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Re: [Libguestfs] [PATCH V5] virt-diff: add new virt-diff tool



Steve:

See patch below.

Rich.

On Wed, Sep 26, 2012 at 04:05:47PM +0800, Wanlong Gao wrote:
> add new virt-diff tool
> 
> Signed-off-by: Wanlong Gao <gaowanlong cn fujitsu com>
> ---
>  cat/Makefile.am   |  35 +++-
>  cat/virt-diff.c   | 589 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  cat/virt-diff.pod | 214 ++++++++++++++++++++
>  po/POTFILES       |   2 +
>  4 files changed, 837 insertions(+), 3 deletions(-)
>  create mode 100644 cat/virt-diff.c
>  create mode 100755 cat/virt-diff.pod
> 
> diff --git a/cat/Makefile.am b/cat/Makefile.am
> index 3549248..dd4b80f 100644
> --- a/cat/Makefile.am
> +++ b/cat/Makefile.am
> @@ -27,7 +27,7 @@ EXTRA_DIST = \
>  
>  CLEANFILES = stamp-virt-cat.pod stamp-virt-ls.pod stamp-virt-filesystems.pod
>  
> -bin_PROGRAMS = virt-cat virt-filesystems virt-ls
> +bin_PROGRAMS = virt-cat virt-filesystems virt-ls virt-diff
>  
>  SHARED_SOURCE_FILES = \
>  	../fish/config.c \
> @@ -91,13 +91,32 @@ virt_ls_LDADD = \
>  	$(top_builddir)/src/libguestfs.la \
>  	../gnulib/lib/libgnu.la
>  
> +virt_diff_SOURCES = \
> +	../fish/keys.c \
> +	virt-diff.c
> +
> +virt_diff_CFLAGS = \
> +	-DGUESTFS_WARN_DEPRECATED=1 \
> +	-I$(top_srcdir)/src -I$(top_builddir)/src \
> +	-I$(top_srcdir)/fish \
> +	-I$(srcdir)/../gnulib/lib -I../gnulib/lib \
> +	-DLOCALEBASEDIR=\""$(datadir)/locale"\" \
> +	$(WARN_CFLAGS) $(WERROR_CFLAGS) \
> +	$(LIBCONFIG_CFLAGS)
> +
> +virt_diff_LDADD = \
> +	$(LIBCONFIG_LIBS) \
> +	$(top_builddir)/src/libguestfs.la \
> +	../gnulib/lib/libgnu.la
> +
>  # Manual pages and HTML files for the website.
> -man_MANS = virt-cat.1 virt-filesystems.1 virt-ls.1
> +man_MANS = virt-cat.1 virt-filesystems.1 virt-ls.1 virt-diff.1
>  
>  noinst_DATA = \
>  	$(top_builddir)/html/virt-cat.1.html \
>  	$(top_builddir)/html/virt-filesystems.1.html \
> -	$(top_builddir)/html/virt-ls.1.html
> +	$(top_builddir)/html/virt-ls.1.html \
> +	$(top_builddir)/html/virt-diff.1.html
>  
>  virt-cat.1 $(top_builddir)/html/virt-cat.1.html: stamp-virt-cat.pod
>  
> @@ -129,6 +148,16 @@ stamp-virt-filesystems.pod: virt-filesystems.pod
>  	  $<
>  	touch $@
>  
> +virt-diff.1 $(top_builddir)/html/virt-diff.1.html: stamp-virt-diff.pod
> +
> +stamp-virt-diff.pod: virt-diff.pod
> +	$(PODWRAPPER) \
> +	  --man virt-diff.1 \
> +	  --html $(top_builddir)/html/virt-diff.1.html \
> +	  --license GPLv2+ \
> +	  $<
> +	touch $@
> +
>  # Tests.
