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qemu-img: Add compare subcommand

This patch adds new qemu-img subcommand that compares content of two disk
images.

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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1 parent f382d43 commit d14ed18c8d10a936e6f8b55f56afb4b75c305e10 @LaneWolf LaneWolf committed with Kevin Wolf
Showing with 348 additions and 1 deletion.
  1. +6 −0 qemu-img-cmds.hx
  2. +289 −1 qemu-img.c
  3. +53 −0 qemu-img.texi
View
6 qemu-img-cmds.hx
@@ -27,6 +27,12 @@ STEXI
@item commit [-q] [-f @var{fmt}] [-t @var{cache}] @var{filename}
ETEXI
+DEF("compare", img_compare,
+ "compare [-f fmt] [-F fmt] [-p] [-q] [-s] filename1 filename2")
+STEXI
+@item compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-q] [-s] @var{filename1} @var{filename2}
+ETEXI
+
DEF("convert", img_convert,
"convert [-c] [-p] [-q] [-f fmt] [-t cache] [-O output_fmt] [-o options] [-s snapshot_name] [-S sparse_size] filename [filename2 [...]] output_filename")
STEXI
View
290 qemu-img.c
@@ -113,7 +113,12 @@ static void help(void)
" '-a' applies a snapshot (revert disk to saved state)\n"
" '-c' creates a snapshot\n"
" '-d' deletes a snapshot\n"
- " '-l' lists all snapshots in the given image\n";
+ " '-l' lists all snapshots in the given image\n"
+ "\n"
+ "Parameters to compare subcommand:\n"
+ " '-f' first image format\n"
+ " '-F' second image format\n"
+ " '-s' run in Strict mode - fail on different image size or sector allocation\n";
printf("%s\nSupported formats:", help_msg);
bdrv_iterate_format(format_print, NULL);
@@ -820,6 +825,289 @@ static int compare_sectors(const uint8_t *buf1, const uint8_t *buf2, int n,
#define IO_BUF_SIZE (2 * 1024 * 1024)
+static int64_t sectors_to_bytes(int64_t sectors)
+{
+ return sectors << BDRV_SECTOR_BITS;
+}
+
+static int64_t sectors_to_process(int64_t total, int64_t from)
+{
+ return MIN(total - from, IO_BUF_SIZE >> BDRV_SECTOR_BITS);
+}
+
+/*
+ * Check if passed sectors are empty (not allocated or contain only 0 bytes)
+ *
+ * Returns 0 in case sectors are filled with 0, 1 if sectors contain non-zero
+ * data and negative value on error.
+ *
+ * @param bs: Driver used for accessing file
+ * @param sect_num: Number of first sector to check
+ * @param sect_count: Number of sectors to check
+ * @param filename: Name of disk file we are checking (logging purpose)
+ * @param buffer: Allocated buffer for storing read data
+ * @param quiet: Flag for quiet mode
+ */
+static int check_empty_sectors(BlockDriverState *bs, int64_t sect_num,
+ int sect_count, const char *filename,
+ uint8_t *buffer, bool quiet)
+{
+ int pnum, ret = 0;
+ ret = bdrv_read(bs, sect_num, buffer, sect_count);
+ if (ret < 0) {
+ error_report("Error while reading offset %" PRId64 " of %s: %s",
+ sectors_to_bytes(sect_num), filename, strerror(-ret));
+ return ret;
+ }
+ ret = is_allocated_sectors(buffer, sect_count, &pnum);
+ if (ret || pnum != sect_count) {
+ qprintf(quiet, "Content mismatch at offset %" PRId64 "!\n",
+ sectors_to_bytes(ret ? sect_num : sect_num + pnum));
+ return 1;
+ }
+
+ return 0;
+}
+
+/*
+ * Compares two images. Exit codes:
+ *
+ * 0 - Images are identical
+ * 1 - Images differ
+ * >1 - Error occurred
+ */
+static int img_compare(int argc, char **argv)
+{
+ const char *fmt1 = NULL, *fmt2 = NULL, *filename1, *filename2;
+ BlockDriverState *bs1, *bs2;
+ int64_t total_sectors1, total_sectors2;
+ uint8_t *buf1 = NULL, *buf2 = NULL;
+ int pnum1, pnum2;
+ int allocated1, allocated2;
+ int ret = 0; /* return value - 0 Ident, 1 Different, >1 Error */
+ bool progress = false, quiet = false, strict = false;
+ int64_t total_sectors;
