Commit f7c15533 authored by Reda Sallahi's avatar Reda Sallahi Committed by Max Reitz
Browse files

qemu-img: add skip option to dd 



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: default avatarReda Sallahi <fullmanet@gmail.com>
Message-id: 20160810141609.32727-1-fullmanet@gmail.com
Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
parent 86ce1f6e

qemu-img-cmds.hx

+2 −2
Original line number Diff line number Diff line
@@ -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,

qemu-img.c

+45 −5
Original line number Diff line number Diff line
@@ -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) {

qemu-img.texi

+3 −1
Original line number Diff line number Diff line
@@ -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.

tests/qemu-iotests/160

0 → 100755
+72 −0
Original line number Diff line number Diff line 
#! /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

tests/qemu-iotests/160.out

0 → 100644
+51 −0
Original line number Diff line number Diff line 
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