>  
>  TESTS_ENVIRONMENT = $(top_builddir)/run --test
> diff --git a/cat/virt-diff.c b/cat/virt-diff.c
> new file mode 100644
> index 0000000..1ebcd0b
> --- /dev/null
> +++ b/cat/virt-diff.c
> @@ -0,0 +1,589 @@
> +/* virt-diff
> + * Copyright (C) 2012 Fujitsu Limited.
> + * Copyright (C) 2012 Red Hat Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> + */
> +
> +#include <config.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <termios.h>
> +#include <string.h>
> +#include <inttypes.h>
> +#include <unistd.h>
> +#include <getopt.h>
> +#include <fcntl.h>
> +#include <locale.h>
> +#include <assert.h>
> +#include <time.h>
> +#include <libintl.h>
> +#include <sys/wait.h>
> +
> +#include "c-ctype.h"
> +
> +#include "human.h"
> +#include "progname.h"
> +
> +#include "guestfs.h"
> +#include "options.h"
> +
> +#ifndef O_CLOEXEC
> +#define O_CLOEXEC 0
> +#endif
> +
> +int verbose = 0;
> +int keys_from_stdin = 0;
> +int echo_keys = 0;
> +/* libguestfs handle for seed. */
> +static guestfs_h *sg;
> +
> +/* libguestfs handle for temp. */
> +static guestfs_h *tg;
> +
> +const char *libvirt_uri = NULL;
> +
> +static inline char *
> +diff_bad_case (char const *s)
> +{
> +  return (char *) s;
> +}
> +
> +/* Make a LUKS map name from the partition name,
> + * eg "/dev/vda2" => "luksvda2"
> + */
> +static void
> +diff_make_mapname (const char *device, char *mapname, size_t len)
> +{
> +  size_t i = 0;
> +
> +  if (len < 5)
> +    abort ();
> +  strcpy (mapname, "luks");
> +  mapname += 4;
> +  len -= 4;
> +
> +  if (STRPREFIX (device, "/dev/"))
> +    i = 5;
> +
> +  for (; device[i] != '\0' && len >= 1; ++i) {
> +    if (c_isalnum (device[i])) {
> +      *mapname++ = device[i];
> +      len--;
> +    }
> +  }
> +
> +  *mapname = '\0';
> +}
> +
> +static void
> +free_strings (char **strings)
> +{
> +  size_t i;
> +
> +  for (i = 0; strings[i] != NULL; ++i)
> +    free (strings[i]);
> +  free (strings);
> +}
> +
> +static size_t
> +count_strings (char **strings)
> +{
> +  size_t i;
> +
> +  for (i = 0; strings[i] != NULL; ++i)
> +    ;
> +  return i;
> +}
> +
> +/* Simple implementation of decryption: look for any crypto_LUKS
> + * partitions and decrypt them, then rescan for VGs.  This only works
> + * for Fedora whole-disk encryption.  WIP to make this work for other
> + * encryption schemes.
> + */
> +static void
> +diff_inspect_do_decrypt (guestfs_h *g)
> +{
> +  char **partitions = guestfs_list_partitions (g);
> +  if (partitions == NULL)
> +    exit (EXIT_FAILURE);
> +
> +  int need_rescan = 0;
> +  size_t i;
> +  for (i = 0; partitions[i] != NULL; ++i) {
> +    char *type = guestfs_vfs_type (g, partitions[i]);
> +    if (type && STREQ (type, "crypto_LUKS")) {
> +      char mapname[32];
> +      diff_make_mapname (partitions[i], mapname, sizeof mapname);
> +
> +      char *key = read_key (partitions[i]);
> +      /* XXX Should we call guestfs_luks_open_ro if readonly flag
> +       * is set?  This might break 'mount_ro'.
