603 #: ../src/guestfs.pod:1867
3605 "Finally, the child process sends asynchronous messages back to the main "
3606 "program, such as kernel log messages. You can register a callback to "
3607 "receive these messages."
3611 #: ../src/guestfs.pod:1871
3616 #: ../src/guestfs.pod:1873
3617 msgid "COMMUNICATION PROTOCOL"
3621 #: ../src/guestfs.pod:1875
3623 "Don't rely on using this protocol directly. This section documents how it "
3624 "currently works, but it may change at any time."
3628 #: ../src/guestfs.pod:1878
3630 "The protocol used to talk between the library and the daemon running inside "
3631 "the qemu virtual machine is a simple RPC mechanism built on top of XDR (RFC "
3632 "1014, RFC 1832, RFC 4506)."
3636 #: ../src/guestfs.pod:1882
3638 "The detailed format of structures is in C<src/guestfs_protocol.x> (note: "
3639 "this file is automatically generated)."
3643 #: ../src/guestfs.pod:1885
3645 "There are two broad cases, ordinary functions that don't have any C<FileIn> "
3646 "and C<FileOut> parameters, which are handled with very simple request/reply "
3647 "messages. Then there are functions that have any C<FileIn> or C<FileOut> "
3648 "parameters, which use the same request and reply messages, but they may also "
3649 "be followed by files sent using a chunked encoding."
3653 #: ../src/guestfs.pod:1892
3654 msgid "ORDINARY FUNCTIONS (NO FILEIN/FILEOUT PARAMS)"
3658 #: ../src/guestfs.pod:1894
3659 msgid "For ordinary functions, the request message is:"
3663 #: ../src/guestfs.pod:1896
3666 " total length (header + arguments,\n"
3667 " but not including the length word itself)\n"
3668 " struct guestfs_message_header (encoded as XDR)\n"
3669 " struct guestfs_<foo>_args (encoded as XDR)\n"
3674 #: ../src/guestfs.pod:1901
3676 "The total length field allows the daemon to allocate a fixed size buffer "
3677 "into which it slurps the rest of the message. As a result, the total length "
3678 "is limited to C<GUESTFS_MESSAGE_MAX> bytes (currently 4MB), which means the "
3679 "effective size of any request is limited to somewhere under this size."
3683 #: ../src/guestfs.pod:1907
3685 "Note also that many functions don't take any arguments, in which case the "
3686 "C<guestfs_I<foo>_args> is completely omitted."
3690 #: ../src/guestfs.pod:1910
3692 "The header contains the procedure number (C<guestfs_proc>) which is how the "
3693 "receiver knows what type of args structure to expect, or none at all."
3697 #: ../src/guestfs.pod:1914
3699 "For functions that take optional arguments, the optional arguments are "
3700 "encoded in the C<guestfs_I<foo>_args> structure in the same way as ordinary "
3701 "arguments. A bitmask in the header indicates which optional arguments are "
3702 "meaningful. The bitmask is also checked to see if it contains bits set "
3703 "which the daemon does not know about (eg. if more optional arguments were "
3704 "added in a later version of the library), and this causes the call to be "
3709 #: ../src/guestfs.pod:1922
3710 msgid "The reply message for ordinary functions is:"
3714 #: ../src/guestfs.pod:1924
3717 " total length (header + ret,\n"
3718 " but not including the length word itself)\n"
3719 " struct guestfs_message_header (encoded as XDR)\n"
3720 " struct guestfs_<foo>_ret (encoded as XDR)\n"
3725 #: ../src/guestfs.pod:1929
3727 "As above the C<guestfs_I<foo>_ret> structure may be completely omitted for "
3728 "functions that return no formal return values."
3732 #: ../src/guestfs.pod:1932
3733 msgid "As above the total length of the reply is limited to C<GUESTFS_MESSAGE_MAX>."
3737 #: ../src/guestfs.pod:1935
3739 "In the case of an error, a flag is set in the header, and the reply message "
3740 "is slightly changed:"
3744 #: ../src/guestfs.pod:1938
3747 " total length (header + error,\n"
3748 " but not including the length word itself)\n"
3749 " struct guestfs_message_header (encoded as XDR)\n"
3750 " struct guestfs_message_error (encoded as XDR)\n"
3755 #: ../src/guestfs.pod:1943
3757 "The C<guestfs_message_error> structure contains the error message as a "
3762 #: ../src/guestfs.pod:1946
3763 msgid "FUNCTIONS THAT HAVE FILEIN PARAMETERS"
3767 #: ../src/guestfs.pod:1948
3769 "A C<FileIn> parameter indicates that we transfer a file I<into> the guest. "
3770 "The normal request message is sent (see above). However this is followed by "
3771 "a sequence of file chunks."
