The qemu-img info --backing-chain option enumerates the backing file chain. For example, for base.qcow2 <- snap1.qcow2 <- snap2.qcow2 the output becomes:
$ qemu-img info --backing-chain snap2.qcow2 image: snap2.qcow2 file format: qcow2 virtual size: 100M (104857600 bytes) disk size: 196K cluster_size: 65536 backing file: snap1.qcow2 backing file format: qcow2 image: snap1.qcow2 file format: qcow2 virtual size: 100M (104857600 bytes) disk size: 196K cluster_size: 65536 backing file: base.qcow2 backing file format: qcow2 image: base.qcow2 file format: qcow2 virtual size: 100M (104857600 bytes) disk size: 136K cluster_size: 65536 Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> --- qemu-img.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 76 insertions(+), 22 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index f17f187..c717f3e 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1249,7 +1249,10 @@ static void dump_human_image_info(ImageInfo *info) } } -enum {OPTION_OUTPUT = 256}; +enum { + OPTION_OUTPUT = 256, + OPTION_BACKING_CHAIN = 257, +}; typedef enum OutputFormat { OFORMAT_JSON, @@ -1260,7 +1263,9 @@ static int img_info(int argc, char **argv) { int c; OutputFormat output_format = OFORMAT_HUMAN; - const char *filename, *fmt, *output; + bool chain = false; + const char *output; + char *filename, *fmt; BlockDriverState *bs; ImageInfo *info; @@ -1272,6 +1277,7 @@ static int img_info(int argc, char **argv) {"help", no_argument, 0, 'h'}, {"format", required_argument, 0, 'f'}, {"output", required_argument, 0, OPTION_OUTPUT}, + {"backing-chain", no_argument, 0, OPTION_BACKING_CHAIN}, {0, 0, 0, 0} }; c = getopt_long(argc, argv, "f:h", @@ -1285,17 +1291,20 @@ static int img_info(int argc, char **argv) help(); break; case 'f': - fmt = optarg; + fmt = g_strdup(optarg); break; case OPTION_OUTPUT: output = optarg; break; + case OPTION_BACKING_CHAIN: + chain = true; + break; } } if (optind >= argc) { help(); } - filename = argv[optind++]; + filename = g_strdup(argv[optind++]); if (output && !strcmp(output, "json")) { output_format = OFORMAT_JSON; @@ -1303,31 +1312,76 @@ static int img_info(int argc, char **argv) output_format = OFORMAT_HUMAN; } else if (output) { error_report("--output must be used with human or json as argument."); - return 1; + goto err; } - bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING, false); - if (!bs) { - return 1; + if (chain && output_format == OFORMAT_JSON) { + printf("[\n"); } - info = g_new0(ImageInfo, 1); - collect_image_info(bs, info, filename, fmt); + do { + bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING, + false); + if (!bs) { + goto err; + } - switch (output_format) { - case OFORMAT_HUMAN: - dump_human_image_info(info); - dump_snapshots(bs); - break; - case OFORMAT_JSON: - collect_snapshots(bs, info); - dump_json_image_info(info); - break; - } + info = g_new0(ImageInfo, 1); + collect_image_info(bs, info, filename, fmt); - qapi_free_ImageInfo(info); - bdrv_delete(bs); + switch (output_format) { + case OFORMAT_HUMAN: + dump_human_image_info(info); + dump_snapshots(bs); + break; + case OFORMAT_JSON: + collect_snapshots(bs, info); + dump_json_image_info(info); + break; + } + + g_free(filename); + g_free(fmt); + filename = NULL; + fmt = NULL; + + if (chain) { + if (info->has_full_backing_filename) { + filename = g_strdup(info->full_backing_filename); + } else if (info->has_backing_filename) { + filename = g_strdup(info->backing_filename); + } + + if (filename && info->has_backing_filename_format) { + fmt = g_strdup(info->backing_filename_format); + } + + /* Print delimiters between items */ + if (filename) { + switch (output_format) { + case OFORMAT_HUMAN: + printf("\n"); + break; + case OFORMAT_JSON: + printf(",\n"); + break; + } + } + } + + qapi_free_ImageInfo(info); + bdrv_delete(bs); + } while (filename); + + if (chain && output_format == OFORMAT_JSON) { + printf("]\n"); + } return 0; + +err: + g_free(filename); + g_free(fmt); + return 1; } #define SNAPSHOT_LIST 1 -- 1.7.11.4