> +       */
> +      if (guestfs_luks_open (g, partitions[i], key, mapname) == -1)
> +        exit (EXIT_FAILURE);
> +
> +      free (key);
> +
> +      need_rescan = 1;
> +    }
> +    free (type);
> +  }
> +
> +  free_strings (partitions);
> +
> +  if (need_rescan) {
> +    if (guestfs_vgscan (g) == -1)
> +      exit (EXIT_FAILURE);
> +    if (guestfs_vg_activate_all (g, 1) == -1)
> +      exit (EXIT_FAILURE);
> +  }
> +}
> +
> +static int
> +compare_keys (const void *p1, const void *p2)
> +{
> +  const char *key1 = * (char * const *) p1;
> +  const char *key2 = * (char * const *) p2;
> +
> +  return strcmp (key1, key2);
> +}
> +
> +static int
> +compare_keys_len (const void *p1, const void *p2)
> +{
> +  const char *key1 = * (char * const *) p1;
> +  const char *key2 = * (char * const *) p2;
> +  int c;
> +
> +  c = strlen (key1) - strlen (key2);
> +  if (c != 0)
> +    return c;
> +
> +  return compare_keys (p1, p2);
> +}
> +
> +static void
> +diff_inspect_mount_root (guestfs_h *g, const char *root)
> +{
> +  char **mountpoints = guestfs_inspect_get_mountpoints (g, root);
> +  if (mountpoints == NULL)
> +    exit (EXIT_FAILURE);
> +
> +  /* Sort by key length, shortest key first, so that we end up
> +   * mounting the filesystems in the correct order.
> +   */
> +  qsort (mountpoints, count_strings (mountpoints) / 2, 2 * sizeof (char *),
> +         compare_keys_len);
> +
> +  size_t i;
> +  size_t mount_errors = 0;
> +  for (i = 0; mountpoints[i] != NULL; i += 2) {
> +    int r;
> +    r = guestfs_mount_ro (g, mountpoints[i+1], mountpoints[i]);
> +    if (r == -1) {
> +      /* If the "/" filesystem could not be mounted, give up, else
> +       * just count the errors and print a warning.
> +       */
> +      if (STREQ (mountpoints[i], "/"))
> +        exit (EXIT_FAILURE);
> +      mount_errors++;
> +    }
> +  }
> +
> +  free_strings (mountpoints);
> +
> +  if (mount_errors)
> +    fprintf (stderr, _("%s: some filesystems could not be mounted (ignored)\n"),
> +             program_name);
> +}
> +
> +/* This function implements the -i option. */
> +static void
> +diff_inspect_mount (guestfs_h *g)
> +{
> +  const char *root = NULL;
> +  diff_inspect_do_decrypt (g);
> +
> +  char **roots = guestfs_inspect_os (g);
> +  if (roots == NULL)
> +    exit (EXIT_FAILURE);
> +
> +  if (roots[0] == NULL) {
> +    fprintf (stderr,
> +      _("%s: no operating system was found on this disk\n"), program_name);
> +    free_strings (roots);
> +    exit (EXIT_FAILURE);
> +  }
> +
> +  if (roots[1] != NULL) {
> +    fprintf (stderr,
> +      _("%s: multi-boot operating systems are not supported\n"), program_name);
> +    free_strings (roots);
> +    exit (EXIT_FAILURE);
> +  }
> +
> +  root = roots[0];
> +  free (roots);
> +
> +  diff_inspect_mount_root (g, root);
> +}
> +
> +static void
> +free_drive (struct drv *drv)
> +{
> +  if (!drv) return;
> +
> +  free (drv->device);
> +  free (drv);
> +}
> +
> +static int
> +diff_command (const char *stmpdir, const char *ttmpdir, const char *dir)
> +{
> +  char *spath = NULL, *tpath = NULL;
> +  pid_t pid;
> +
> +  if (asprintf (&spath, "%s%s", stmpdir, dir) == -1)
> +    goto error;
> +
> +  if (asprintf (&tpath, "%s%s", ttmpdir, dir) == -1)
> +    goto error;
> +
> +  pid = fork();
> +  if (pid == -1)
