=head1 SYNOPSIS
#include <guestfs.h>
-
+
guestfs_h *handle = guestfs_create ();
guestfs_add_drive (handle, "guest.img");
guestfs_launch (handle);
functions in the following order:
guestfs_h *handle = guestfs_create ();
-
+
guestfs_add_drive (handle, "guest.img");
/* call guestfs_add_drive additional times if the guest has
* multiple disks
*/
-
+
guestfs_launch (handle);
guestfs_wait_ready (handle);
/* now you can examine what partitions, LVs etc are available
* you have to mount / at least
- */
+ */
guestfs_mount (handle, "/dev/sda1", "/");
/* now you can perform actions on the guest disk image */
guestfs_touch (handle, "/hello");
-
+
/* you only need to call guestfs_sync if you have made
* changes to the guest image
*/
guestfs_sync (handle);
-
+
guestfs_close (handle);
C<guestfs_wait_ready> and all of the actions including C<guestfs_sync>
Returns the current error handler callback.
-=head2 guestfs_set_out_of_memory_handler
+=head2 guestfs_set_out_of_memory_handler
typedef void (*guestfs_abort_cb) (void);
int guestfs_set_out_of_memory_handler (guestfs_h *handle,
or C<.>. For example C<LIBGUESTFS_PATH=:/usr/lib/guestfs> would
search the current directory and then C</usr/lib/guestfs>.
+=head1 API OVERVIEW
+
+This section provides additional documentation for groups of API
+calls, which may not be obvious from reading about the individual
+calls below.
+
+=head2 LVM2
+
+Libguestfs provides access to a large part of the LVM2 API. It won't
+make much sense unless you familiarize yourself with the concepts of
+physical volumes, volume groups and logical volumes.
+
+This author strongly recommends reading the LVM HOWTO, online at
+L<http://tldp.org/HOWTO/LVM-HOWTO/>.
+
+=head2 PARTITIONING
+
+To create MBR-style (ie. normal PC) partitions use one of the
+C<guestfs_sfdisk*> variants. These calls use the external
+L<sfdisk(8)> command.
+
+The simplest call is:
+
+ char *lines[] = { ",", NULL };
+ guestfs_sfdiskM (g, "/dev/sda", lines);
+
+This will create a single partition on C</dev/sda> called
+C</dev/sda1> covering the whole disk.
+
+In general MBR partitions are both unnecessarily complicated and
+depend on archaic details, namely the Cylinder-Head-Sector (CHS)
+geometry of the disk. C<guestfs_sfdiskM> allows you to specify sizes
+in megabytes instead of cylinders, which is a small win.
+C<guestfs_sfdiskM> will choose the nearest cylinder to approximate the
+requested size. There's a lot of crazy stuff to do with IDE and
+virtio disks having different, incompatible CHS geometries, that you
+probably don't want to know about. My advice: make a single partition
+to cover the whole disk, then use LVM on top.
+
+In future we aim to provide access to libparted.
+
+=head2 UPLOADING
+
+For small, single files, use C<guestfs_write_file>. In some versions
+of libguestfs there was a bug which limited this call to text files
+(not containing ASCII NUL characters).
+
+To upload a single file, use C<guestfs_upload>. This call has no
+limits on file content or size (even files larger than 4 GB).
+
+To upload multiple files, see C<guestfs_tar_in> and C<guestfs_tgz_in>.
+
+However the fastest way to upload I<large numbers of arbitrary files>
+is to turn them into a squashfs or CD ISO (see L<mksquashfs(8)> and
+L<mkisofs(8)>), then attach this using C<guestfs_add_drive_ro>. If
+you add the drive in a predictable way (eg. adding it last after all
+other drives) then you can get the device name from
+C<guestfs_list_devices> and mount it directly using
+C<guestfs_mount_ro>. Note that squashfs images are sometimes
+non-portable between kernel versions, and they don't support labels or
+UUIDs. If you want to pre-build an image or you need to mount it
+using a label or UUID, use an ISO image instead.
