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Support for probing qed image metadata

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Implement getBackingStore() for QED images.  The header format is defined in
the QED spec: http://wiki.qemu.org/Features/QED .

Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: Stefan Hajnoczi <stefan.hajnoczi@uk.ibm.com>
Cc: Anthony Liguori <aliguori@linux.vnet.ibm.com>
This commit is contained in:
Adam Litke 2010-11-19 16:19:24 -07:00 committed by Eric Blake
parent fd93d46642
commit c9f48f4e50
1 changed files with 76 additions and 2 deletions
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78
src/util/storage_file.c
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@ -90,6 +90,8 @@ static int qcow2GetBackingStore(char **, int *,
const unsigned char *, size_t);
static int vmdk4GetBackingStore(char **, int *,
const unsigned char *, size_t);
static int
qedGetBackingStore(char **, int *, const unsigned char *, size_t);
#define QCOWX_HDR_VERSION (4)
#define QCOWX_HDR_BACKING_FILE_OFFSET (QCOWX_HDR_VERSION+4)
@ -105,7 +107,12 @@ static int vmdk4GetBackingStore(char **, int *,
#define QCOW2_HDR_EXTENSION_END 0
#define QCOW2_HDR_EXTENSION_BACKING_FORMAT 0xE2792ACA
#define QED_HDR_IMAGE_SIZE (4+4+4+4+8+8+8)
#define QED_HDR_FEATURES_OFFSET (4+4+4+4)
#define QED_HDR_IMAGE_SIZE (QED_HDR_FEATURES_OFFSET+8+8+8)
#define QED_HDR_BACKING_FILE_OFFSET (QED_HDR_IMAGE_SIZE+8+8)
#define QED_HDR_BACKING_FILE_SIZE (QED_HDR_BACKING_FILE_OFFSET+4)
#define QED_F_BACKING_FILE 0x01
#define QED_F_BACKING_FORMAT_NO_PROBE 0x04
/* VMDK needs at least this to find backing store,
* other formats need less */
@ -158,7 +165,7 @@ static struct FileTypeInfo const fileTypeInfo[] = {
/* http://wiki.qemu.org/Features/QED */
"QED\0", NULL,
LV_LITTLE_ENDIAN, -1, -1,
QED_HDR_IMAGE_SIZE, 8, 1, -1, NULL,
QED_HDR_IMAGE_SIZE, 8, 1, -1, qedGetBackingStore,
},
[VIR_STORAGE_FILE_VMDK] = {
"KDMV", NULL,
@ -418,6 +425,73 @@ cleanup:
return ret;
}
static unsigned long
qedGetHeaderUL(const unsigned char *loc)
{
return ( ((unsigned long)loc[3] << 24)
| ((unsigned long)loc[2] << 16)
| ((unsigned long)loc[1] << 8)
| ((unsigned long)loc[0] << 0));
}
static unsigned long long
qedGetHeaderULL(const unsigned char *loc)
{
return ( ((unsigned long)loc[7] << 56)
| ((unsigned long)loc[6] << 48)
| ((unsigned long)loc[5] << 40)
| ((unsigned long)loc[4] << 32)
| ((unsigned long)loc[3] << 24)
| ((unsigned long)loc[2] << 16)
| ((unsigned long)loc[1] << 8)
| ((unsigned long)loc[0] << 0));
}
static int
qedGetBackingStore(char **res,
int *format,
const unsigned char *buf,
size_t buf_size)
{
unsigned long long flags;
unsigned long offset, size;
*res = NULL;
/* Check if this image has a backing file */
if (buf_size < QED_HDR_FEATURES_OFFSET+8)
return BACKING_STORE_INVALID;
flags = qedGetHeaderULL(buf + QED_HDR_FEATURES_OFFSET);
if (!(flags & QED_F_BACKING_FILE))
return BACKING_STORE_OK;
/* Parse the backing file */
if (buf_size < QED_HDR_BACKING_FILE_OFFSET+8)
return BACKING_STORE_INVALID;
offset = qedGetHeaderUL(buf + QED_HDR_BACKING_FILE_OFFSET);
if (offset > buf_size)
return BACKING_STORE_INVALID;
size = qedGetHeaderUL(buf + QED_HDR_BACKING_FILE_SIZE);
if (size == 0)
return BACKING_STORE_OK;
if (offset + size > buf_size || offset + size < offset)
return BACKING_STORE_INVALID;
if (VIR_ALLOC_N(*res, size + 1) < 0) {
virReportOOMError();
return BACKING_STORE_ERROR;
}
memcpy(*res, buf + offset, size);
(*res)[size] = '\0';
if (format) {
if (flags & QED_F_BACKING_FORMAT_NO_PROBE)
*format = virStorageFileFormatTypeFromString("raw");
else
*format = VIR_STORAGE_FILE_AUTO_SAFE;
}
return BACKING_STORE_OK;
}
/**
* Return an absolute path corresponding to PATH, which is absolute or relative
* to the directory containing BASE_FILE, or NULL on error