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rescue: Add --suggest option to suggest mount commands.

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This commit is contained in:
Richard W.M. Jones
2011-11-01 09:47:25 +00:00
parent b4da051d54
commit 0257e27e17
2 changed files with 212 additions and 8 deletions
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166
rescue/virt-rescue.c
View File

@@ -36,6 +36,8 @@
#include "guestfs.h"
#include "options.h"
static void do_suggestion (struct drv *drvs);
/* Currently open libguestfs handle. */
guestfs_h *g;
@@ -78,6 +80,7 @@ usage (int status)
" -r|--ro Access read-only\n"
" --selinux Enable SELinux\n"
" --smp N Enable SMP with N >= 2 virtual CPUs\n"
" --suggest Suggest mount commands for this guest\n"
" -v|--verbose Verbose messages\n"
" -V|--version Display version and exit\n"
" -w|--rw Mount read-write\n"
@@ -117,6 +120,7 @@ main (int argc, char *argv[])
{ "rw", 0, 0, 'w' },
{ "selinux", 0, 0, 0 },
{ "smp", 1, 0, 0 },
{ "suggest", 0, 0, 0 },
{ "verbose", 0, 0, 'v' },
{ "version", 0, 0, 'V' },
{ 0, 0, 0, 0 }
@@ -131,6 +135,7 @@ main (int argc, char *argv[])
char *append_full;
int memsize = 0;
int smp = 0;
int suggest = 0;
g = guestfs_create ();
if (g == NULL) {
@@ -168,6 +173,8 @@ main (int argc, char *argv[])
program_name, optarg);
exit (EXIT_FAILURE);
}
} else if (STREQ (long_options[option_index].name, "suggest")) {
suggest = 1;
} else {
fprintf (stderr, _("%s: unknown long option: %s (%d)\n"),
program_name, long_options[option_index].name, option_index);
@@ -259,6 +266,12 @@ main (int argc, char *argv[])
}
}
/* --suggest flag */
if (suggest) {
do_suggestion (drvs);
exit (EXIT_SUCCESS);
}
/* These are really constants, but they have to be variables for the
* options parsing code. Assert here that they have known-good
* values.
@@ -315,6 +328,159 @@ main (int argc, char *argv[])
exit (EXIT_SUCCESS);
}
static void suggest_filesystems (void);
static int
compare_keys_len (const void *p1, const void *p2)
{
const char *key1 = * (char * const *) p1;
const char *key2 = * (char * const *) p2;
return strlen (key1) - strlen (key2);
}
static size_t
count_strings (char *const *argv)
{
size_t i;
for (i = 0; argv[i]; ++i)
;
return i;
}
/* virt-rescue --suggest flag does a kind of inspection on the
* drives and suggests mount commands that you should use.
*/
static void
do_suggestion (struct drv *drvs)
{
char **roots;
size_t i, j;
char *type, *distro, *product_name;
int major, minor;
char **mps;
/* For inspection, force add_drives to add the drives read-only. */
read_only = 1;
/* Add drives. */
add_drives (drvs, 'a');
/* Free up data structures, no longer needed after this point. */
free_drives (drvs);
printf (_("Inspecting the virtual machine or disk image ...\n\n"));
fflush (stdout);
if (guestfs_launch (g) == -1)
exit (EXIT_FAILURE);
/* Don't use inspect_mount, since for virt-rescue we should allow
* arbitrary disks and disks with more than one OS on them. Let's
* do this using the basic API instead.
*/
roots = guestfs_inspect_os (g);
if (roots == NULL)
exit (EXIT_FAILURE);
if (roots[0] == NULL) {
suggest_filesystems ();
return;
}
printf (_("This disk contains one or more operating systems. You can use these mount\n"
"commands in virt-rescue (at the ><rescue> prompt) to mount the filesystems.\n\n"));
for (i = 0; roots[i] != NULL; ++i) {
type = guestfs_inspect_get_type (g, roots[i]);
distro = guestfs_inspect_get_distro (g, roots[i]);
product_name = guestfs_inspect_get_product_name (g, roots[i]);
major = guestfs_inspect_get_major_version (g, roots[i]);
minor = guestfs_inspect_get_minor_version (g, roots[i]);
printf (_("# %s is the root of a %s operating system\n"
"# type: %s, distro: %s, version: %d.%d\n"
"# %s\n\n"),
roots[i], type ? : "unknown",
type ? : "unknown", distro ? : "unknown", major, minor,
product_name ? : "");
mps = guestfs_inspect_get_mountpoints (g, roots[i]);
if (mps == NULL)
exit (EXIT_FAILURE);
/* Sort by key length, shortest key first, so that we end up
* mounting the filesystems in the correct order.
*/
qsort (mps, count_strings (mps) / 2, 2 * sizeof (char *),
compare_keys_len);
for (j = 0; mps[j] != NULL; j += 2) {
printf ("mount %s /sysroot%s\n", mps[j+1], mps[j]);
free (mps[j]);
free (mps[j+1]);
}
/* If it's Linux, print the bind-mounts. */
if (type && STREQ (type, "linux")) {
printf ("mount --bind /dev /sysroot/dev\n");
printf ("mount --bind /dev/pts /sysroot/dev/pts\n");
printf ("mount --bind /proc /sysroot/proc\n");
printf ("mount --bind /sys /sysroot/sys\n");
}
printf ("\n");
free (type);
free (distro);
free (product_name);
free (roots[i]);
}
free (roots);
}
/* Inspection failed, so it doesn't contain any OS that we recognise.
* However there might still be filesystems so print some suggestions
* for those.
*/
static void
suggest_filesystems (void)
{
char **fses;
size_t i;
fses = guestfs_list_filesystems (g);
if (fses == NULL)
exit (EXIT_FAILURE);
if (fses[0] == NULL) {
printf (_("This disk contains no filesystems that we recognize.\n\n"
"However you can still use virt-rescue on the disk image, to try to mount\n"
"filesystems that are not recognized by libguestfs, or to create partitions,\n"
"logical volumes and filesystems on a blank disk.\n"));
return;
}
printf (_("This disk contains one or more filesystems, but we don't recognize any\n"
"operating system. You can use these mount commands in virt-rescue (at the\n"
"><rescue> prompt) to mount these filesystems.\n\n"));
for (i = 0; fses[i] != NULL; i += 2) {
printf (_("# %s has type '%s'\n"), fses[i], fses[i+1]);
if (STRNEQ (fses[i+1], "swap") && STRNEQ (fses[i+1], "unknown"))
printf ("mount %s /sysroot\n", fses[i]);
printf ("\n");
free (fses[i]);
free (fses[i+1]);
}
free (fses);
}
/* The following was a nice idea, but in fact it doesn't work. This is
* because qemu has some (broken) pty emulation itself.
*/

