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From 43c680e82e94061bf1b522466054730d8f3d8c22 Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Fri, 18 Oct 2013 08:14:42 +0200
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Subject: [PATCH 17/81] qemu-img: add a "map" subcommand
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <1382084091-16636-18-git-send-email-pbonzini@redhat.com>
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Patchwork-id: 55000
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O-Subject: [RHEL 7.0 qemu-kvm PATCH 17/26] qemu-img: add a "map" subcommand
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Bugzilla: 989646
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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This command dumps the metadata of an entire chain, in either tabular or JSON
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format.
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 4c93a13b5daf9bd5fca1a547661b0fb9a2f0ca52)
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---
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 qemu-img-cmds.hx |   6 ++
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 qemu-img.c       | 192 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
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 2 files changed, 198 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 qemu-img-cmds.hx |    6 ++
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 qemu-img.c       |  192 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
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 2 files changed, 198 insertions(+), 0 deletions(-)
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diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
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index 4ca7e95..c97a1f4 100644
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--- a/qemu-img-cmds.hx
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+++ b/qemu-img-cmds.hx
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@@ -45,6 +45,12 @@ STEXI
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 @item info [-f @var{fmt}] [--output=@var{ofmt}] [--backing-chain] @var{filename}
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 ETEXI
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+DEF("map", img_map,
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+    "map [-f fmt] [--output=ofmt] filename")
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+STEXI
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+@item map [-f @var{fmt}] [--output=@var{ofmt}] @var{filename}
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+ETEXI
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+
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 DEF("snapshot", img_snapshot,
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     "snapshot [-q] [-l | -a snapshot | -c snapshot | -d snapshot] filename")
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 STEXI
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diff --git a/qemu-img.c b/qemu-img.c
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index a9aabd5..e58c052 100644
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--- a/qemu-img.c
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+++ b/qemu-img.c
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@@ -1919,6 +1919,198 @@ static int img_info(int argc, char **argv)
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     return 0;
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 }
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+
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+typedef struct MapEntry {
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+    int flags;
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+    int depth;
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+    int64_t start;
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+    int64_t length;
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+    int64_t offset;
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+    BlockDriverState *bs;
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+} MapEntry;
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+
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+static void dump_map_entry(OutputFormat output_format, MapEntry *e,
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+                           MapEntry *next)
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+{
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+    switch (output_format) {
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+    case OFORMAT_HUMAN:
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+        if ((e->flags & BDRV_BLOCK_DATA) &&
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+            !(e->flags & BDRV_BLOCK_OFFSET_VALID)) {
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+            error_report("File contains external, encrypted or compressed clusters.");
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+            exit(1);
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+        }
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+        if ((e->flags & (BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO)) == BDRV_BLOCK_DATA) {
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+            printf("%#-16"PRIx64"%#-16"PRIx64"%#-16"PRIx64"%s\n",
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+                   e->start, e->length, e->offset, e->bs->filename);
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+        }
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+        /* This format ignores the distinction between 0, ZERO and ZERO|DATA.
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+         * Modify the flags here to allow more coalescing.
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+         */
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+        if (next &&
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+            (next->flags & (BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO)) != BDRV_BLOCK_DATA) {
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+            next->flags &= ~BDRV_BLOCK_DATA;
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+            next->flags |= BDRV_BLOCK_ZERO;
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+        }
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+        break;
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+    case OFORMAT_JSON:
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+        printf("%s{ \"start\": %"PRId64", \"length\": %"PRId64", \"depth\": %d,"
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+               " \"zero\": %s, \"data\": %s",
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+               (e->start == 0 ? "[" : ",\n"),
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+               e->start, e->length, e->depth,
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+               (e->flags & BDRV_BLOCK_ZERO) ? "true" : "false",
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+               (e->flags & BDRV_BLOCK_DATA) ? "true" : "false");
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+        if (e->flags & BDRV_BLOCK_OFFSET_VALID) {
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+            printf(", 'offset': %"PRId64"", e->offset);
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+        }
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+        putchar('}');
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+
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+        if (!next) {
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+            printf("]\n");
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+        }
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+        break;
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+    }
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+}
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+
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+static int get_block_status(BlockDriverState *bs, int64_t sector_num,
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+                            int nb_sectors, MapEntry *e)
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+{
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+    int64_t ret;
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+    int depth;
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+
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+    /* As an optimization, we could cache the current range of unallocated
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+     * clusters in each file of the chain, and avoid querying the same
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+     * range repeatedly.