3775 #: ../src/guestfs.pod:1952
3778 " total length (header + arguments,\n"
3779 " but not including the length word itself,\n"
3780 " and not including the chunks)\n"
3781 " struct guestfs_message_header (encoded as XDR)\n"
3782 " struct guestfs_<foo>_args (encoded as XDR)\n"
3783 " sequence of chunks for FileIn param #0\n"
3784 " sequence of chunks for FileIn param #1 etc.\n"
3789 #: ../src/guestfs.pod:1960
3790 msgid "The \"sequence of chunks\" is:"
3794 #: ../src/guestfs.pod:1962
3797 " length of chunk (not including length word itself)\n"
3798 " struct guestfs_chunk (encoded as XDR)\n"
3799 " length of chunk\n"
3800 " struct guestfs_chunk (encoded as XDR)\n"
3802 " length of chunk\n"
3803 " struct guestfs_chunk (with data.data_len == 0)\n"
3808 #: ../src/guestfs.pod:1970
3810 "The final chunk has the C<data_len> field set to zero. Additionally a flag "
3811 "is set in the final chunk to indicate either successful completion or early "
3816 #: ../src/guestfs.pod:1974
3818 "At time of writing there are no functions that have more than one FileIn "
3819 "parameter. However this is (theoretically) supported, by sending the "
3820 "sequence of chunks for each FileIn parameter one after another (from left to "
3825 #: ../src/guestfs.pod:1979
3827 "Both the library (sender) I<and> the daemon (receiver) may cancel the "
3828 "transfer. The library does this by sending a chunk with a special flag set "
3829 "to indicate cancellation. When the daemon sees this, it cancels the whole "
3830 "RPC, does I<not> send any reply, and goes back to reading the next request."
3834 #: ../src/guestfs.pod:1985
3836 "The daemon may also cancel. It does this by writing a special word "
3837 "C<GUESTFS_CANCEL_FLAG> to the socket. The library listens for this during "
3838 "the transfer, and if it gets it, it will cancel the transfer (it sends a "
3839 "cancel chunk). The special word is chosen so that even if cancellation "
3840 "happens right at the end of the transfer (after the library has finished "
3841 "writing and has started listening for the reply), the \"spurious\" cancel "
3842 "flag will not be confused with the reply message."
3846 #: ../src/guestfs.pod:1994
3848 "This protocol allows the transfer of arbitrary sized files (no 32 bit "
3849 "limit), and also files where the size is not known in advance (eg. from "
3850 "pipes or sockets). However the chunks are rather small "
3851 "(C<GUESTFS_MAX_CHUNK_SIZE>), so that neither the library nor the daemon need "
3852 "to keep much in memory."
3856 #: ../src/guestfs.pod:2000
3857 msgid "FUNCTIONS THAT HAVE FILEOUT PARAMETERS"
3861 #: ../src/guestfs.pod:2002
3863 "The protocol for FileOut parameters is exactly the same as for FileIn "
3864 "parameters, but with the roles of daemon and library reversed."
3868 #: ../src/guestfs.pod:2005
3871 " total length (header + ret,\n"
3872 " but not including the length word itself,\n"
3873 " and not including the chunks)\n"
3874 " struct guestfs_message_header (encoded as XDR)\n"
3875 " struct guestfs_<foo>_ret (encoded as XDR)\n"
3876 " sequence of chunks for FileOut param #0\n"
3877 " sequence of chunks for FileOut param #1 etc.\n"
3882 #: ../src/guestfs.pod:2013
3883 msgid "INITIAL MESSAGE"
3887 #: ../src/guestfs.pod:2015
3889 "When the daemon launches it sends an initial word (C<GUESTFS_LAUNCH_FLAG>) "
3890 "which indicates that the guest and daemon is alive. This is what "
3891 "L</guestfs_launch> waits for."
