The -n arg to the convert command allows use of a pre-existing image,
rather than creating a new image. This adds equivalent functionality
to the dd command using the 'conv' arg. If 'conv=nocreat' is used,
then it will assume the image already exists. The existing image
will be truncated to match the required output size. 'conv=notrunc'
cna be used to preserve the existing image size.
Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
---
qemu-img-cmds.hx | 4 +-
qemu-img.c | 137 +++++++++++++++++++++++++++++++++++++++++--------------
qemu-img.texi | 10 +++-
3 files changed, 115 insertions(+), 36 deletions(-)
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index f054599..b2c5424 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -46,9 +46,9 @@ STEXI
ETEXI
DEF("dd", img_dd,
- "dd [--image-opts] [-f fmt] [-O output_fmt] [bs=block_size] [count=blocks]
[skip=blocks] if=input of=output")
+ "dd [--image-opts] [-f fmt] [-O output_fmt] [bs=block_size] [count=blocks]
[skip=blocks] [conv=nocreat,notrunc] if=input of=output")
STEXI
-@item dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}]
[bs=@var{block_size}] [count=@var{blocks}] [skip=@var{blocks}] if=@var{input}
of=@var{output}
+@item dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}]
[bs=@var{block_size}] [count=@var{blocks}] [skip=@var{blocks}]
[conv=nocreat,notrunc] if=@var{input} of=@var{output}
ETEXI
DEF("info", img_info,
diff --git a/qemu-img.c b/qemu-img.c
index 629f9e9..c9ab9e5 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -174,7 +174,9 @@ static void QEMU_NORETURN help(void)
" 'count=N' copy only N input blocks\n"
" 'if=FILE' read from FILE\n"
" 'of=FILE' write to FILE\n"
- " 'skip=N' skip N bs-sized blocks at the start of input\n";
+ " 'skip=N' skip N bs-sized blocks at the start of input\n"
+ " 'conv=nocreat' don't create the output file\n"
+ " 'conv=notrunc' don't truncate the output file\n";
printf("%s\nSupported formats:", help_msg);
bdrv_iterate_format(format_print, NULL);
@@ -3814,11 +3816,13 @@ out:
return 0;
}
-#define C_BS 01
-#define C_COUNT 02
-#define C_IF 04
-#define C_OF 010
-#define C_SKIP 020
+#define C_BS (1 << 0)
+#define C_COUNT (1 << 1)
+#define C_IF (1 << 2)
+#define C_OF (1 << 3)
+#define C_SKIP (1 << 4)
+#define C_NOCREAT (1 << 5)
+#define C_NOTRUNC (1 << 6)
struct DdInfo {
unsigned int flags;
@@ -3906,6 +3910,31 @@ static int img_dd_skip(const char *arg,
return 0;
}
+static int img_dd_conv(const char *arg,
+ struct DdIo *in, struct DdIo *out,
+ struct DdInfo *dd)
+{
+ char **flags, **tmp;
+
+ tmp = flags = g_strsplit(arg, ",", 0);
+
+ while (tmp && *tmp) {
+ if (g_str_equal(*tmp, "noconv")) {
+ dd->flags |= C_NOCREAT;
+ } else if (g_str_equal(*tmp, "notrunc")) {
+ dd->flags |= C_NOTRUNC;
+ } else {
+ error_report("invalid conv argument: '%s'", *tmp);
+ g_strfreev(flags);
+ return 1;
+ }
+ tmp++;
+ }
+
+ g_strfreev(flags);
+ return 0;
+}
+
static int img_dd(int argc, char **argv)
{
int ret = 0;
@@ -3920,7 +3949,7 @@ static int img_dd(int argc, char **argv)
int c, i;
const char *out_fmt = "raw";
const char *fmt = NULL;
- int64_t size = 0;
+ int64_t size = 0, out_size;
int64_t block_count = 0, out_pos, in_pos;
struct DdInfo dd = {
.flags = 0,
@@ -3945,6 +3974,7 @@ static int img_dd(int argc, char **argv)
{ "if", img_dd_if, C_IF },
{ "of", img_dd_of, C_OF },
{ "skip", img_dd_skip, C_SKIP },
+ { "conv", img_dd_conv, 0 },
{ NULL, NULL, 0 }
};
const struct option long_options[] = {
@@ -3954,7 +3984,7 @@ static int img_dd(int argc, char **argv)
{ 0, 0, 0, 0 }
};
- while ((c = getopt_long(argc, argv, "hf:O:", long_options, NULL))) {