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+     */
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+
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+    depth = 0;
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+    for (;;) {
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+        ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &nb_sectors);
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+        if (ret < 0) {
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+            return ret;
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+        }
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+        assert(nb_sectors);
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+        if (ret & (BDRV_BLOCK_ZERO|BDRV_BLOCK_DATA)) {
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+            break;
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+        }
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+        bs = bs->backing_hd;
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+        if (bs == NULL) {
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+            ret = 0;
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+            break;
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+        }
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+
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+        depth++;
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+    }
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+
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+    e->start = sector_num * BDRV_SECTOR_SIZE;
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+    e->length = nb_sectors * BDRV_SECTOR_SIZE;
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+    e->flags = ret & ~BDRV_BLOCK_OFFSET_MASK;
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+    e->offset = ret & BDRV_BLOCK_OFFSET_MASK;
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+    e->depth = depth;
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+    e->bs = bs;
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+    return 0;
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+}
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+
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+static int img_map(int argc, char **argv)
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+{
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+    int c;
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+    OutputFormat output_format = OFORMAT_HUMAN;
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+    BlockDriverState *bs;
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+    const char *filename, *fmt, *output;
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+    int64_t length;
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+    MapEntry curr = { .length = 0 }, next;
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+    int ret = 0;
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+
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+    fmt = NULL;
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+    output = NULL;
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+    for (;;) {
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+        int option_index = 0;
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+        static const struct option long_options[] = {
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+            {"help", no_argument, 0, 'h'},
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+            {"format", required_argument, 0, 'f'},
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+            {"output", required_argument, 0, OPTION_OUTPUT},
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+            {0, 0, 0, 0}
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+        };
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+        c = getopt_long(argc, argv, "f:h",
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+                        long_options, &option_index);
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+        if (c == -1) {
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+            break;
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+        }
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+        switch (c) {
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+        case '?':
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+        case 'h':
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+            help();
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+            break;
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+        case 'f':
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+            fmt = optarg;
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+            break;
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+        case OPTION_OUTPUT:
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+            output = optarg;
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+            break;
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+        }
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+    }
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+    if (optind >= argc) {
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+        help();
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+    }
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+    filename = argv[optind++];
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+
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+    if (output && !strcmp(output, "json")) {
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+        output_format = OFORMAT_JSON;
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+    } else if (output && !strcmp(output, "human")) {
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+        output_format = OFORMAT_HUMAN;
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+    } else if (output) {
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+        error_report("--output must be used with human or json as argument.");
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+        return 1;
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+    }
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+
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+    bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS, true, false);
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+    if (!bs) {
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+        return 1;
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+    }
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+
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+    if (output_format == OFORMAT_HUMAN) {
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+        printf("%-16s%-16s%-16s%s\n", "Offset", "Length", "Mapped to", "File");
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+    }
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+
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+    length = bdrv_getlength(bs);
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+    while (curr.start + curr.length < length) {
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+        int64_t nsectors_left;
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+        int64_t sector_num;
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+        int n;
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+
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+        sector_num = (curr.start + curr.length) >> BDRV_SECTOR_BITS;
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+
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+        /* Probe up to 1 GiB at a time.  */
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+        nsectors_left = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE) - sector_num;
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+        n = MIN(1 << (30 - BDRV_SECTOR_BITS), nsectors_left);
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+        ret = get_block_status(bs, sector_num, n, &next;;
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+
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+        if (ret < 0) {
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+            error_report("Could not read file metadata: %s", strerror(-ret));
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+            goto out;
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+        }
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+
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+        if (curr.length != 0 && curr.flags == next.flags &&
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+            curr.depth == next.depth &&
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+            ((curr.flags & BDRV_BLOCK_OFFSET_VALID) == 0 ||
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+             curr.offset + curr.length == next.offset)) {
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+            curr.length += next.length;
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+            continue;
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+        }
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+
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+        if (curr.length > 0) {
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+            dump_map_entry(output_format, &curr, &next;;
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+        }
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+        curr = next;
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+    }
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+
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+    dump_map_entry(output_format, &curr, NULL);
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+
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+out:
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+    bdrv_close(bs);
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+    bdrv_delete(bs);
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+    return ret < 0;
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+}
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+
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 #define SNAPSHOT_LIST   1
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 #define SNAPSHOT_CREATE 2
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 #define SNAPSHOT_APPLY  3
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-- 
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1.7.1
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