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Re: [Qemu-devel] [PATCH] qemu-img: add conv=notrunc option to dd
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From: |
Fam Zheng |
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Subject: |
Re: [Qemu-devel] [PATCH] qemu-img: add conv=notrunc option to dd |
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Date: |
Thu, 11 Aug 2016 11:12:02 +0800 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, 08/11 05:07, Reda Sallahi wrote:
> This adds the conv=notrunc option to dd which tells dd to not truncate the
> output.
>
> For the time being we make it mandatory to specify conv=notrunc.
>
> Signed-off-by: Reda Sallahi <address@hidden>
> ---
> qemu-img-cmds.hx | 4 ++--
> qemu-img.c | 31 ++++++++++++++++++++++++++++---
> qemu-img.texi | 15 +++++++++------
> tests/qemu-iotests/158 | 2 +-
> tests/qemu-iotests/159 | 3 ++-
> tests/qemu-iotests/160 | 7 ++++---
> 6 files changed, 46 insertions(+), 16 deletions(-)
>
> diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
> index f054599..18685ac 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=notrunc] if=input of=output")
> STEXI
> address@hidden dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}]
> address@hidden address@hidden address@hidden address@hidden address@hidden
> address@hidden dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}]
> address@hidden address@hidden address@hidden [conv=notrunc] address@hidden
> address@hidden
> ETEXI
>
> DEF("info", img_info,
> diff --git a/qemu-img.c b/qemu-img.c
> index 3adec86..16b56b8 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -174,7 +174,8 @@ 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=notrunc' do not truncate the output file\n";
>
> printf("%s\nSupported formats:", help_msg);
> bdrv_iterate_format(format_print, NULL);
> @@ -3807,10 +3808,12 @@ out:
> #define C_IF 04
> #define C_OF 010
> #define C_SKIP 020
> +#define C_CONV 040
>
> struct DdInfo {
> unsigned int flags;
> int64_t count;
> + unsigned int conv;
> };
>
> struct DdIo {
> @@ -3894,6 +3897,21 @@ static int img_dd_skip(const char *arg,
> return 0;
> }
>
> +#define C_NOTRUNC 01
> +
> +static int img_dd_conv(const char *arg,
> + struct DdIo *in, struct DdIo *out,
> + struct DdInfo *dd)
> +{
> + if (!strcmp(arg, "notrunc")) {
> + dd->conv |= C_NOTRUNC;
> + return 0;
> + } else {
> + error_report("invalid conversion: '%s'", arg);
> + return 1;
> + }
> +}
> +
> static int img_dd(int argc, char **argv)
> {
> int ret = 0;
> @@ -3909,10 +3927,11 @@ static int img_dd(int argc, char **argv)
> const char *out_fmt = "raw";
> const char *fmt = NULL;
> int64_t size = 0;
> - int64_t block_count = 0, out_pos, in_pos;
> + int64_t out_pos, in_pos;
This change is not related to this patch. It should probably done by another
patch, or removed.
> struct DdInfo dd = {
> .flags = 0,
> .count = 0,
> + .conv = 0
> };
> struct DdIo in = {
> .bsz = 512, /* Block size is by default 512 bytes */
> @@ -3933,6 +3952,7 @@ 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, C_CONV },
> { NULL, NULL, 0 }
> };
> const struct option long_options[] = {
> @@ -3997,6 +4017,11 @@ static int img_dd(int argc, char **argv)
> g_free(arg);
> arg = NULL;
> }
> + if (!(dd.conv & C_NOTRUNC)) {
> + error_report("conv=notrunc not specified");
A comment and/or a more detailed error message explaining the situation why we
do this now would be necessary, so that in the future we'll remember to do the
right thing once it's decided.