+ int64_t sector_num = 0;
+ int64_t nb_sectors;
+ int c, pnum;
+ uint64_t bs_sectors;
+ uint64_t progress_base;
+
+ for (;;) {
+ c = getopt(argc, argv, "hpf:F:sq");
+ if (c == -1) {
+ break;
+ }
+ switch (c) {
+ case '?':
+ case 'h':
+ help();
+ break;
+ case 'f':
+ fmt1 = optarg;
+ break;
+ case 'F':
+ fmt2 = optarg;
+ break;
+ case 'p':
+ progress = true;
+ break;
+ case 'q':
+ quiet = true;
+ break;
+ case 's':
+ strict = true;
+ break;
+ }
+ }
+
+ /* Progress is not shown in Quiet mode */
+ if (quiet) {
+ progress = false;
+ }
+
+
+ if (optind > argc - 2) {
+ help();
+ }
+ filename1 = argv[optind++];
+ filename2 = argv[optind++];
+
+ /* Initialize before goto out */
+ qemu_progress_init(progress, 2.0);
+
+ bs1 = bdrv_new_open(filename1, fmt1, BDRV_O_FLAGS, true, quiet);
+ if (!bs1) {
+ error_report("Can't open file %s", filename1);
+ ret = 2;
+ goto out3;
+ }
+
+ bs2 = bdrv_new_open(filename2, fmt2, BDRV_O_FLAGS, true, quiet);
+ if (!bs2) {
+ error_report("Can't open file %s", filename2);
+ ret = 2;
+ goto out2;
+ }
+
+ buf1 = qemu_blockalign(bs1, IO_BUF_SIZE);
+ buf2 = qemu_blockalign(bs2, IO_BUF_SIZE);
+ bdrv_get_geometry(bs1, &bs_sectors);
+ total_sectors1 = bs_sectors;
+ bdrv_get_geometry(bs2, &bs_sectors);
+ total_sectors2 = bs_sectors;
+ total_sectors = MIN(total_sectors1, total_sectors2);
+ progress_base = MAX(total_sectors1, total_sectors2);
+
+ qemu_progress_print(0, 100);
+
+ if (strict && total_sectors1 != total_sectors2) {
+ ret = 1;
+ qprintf(quiet, "Strict mode: Image size mismatch!\n");
+ goto out;
+ }
+
+ for (;;) {
+ nb_sectors = sectors_to_process(total_sectors, sector_num);
+ if (nb_sectors <= 0) {
+ break;
+ }
+ allocated1 = bdrv_is_allocated_above(bs1, NULL, sector_num, nb_sectors,
+ &pnum1);
+ if (allocated1 < 0) {
+ ret = 3;
+ error_report("Sector allocation test failed for %s", filename1);
+ goto out;
+ }
+
+ allocated2 = bdrv_is_allocated_above(bs2, NULL, sector_num, nb_sectors,
+ &pnum2);
+ if (allocated2 < 0) {
+ ret = 3;
+ error_report("Sector allocation test failed for %s", filename2);
+ goto out;
+ }
+ nb_sectors = MIN(pnum1, pnum2);
+
+ if (allocated1 == allocated2) {
+ if (allocated1) {
+ ret = bdrv_read(bs1, sector_num, buf1, nb_sectors);
+ if (ret < 0) {
+ error_report("Error while reading offset %" PRId64 " of %s:"
+ " %s", sectors_to_bytes(sector_num), filename1,
+ strerror(-ret));
+ ret = 4;
+ goto out;
+ }
+ ret = bdrv_read(bs2, sector_num, buf2, nb_sectors);
+ if (ret < 0) {
+ error_report("Error while reading offset %" PRId64
+ " of %s: %s", sectors_to_bytes(sector_num),
+ filename2, strerror(-ret));
+ ret = 4;
+ goto out;
+ }
+ ret = compare_sectors(buf1, buf2, nb_sectors, &pnum);
+ if (ret || pnum != nb_sectors) {
+ ret = 1;
+ qprintf(quiet, "Content mismatch at offset %" PRId64 "!\n",
+ sectors_to_bytes(
+ ret ? sector_num : sector_num + pnum));
+ goto out;
+ }
+ }
+ } else {
+ if (strict) {
+ ret = 1;
+ qprintf(quiet, "Strict mode: Offset %" PRId64
+ " allocation mismatch!\n",
+ sectors_to_bytes(sector_num));
+ goto out;
+ }
+
+ if (allocated1) {
+ ret = check_empty_sectors(bs1, sector_num, nb_sectors,
+ filename1, buf1, quiet);
+ } else {
+ ret = check_empty_sectors(bs2, sector_num, nb_sectors,
+ filename2, buf1, quiet);
+ }
+ if (ret) {
+ if (ret < 0) {
+ ret = 4;
+ error_report("Error while reading offset %" PRId64 ": %s",
+ sectors_to_bytes(sector_num), strerror(-ret));
+ }
+ goto out;
+ }
+ }
+ sector_num += nb_sectors;
+ qemu_progress_print(((float) nb_sectors / progress_base)*100, 100);
+ }
+
+ if (total_sectors1 != total_sectors2) {
+ BlockDriverState *bs_over;
+ int64_t total_sectors_over;
+ const char *filename_over;
