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storagefile: Push 'start' into qcow2GetBackingStoreFormat

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This is a step towards making this qcow2GetBackingStoreFormat into
a generic qcow2 extensions parser

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
This commit is contained in:
Cole Robinson 2019-10-04 19:51:31 -04:00
parent 242e7ac590
commit bd6b4646c7
1 changed files with 17 additions and 16 deletions
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31
src/util/virstoragefile.c
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@ -430,10 +430,22 @@ static int
qcow2GetBackingStoreFormat(int *format, qcow2GetBackingStoreFormat(int *format,
const char *buf, const char *buf,
size_t buf_size, size_t buf_size,
size_t extension_start,
size_t extension_end) size_t extension_end)
{ {
size_t offset = extension_start; size_t offset;
size_t extension_start;
int version = virReadBufInt32BE(buf + QCOWX_HDR_VERSION);
if (version < 2) {
/* QCow1 doesn't have the extensions capability
* used to store backing format */
return 0;
}
if (version == 2)
extension_start = QCOW2_HDR_TOTAL_SIZE;
else
extension_start = virReadBufInt32BE(buf + QCOW2v3_HDR_SIZE);
/* /*
* The extensions take format of * The extensions take format of
@ -445,6 +457,7 @@ qcow2GetBackingStoreFormat(int *format,
* Unknown extensions can be ignored by skipping * Unknown extensions can be ignored by skipping
* over "length" bytes in the data stream. * over "length" bytes in the data stream.
*/ */
offset = extension_start;
while (offset < (buf_size-8) && while (offset < (buf_size-8) &&
offset < (extension_end-8)) { offset < (extension_end-8)) {
unsigned int magic = virReadBufInt32BE(buf + offset); unsigned int magic = virReadBufInt32BE(buf + offset);
@ -487,8 +500,6 @@ qcowXGetBackingStore(char **res,
{ {
unsigned long long offset; unsigned long long offset;
unsigned int size; unsigned int size;
unsigned long long start;
int version;
*res = NULL; *res = NULL;
*format = VIR_STORAGE_FILE_AUTO; *format = VIR_STORAGE_FILE_AUTO;
@ -546,18 +557,8 @@ qcowXGetBackingStore(char **res,
* is stored at QCOW2v3_HDR_SIZE * is stored at QCOW2v3_HDR_SIZE
*/ */
version = virReadBufInt32BE(buf + QCOWX_HDR_VERSION); if (qcow2GetBackingStoreFormat(format, buf, buf_size, offset) < 0)
if (version >= 2) {
/* QCow1 doesn't have the extensions capability
* used to store backing format */
if (version == 2)
start = QCOW2_HDR_TOTAL_SIZE;
else
start = virReadBufInt32BE(buf + QCOW2v3_HDR_SIZE);
if (qcow2GetBackingStoreFormat(format, buf, buf_size,
start, offset) < 0)
return BACKING_STORE_INVALID; return BACKING_STORE_INVALID;
}
return BACKING_STORE_OK; return BACKING_STORE_OK;
} }