3895 #: ../src/guestfs.pod:2019
3896 msgid "PROGRESS NOTIFICATION MESSAGES"
3900 #: ../src/guestfs.pod:2021
3902 "The daemon may send progress notification messages at any time. These are "
3903 "distinguished by the normal length word being replaced by "
3904 "C<GUESTFS_PROGRESS_FLAG>, followed by a fixed size progress message."
3908 #: ../src/guestfs.pod:2025
3910 "The library turns them into progress callbacks (see "
3911 "C<guestfs_set_progress_callback>) if there is a callback registered, or "
3912 "discards them if not."
3916 #: ../src/guestfs.pod:2029
3918 "The daemon self-limits the frequency of progress messages it sends (see "
3919 "C<daemon/proto.c:notify_progress>). Not all calls generate progress "
3924 #: ../src/guestfs.pod:2033
3925 msgid "LIBGUESTFS VERSION NUMBERS"
3929 #: ../src/guestfs.pod:2035
3931 "Since April 2010, libguestfs has started to make separate development and "
3932 "stable releases, along with corresponding branches in our git repository. "
3933 "These separate releases can be identified by version number:"
3937 #: ../src/guestfs.pod:2040
3940 " even numbers for stable: 1.2.x, 1.4.x, ...\n"
3941 " .-------- odd numbers for development: 1.3.x, 1.5.x, ...\n"
3947 " | `-------- sub-version\n"
3949 " `------ always '1' because we don't change the ABI\n"
3954 #: ../src/guestfs.pod:2051
3955 msgid "Thus \"1.3.5\" is the 5th update to the development branch \"1.3\"."
3959 #: ../src/guestfs.pod:2053
3961 "As time passes we cherry pick fixes from the development branch and backport "
3962 "those into the stable branch, the effect being that the stable branch should "
3963 "get more stable and less buggy over time. So the stable releases are ideal "
3964 "for people who don't need new features but would just like the software to "
3969 #: ../src/guestfs.pod:2059
3970 msgid "Our criteria for backporting changes are:"
3974 #: ../src/guestfs.pod:2065
3976 "Documentation changes which don't affect any code are backported unless the "
3977 "documentation refers to a future feature which is not in stable."
3981 #: ../src/guestfs.pod:2071
3983 "Bug fixes which are not controversial, fix obvious problems, and have been "
3984 "well tested are backported."
3988 #: ../src/guestfs.pod:2076
3990 "Simple rearrangements of code which shouldn't affect how it works get "
3991 "backported. This is so that the code in the two branches doesn't get too "
3992 "far out of step, allowing us to backport future fixes more easily."
3996 #: ../src/guestfs.pod:2082
3998 "We I<don't> backport new features, new APIs, new tools etc, except in one "
3999 "exceptional case: the new feature is required in order to implement an "
4000 "important bug fix."
4004 #: ../src/guestfs.pod:2088
4006 "A new stable branch starts when we think the new features in development are "
4007 "substantial and compelling enough over the current stable branch to warrant "
4008 "it. When that happens we create new stable and development versions 1.N.0 "
4009 "and 1.(N+1).0 [N is even]. The new dot-oh release won't necessarily be so "
4010 "stable at this point, but by backporting fixes from development, that branch "
4011 "will stabilize over time."
4015 #: ../src/guestfs.pod:2096
4016 msgid "EXTENDING LIBGUESTFS"
4020 #: ../src/guestfs.pod:2098
4021 msgid "ADDING A NEW API ACTION"
4025 #: ../src/guestfs.pod:2100
4027 "Large amounts of boilerplate code in libguestfs (RPC, bindings, "
4028 "documentation) are generated, and this makes it easy to extend the "
4033 #: ../src/guestfs.pod:2104
4034 msgid "To add a new API action there are two changes:"
4038 #: ../src/guestfs.pod:2110
4040 "You need to add a description of the call (name, parameters, return type, "
4041 "tests, documentation) to C<generator/generator_actions.ml>."
4045 #: ../src/guestfs.pod:2113
4047 "There are two sorts of API action, depending on whether the call goes "
4048 "through to the daemon in the appliance, or is serviced entirely by the "
4049 "library (see L</ARCHITECTURE> above). L</guestfs_sync> is an example of the "
4050 "former, since the sync is done in the appliance. L</guestfs_set_trace> is "
4051 "an example of the latter, since a trace flag is maintained in the handle and "
4052 "all tracing is done on the library side."
