From 0257e27e17214d84f49a51e1138fb46b23d6b024 Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" Date: Tue, 1 Nov 2011 09:47:25 +0000 Subject: [PATCH] rescue: Add --suggest option to suggest mount commands. --- rescue/virt-rescue.c | 166 +++++++++++++++++++++++++++++++++++++++++++++++++ rescue/virt-rescue.pod | 54 +++++++++++++--- 2 files changed, 212 insertions(+), 8 deletions(-) diff --git a/rescue/virt-rescue.c b/rescue/virt-rescue.c index 7ad39b5..0c00364 100644 --- a/rescue/virt-rescue.c +++ b/rescue/virt-rescue.c @@ -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 > 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" + "> 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. */ diff --git a/rescue/virt-rescue.pod b/rescue/virt-rescue.pod index e25b6ed..dc139dc 100755 --- a/rescue/virt-rescue.pod +++ b/rescue/virt-rescue.pod @@ -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 where you can mount filesystems. -In the example below, we list logical volumes, then choose one to -mount under C: +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 > 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) and +partitions (with L) and mount them by hand: > 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 - > mount /dev/vg_f11x64/lv_root /sysroot + lv_root vg_f15x32 -wi-a- 8.83G + lv_swap vg_f15x32 -wi-a- 992.00M + > mount /dev/vg_f15x32/lv_root /sysroot + > mount /dev/vda1 /sysroot/boot > ls /sysroot -If you don't know what filesystems are available on the virtual -machine then you can use commands such as L and L -to find out. +Another command to list available filesystems is +L. + +To run commands in a Linux guest (for example, grub), you should +chroot into the /sysroot directory first: + + > chroot /sysroot =head2 NOTES @@ -179,6 +207,15 @@ L before using this option. Enable N E 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, L, L, L, +L, L. =head1 AUTHOR -- 1.8.3.1