> +    goto error;
> +
> +  if (pid == 0) {
> +    execlp ("diff", "diff", "-urN", spath, tpath, NULL);
> +    perror ("running command: diff");
> +    _exit (EXIT_FAILURE);
> +  }
> +
> +  if (waitpid (pid, NULL, 0) == -1)
> +    goto error;
> +
> +  return 0;
> +
> +error:
> +  perror ("running command: diff");
> +  if (spath) free (spath);
> +  if (tpath) free (tpath);
> +  return -1;
> +}
> +
> +static void __attribute__((noreturn))
> +diff_usage (int status)
> +{
> +  if (status != EXIT_SUCCESS) {
> +    fprintf (stderr, _("Try `%s --help' for more information.\n"),
> +             program_name);
> +  } else {
> +    fprintf (stdout,
> +           _("%s: Show the differences between seed and target Guest\n"
> +             "Copyright (C) 2012 Fujitsu Limited.\n"
> +             "Copyright (C) 2012 Red Hat Inc.\n"
> +             "Usage:\n"
> +             "  %s [--options] -s domname -t domname path\n"
> +             "  %s [--options] -a disk.img -d disk.img path\n"
> +             "Options:\n"
> +             "  -c|--connect uri     Specify libvirt URI for -s and -m options\n"
> +             "  -s|--sd guest        Add seed disk from libvirt guest\n"
> +             "  -t|--td guest        Add target disk from libvirt guest\n"
> +             "  -a|--sa image        Add seed disk from disk image\n"
> +             "  -d|--ta image        Add target disk from libvirt guest\n"
> +             "  --format[=raw|..]    Force disk format for -a and -d options\n"
> +             "  --keys-from-stdin    Read passphrases from stdin\n"
> +             "  --echo-keys          Don't turn off echo for passphrases\n"
> +             "  --help               Display brief help\n"
> +             "  -v|--verbose         Verbose messages\n"
> +             "  -V|--version         Display version and exit\n"
> +             "  -x                   Trace libguestfs API calls\n"
> +             "For more information, see the manpage %s(1).\n"),
> +             program_name, program_name, program_name, program_name);
> +  }
> +  exit (status);
> +}
> +
> +int
> +main (int argc, char *argv[])
> +{
> +  /* set global program name that is not polluted with libtool artifacts. */
> +  set_program_name (argv[0]);
> +  bindtextdomain (PACKAGE, LOCALEBASEDIR);
> +  textdomain (PACKAGE);
> +
> +  enum { HELP_OPTION = CHAR_MAX + 1 };
> +
> +  static const char *options = "c:a:s:d:t:vVx";
> +  static const struct option long_options[] = {
> +    { "connect", 1, 0, 'c' },
> +    { "sa", 1, 0, 'a' },
> +    { "sd", 1, 0, 's' },
> +    { "ta", 1, 0, 'd' },
> +    { "td", 1, 0, 't' },
> +    { "format", 2, 0, 0 },
> +    { "keys-from-stdin", 0, 0, 0 },
> +    { "echo-keys", 0, 0, 0 },
> +    { "help", 0, 0, HELP_OPTION },
> +    { "verbose", 0, 0, 'v' },
> +    { "version", 0, 0, 'V' },
> +    {0, 0, 0, 0}
> +  };
> +
> +  struct drv *sdrv = NULL;
> +  struct drv *tdrv = NULL;
> +  const char *format = NULL;
> +  int c, nr;
> +  int option_index;
> +  int spid, tpid;
> +
> +  sg = guestfs_create ();
> +  if (sg == NULL) {
> +    fprintf (stderr, _("guestfs_create: failed to create seed handle\n"));
> +    exit (EXIT_FAILURE);
> +  }
> +
> +  tg = guestfs_create ();
> +  if (tg == NULL) {
> +    fprintf (stderr, _("guestfs_create: failed to create comparison handle\n"));