+
+ qprintf(quiet, "Warning: Image size mismatch!\n");
+ if (total_sectors1 > total_sectors2) {
+ total_sectors_over = total_sectors1;
+ bs_over = bs1;
+ filename_over = filename1;
+ } else {
+ total_sectors_over = total_sectors2;
+ bs_over = bs2;
+ filename_over = filename2;
+ }
+
+ for (;;) {
+ nb_sectors = sectors_to_process(total_sectors_over, sector_num);
+ if (nb_sectors <= 0) {
+ break;
+ }
+ ret = bdrv_is_allocated_above(bs_over, NULL, sector_num,
+ nb_sectors, &pnum);
+ if (ret < 0) {
+ ret = 3;
+ error_report("Sector allocation test failed for %s",
+ filename_over);
+ goto out;
+
+ }
+ nb_sectors = pnum;
+ if (ret) {
+ ret = check_empty_sectors(bs_over, sector_num, nb_sectors,
+ filename_over, buf1, quiet);
+ if (ret) {
+ if (ret < 0) {
+ ret = 4;
+ error_report("Error while reading offset %" PRId64
+ " of %s: %s", sectors_to_bytes(sector_num),
+ filename_over, strerror(-ret));
+ }
+ goto out;
+ }
+ }
+ sector_num += nb_sectors;
+ qemu_progress_print(((float) nb_sectors / progress_base)*100, 100);
+ }
+ }
+
+ qprintf(quiet, "Images are identical.\n");
+ ret = 0;
+
+out:
+ bdrv_delete(bs2);
+ qemu_vfree(buf1);
+ qemu_vfree(buf2);
+out2:
+ bdrv_delete(bs1);
+out3:
+ qemu_progress_end();
+ return ret;
+}
+
static int img_convert(int argc, char **argv)
{
int c, ret = 0, n, n1, bs_n, bs_i, compress, cluster_size, cluster_sectors;
View
53 qemu-img.texi
@@ -84,6 +84,18 @@ deletes a snapshot
lists all snapshots in the given image
@end table
+Parameters to compare subcommand:
+
+@table @option
+
+@item -f
+First image format
+@item -F
+Second image format
+@item -s
+Strict mode - fail on on different image size or sector allocation
+@end table
+
Command description:
@table @option
@@ -118,6 +130,47 @@ it doesn't need to be specified separately in this case.
Commit the changes recorded in @var{filename} in its base image.
+@item compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-s] [-q] @var{filename1} @var{filename2}
+
+Check if two images have the same content. You can compare images with
+different format or settings.
+
+The format is probed unless you specify it by @var{-f} (used for
+@var{filename1}) and/or @var{-F} (used for @var{filename2}) option.
+
+By default, images with different size are considered identical if the larger
+image contains only unallocated and/or zeroed sectors in the area after the end
+of the other image. In addition, if any sector is not allocated in one image
+and contains only zero bytes in the second one, it is evaluated as equal. You
+can use Strict mode by specifying the @var{-s} option. When compare runs in
+Strict mode, it fails in case image size differs or a sector is allocated in
+one image and is not allocated in the second one.
+
+By default, compare prints out a result message. This message displays
+information that both images are same or the position of the first different
+byte. In addition, result message can report different image size in case
+Strict mode is used.
+
+Compare exits with @code{0} in case the images are equal and with @code{1}
+in case the images differ. Other exit codes mean an error occurred during
+execution and standard error output should contain an error message.
+The following table sumarizes all exit codes of the compare subcommand:
+
+@table @option
+
+@item 0
+Images are identical
+@item 1
+Images differ
+@item 2
+Error on opening an image
+@item 3
+Error on checking a sector allocation
+@item 4
+Error on reading data
+
+@end table
+
@item convert [-c] [-p] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to disk image @var{output_filename}

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