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block/file-*: *_parse_filename() and colons

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The file drivers' *_parse_filename() implementations just strip the
optional protocol prefix off the filename. However, for e.g.
"file:foo:bar", this would lead to "foo:bar" being stored as the BDS's
filename which looks like it should be managed using the "foo" protocol.
This is especially troublesome if you then try to resolve a backing
filename based on "foo:bar".

This issue can only occur if the stripped part is a relative filename
("file:/foo:bar" will be shortened to "/foo:bar" and having a slash
before the first colon means that "/foo" is not recognized as a protocol
part). Therefore, we can easily fix it by prepending "./" to such
filenames.

Before this patch:
$ ./qemu-img create -f qcow2 backing.qcow2 64M
Formatting 'backing.qcow2', fmt=qcow2 size=67108864 encryption=off
    cluster_size=65536 lazy_refcounts=off refcount_bits=16
$ ./qemu-img create -f qcow2 -b backing.qcow2 file🔝image.qcow2
Formatting 'file🔝image.qcow2', fmt=qcow2 size=67108864
    backing_file=backing.qcow2 encryption=off cluster_size=65536
    lazy_refcounts=off refcount_bits=16
$ ./qemu-io file🔝image.qcow2
can't open device file🔝image.qcow2: Could not open backing file:
    Unknown protocol 'top'

After this patch:
$ ./qemu-io file🔝image.qcow2
[no error]

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170522195217.12991-3-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2017-05-22 21:52:16 +02:00
parent 0d54a6fed3
commit 03c320d803
4 changed files with 43 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

17
block/file-posix.c
View file

@ -381,12 +381,7 @@ static void raw_parse_flags(int bdrv_flags, int *open_flags)
static void raw_parse_filename(const char *filename, QDict *options,
Error **errp)
{
/* The filename does not have to be prefixed by the protocol name, since
* "file" is the default protocol; therefore, the return value of this
* function call can be ignored. */
strstart(filename, "file:", &filename);
qdict_put_str(options, "filename", filename);
bdrv_parse_filename_strip_prefix(filename, "file:", options);
}
static QemuOptsList raw_runtime_opts = {
@ -2395,10 +2390,7 @@ static int check_hdev_writable(BDRVRawState *s)
static void hdev_parse_filename(const char *filename, QDict *options,
Error **errp)
{
/* The prefix is optional, just as for "file". */
strstart(filename, "host_device:", &filename);
qdict_put_str(options, "filename", filename);
bdrv_parse_filename_strip_prefix(filename, "host_device:", options);
}
static bool hdev_is_sg(BlockDriverState *bs)
@ -2697,10 +2689,7 @@ static BlockDriver bdrv_host_device = {
static void cdrom_parse_filename(const char *filename, QDict *options,
Error **errp)
{
/* The prefix is optional, just as for "file". */
strstart(filename, "host_cdrom:", &filename);
qdict_put_str(options, "filename", filename);
bdrv_parse_filename_strip_prefix(filename, "host_cdrom:", options);
}
#endif