4056 #: ../src/guestfs.pod:2121
4058 "Most new actions are of the first type, and get added to the "
4059 "C<daemon_functions> list. Each function has a unique procedure number used "
4060 "in the RPC protocol which is assigned to that action when we publish "
4061 "libguestfs and cannot be reused. Take the latest procedure number and "
4066 #: ../src/guestfs.pod:2127
4068 "For library-only actions of the second type, add to the "
4069 "C<non_daemon_functions> list. Since these functions are serviced by the "
4070 "library and do not travel over the RPC mechanism to the daemon, these "
4071 "functions do not need a procedure number, and so the procedure number is set "
4076 #: ../src/guestfs.pod:2135
4077 msgid "Implement the action (in C):"
4081 #: ../src/guestfs.pod:2137
4083 "For daemon actions, implement the function C<do_E<lt>nameE<gt>> in the "
4084 "C<daemon/> directory."
4088 #: ../src/guestfs.pod:2140
4090 "For library actions, implement the function C<guestfs__E<lt>nameE<gt>> "
4091 "(note: double underscore) in the C<src/> directory."
4095 #: ../src/guestfs.pod:2143
4096 msgid "In either case, use another function as an example of what to do."
4100 #: ../src/guestfs.pod:2147
4101 msgid "After making these changes, use C<make> to compile."
4105 #: ../src/guestfs.pod:2149
4107 "Note that you don't need to implement the RPC, language bindings, manual "
4108 "pages or anything else. It's all automatically generated from the OCaml "
4113 #: ../src/guestfs.pod:2153
4114 msgid "ADDING TESTS FOR AN API ACTION"
4118 #: ../src/guestfs.pod:2155
4120 "You can supply zero or as many tests as you want per API call. The tests "
4121 "can either be added as part of the API description "
4122 "(C<generator/generator_actions.ml>), or in some rarer cases you may want to "
4123 "drop a script into C<regressions/>. Note that adding a script to "
4124 "C<regressions/> is slower, so if possible use the first method."
4128 #: ../src/guestfs.pod:2161
4130 "The following describes the test environment used when you add an API test "
4131 "in C<generator_actions.ml>."
4135 #: ../src/guestfs.pod:2164
4136 msgid "The test environment has 4 block devices:"
4140 #: ../src/guestfs.pod:2168
4141 msgid "C</dev/sda> 500MB"
4145 #: ../src/guestfs.pod:2170
4146 msgid "General block device for testing."
4150 #: ../src/guestfs.pod:2172
4151 msgid "C</dev/sdb> 50MB"
4155 #: ../src/guestfs.pod:2174
4157 "C</dev/sdb1> is an ext2 filesystem used for testing filesystem write "
4162 #: ../src/guestfs.pod:2177
4163 msgid "C</dev/sdc> 10MB"
4167 #: ../src/guestfs.pod:2179
4168 msgid "Used in a few tests where two block devices are needed."
4172 #: ../src/guestfs.pod:2181
4177 #: ../src/guestfs.pod:2183
4178 msgid "ISO with fixed content (see C<images/test.iso>)."
4182 #: ../src/guestfs.pod:2187
4184 "To be able to run the tests in a reasonable amount of time, the libguestfs "
4185 "appliance and block devices are reused between tests. So don't try testing "
4186 "L</guestfs_kill_subprocess> :-x"
4190 #: ../src/guestfs.pod:2191
4192 "Each test starts with an initial scenario, selected using one of the "
4193 "C<Init*> expressions, described in C<generator/generator_types.ml>. These "
4194 "initialize the disks mentioned above in a particular way as documented in "
4195 "C<generator_types.ml>. You should not assume anything about the previous "
4196 "contents of other disks that are not initialized."
4200 #: ../src/guestfs.pod:2197
4202 "You can add a prerequisite clause to any individual test. This is a "
4203 "run-time check, which, if it fails, causes the test to be skipped. Useful "
4204 "if testing a command which might not work on all variations of libguestfs "
4205 "builds. A test that has prerequisite of C<Always> means to run "
4210 #: ../src/guestfs.pod:2203
4212 "In addition, packagers can skip individual tests by setting environment "
4213 "variables before running C<make check>."
