From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Fabian Ebner <f.ebner@proxmox.com>
Date: Mon, 7 Feb 2022 14:21:01 +0100
Subject: [PATCH] qemu-img: dd: add -l option for loading a snapshot

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
 docs/tools/qemu-img.rst |  6 +++---
 qemu-img-cmds.hx        |  4 ++--
 qemu-img.c              | 33 +++++++++++++++++++++++++++++++--
 3 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 5e713e231d..9390d5e5cf 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -492,10 +492,10 @@ Command description:
   it doesn't need to be specified separately in this case.
 
 
-.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [-n] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] if=INPUT of=OUTPUT
+.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [-n] [-l SNAPSHOT_PARAM] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] if=INPUT of=OUTPUT
 
-  dd copies from *INPUT* file to *OUTPUT* file converting it from
-  *FMT* format to *OUTPUT_FMT* format.
+  dd copies from *INPUT* file or snapshot *SNAPSHOT_PARAM* to *OUTPUT* file
+  converting it from *FMT* format to *OUTPUT_FMT* format.
 
   The data is by default read and written using blocks of 512 bytes but can be
   modified by specifying *BLOCK_SIZE*. If count=\ *BLOCKS* is specified
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index b5b0bb4467..36f97e1f19 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -58,9 +58,9 @@ SRST
 ERST
 
 DEF("dd", img_dd,
-    "dd [--image-opts] [-U] [-f fmt] [-O output_fmt] [-n] [bs=block_size] [count=blocks] [skip=blocks] [osize=output_size] if=input of=output")
+    "dd [--image-opts] [-U] [-f fmt] [-O output_fmt] [-n] [-l snapshot_param] [bs=block_size] [count=blocks] [skip=blocks] [osize=output_size] if=input of=output")
 SRST
-.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [-n] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] [osize=OUTPUT_SIZE] if=INPUT of=OUTPUT
+.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [-n] [-l SNAPSHOT_PARAM] [bs=BLOCK_SIZE] [count=BLOCKS] [skip=BLOCKS] [osize=OUTPUT_SIZE] if=INPUT of=OUTPUT
 ERST
 
 DEF("info", img_info,
diff --git a/qemu-img.c b/qemu-img.c
index 59c403373b..065a54cc42 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4946,6 +4946,7 @@ static int img_dd(int argc, char **argv)
     BlockDriver *drv = NULL, *proto_drv = NULL;
     BlockBackend *blk1 = NULL, *blk2 = NULL;
     QemuOpts *opts = NULL;
+    QemuOpts *sn_opts = NULL;
     QemuOptsList *create_opts = NULL;
     Error *local_err = NULL;
     bool image_opts = false;
@@ -4955,6 +4956,7 @@ static int img_dd(int argc, char **argv)
     int64_t size = 0, readsize = 0;
     int64_t out_pos, in_pos;
     bool force_share = false, skip_create = false;
+    const char *snapshot_name = NULL;
     struct DdInfo dd = {
         .flags = 0,
         .count = 0,
@@ -4992,7 +4994,7 @@ static int img_dd(int argc, char **argv)
         { 0, 0, 0, 0 }
     };
 
-    while ((c = getopt_long(argc, argv, ":hf:O:Un", long_options, NULL))) {
+    while ((c = getopt_long(argc, argv, ":hf:O:l:Un", long_options, NULL))) {
         if (c == EOF) {
             break;
         }
@@ -5015,6 +5017,19 @@ static int img_dd(int argc, char **argv)
         case 'n':
             skip_create = true;
             break;
+        case 'l':
+            if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) {
+                sn_opts = qemu_opts_parse_noisily(&internal_snapshot_opts,
+                                                  optarg, false);
+                if (!sn_opts) {
+                    error_report("Failed in parsing snapshot param '%s'",
+                                 optarg);
+                    goto out;
+                }
+            } else {
+                snapshot_name = optarg;
+            }
+            break;
         case 'U':
             force_share = true;
             break;
@@ -5074,11 +5089,24 @@ static int img_dd(int argc, char **argv)
     if (dd.flags & C_IF) {
         blk1 = img_open(image_opts, in.filename, fmt, 0, false, false,
                         force_share);
-
         if (!blk1) {
             ret = -1;
             goto out;
         }
+        if (sn_opts) {
+            bdrv_snapshot_load_tmp(blk_bs(blk1),
+                                   qemu_opt_get(sn_opts, SNAPSHOT_OPT_ID),
+                                   qemu_opt_get(sn_opts, SNAPSHOT_OPT_NAME),
+                                   &local_err);
+        } else if (snapshot_name != NULL) {
+            bdrv_snapshot_load_tmp_by_id_or_name(blk_bs(blk1), snapshot_name,
+                                                 &local_err);
+        }
+        if (local_err) {
+            error_reportf_err(local_err, "Failed to load snapshot: ");
+            ret = -1;
+            goto out;
+        }
     }
 
     if (dd.flags & C_OSIZE) {
@@ -5233,6 +5261,7 @@ static int img_dd(int argc, char **argv)
 out:
     g_free(arg);
     qemu_opts_del(opts);
+    qemu_opts_del(sn_opts);
     qemu_opts_free(create_opts);
     blk_unref(blk1);
     blk_unref(blk2);
