#define PATH_LEN_V1 256
-typedef __u32 time32_t;
-
struct cow_header_v1 {
- __s32 magic;
- __s32 version;
+ int magic;
+ int version;
char backing_file[PATH_LEN_V1];
- time32_t mtime;
+ time_t mtime;
__u64 size;
- __s32 sectorsize;
-} __attribute__((packed));
+ int sectorsize;
+};
-/* Define PATH_LEN_V3 as the usual value of MAXPATHLEN, just hard-code it in
- * case other systems have different values for MAXPATHLEN.
- *
- * The same must hold for V2 - we want file format compatibility, not anything
- * else.
- */
-#define PATH_LEN_V3 4096
-#define PATH_LEN_V2 PATH_LEN_V3
+#define PATH_LEN_V2 MAXPATHLEN
struct cow_header_v2 {
__u32 magic;
__u32 version;
char backing_file[PATH_LEN_V2];
- time32_t mtime;
+ time_t mtime;
__u64 size;
- __s32 sectorsize;
-} __attribute__((packed));
+ int sectorsize;
+};
+
+/* Define PATH_LEN_V3 as the usual value of MAXPATHLEN, just hard-code it in
+ * case other systems have different values for MAXPATHLEN
+ */
+#define PATH_LEN_V3 4096
/* Changes from V2 -
* PATH_LEN_V3 as described above
* Fixed (finally!) the rounding bug
*/
-/* Until Dec2005, __attribute__((packed)) was left out from the below
- * definition, leading on 64-bit systems to 4 bytes of padding after mtime, to
- * align size to 8-byte alignment. This shifted all fields above (no padding
- * was present on 32-bit, no other padding was added).
- *
- * However, this _can be detected_: it means that cow_format (always 0 until
- * now) is shifted onto the first 4 bytes of backing_file, where it is otherwise
- * impossible to find 4 zeros. -bb */
-
struct cow_header_v3 {
__u32 magic;
__u32 version;
__u32 alignment;
__u32 cow_format;
char backing_file[PATH_LEN_V3];
-} __attribute__((packed));
-
-/* This is the broken layout used by some 64-bit binaries. */
-struct cow_header_v3_broken {
- __u32 magic;
- __u32 version;
- __s64 mtime;
- __u64 size;
- __u32 sectorsize;
- __u32 alignment;
- __u32 cow_format;
- char backing_file[PATH_LEN_V3];
};
/* COW format definitions - for now, we have only the usual COW bitmap */
struct cow_header_v1 v1;
struct cow_header_v2 v2;
struct cow_header_v3 v3;
- struct cow_header_v3_broken v3_b;
};
#define COW_MAGIC 0x4f4f4f4d /* MOOO */
err = -EINVAL;
if(strlen(backing_file) > sizeof(header->backing_file) - 1){
- /* Below, %zd is for a size_t value */
cow_printf("Backing file name \"%s\" is too long - names are "
- "limited to %zd characters\n", backing_file,
+ "limited to %d characters\n", backing_file,
sizeof(header->backing_file) - 1);
goto out_free;
}
*align_out = *sectorsize_out;
file = header->v2.backing_file;
}
- /* This is very subtle - see above at union cow_header definition */
- else if(version == 3 && (*((int*)header->v3.backing_file) != 0)){
+ else if(version == 3){
if(n < sizeof(header->v3)){
cow_printf("read_cow_header - failed to read V3 "
"header\n");
*size_out = ntohll(header->v3.size);
*sectorsize_out = ntohl(header->v3.sectorsize);
*align_out = ntohl(header->v3.alignment);
- if (*align_out == 0) {
- cow_printf("read_cow_header - invalid COW header, "
- "align == 0\n");
- }
*bitmap_offset_out = ROUND_UP(sizeof(header->v3), *align_out);
file = header->v3.backing_file;
}
- else if(version == 3){
- cow_printf("read_cow_header - broken V3 file with"
- " 64-bit layout - recovering content.\n");
-
- if(n < sizeof(header->v3_b)){
- cow_printf("read_cow_header - failed to read V3 "
- "header\n");
- goto out;
- }
-
- /* this was used until Dec2005 - 64bits are needed to represent
- * 2038+. I.e. we can safely do this truncating cast.
- *
- * Additionally, we must use ntohl() instead of ntohll(), since
- * the program used to use the former (tested - I got mtime
- * mismatch "0 vs whatever").
- *
- * Ever heard about bug-to-bug-compatibility ? ;-) */
- *mtime_out = (time32_t) ntohl(header->v3_b.mtime);
-
- *size_out = ntohll(header->v3_b.size);
- *sectorsize_out = ntohl(header->v3_b.sectorsize);
- *align_out = ntohl(header->v3_b.alignment);
- if (*align_out == 0) {
- cow_printf("read_cow_header - invalid COW header, "
- "align == 0\n");
- }
- *bitmap_offset_out = ROUND_UP(sizeof(header->v3_b), *align_out);
- file = header->v3_b.backing_file;
- }
else {
cow_printf("read_cow_header - invalid COW version\n");
goto out;