4217 #: ../src/guestfs.pod:2206
4220 " SKIP_TEST_<CMD>_<NUM>=1\n"
4225 #: ../src/guestfs.pod:2208
4226 msgid "eg: C<SKIP_TEST_COMMAND_3=1> skips test #3 of L</guestfs_command>."
4230 #: ../src/guestfs.pod:2210
4235 #: ../src/guestfs.pod:2212
4238 " SKIP_TEST_<CMD>=1\n"
4243 #: ../src/guestfs.pod:2214
4244 msgid "eg: C<SKIP_TEST_ZEROFREE=1> skips all L</guestfs_zerofree> tests."
4248 #: ../src/guestfs.pod:2216
4249 msgid "Packagers can run only certain tests by setting for example:"
4253 #: ../src/guestfs.pod:2218
4256 " TEST_ONLY=\"vfs_type zerofree\"\n"
4261 #: ../src/guestfs.pod:2220
4263 "See C<capitests/tests.c> for more details of how these environment variables "
4268 #: ../src/guestfs.pod:2223
4269 msgid "DEBUGGING NEW API ACTIONS"
4273 #: ../src/guestfs.pod:2225
4274 msgid "Test new actions work before submitting them."
4278 #: ../src/guestfs.pod:2227
4279 msgid "You can use guestfish to try out new commands."
4283 #: ../src/guestfs.pod:2229
4285 "Debugging the daemon is a problem because it runs inside a minimal "
4286 "environment. However you can fprintf messages in the daemon to stderr, and "
4287 "they will show up if you use C<guestfish -v>."
4291 #: ../src/guestfs.pod:2233
4292 msgid "FORMATTING CODE AND OTHER CONVENTIONS"
4296 #: ../src/guestfs.pod:2235
4298 "Our C source code generally adheres to some basic code-formatting "
4299 "conventions. The existing code base is not totally consistent on this "
4300 "front, but we do prefer that contributed code be formatted similarly. In "
4301 "short, use spaces-not-TABs for indentation, use 2 spaces for each "
4302 "indentation level, and other than that, follow the K&R style."
4306 #: ../src/guestfs.pod:2241
4308 "If you use Emacs, add the following to one of one of your start-up files "
4309 "(e.g., ~/.emacs), to help ensure that you get indentation right:"
4313 #: ../src/guestfs.pod:2244
4316 " ;;; In libguestfs, indent with spaces everywhere (not TABs).\n"
4317 " ;;; Exceptions: Makefile and ChangeLog modes.\n"
4318 " (add-hook 'find-file-hook\n"
4319 " '(lambda () (if (and buffer-file-name\n"
4320 " (string-match \"/libguestfs\\\\>\"\n"
4321 " (buffer-file-name))\n"
4322 " (not (string-equal mode-name \"Change Log\"))\n"
4323 " (not (string-equal mode-name \"Makefile\")))\n"
4324 " (setq indent-tabs-mode nil))))\n"
4329 #: ../src/guestfs.pod:2254
4332 " ;;; When editing C sources in libguestfs, use this style.\n"
4333 " (defun libguestfs-c-mode ()\n"
4334 " \"C mode with adjusted defaults for use with libguestfs.\"\n"
4336 " (c-set-style \"K&R\")\n"
4337 " (setq c-indent-level 2)\n"
4338 " (setq c-basic-offset 2))\n"
4339 " (add-hook 'c-mode-hook\n"
4340 " '(lambda () (if (string-match \"/libguestfs\\\\>\"\n"
4341 " (buffer-file-name))\n"
4342 " (libguestfs-c-mode))))\n"
4347 #: ../src/guestfs.pod:2266
4348 msgid "Enable warnings when compiling (and fix any problems this finds):"
4352 #: ../src/guestfs.pod:2269
4355 " ./configure --enable-gcc-warnings\n"
4360 #: ../src/guestfs.pod:2271
4361 msgid "Useful targets are:"
4365 #: ../src/guestfs.pod:2273
4368 " make syntax-check # checks the syntax of the C code\n"
4369 " make check # runs the test suite\n"
4374 #: ../src/guestfs.pod:2276
4375 msgid "DAEMON CUSTOM PRINTF FORMATTERS"
4379 #: ../src/guestfs.pod:2278
4381 "In the daemon code we have created custom printf formatters C<%Q> and C<%R>, "
4382 "which are used to do shell quoting."