> +    exit (EXIT_FAILURE);
> +  }
> +
> +  argv[0] = diff_bad_case (program_name);
> +
> +  for (;;) {
> +    c = getopt_long (argc, argv, options, long_options, &option_index);
> +    if (c == -1) break;
> +
> +    switch (c) {
> +    case 0:
> +      if (STREQ (long_options[option_index].name, "keys-from-stdin")) {
> +        keys_from_stdin = 1;
> +      } else if (STREQ (long_options[option_index].name, "echo-keys")) {
> +        echo_keys = 1;
> +      } else if (STREQ (long_options[option_index].name, "format")) {
> +        if (!optarg || STREQ (optarg, ""))
> +          format = NULL;
> +        else
> +          format = optarg;
> +      }  else {
> +        fprintf (stderr, _("%s: unknown long option: %s (%d)\n"),
> +                 program_name, long_options[option_index].name, option_index);
> +        exit (EXIT_FAILURE);
> +      }
> +      break;
> +
> +    case 'c':
> +      libvirt_uri = optarg;
> +      break;
> +
> +    case 's':
> +      if (sdrv) {
> +        fprintf(stderr, _("Only one seed device"));
> +        exit (EXIT_FAILURE);
> +      }
> +      sdrv = calloc (1, sizeof (struct drv));
> +      if (!sdrv) {
> +        perror ("malloc");
> +        exit (EXIT_FAILURE);
> +      }
> +      sdrv->type = drv_d;
> +      sdrv->nr_drives = -1;
> +      sdrv->d.guest = optarg;
> +      sdrv->next = NULL;
> +      break;
> +
> +    case 't':
> +      if (tdrv) {
> +        fprintf (stderr, _("Only one diff device"));
> +        exit (EXIT_FAILURE);
> +      }
> +      tdrv = calloc (1, sizeof (struct drv));
> +      if (!tdrv) {
> +        perror ("malloc");
> +        exit (EXIT_FAILURE);
> +      }
> +      tdrv->type = drv_d;
> +      tdrv->nr_drives = -1;
> +      tdrv->d.guest = optarg;
> +      tdrv->next = NULL;
> +      break;
> +
> +    case 'a':
> +      if (sdrv) {
> +        fprintf (stderr, _("Only one seed device"));
> +        exit (EXIT_FAILURE);
> +      }
> +      sdrv = calloc (1, sizeof (struct drv));
> +      if (!sdrv) {
> +        perror ("malloc");
> +        exit (EXIT_FAILURE);
> +      }
> +      sdrv->type = drv_a;
> +      sdrv->nr_drives = -1;
> +      sdrv->a.filename = optarg;
> +      sdrv->a.format = format;
> +      sdrv->next = NULL;
> +      break;
> +
> +    case 'd':
> +      if (tdrv) {
> +        fprintf (stderr, _("Only one diff device"));
> +        exit (EXIT_FAILURE);
> +      }
> +      tdrv = calloc (1, sizeof (struct drv));
> +      if (!tdrv) {
> +        perror ("malloc");
> +        exit (EXIT_FAILURE);
> +      }
> +      tdrv->type = drv_a;
> +      tdrv->nr_drives = -1;
> +      tdrv->a.filename = optarg;
> +      tdrv->a.format = format;
> +      tdrv->next = NULL;
> +      break;
> +
> +    case HELP_OPTION:
> +      diff_usage (EXIT_SUCCESS);
> +
> +    case 'v':
> +      verbose++;
> +      guestfs_set_verbose (sg, verbose);
> +      guestfs_set_verbose (tg, verbose);
> +      break;
> +
> +    case 'V':
> +      {
> +        struct guestfs_version *v = guestfs_version (sg);
> +        printf ("%s %"PRIi64".%"PRIi64".%"PRIi64"%s\n",
> +                program_name,
> +                v->major, v->minor, v->release, v->extra);
> +        exit (EXIT_SUCCESS);
> +      }
> +      break; 
> +
> +    case 'x':
> +      guestfs_set_trace (sg, 1);