> + ret = -1;
> + goto out;
> + }
>
> if (!(dd.flags & C_IF && dd.flags & C_OF)) {
> error_report("Must specify both input and output files");
> @@ -4091,7 +4116,7 @@ static int img_dd(int argc, char **argv)
>
> in.buf = g_new(uint8_t, in.bsz);
>
> - for (out_pos = 0; in_pos < size; block_count++) {
> + for (out_pos = 0; in_pos < size; ) {
> int in_ret, out_ret;
>
> if (in_pos + in.bsz > size) {
> diff --git a/qemu-img.texi b/qemu-img.texi
> index 174aae3..891af14 100644
> --- a/qemu-img.texi
> +++ b/qemu-img.texi
> @@ -144,15 +144,18 @@ Parameters to dd subcommand:
> @table @option
>
> @item address@hidden
> -defines the block size
> +Defines the block size.
> @item address@hidden
> -sets the number of input blocks to copy
> +Sets the number of input blocks to copy.
> @item address@hidden
> -sets the input file
> +Sets the input file.
> @item address@hidden
> -sets the output file
> +Sets the output file. dd truncates the output file to zero if 'conv=notrunc'
> +is not specified.
> @item address@hidden
> -sets the number of input blocks to skip
> +Sets the number of input blocks to skip.
> address@hidden conv=notrunc
> +Makes dd not truncate output file to zero.
Capitalizing other sentences should go as a sepearte patch.
> @end table
>
> Command description:
> @@ -326,7 +329,7 @@ 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.
>
> address@hidden dd [-f @var{fmt}] [-O @var{output_fmt}] address@hidden
> address@hidden address@hidden address@hidden address@hidden
> address@hidden dd [-f @var{fmt}] [-O @var{output_fmt}] address@hidden
> address@hidden address@hidden [conv=notrunc] address@hidden address@hidden
>
> Dd copies from @var{input} file to @var{output} file converting it from
> @var{fmt} format to @var{output_fmt} format.
> diff --git a/tests/qemu-iotests/158 b/tests/qemu-iotests/158
> index 5b335db..63e2a10 100755
> --- a/tests/qemu-iotests/158
> +++ b/tests/qemu-iotests/158
> @@ -53,7 +53,7 @@ $QEMU_IO -c "write -P 0xa 0 $size" "$TEST_IMG" |
> _filter_qemu_io
> echo
> echo "== Converting the image with dd =="
>
> -$QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" -O "$IMGFMT"
> +$QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" conv=notrunc -O "$IMGFMT"
> TEST_IMG="$TEST_IMG.out" _check_test_img
>
> echo
> diff --git a/tests/qemu-iotests/159 b/tests/qemu-iotests/159
> index 825f05f..d68a19f 100755
> --- a/tests/qemu-iotests/159
> +++ b/tests/qemu-iotests/159
> @@ -55,7 +55,8 @@ for bs in $TEST_SIZES; do
> echo
> echo "== Converting the image with dd with a block size of $bs =="
>
> - $QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" bs=$bs -O "$IMGFMT"
> + $QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" bs=$bs conv=notrunc \
> + -O "$IMGFMT"
> TEST_IMG="$TEST_IMG.out" _check_test_img
>
> echo
> diff --git a/tests/qemu-iotests/160 b/tests/qemu-iotests/160
> index 5c910e5..53b3c30 100755
> --- a/tests/qemu-iotests/160
> +++ b/tests/qemu-iotests/160
> @@ -55,10 +55,11 @@ for skip in $TEST_SKIP_BLOCKS; do
> echo
> echo "== Converting the image with dd with skip=$skip =="
>
> - $QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" skip="$skip" -O "$IMGFMT"
> \
> - 2> /dev/null
> + $QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" skip="$skip" conv=notrunc
> \
> + -O "$IMGFMT" 2> /dev/null
> TEST_IMG="$TEST_IMG.out" _check_test_img
> - dd if="$TEST_IMG" of="$TEST_IMG.out.dd" skip="$skip" status=none
> + dd if="$TEST_IMG" of="$TEST_IMG.out.dd" skip="$skip" conv=notrunc \
> + status=none
>
> echo
> echo "== Compare the images with qemu-img compare =="
> --
> 2.9.2
>
Apart from above, the conv=notrunc code looks good to me. Thanks!
Fam