[Libguestfs] [RFC] virt-diff: add new virt-diff tool
Wanlong Gao
gaowanlong at cn.fujitsu.com
Mon Jul 2 11:34:12 UTC 2012
On 07/02/2012 05:28 PM, Richard W.M. Jones wrote:
> On Tue, Jun 19, 2012 at 05:24:26PM +0800, Wanlong Gao wrote:
>> add new virt-diff tool
>>
>> Signed-off-by: Wanlong Gao <gaowanlong at cn.fujitsu.com>
>> ---
>>
>> Hi Rich,
>> This just a thought of virt-diff tool, I send it out ASAP
>> to ask your opinions.
>>
>> Now, I just implement two guest, one SEED guest and one
>> DIFF guest, and the patch is wholly untested.
>> Please take patient to review.
>> And it's hard for me to start two guest handler, if you
>> have time, please help or just handle this work.
>>
>> PS, I attended the LinuxCon Japan this month, so the plan
>> delayed.
>
> The outline of the code seems to be:
>
> * create two handles
> * add both disks
> * inspect both disks
> * mount-local both disks on separate temporary directories
> * run regular 'diff' command across the temporary directories
>
> These is a reasonable approach for code simplicity, but I guess it'll
> be very slow in practice.
If you have a better idea in mind, please teach me.
Thanks,
Wanlong Gao
>
>> cat/virt-diff.c | 423 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 423 insertions(+)
>> create mode 100644 cat/virt-diff.c
>>
>> diff --git a/cat/virt-diff.c b/cat/virt-diff.c
>> new file mode 100644
>> index 0000000..4bd8730
>> --- /dev/null
>> +++ b/cat/virt-diff.c
>> @@ -0,0 +1,423 @@
>> +/* virt-diff
>> + * Copyright (C) 2012 FUJITSU LIMITED.
>> + * Copyright (C) 2010-2012 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 <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 "human.h"
>> +#include "progname.h"
>> +
>> +#include "guestfs.h"
>> +#include "options.h"
>> +
>> +#ifndef O_CLOEXEC
>> +#define O_CLOEXEC 0
>> +#endif
>> +
>> +/* libguestfs handle for seed. */
>> +static guestfs_h *sg;
>> +
>> +/* libguestfs handle for temp. */
>> +static guestfs_h *g;
>> +
>> +static int live = 0;
>> +static int verbose = 0;
>> +static int keys_from_stdin = 0;
>> +static int echo_keys = 0;
>> +static const char *libvirt_uri = NULL;
>> +static int inspector = 1;
>> +
>> +static doing_diff = 1;
>> +
>> +static inline char *
>> +diff_bad_case (char const *s)
>> +{
>> + return (char *) s;
>> +}
>> +
>> +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 Guest and the others\n"
>> + "Copyright (C) 2012 Fujitsu Limited.\n"
>> + "Copyright (C) 2010-2012 Red Hat Inc.\n"
>> + "Usage:\n"
>> + "\n"
>> + "\n"
>> + "Options:\n"
>> + " -a|--add image Add image\n"
>> + " --checksum[=...] Display file checksums\n"),
>> + program_name);
>> + }
>> + exit (status);
>> +}
>> +
>> +
>> +/* 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];
>> + 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 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)
>> +{
>> + 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"
>> + "\n"
>> + "If using guestfish '-i' option, remove this option and instead\n"
>> + "use the commands 'run' followed by 'list-filesystems'.\n"
>> + "You can then mount filesystems you want by hand using the\n"
>> + "'mount' or 'mount-ro' command.\n"
>> + "\n"
>> + "If using guestmount '-i', remove this option and choose the\n"
>> + "filesystem(s) you want to see by manually adding '-m' option(s).\n"
>> + "Use 'virt-filesystems' to see what filesystems are available.\n"
>> + "\n"
>> + "If using other virt tools, this disk image won't work\n"
>> + "with these tools. Use the guestfish equivalent commands\n"
>> + "(see the virt tool manual page).\n"),
>> + program_name);
>> + free_strings (roots);
>> + exit (EXIT_FAILURE);
>> + }
>> +
>> + if (roots[1] != NULL) {
>> + fprintf (stderr,
>> + _("%s: multi-boot operating systems are not supported\n"
>> + "\n"
>> + "If using guestfish '-i' option, remove this option and instead\n"
>> + "use the commands 'run' followed by 'list-filesystems'.\n"
>> + "You can then mount filesystems you want by hand using the\n"
>> + "'mount' or 'mount-ro' command.\n"
>> + "\n"
>> + "If using guestmount '-i', remove this option and choose the\n"
>> + "filesystem(s) you want to see by manually adding '-m' option(s).\n"
>> + "Use 'virt-filesystems' to see what filesystems are available.\n"
>> + "\n"
>> + "If using other virt tools, multi-boot operating systems won't work\n"
>> + "with these tools. Use the guestfish equivalent commands\n"
>> + "(see the virt tool manual page).\n"),
>> + program_name);
>> + free_strings (roots);
>> + exit (EXIT_FAILURE);
>> + }
>> +
>> + root = roots[0];
>> + free (roots);
>> +
>> + diff_inspect_mount_root (root);
>> +}
>> +
>> +int
>> +main (int argc, int *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 = "s:d:";
>> + static const struct option long_options[] = {
>> + {"seed", 1, 0, 's'},
>> + {"domain", 1, 0, 'd'},
>> + {0, 0, 0, 0}
>> + };
>
> Eventually you'll need to support all the other options too, or
> at least --help.
