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[PATCH 2/4] qemu-img: dd: add isize parameter
From: |
Fabian Ebner |
Subject: |
[PATCH 2/4] qemu-img: dd: add isize parameter |
Date: |
Thu, 10 Feb 2022 14:31:21 +0100 |
From: Wolfgang Bumiller <w.bumiller@proxmox.com>
for writing small images from stdin to bigger ones.
In order to distinguish between an actually unexpected and
an expected end of input.
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
[FE: override size earlier
use flag to detect parameter
add documenation]
Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
---
docs/tools/qemu-img.rst | 10 ++++++++--
qemu-img-cmds.hx | 4 ++--
qemu-img.c | 24 +++++++++++++++++++++++-
3 files changed, 33 insertions(+), 5 deletions(-)
diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 775eaf3097..43328fe108 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -230,6 +230,10 @@ Parameters to dd subcommand:
Sets the number of input blocks to skip
+.. option:: isize=INPUT_SIZE
+
+ Treat the input image or stream as if it had this size
+
.. option:: osize=OUTPUT_SIZE
Sets the output image's size
@@ -492,7 +496,7 @@ Command description:
it doesn't need to be specified separately in this case.
-.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [bs=BLOCK_SIZE]
[count=BLOCKS] [skip=BLOCKS] [osize=OUTPUT_SIZE] [if=INPUT] [of=OUTPUT]
+.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [bs=BLOCK_SIZE]
[count=BLOCKS] [skip=BLOCKS] [isize=INPUT_SIZE] [osize=OUTPUT_SIZE] [if=INPUT]
[of=OUTPUT]
dd copies from *INPUT* file (default: STDIN) to *OUTPUT* file (default:
STDOUT) converting it from *FMT* format to *OUTPUT_FMT* format.
@@ -504,7 +508,9 @@ Command description:
The size syntax is similar to :manpage:`dd(1)`'s size syntax.
The output image will be created with size *OUTPUT_SIZE* and at most this
many
- bytes will be copied.
+ bytes will be copied. When *INPUT_SIZE* is positive, it overrides the input
+ image's size for the copy operation. When *INPUT_SIZE* is zero and reading
+ from STDIN, do not treat premature end of the input stream as an error.
.. option:: info [--object OBJECTDEF] [--image-opts] [-f FMT] [--output=OFMT]
[--backing-chain] [-U] FILENAME
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index e4935365c9..50993e6c47 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] [bs=block_size]
[count=blocks] [skip=blocks] [osize=output_size] [if=input] [of=output]")
+ "dd [--image-opts] [-U] [-f fmt] [-O output_fmt] [bs=block_size]
[count=blocks] [skip=blocks] [isize=input_size] [osize=output_size] [if=input]
[of=output]")
SRST
-.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [bs=BLOCK_SIZE]
[count=BLOCKS] [skip=BLOCKS] [osize=OUTPUT_SIZE] [if=INPUT] [of=OUTPUT]
+.. option:: dd [--image-opts] [-U] [-f FMT] [-O OUTPUT_FMT] [bs=BLOCK_SIZE]
[count=BLOCKS] [skip=BLOCKS] [isize=INPUT_SIZE] [osize=OUTPUT_SIZE] [if=INPUT]
[of=OUTPUT]
ERST
DEF("info", img_info,
diff --git a/qemu-img.c b/qemu-img.c
index ea488fd190..630928773d 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4820,11 +4820,13 @@ static int img_bitmap(int argc, char **argv)
#define C_OF 010
#define C_SKIP 020
#define C_OSIZE 040
+#define C_ISIZE 0100
struct DdInfo {
unsigned int flags;
int64_t count;
int64_t osize;
+ int64_t isize;
};
struct DdIo {
@@ -4913,6 +4915,19 @@ static int img_dd_osize(const char *arg,
return 0;
}
+static int img_dd_isize(const char *arg,
+ struct DdIo *in, struct DdIo *out,
+ struct DdInfo *dd)
+{
+ dd->isize = cvtnum("isize", arg);
+
+ if (dd->isize < 0) {
+ return 1;
+ }
+
+ return 0;
+}
+
static int img_dd(int argc, char **argv)
{
int ret = 0;
@@ -4934,6 +4949,7 @@ static int img_dd(int argc, char **argv)
.flags = 0,
.count = 0,
.osize = 0,
+ .isize = 0,
};
struct DdIo in = {
.bsz = 512, /* Block size is by default 512 bytes */
@@ -4955,6 +4971,7 @@ static int img_dd(int argc, char **argv)
{ "of", img_dd_of, C_OF },
{ "skip", img_dd_skip, C_SKIP },
{ "osize", img_dd_osize, C_OSIZE },
+ { "isize", img_dd_isize, C_ISIZE },
{ NULL, NULL, 0 }
};
const struct option long_options[] = {
@@ -5061,7 +5078,9 @@ static int img_dd(int argc, char **argv)
}
}
- if (dd.flags & C_IF) {
+ if (dd.flags & C_ISIZE && dd.isize > 0) {
+ size = dd.isize;
+ } else if (dd.flags & C_IF) {
size = blk_getlength(blk1);
if (size < 0) {
error_report("Failed to get size for '%s'", in.filename);
@@ -5174,6 +5193,9 @@ static int img_dd(int argc, char **argv)
} else {
in_ret = read(STDIN_FILENO, in.buf, in_bsz);
if (in_ret == 0) {
+ if (dd.flags & C_ISIZE && dd.isize == 0) {
+ goto out;
+ }
/* early EOF is considered an error */
error_report("Input ended unexpectedly");
ret = -1;
--
2.30.2