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block: Use bdrv_dirname() for relative filenames

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bdrv_get_full_backing_filename_from_filename() breaks down when it comes
to JSON filenames. Using bdrv_dirname() as the basis is better because
since we have BDS, we can descend through the BDS tree to the protocol
layer, which gives us a greater probability of finding a non-JSON name;
also, bdrv_dirname() is more correct as it allows block drivers to
override the generation of that directory name in a protocol-specific
way.

We still need to keep bdrv_get_full_backing_filename_from_filename(),
though, because it has valid callers which need it during image creation
when no BDS is available yet.

This makes a test case in qemu-iotest 110, which was supposed to fail,
work. That is actually good, but we need to change the reference output
(and the comment in 110) accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-20-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2019-02-01 20:29:23 +01:00
parent 0dcbc54a95
commit 8df686165b
3 changed files with 16 additions and 9 deletions
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20
block.c
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@ -337,16 +337,22 @@ char *bdrv_get_full_backing_filename_from_filename(const char *backed,
static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
const char *filename, Error **errp)
{
char *bs_filename;
char *dir, *full_name;
bdrv_refresh_filename(relative_to);
if (!filename || filename[0] == '\0') {
return NULL;
} else if (path_has_protocol(filename) || path_is_absolute(filename)) {
return g_strdup(filename);
}
bs_filename = relative_to->exact_filename[0]
? relative_to->exact_filename
: relative_to->filename;
dir = bdrv_dirname(relative_to, errp);
if (!dir) {
return NULL;
}
return bdrv_get_full_backing_filename_from_filename(bs_filename,
filename ?: "", errp);
full_name = g_strconcat(dir, filename, NULL);
g_free(dir);
return full_name;
}
char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)

3
tests/qemu-iotests/110
View File

@ -60,7 +60,8 @@ echo '=== Non-reconstructable filename ==='
echo
# Across blkdebug without a config file, you cannot reconstruct filenames, so
# qemu is incapable of knowing the directory of the top image
# qemu is incapable of knowing the directory of the top image from the filename
# alone. However, using bdrv_dirname(), it should still work.
TEST_IMG="json:{
'driver': '$IMGFMT',
'file': {

2
tests/qemu-iotests/110.out
View File

@ -14,7 +14,7 @@ backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
image: json:{"driver": "IMGFMT", "file": {"set-state.0.event": "read_aio", "image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug", "set-state.0.new_state": 42}}
file format: IMGFMT
virtual size: 64M (67108864 bytes)
backing file: t.IMGFMT.base (cannot determine actual path)
backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
=== Backing name is always relative to the backed image ===