>
>> + struct drv *sdrv = NULL;
>> + struct drv *drv = NULL;
>> + int c;
>> +
>> + sg = guestfs_create ();
>> + if (sg == NULL) {
>> + fprintf (stderr, _("guestfs_create: failed to create seed handle\n"));
>> + exit (EXIT_FAILURE);
>> + }
>> +
>> + g = guestfs_create ();
>> + if (g == NULL) {
>> + fprintf (stderr, _("guestfs_create: failed to create comparison handle\n"));
>> + exit (EXIT_FAILURE);
>> + }
>> +
>> + argv[0] = 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, "seed")) {
>> + if (sdrv) {
>> + fprintf(stderr, _("...."));
>> + 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;
>> + } else if (STREQ (long_options[option_index].name, "domain")) {
>> + drv = calloc ("malloc");
>> + if (!drv) {
>> + perror ("malloc");
>> + exit (EXIT_FAILURE);
>> + }
>> + drv->type = drv_d;
>> + drv->nr_drives = -1;
>> + drv->d.guest = optarg;
>> + drv->next = NULL;
>> + } else {
>> + fprintf (stderr, _("%s: unknown long option: %s (%d)\n"),
>> + program_name, long_options[option_index].name, option_index);
>> + exit (EXIT_FAILURE);
>> + }
>> + break;
>> +
>> + case 'd':
>> + OPTION_d;
>> + break;
>> +
>> + case 's':
>> + if (sdrv) {
>> + fprintf(stderr, _("...."));
>> + 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 HELP_OPTION:
>> + usage (EXIT_SUCCESS);
>> +
>> + default:
>> + usage (EXIT_FAILURE);
>> + }
>> + }
>> +
>> + if (sdrv == NULL)
>> + usage (EXIT_FAILURE);
>> + if (drv == NULL)
>> + usage (EXIT_FAILURE);
>> +
>> + struct guestfs_add_domain_argv optargs = {
>> + .bitmask = 0;
>> + .libvirturi = NULL;
>> + .readonly = 1;
>> + .allowuuid = 1;
>> + .readonlydisk = "read";
>> + };
>> + nr = guestfs_add_domain_argv (sg, sdrv->d.guest, &optargs);
>> + if (r == -1)
>> + exit (EXIT_FAILURE);
>> + sdrv->nr_drives = nr;
>> + nr = guestfs_add_domain_argv (g, drv->d.guest, &optargs);
>> + if (r == -1)
>> + exit (EXIT_FAILURE);
>> + drv->nr_drives = nr;
>> +
>> + if (guestfs_launch (sg) == -1)
>> + exit (EXIT_FAILURE);
>> + if (guestfs_launch (g) == -1)
>> + exit (EXIT_FAILURE);
>> +
>> + diff_inspect_mount (sg);
>> + diff_inspect_mount (g);
>> +
>> + char stempdir = "/tmp/sGuestXXXXXX";
>> + char tempdir = "/tmp/GuestXXXXXX";
>> + char sdir[256];
>> + char dir[256];
>> +
>> + if (mkdtemp (stempdir) == NULL) {
>> + perror ("mkdtemp");
>> + exit (EXIT_FAILURE);
>> + }
>> + if (mkdtemp (tempdir) == NULL) {
>> + perror ("mkdtemp");
>> + exit (EXIT_FAILURE);
>> + }
>> +
>> + if (guestfs_mount_local (sg, stempdir, -1) == -1)
>> + exit (EXIT_FAILURE);
>> + if (guestfs_mount_local (g, tempdir, -1) == -1)
>> + exit (EXIT_FAILURE);
>> +
>> + spid = fork ();
>> + if (spid == -1) {
>> + perror ("fork");
>> + exit (EXIT_FAILURE);
>> + }
>> + if (spid == 0) {
>> + while (doing_diff)
>> + sleep (1);
>> + guestfs_umount_local (sg, GUESTFS_UMOUNT_LOCAL_RETRY, 1, -1);
>> + _exit (EXIT_SUCCESS);
>> + }
>> +
>> + pid = fork();
>> + if (pid == -1) {
>> + perror ("fork");
>> + exit (EXIT_FAILURE);
>> + }
>> + if (pid == 0) {
>> + while (doing_diff)
>> + sleep (1);
>> + guestfs_umount_local (g, GUESTFS_UMOUNT_LOCAL_RETRY, 1, -1);
>> + _exit (EXIT_SUCCESS);
>> + }
>
> The doing_diff variable isn't shared between forked processes, so the
> child processes will simply busy-wait forever. In any case the main
> program never even sets doing_diff.
>
> This code is going to be far more complex in the final version.
>
>> + if (guestfs_mount_local_run (sg) == -1)
>> + exit (EXIT_FAILURE);
>> + if (guestfs_mount_local_run (g) == -1)
>> + exit (EXIT_FAILURE);
>> +
>> + const char *dir = argv[optind];
>> + char system_arg[BUFSIZ];
>> + sprintf (system_arg, "diff -urN %s%s %s%s", stempdir, dir,
>> + tempdir, dir);
>> + system(system_arg);
>> +
>> + waitpid (spid, NULL, 0);
>> + waitpid (pid, NULL, 0);
>> +
>> + if (guestfs_umount (sg, "/") == -1)
>> + exit (EXIT_FAILURE);
>> + if (guestfs_umount (g, "/") == -1)
>> + exit (EXIT_FAILURE);
>> +
>> + free_drives (sdrvs);
>> + free_drives (drv);
>> +
>> + guestfs_close (sg);
>> + guestfs_close (g);
>> +
>> + exit (EXIT_SUCCESS);
>> +}
>> --
>> 1.7.11.rc0
>
> Rich.
>
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