+ while ((c = getopt_long(argc, argv, "hnf:O:", long_options, NULL))) {
if (c == EOF) {
break;
}
@@ -4051,22 +4081,25 @@ static int img_dd(int argc, char **argv)
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);
+ if (!(dd.flags & C_NOCREAT)) {
+ 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);
+ }
size = blk_getlength(blk1);
if (size < 0) {
@@ -4083,19 +4116,22 @@ static int img_dd(int argc, char **argv)
/* 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);
+ out_size = 0;
} else {
- qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
- size - in.bsz * in.offset, &error_abort);
+ out_size = size - in.bsz * in.offset;
}
- 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;
+ if (!(dd.flags & C_NOCREAT)) {
+ qemu_opt_set_number(opts, BLOCK_OPT_SIZE, out_size, &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;
+ }
}
/* TODO, we can't honour --image-opts for the target,
@@ -4111,6 +4147,41 @@ static int img_dd(int argc, char **argv)
goto out;
}
+ if (dd.flags & C_NOCREAT) {
+ if (dd.flags & C_NOTRUNC) {
+ int64_t existing_size = blk_getlength(blk2);
+ if (existing_size < 0) {
+ error_report("unable to get output image length: %s",
+ strerror(-existing_size));
+ ret = -1;
+ goto out;
+ } else if (existing_size < out_size) {
+ /* Not large enough, so we must enlarge it */
+ ret = blk_truncate(blk2, out_size);
+ if (ret < 0) {
+ error_reportf_err(local_err,
+ "%s: error while enlarging output image:
",
+ out.filename);
+ ret = -1;
+ goto out;
+ }
+ }
+ } else {
+ /* dd would truncate to 0 length, then append out_size
+ * worth of data. Our images don't grow on demand, so
+ * we just truncate to final output size straight away
+ */
+ ret = blk_truncate(blk2, out_size);
+ if (ret < 0) {
+ error_reportf_err(local_err,
+ "%s: error while truncating output image: ",
+ out.filename);
+ ret = -1;
+ goto out;
+ }
+ }
+ }
+
if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
size < in.offset * in.bsz)) {
/* We give a warning if the skip option is bigger than the input
diff --git a/qemu-img.texi b/qemu-img.texi
index 174aae3..9f10562 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -326,7 +326,7 @@ skipped. This is useful for formats such as @code{rbd} if
the target
volume has already been created with site specific options that cannot
be supplied through qemu-img.
-@item dd [-f @var{fmt}] [-O @var{output_fmt}] [bs=@var{block_size}]
[count=@var{blocks}] [skip=@var{blocks}] if=@var{input} of=@var{output}
+@item dd [-f @var{fmt}] [-O @var{output_fmt}] [bs=@var{block_size}]
[count=@var{blocks}] [skip=@var{blocks}] [conv=nocreat,notrunc] if=@var{input}
of=@var{output}
Dd copies from @var{input} file to @var{output} file converting it from
@var{fmt} format to @var{output_fmt} format.
@@ -337,6 +337,14 @@ dd will stop reading input after reading @var{blocks}
input blocks.
The size syntax is similar to dd(1)'s size syntax.
+If the @code{conv=nocreat} option is specified, the target volume creation
+will be skipped. Its length will be truncated to match data length, if it
+is longer than the required data size. If the @code{conv=notrunc} option
+is specified, no file size shrinking will be done. If the existing output
+file is too small it will be enlarged to fit. These options are useful for
+formats such as @code{rbd} if the target volume has already been created
+with site specific options that cannot be supplied through qemu-img.
+
@item info [-f @var{fmt}] [--output=@var{ofmt}] [--backing-chain]
@var{filename}
Give information about the disk image @var{filename}. Use it in
--
2.9.3
