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[Libguestfs] [PATCH V4] virt-diff: add new virt-diff tool



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..050ecaa
--- /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:";
+  static const struct option long_options[] = {
+    { "connect", 1, 0, 'c' },
+    { "sa", 1, 0, 'a' },
+    { "sd", 1, 0, 's' },
+    { "da", 1, 0, 'd' },
+    { "dd", 1, 0, 'm' },
+    { "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 %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


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