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qemu-img: Add compare subcommand

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This patch adds new qemu-img subcommand that compares content of two disk
images.

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Miroslav Rezanina 2013-02-13 09:09:41 +01:00 • committed by Kevin Wolf
parent f382d43a91
commit d14ed18c8d
3 changed files with 348 additions and 1 deletions
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53
qemu-img.texi
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@ -84,6 +84,18 @@ deletes a snapshot
lists all snapshots in the given image
@end table
Parameters to compare subcommand:
@table @option
@item -f
First image format
@item -F
Second image format
@item -s
Strict mode - fail on on different image size or sector allocation
@end table
Command description:
@table @option
@ -118,6 +130,47 @@ it doesn't need to be specified separately in this case.
Commit the changes recorded in @var{filename} in its base image.
@item compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-s] [-q] @var{filename1} @var{filename2}
Check if two images have the same content. You can compare images with
different format or settings.
The format is probed unless you specify it by @var{-f} (used for
@var{filename1}) and/or @var{-F} (used for @var{filename2}) option.
By default, images with different size are considered identical if the larger
image contains only unallocated and/or zeroed sectors in the area after the end
of the other image. In addition, if any sector is not allocated in one image
and contains only zero bytes in the second one, it is evaluated as equal. You
can use Strict mode by specifying the @var{-s} option. When compare runs in
Strict mode, it fails in case image size differs or a sector is allocated in
one image and is not allocated in the second one.
By default, compare prints out a result message. This message displays
information that both images are same or the position of the first different
byte. In addition, result message can report different image size in case
Strict mode is used.
Compare exits with @code{0} in case the images are equal and with @code{1}
in case the images differ. Other exit codes mean an error occurred during
execution and standard error output should contain an error message.
The following table sumarizes all exit codes of the compare subcommand:
@table @option
@item 0
Images are identical
@item 1
Images differ
@item 2
Error on opening an image
@item 3
Error on checking a sector allocation
@item 4
Error on reading data
@end table
@item convert [-c] [-p] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to disk image @var{output_filename}