54
rescue/virt-rescue.pod
View File

@@ -10,6 +10,8 @@ virt-rescue - Run a rescue shell on a virtual machine
virt-rescue [--options] -a disk.img [-a disk.img ...]
virt-rescue --suggest (-d domname | -a disk.img ...)
Old style:
virt-rescue [--options] domname
@@ -51,19 +53,45 @@ rescue appliance. You must mount the virtual machine's filesystems by
hand. There is an empty directory called C</sysroot> where you can
mount filesystems.
In the example below, we list logical volumes, then choose one to
mount under C</sysroot>:
You can get virt-rescue to suggest mount commands for you by using the
I<--suggest> option (in another terminal):
$ virt-rescue --suggest -d Fedora15
Inspecting the virtual machine or disk image ...
This disk contains one or more operating systems. You can use these
mount commands in virt-rescue (at the ><rescue> prompt) to mount the
filesystems.
# /dev/vg_f15x32/lv_root is the root of a linux operating system
# type: linux, distro: fedora, version: 15.0
# Fedora release 15 (Lovelock)
mount /dev/vg_f15x32/lv_root /sysroot/
mount /dev/vda1 /sysroot/boot
mount --bind /dev /sysroot/dev
mount --bind /dev/pts /sysroot/dev/pts
mount --bind /proc /sysroot/proc
mount --bind /sys /sysroot/sys
Another way is to list the logical volumes (with L<lvs(8)>) and
partitions (with L<parted(8)>) and mount them by hand:
><rescue> lvs
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
lv_root vg_f11x64 -wi-a- 8.83G
lv_swap vg_f11x64 -wi-a- 992.00M
><rescue> mount /dev/vg_f11x64/lv_root /sysroot
lv_root vg_f15x32 -wi-a- 8.83G
lv_swap vg_f15x32 -wi-a- 992.00M
><rescue> mount /dev/vg_f15x32/lv_root /sysroot
><rescue> mount /dev/vda1 /sysroot/boot
><rescue> ls /sysroot
If you don't know what filesystems are available on the virtual
machine then you can use commands such as L<parted(8)> and L<lvs(8)>
to find out.
Another command to list available filesystems is
L<virt-filesystems(1)>.
To run commands in a Linux guest (for example, grub), you should
chroot into the /sysroot directory first:
><rescue> chroot /sysroot
=head2 NOTES
@@ -179,6 +207,15 @@ L<guestfs(3)/SELINUX> before using this option.
Enable N E<ge> 2 virtual CPUs in the rescue appliance.
=item B<--suggest>
Inspect the disk image and suggest what mount commands should be used
to mount the disks. You should use the I<--suggest> option in a
second terminal, then paste the commands into another virt-rescue.
This option implies I<--ro> and is safe to use even if the guest is up
or if another virt-rescue is running.
=item B<-v>
=item B<--verbose>
@@ -291,6 +328,7 @@ L<guestfs(3)>,
L<guestfish(1)>,
L<virt-cat(1)>,
L<virt-edit(1)>,
L<virt-filesystems(1)>,
L<http://libguestfs.org/>.
=head1 AUTHOR