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qemu-img: add skip option to dd

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This adds the skip option which allows qemu-img dd to skip a number of blocks
before copying the input.

A test case was added to test the skip option.

Signed-off-by: Reda Sallahi <fullmanet@gmail.com>
Message-id: 20160810141609.32727-1-fullmanet@gmail.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Reda Sallahi 2016-08-10 16:16:09 +02:00 committed by Max Reitz
parent 86ce1f6e2b
commit f7c1553388
6 changed files with 174 additions and 8 deletions
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4
qemu-img-cmds.hx
View File

@ -46,9 +46,9 @@ STEXI
ETEXI
DEF("dd", img_dd,
"dd [--image-opts] [-f fmt] [-O output_fmt] [bs=block_size] [count=blocks] if=input of=output")
"dd [--image-opts] [-f fmt] [-O output_fmt] [bs=block_size] [count=blocks] [skip=blocks] if=input of=output")
STEXI
@item dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}] [bs=@var{block_size}] [count=@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}] if=@var{input} of=@var{output}
ETEXI
DEF("info", img_info,

50
qemu-img.c
View File

@ -173,7 +173,8 @@ static void QEMU_NORETURN help(void)
"(default: 512)\n"
" 'count=N' copy only N input blocks\n"
" 'if=FILE' read from FILE\n"
" 'of=FILE' write to FILE\n";
" 'of=FILE' write to FILE\n"
" 'skip=N' skip N bs-sized blocks at the start of input\n";
printf("%s\nSupported formats:", help_msg);
bdrv_iterate_format(format_print, NULL);
@ -3807,6 +3808,7 @@ out:
#define C_COUNT 02
#define C_IF 04
#define C_OF 010
#define C_SKIP 020
struct DdInfo {
unsigned int flags;
@ -3817,6 +3819,7 @@ struct DdIo {
int bsz; /* Block size */
char *filename;
uint8_t *buf;
int64_t offset;
};
struct DdOpts {
@ -3877,6 +3880,22 @@ static int img_dd_of(const char *arg,
return 0;
}
static int img_dd_skip(const char *arg,
struct DdIo *in, struct DdIo *out,
struct DdInfo *dd)
{
char *end;
in->offset = qemu_strtosz_suffix(arg, &end, QEMU_STRTOSZ_DEFSUFFIX_B);
if (in->offset < 0 || *end) {
error_report("invalid number: '%s'", arg);
return 1;
}
return 0;
}
static int img_dd(int argc, char **argv)
{
int ret = 0;
@ -3900,12 +3919,14 @@ static int img_dd(int argc, char **argv)
struct DdIo in = {
.bsz = 512, /* Block size is by default 512 bytes */
.filename = NULL,
.buf = NULL
.buf = NULL,
.offset = 0
};
struct DdIo out = {
.bsz = 512,
.filename = NULL,
.buf = NULL
.buf = NULL,
.offset = 0
};
const struct DdOpts options[] = {
@ -3913,6 +3934,7 @@ static int img_dd(int argc, char **argv)
{ "count", img_dd_count, C_COUNT },
{ "if", img_dd_if, C_IF },
{ "of", img_dd_of, C_OF },
{ "skip", img_dd_skip, C_SKIP },
{ NULL, NULL, 0 }
};
const struct option long_options[] = {
@ -4032,7 +4054,14 @@ static int img_dd(int argc, char **argv)
size = dd.count * in.bsz;
}
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &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.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);
}
ret = bdrv_create(drv, out.filename, opts, &local_err);
if (ret < 0) {
@ -4051,9 +4080,20 @@ static int img_dd(int argc, char **argv)
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
* size and create an empty output disk image (i.e. like dd(1)).
*/
error_report("%s: cannot skip to specified offset", in.filename);
in_pos = size;
} else {
in_pos = in.offset * in.bsz;
}
in.buf = g_new(uint8_t, in.bsz);
for (in_pos = 0, out_pos = 0; in_pos < size; block_count++) {
for (out_pos = 0; in_pos < size; block_count++) {
int in_ret, out_ret;
if (in_pos + in.bsz > size) {

4
qemu-img.texi
View File

@ -151,6 +151,8 @@ sets the number of input blocks to copy
sets the input file
@item of=@var{output}
sets the output file
@item skip=@var{blocks}
sets the number of input blocks to skip
@end table
Command description:
@ -324,7 +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}] 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}] 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.

72
tests/qemu-iotests/160 Executable file
View File

@ -0,0 +1,72 @@
#! /bin/bash
#
# qemu-img dd test for the skip option
#
# Copyright (C) 2016 Reda Sallahi
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
owner=fullmanet@gmail.com
seq="$(basename $0)"
echo "QA output created by $seq"
here="$PWD"
status=1
_cleanup()
{
_cleanup_test_img
rm -f "$TEST_IMG.out" "$TEST_IMG.out.dd"
}
trap "_cleanup; exit \$status" 0 1 2 3 15
. ./common.rc
. ./common.filter
. ./common.pattern
_supported_fmt raw
_supported_proto file
_supported_os Linux
TEST_SKIP_BLOCKS="1 2 30 30K"
for skip in $TEST_SKIP_BLOCKS; do
echo
echo "== Creating image =="
size=1M
_make_test_img $size
_check_test_img
$QEMU_IO -c "write -P 0xa 24 512k" "$TEST_IMG" | _filter_qemu_io
echo
echo "== Converting the image with dd with skip=$skip =="
$QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" skip="$skip" -O "$IMGFMT" \
2> /dev/null
TEST_IMG="$TEST_IMG.out" _check_test_img
dd if="$TEST_IMG" of="$TEST_IMG.out.dd" skip="$skip" status=none
echo
echo "== Compare the images with qemu-img compare =="
$QEMU_IMG compare "$TEST_IMG.out.dd" "$TEST_IMG.out"
done
echo
echo "*** done"
rm -f "$seq.full"
status=0

51
tests/qemu-iotests/160.out Normal file
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@ -0,0 +1,51 @@
QA output created by 160
== Creating image ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
No errors were found on the image.
wrote 524288/524288 bytes at offset 24
512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
== Converting the image with dd with skip=1 ==
No errors were found on the image.
== Compare the images with qemu-img compare ==
Images are identical.
== Creating image ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
No errors were found on the image.
wrote 524288/524288 bytes at offset 24
512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
== Converting the image with dd with skip=2 ==
No errors were found on the image.
== Compare the images with qemu-img compare ==
Images are identical.
== Creating image ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
No errors were found on the image.
wrote 524288/524288 bytes at offset 24
512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
== Converting the image with dd with skip=30 ==
No errors were found on the image.
== Compare the images with qemu-img compare ==
Images are identical.
== Creating image ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
No errors were found on the image.
wrote 524288/524288 bytes at offset 24
512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
== Converting the image with dd with skip=30K ==
No errors were found on the image.
== Compare the images with qemu-img compare ==
Images are identical.
*** done

1
tests/qemu-iotests/group
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@ -158,5 +158,6 @@
156 rw auto quick
157 auto
159 rw auto quick
160 rw auto quick
162 auto quick
170 rw auto quick