> +      guestfs_set_trace (tg, 1);
> +      break;
> +
> +    default:
> +      diff_usage (EXIT_FAILURE);
> +    }
> +  }
> +
> +  if (sdrv == NULL)
> +    diff_usage (EXIT_FAILURE);
> +  if (tdrv == NULL)
> +    diff_usage (EXIT_FAILURE);
> +
> +  struct guestfs_add_domain_argv optargs = {
> +    .bitmask = 0,
> +    .libvirturi = libvirt_uri,
> +    .readonly = 1,
> +    .allowuuid = 1,
> +    .readonlydisk = "read",
> +  };
> +
> +  nr = guestfs_add_domain_argv (sg, sdrv->d.guest, &optargs);
> +  if (nr == -1)
> +    exit (EXIT_FAILURE);
> +  sdrv->nr_drives = nr;
> +  nr = guestfs_add_domain_argv (tg, tdrv->d.guest, &optargs);
> +  if (nr == -1)
> +    exit (EXIT_FAILURE);
> +  tdrv->nr_drives = nr;
> +
> +  if (guestfs_launch (sg) == -1)
> +    exit (EXIT_FAILURE);
> +  if (guestfs_launch (tg) == -1)
> +    exit (EXIT_FAILURE);
> +
> +  diff_inspect_mount (sg);
> +  diff_inspect_mount (tg);
> +
> +  char stempdir[] = "/tmp/sGuestXXXXXX";
> +  char ttempdir[] = "/tmp/tGuestXXXXXX";
> +
> +  if (mkdtemp (stempdir) == NULL) {
> +    perror ("mkdtemp");
> +    exit (EXIT_FAILURE);
> +  }
> +  if (mkdtemp (ttempdir) == NULL) {
> +    perror ("mkdtemp");
> +    exit (EXIT_FAILURE);
> +  }
> +
> +  if (guestfs_mount_local (sg, stempdir, -1) == -1)
> +    exit (EXIT_FAILURE);
> +  if (guestfs_mount_local (tg, ttempdir, -1) == -1)
> +    exit (EXIT_FAILURE);
> +
> +  spid = fork ();
> +  if (spid == -1) {
> +    perror ("fork");
> +    exit (EXIT_FAILURE);
> +  }
> +  if (spid == 0) {
> +    if (guestfs_mount_local_run (sg) == -1)
> +      exit (EXIT_FAILURE);
> +    _exit (EXIT_SUCCESS);
> +  }
> +
> +  tpid = fork();
> +  if (tpid == -1) {
> +    perror ("fork");
> +    exit (EXIT_FAILURE);
> +  }
> +  if (tpid == 0) {
> +    if (guestfs_mount_local_run (tg) == -1)
> +      exit (EXIT_FAILURE);
> +    _exit (EXIT_SUCCESS);
> +  }
> +
> +  const char *dir = argv[optind];
> +
> +  if (diff_command (stempdir, ttempdir, dir) == -1)
> +    exit (EXIT_FAILURE);
> +
> +  if (guestfs_umount_local (sg, GUESTFS_UMOUNT_LOCAL_RETRY, 1, -1) == -1)
> +    exit (EXIT_FAILURE);
> +  if (waitpid (spid, NULL, 0) == -1)
> +    exit (EXIT_FAILURE);
> +  if (guestfs_umount_local (tg, GUESTFS_UMOUNT_LOCAL_RETRY, 1, -1) == -1)
> +    exit (EXIT_FAILURE);
> +  if (waitpid (tpid, NULL, 0) == -1)
> +    exit (EXIT_FAILURE);
> +
> +  if (rmdir (stempdir) == -1)
> +    exit (EXIT_FAILURE);
> +  if (rmdir (ttempdir) == -1)
> +    exit (EXIT_FAILURE);
> +
> +  if (guestfs_shutdown (sg) == -1)
> +    exit (EXIT_FAILURE);
> +  if (guestfs_shutdown (tg) == -1)
> +    exit (EXIT_FAILURE);
> +
> +  free_drive (sdrv);
> +  free_drive (tdrv);
> +
> +  guestfs_close (sg);
> +  guestfs_close (tg);
> +
> +  exit (EXIT_SUCCESS);
> +}
> diff --git a/cat/virt-diff.pod b/cat/virt-diff.pod
> new file mode 100755
> index 0000000..45e9b74
> --- /dev/null
> +++ b/cat/virt-diff.pod
> @@ -0,0 +1,214 @@
> +=encoding utf8
> +
> +=head1 NAME
> +
> +virt-diff - Compare files between two virtual machines
> +
> +=head1 SYNOPSIS
> +
> + virt-diff [--options] -s domname -d domname file
> +
> + virt-diff [--options] -a disk.img -d disk.img file
> +
> +
> +=head1 DESCRIPTION
> +
> +C<virt-diff> is a command line tool to compare files or directories
> +between two virtual machines.
