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* [Qemu-devel] [PATCH] qemu-img: change opening method for the output in dd
@ 2016-08-11  4:02 Reda Sallahi
  2016-08-11  8:53 ` Fam Zheng
  2016-08-11  9:00 ` Stefan Hajnoczi
  0 siblings, 2 replies; 3+ messages in thread
From: Reda Sallahi @ 2016-08-11  4:02 UTC (permalink / raw)
  To: qemu-devel
  Cc: qemu-block, Kevin Wolf, Max Reitz, Fam Zheng, Stefan Hajnoczi,
	Reda Sallahi

dd was creating an output image regardless of whether there was one already
created. With this patch we try to open first the output image and resize it
if necessary.

Signed-off-by: Reda Sallahi <fullmanet@gmail.com>
---
Depends on:
[PATCH v2] qemu-img: add conv=notrunc option to dd

 qemu-img.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 76 insertions(+), 15 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 7c546c1..dfa0e63 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3919,6 +3919,8 @@ static int img_dd(int argc, char **argv)
     char *tmp;
     BlockDriver *drv = NULL, *proto_drv = NULL;
     BlockBackend *blk1 = NULL, *blk2 = NULL;
+    BlockDriverState *bs = NULL;
+    QDict *qoptions = NULL;
     QemuOpts *opts = NULL;
     QemuOptsList *create_opts = NULL;
     Error *local_err = NULL;
@@ -4080,22 +4082,60 @@ static int img_dd(int argc, char **argv)
         size = dd.count * in.bsz;
     }
 
-    /* Overflow means the specified offset is beyond input image's size */
-    if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
-                              size < in.bsz * in.offset)) {
-        qemu_opt_set_number(opts, BLOCK_OPT_SIZE, 0, &error_abort);
-    } else {
-        qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
-                            size - in.bsz * in.offset, &error_abort);
-    }
+    qoptions = qdict_new();
+    qdict_put(qoptions, "driver", qstring_from_str(out_fmt));
 
-    ret = bdrv_create(drv, out.filename, opts, &local_err);
-    if (ret < 0) {
-        error_reportf_err(local_err,
-                          "%s: error while creating output image: ",
-                          out.filename);
-        ret = -1;
-        goto out;
+    bs = bdrv_open(out.filename, NULL, qoptions, BDRV_O_RDWR, &local_err);
+
+    if (!bs) {
+        drv = bdrv_find_format(out_fmt);
+        if (!drv) {
+            error_report("Unknown file format");
+            ret = -1;
+            goto out;
+        }
+        proto_drv = bdrv_find_protocol(out.filename, true, &local_err);
+
+        if (!proto_drv) {
+            error_report_err(local_err);
+            ret = -1;
+            goto out;
+        }
+        if (!drv->create_opts) {
+            error_report("Format driver '%s' does not support image creation",
+                         drv->format_name);
+            ret = -1;
+            goto out;
+        }
+        if (!proto_drv->create_opts) {
+            error_report("Protocol driver '%s' does not support image creation",
+                         proto_drv->format_name);
+            ret = -1;
+            goto out;
+        }
+        create_opts = qemu_opts_append(create_opts, drv->create_opts);
+        create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
+
+        opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
+
+        /* Overflow means the specified offset is beyond input image's size */
+        if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
+                                  size < in.offset * in.bsz)) {
+            qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
+                                0, &error_abort);
+        } else {
+            qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
+                                size - in.offset * in.bsz, &error_abort);
+        }
+
+        ret = bdrv_create(drv, out.filename, opts, &local_err);
+        if (ret < 0) {
+            error_reportf_err(local_err,
+                              "%s: error while creating output image: ",
+                              out.filename);
+            ret = -1;
+            goto out;
+        }
     }
 
     blk2 = img_open(image_opts, out.filename, out_fmt, BDRV_O_RDWR,
@@ -4117,6 +4157,26 @@ static int img_dd(int argc, char **argv)
         in_pos = in.offset * in.bsz;
     }
 
+    if (bs) {
+        int64_t blk2sz = blk_getlength(blk2);
+        if (blk2sz < 0) {
+            error_report("Failed to get size for '%s'", in.filename);
+            ret = -1;
+            goto out;
+        }
+
+        if (!(dd.conv & C_NOTRUNC)) {
+            blk_truncate(blk2, 0);
+        }
+        if (!(dd.flags & C_SKIP) || (in.offset <= INT64_MAX / in.bsz &&
+                                  size >= in.offset * in.bsz)) {
+            if (!(dd.conv & C_NOTRUNC) ||
+                blk2sz < size - in.offset * in.bsz) {
+                blk_truncate(blk2, size - in.offset * in.bsz);
+            }
+        }
+    }
+
     in.buf = g_new(uint8_t, in.bsz);
 
     for (out_pos = 0; in_pos < size; block_count++) {
@@ -4152,6 +4212,7 @@ out:
     qemu_opts_free(create_opts);
     blk_unref(blk1);
     blk_unref(blk2);
+    bdrv_unref(bs);
     g_free(in.filename);
     g_free(out.filename);
     g_free(in.buf);
-- 
2.9.2

^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-08-11  9:00 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2016-08-11  4:02 [Qemu-devel] [PATCH] qemu-img: change opening method for the output in dd Reda Sallahi
2016-08-11  8:53 ` Fam Zheng
2016-08-11  9:00 ` Stefan Hajnoczi

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