+
+=head2 DOWNLOADING
+
+Use C<guestfs_cat> to download small, text only files. This call
+is limited to files which are less than 2 MB and which cannot contain
+any ASCII NUL (C<\0>) characters. However it has a very simple
+to use API.
+
+C<guestfs_read_file> can be used to read files which contain
+arbitrary 8 bit data, since it returns a (pointer, size) pair.
+However it is still limited to "small" files, less than 2 MB.
+
+C<guestfs_download> can be used to download any file, with no
+limits on content or size (even files larger than 4 GB).
+
+To download multiple files, see C<guestfs_tar_out> and
+C<guestfs_tgz_out>.
+
+=head2 RUNNING COMMANDS
+
+Although libguestfs is a primarily an API for manipulating files
+inside guest images, we also provide some limited facilities for
+running commands inside guests.
+
+There are many limitations to this:
+
+=over 4
+
+=item *
+
+The kernel version that the command runs under will be different
+from what it expects.
+
+=item *
+
+If the command needs to communicate with daemons, then most likely
+they won't be running.
+
+=item *
+
+The command will be running in limited memory.
+
+=item *
+
+Only supports Linux guests (not Windows, BSD, etc).
+
+=item *
+
+Architecture limitations (eg. won't work for a PPC guest on
+an X86 host).
+
+=back
+
+The two main API calls to run commands are C<guestfs_command> and
+C<guestfs_sh> (there are also variations).
+
+The difference is that C<guestfs_sh> runs commands using the shell, so
+any shell globs, redirections, etc will work.
+
+=head2 LISTING FILES
+
+C<guestfs_ll> is just designed for humans to read (mainly when using
+the L<guestfish(1)>-equivalent command C<ll>).
+
+C<guestfs_ls> is a quick way to get a list of files in a directory
+from programs.
+
+C<guestfs_readdir> is a programmatic way to get a list of files in a
+directory, plus additional information about each one.
+
+C<guestfs_find> can be used to recursively list files.
+
=head1 HIGH-LEVEL API ACTIONS
+=head2 ABI GUARANTEE
+
+We guarantee the libguestfs ABI (binary interface), for public,
+high-level actions as outlined in this section. Although we will
+deprecate some actions, for example if they get replaced by newer
+calls, we will keep the old actions forever. This allows you the
+developer to program in confidence against libguestfs.
+
@ACTIONS@
=head1 STRUCTURES
This isn't documented. Please see the libguestfs-select and
libguestfs-glib implementations.
+=head1 BLOCK DEVICE NAMING
+
+In the kernel there is now quite a profusion of schemata for naming
+block devices (in this context, by I<block device> I mean a physical
+or virtual hard drive). The original Linux IDE driver used names
+starting with C</dev/hd*>. SCSI devices have historically used a
+different naming scheme, C</dev/sd*>. When the Linux kernel I<libata>
+driver became a popular replacement for the old IDE driver
+(particularly for SATA devices) those devices also used the
+C</dev/sd*> scheme. Additionally we now have virtual machines with
+paravirtualized drivers. This has created several different naming
+systems, such as C</dev/vd*> for virtio disks and C</dev/xvd*> for Xen
+PV disks.
+
+As discussed above, libguestfs uses a qemu appliance running an
+embedded Linux kernel to access block devices. We can run a variety
+of appliances based on a variety of Linux kernels.
+
+This causes a problem for libguestfs because many API calls use device
+or partition names. Working scripts and the recipe (example) scripts
+that we make available over the internet could fail if the naming
+scheme changes.
+
+Therefore libguestfs defines C</dev/sd*> as the I<standard naming
+scheme>. Internally C</dev/sd*> names are translated, if necessary,
+to other names as required. For example, under RHEL 5 which uses the
+C</dev/hd*> scheme, any device parameter C</dev/sda2> is translated to
+C</dev/hda2> transparently.
+
+Note that this I<only> applies to parameters. The
+C<guestfs_list_devices>, C<guestfs_list_partitions> and similar calls
+return the true names of the devices and partitions as known to the
+appliance.
