uint32_t len;
} QCowExtension;
#define QCOW_EXT_MAGIC_END 0
+#define QCOW_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
typedef struct __attribute__((packed)) QCowSnapshotHeader {
switch (ext.magic) {
case QCOW_EXT_MAGIC_END:
return 0;
+
+ case QCOW_EXT_MAGIC_BACKING_FORMAT:
+ if (ext.len >= sizeof(bs->backing_format)) {
+ fprintf(stderr, "ERROR: ext_backing_format: len=%u too large"
+ " (>=%lu)\n",
+ ext.len, sizeof(bs->backing_format));
+ return 2;
+ }
+ if (bdrv_pread(s->hd, offset , bs->backing_format,
+ ext.len) != ext.len)
+ return 3;
+ bs->backing_format[ext.len] = '\0';
+#ifdef DEBUG_EXT
+ printf("Qcow2: Got format extension %s\n", bs->backing_format);
+#endif
+ offset += ((ext.len + 7) & ~7);
+ break;
+
default:
/* unknown magic -- just skip it */
offset += ((ext.len + 7) & ~7);
}
}
-static int qcow_create(const char *filename, int64_t total_size,
- const char *backing_file, int flags)
+static int qcow_create2(const char *filename, int64_t total_size,
+ const char *backing_file, const char *backing_format,
+ int flags)
{
+
int fd, header_size, backing_filename_len, l1_size, i, shift, l2_bits;
+ int backing_format_len = 0;
QCowHeader header;
uint64_t tmp, offset;
QCowCreateState s1, *s = &s1;
+ QCowExtension ext_bf = {0, 0};
+
memset(s, 0, sizeof(*s));
header_size = sizeof(header);
backing_filename_len = 0;
if (backing_file) {
+ if (backing_format) {
+ ext_bf.magic = QCOW_EXT_MAGIC_BACKING_FORMAT;
+ backing_format_len = strlen(backing_format);
+ ext_bf.len = (backing_format_len + 7) & ~7;
+ header_size += ((sizeof(ext_bf) + ext_bf.len + 7) & ~7);
+ }
header.backing_file_offset = cpu_to_be64(header_size);
backing_filename_len = strlen(backing_file);
header.backing_file_size = cpu_to_be32(backing_filename_len);
/* write all the data */
write(fd, &header, sizeof(header));
if (backing_file) {
+ if (backing_format_len) {
+ char zero[16];
+ int d = ext_bf.len - backing_format_len;
+
+ memset(zero, 0, sizeof(zero));
+ cpu_to_be32s(&ext_bf.magic);
+ cpu_to_be32s(&ext_bf.len);
+ write(fd, &ext_bf, sizeof(ext_bf));
+ write(fd, backing_format, backing_format_len);
+ if (d>0) {
+ write(fd, zero, d);
+ }
+ }
write(fd, backing_file, backing_filename_len);
}
lseek(fd, s->l1_table_offset, SEEK_SET);
return 0;
}
+static int qcow_create(const char *filename, int64_t total_size,
+ const char *backing_file, int flags)
+{
+ return qcow_create2(filename, total_size, backing_file, NULL, flags);
+}
+
static int qcow_make_empty(BlockDriverState *bs)
{
#if 0
.bdrv_snapshot_delete = qcow_snapshot_delete,
.bdrv_snapshot_list = qcow_snapshot_list,
.bdrv_get_info = qcow_get_info,
+
+ .bdrv_create2 = qcow_create2,
};