> +
> +=head1 EXAMPLES
> +
> +Compare C</etc/fstab> file from inside the libvirt VM called
> +C<sdomain> to inside the libvirt VM called C<ddomain>:
> +
> + virt-diff -s sdomain -m ddomain /etc/fstab
> +
> +Compare C</etc/hostname>  file from a VM disk image C<a.img>
> +to another VM disk image C<b.img>:
> +
> + virt-diff -a a.img -d b.img /etc/hostname
> +
> +Compare C</etc/> directory recursely from one libvirt VM called
> +C<sdomain> to another libvirt VM called C<ddomain>:
> +
> + virt-diff -s sdomain -m ddomain /etc
> +
> +=head1 OPTIONS
> +
> +=over 4
> +
> +=item B<--help>
> +
> +Display brief help.
> +
> +=item B<-c> URI
> +
> +=item B<--connect> URI
> +
> +If using libvirt, connect to the given I<URI>.  If omitted, then we
> +connect to the default libvirt hypervisor.
> +
> +If you specify guest block devices directly (I<-a>), then libvirt is
> +not used at all.
> +
> +=item B<-s> guest
> +
> +=item B<--sd> guest
> +
> +Add the seed disks from the named libvirt guest. Domain UUIDs can be
> +used instead of names.
> +
> +=item B<-t> guest
> +
> +=item B<--td> guest
> +
> +Add the taget disks from the named libvirt guest.  Domain UUIDs can be
> +used instead of names.
> +
> +=item B<-a> file
> +
> +=item B<--sa> file
> +
> +Add the seed disk image which should be a disk image from a virtual machine.
> +
> +The format of the disk image is auto-detected.  To override this and
> +force a particular format use the I<--format=..> option.
> +
> +=item B<-d> file
> +
> +=item B<--ta> file
> +
> +Add the targe disk image which should be a disk image from a virtual machine.
> +
> +The format of the disk image is auto-detected.  To override this and
> +force a particular format use the I<--format=..> option.
> +
> +=item B<--echo-keys>
> +
> +When prompting for keys and passphrases, virt-diff normally turns
> +echoing off so you cannot see what you are typing.  If you are not
> +worried about Tempest attacks and there is no one else in the room you
> +can specify this flag to see what you are typing.
> +
> +=item B<--format=raw|qcow2|..>
> +
> +=item B<--format>
> +
> +The default for the I<-a> and I<-d> option is to auto-detect the format
> +of the disk image.  Using this forces the disk format for I<-a> and I<-d>
> +options which follow on the command line.  Using I<--format> with no argument
> +switches back to auto-detection for subsequent I<-a> and I<-d> options.
> +
> +For example:
> +
> + virt-diff --format=qcow2 -a disk1.img -d disk2.img file
> +
> +forces qcow2 format (no auto-detection) for C<disk1.img> and C<disk2.img>.