4386 #: ../src/guestfs.pod:2283
4391 #: ../src/guestfs.pod:2285
4393 "Simple shell quoted string. Any spaces or other shell characters are "
4398 #: ../src/guestfs.pod:2288
4403 #: ../src/guestfs.pod:2290
4405 "Same as C<%Q> except the string is treated as a path which is prefixed by "
4410 #: ../src/guestfs.pod:2295 ../fish/guestfish.pod:240 ../fish/guestfish.pod:594
4411 msgid "For example:"
4415 #: ../src/guestfs.pod:2297
4418 " asprintf (&cmd, \"cat %R\", path);\n"
4423 #: ../src/guestfs.pod:2299
4424 msgid "would produce C<cat /sysroot/some\\ path\\ with\\ spaces>"
4428 #: ../src/guestfs.pod:2301
4430 "I<Note:> Do I<not> use these when you are passing parameters to the "
4431 "C<command{,r,v,rv}()> functions. These parameters do NOT need to be quoted "
4432 "because they are not passed via the shell (instead, straight to exec). You "
4433 "probably want to use the C<sysroot_path()> function however."
4437 #: ../src/guestfs.pod:2307
4438 msgid "SUBMITTING YOUR NEW API ACTIONS"
4442 #: ../src/guestfs.pod:2309
4444 "Submit patches to the mailing list: "
4445 "L<http://www.redhat.com/mailman/listinfo/libguestfs> and CC to "
4446 "L<rjones@redhat.com>."
4450 #: ../src/guestfs.pod:2313
4451 msgid "INTERNATIONALIZATION (I18N) SUPPORT"
4455 #: ../src/guestfs.pod:2315
4456 msgid "We support i18n (gettext anyhow) in the library."
4460 #: ../src/guestfs.pod:2317
4462 "However many messages come from the daemon, and we don't translate those at "
4463 "the moment. One reason is that the appliance generally has all locale files "
4464 "removed from it, because they take up a lot of space. So we'd have to readd "
4465 "some of those, as well as copying our PO files into the appliance."
4469 #: ../src/guestfs.pod:2323
4471 "Debugging messages are never translated, since they are intended for the "
4476 #: ../src/guestfs.pod:2326
4477 msgid "SOURCE CODE SUBDIRECTORIES"
4481 #: ../src/guestfs.pod:2330
4482 msgid "C<appliance>"
4486 #: ../src/guestfs.pod:2332
4487 msgid "The libguestfs appliance, build scripts and so on."
4491 #: ../src/guestfs.pod:2334
4492 msgid "C<capitests>"
4496 #: ../src/guestfs.pod:2336
4497 msgid "Automated tests of the C API."
4501 #: ../src/guestfs.pod:2338
4506 #: ../src/guestfs.pod:2340
4508 "The L<virt-cat(1)>, L<virt-filesystems(1)> and L<virt-ls(1)> commands and "
4513 #: ../src/guestfs.pod:2343
4518 #: ../src/guestfs.pod:2345
4519 msgid "Outside contributions, experimental parts."
4523 #: ../src/guestfs.pod:2347
4528 #: ../src/guestfs.pod:2349
4530 "The daemon that runs inside the libguestfs appliance and carries out "
4535 #: ../src/guestfs.pod:2352
4540 #: ../src/guestfs.pod:2354
4541 msgid "L<virt-df(1)> command and documentation."
4545 #: ../src/guestfs.pod:2356
4550 #: ../src/guestfs.pod:2358
4551 msgid "C API example code."
4555 #: ../src/guestfs.pod:2360
4560 #: ../src/guestfs.pod:2362
4562 "L<guestfish(1)>, the command-line shell, and various shell scripts built on "
4563 "top such as L<virt-copy-in(1)>, L<virt-copy-out(1)>, L<virt-tar-in(1)>, "
4564 "L<virt-tar-out(1)>."
4568 #: ../src/guestfs.pod:2366
4573 #: ../src/guestfs.pod:2368
4574 msgid "L<guestmount(1)>, FUSE (userspace filesystem) built on top of libguestfs."
4578 #: ../src/guestfs.pod:2370
4579 msgid "C<generator>"
4583 #: ../src/guestfs.pod:2372