+
+=head2 ALGORITHM FOR BLOCK DEVICE NAME TRANSLATION
+
+Usually this translation is transparent. However in some (very rare)
+cases you may need to know the exact algorithm. Such cases include
+where you use C<guestfs_config> to add a mixture of virtio and IDE
+devices to the qemu-based appliance, so have a mixture of C</dev/sd*>
+and C</dev/vd*> devices.
+
+The algorithm is applied only to I<parameters> which are known to be
+either device or partition names. Return values from functions such
+as C<guestfs_list_devices> are never changed.
+
+=over 4
+
+=item *
+
+Is the string a parameter which is a device or partition name?
+
+=item *
+
+Does the string begin with C</dev/sd>?
+
+=item *
+
+Does the named device exist? If so, we use that device.
+However if I<not> then we continue with this algorithm.
+
+=item *
+
+Replace initial C</dev/sd> string with C</dev/hd>.
+
+For example, change C</dev/sda2> to C</dev/hda2>.
+
+If that named device exists, use it. If not, continue.
+
+=item *
+
+Replace initial C</dev/sd> string with C</dev/vd>.
+
+If that named device exists, use it. If not, return an error.
+
+=back
+
+=head2 PORTABILITY CONCERNS
+
+Although the standard naming scheme and automatic translation is
+useful for simple programs and guestfish scripts, for larger programs
+it is best not to rely on this mechanism.
+
+Where possible for maximum future portability programs using
+libguestfs should use these future-proof techniques:
+
+=over 4
+
+=item *
+
+Use C<guestfs_list_devices> or C<guestfs_list_partitions> to list
+actual device names, and then use those names directly.
+
+Since those device names exist by definition, they will never be
+translated.
+
+=item *
+
+Use higher level ways to identify filesystems, such as LVM names,
+UUIDs and filesystem labels.
+
+=back
+
=head1 INTERNALS
=head2 COMMUNICATION PROTOCOL
LIBGUESTFS_QEMU=/tmp/qemu.wrapper guestfish
+Note that libguestfs also calls qemu with the -help and -version
+options in order to determine features.
+
=head1 ENVIRONMENT VARIABLES
=over 4
+=item LIBGUESTFS_APPEND
+
+Pass additional options to the guest kernel.
+
=item LIBGUESTFS_DEBUG
Set C<LIBGUESTFS_DEBUG=1> to enable verbose messages. This
has the same effect as calling C<guestfs_set_verbose (handle, 1)>.
+=item LIBGUESTFS_MEMSIZE
+
+Set the memory allocated to the qemu process, in megabytes. For
+example:
+
+ LIBGUESTFS_MEMSIZE=700
+
=item LIBGUESTFS_PATH
Set the path that libguestfs uses to search for kernel and initrd.img.
See also L<QEMU WRAPPERS> above.
-=item LIBGUESTFS_APPEND
+=item TMPDIR
-Pass additional options to the guest kernel.
+Location of temporary directory, defaults to C</tmp>.
+
+If libguestfs was compiled to use the supermin appliance then each
+handle will require rather a large amount of space in this directory
+for short periods of time (~ 80 MB). You can use C<$TMPDIR> to
+configure another directory to use in case C</tmp> is not large
+enough.
=back
L<guestfish(1)>,
L<qemu(1)>,
L<febootstrap(1)>,
-L<http://et.redhat.com/~rjones/libguestfs>.
+L<http://libguestfs.org/>.
=head1 BUGS
To get a list of bugs against libguestfs use this link:
-L<https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Fedora>
+L<https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools>
To report a new bug against libguestfs use this link:
-L<https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Fedora>
+L<https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools>
When reporting a bug, please check:
=head1 COPYRIGHT
Copyright (C) 2009 Red Hat Inc.
-L<http://et.redhat.com/~rjones/libguestfs>
+L<http://libguestfs.org/>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
git.annexia.org / libguestfs.git / blobdiff