> +
> + virt-diff --format=raw -a disk.img --format -d another.img file
> +
> +forces raw format (no auto-detection) for C<disk.img> and reverts to
> +auto-detection for C<another.img>.
> +
> +If you have untrusted raw-format guest disk images, you should use
> +this option to specify the disk format.  This avoids a possible
> +security problem with malicious guests (CVE-2010-3851).
> +
> +=item B<--keys-from-stdin>
> +
> +Read key or passphrase parameters from stdin.  The default is
> +to try to read passphrases from the user by opening C</dev/tty>.
> +
> +=item B<-v>
> +
> +=item B<--verbose>
> +
> +Enable verbose messages for debugging.
> +
> +=item B<-V>
> +
> +=item B<--version>
> +
> +Display version number and exit.
> +
> +=item B<-x>
> +
> +Enable tracing of libguestfs API calls.
> +
> +=back
> +
> +=head1 WINDOWS PATHS
> +
> +C<virt-diff> has a limited ability to understand Windows drive letters
> +and paths (eg. C<E:\foo\bar.txt>).
> +
> +If and only if the guest is running Windows then:
> +
> +=over 4
> +
> +=item *
> +
> +Drive letter prefixes like C<C:> are resolved against the
> +Windows Registry to the correct filesystem.
> +
> +=item *
> +
> +Any backslash (C<\>) characters in the path are replaced
> +with forward slashes so that libguestfs can process it.
> +
> +=item *
> +
> +The path is resolved case insensitively to locate the file
> +that should be displayed.
> +
> +=back
> +
> +There are some known shortcomings:
> +
> +=over 4
> +
> +=item *
> +
> +Some NTFS symbolic links may not be followed correctly.
> +
> +=item *
> +
> +NTFS junction points that cross filesystems are not followed.
> +
> +=back
> +
> +
> +=head1 SHELL QUOTING
> +
> +Libvirt guest names can contain arbitrary characters, some of which
> +have meaning to the shell such as C<#> and space.  You may need to
> +quote or escape these characters on the command line.  See the shell
> +manual page L<sh(1)> for details.
> +
> +=head1 EXIT STATUS
> +
> +This program returns 0 if successful, or non-zero if there was an
> +error.
> +
> +=head1 SEE ALSO
> +
> +L<guestfs(3)>,
> +L<guestfish(1)>,
> +L<virt-copy-out(1)>,
> +L<virt-cat(1)>,
> +L<virt-ls(1)>,
> +L<virt-edit(1)>,
> +L<virt-tar-out(1)>,
> +L<http://libguestfs.org/>.
> +
> +=head1 AUTHOR
> +
> +Wanlong Gao, Fujitsu Ltd.
> +
> +Richard W.M. Jones L<http://people.redhat.com/~rjones/>
> +
> +=head1 COPYRIGHT
> +
> +Copyright (C) 2012 Fujitsu Ltd.
> +
> +Copyright (C) 2012 Red Hat Inc.
> diff --git a/po/POTFILES b/po/POTFILES
> index 548156c..3625ce6 100644
> --- a/po/POTFILES
> +++ b/po/POTFILES
> @@ -1,6 +1,7 @@
>  align/domains.c
>  align/scan.c
>  cat/virt-cat.c
> +cat/virt-diff.c
>  cat/virt-filesystems.c
>  cat/virt-ls.c
>  daemon/9p.c
> @@ -136,6 +137,7 @@ fish/tilde.c
>  fish/time.c
>  format/format.c
>  fuse/guestmount.c
> +gobject/docs/guestfs-scan.c
>  gobject/src/optargs-add_domain.c
>  gobject/src/optargs-add_drive.c
>  gobject/src/optargs-btrfs_filesystem_resize.c
> -- 
> 1.7.12.1.401.gb5d156c

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/


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