-#include <stddef.h>
-#include <string.h>
-#include <errno.h>
-/* _XOPEN_SOURCE is needed for pread, but we define _GNU_SOURCE, which defines
+/*
+ * Copyright (C) 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
+ * Licensed under the GPL
+ */
+
+/*
+ * _XOPEN_SOURCE is needed for pread, but we define _GNU_SOURCE, which defines
* that.
*/
#include <unistd.h>
#include <byteswap.h>
-#include <sys/time.h>
-#include <sys/param.h>
-#include <sys/user.h>
-#include <netinet/in.h>
-
-#include "os.h"
-
+#include <errno.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <asm/types.h>
#include "cow.h"
#include "cow_sys.h"
#define PATH_LEN_V1 256
+typedef __u32 time32_t;
+
struct cow_header_v1 {
- int magic;
- int version;
+ __s32 magic;
+ __s32 version;
char backing_file[PATH_LEN_V1];
- time_t mtime;
+ time32_t mtime;
__u64 size;
- int sectorsize;
-};
+ __s32 sectorsize;
+} __attribute__((packed));
-#define PATH_LEN_V2 MAXPATHLEN
+/*
+ * 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
struct cow_header_v2 {
__u32 magic;
__u32 version;
char backing_file[PATH_LEN_V2];
- time_t mtime;
+ time32_t mtime;
__u64 size;
- int sectorsize;
-};
+ __s32 sectorsize;
+} __attribute__((packed));
-/* 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 -
+/*
+ * Changes from V2 -
* PATH_LEN_V3 as described above
* Explicitly specify field bit lengths for systems with different
* lengths for the usual C types. Not sure whether char or
* 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 */
int bitmap_offset, unsigned long *bitmap_len_out,
int *data_offset_out)
{
- if(version < 3){
+ if (version < 3) {
*bitmap_len_out = (size + sectorsize - 1) / (8 * sectorsize);
*data_offset_out = bitmap_offset + *bitmap_len_out;
char save_cwd[256], *slash;
int remaining;
- if(getcwd(save_cwd, sizeof(save_cwd)) == NULL) {
+ if (getcwd(save_cwd, sizeof(save_cwd)) == NULL) {
cow_printf("absolutize : unable to get cwd - errno = %d\n",
errno);
- return(-1);
+ return -1;
}
slash = strrchr(from, '/');
- if(slash != NULL){
+ if (slash != NULL) {
*slash = '\0';
- if(chdir(from)){
+ if (chdir(from)) {
*slash = '/';
cow_printf("absolutize : Can't cd to '%s' - "
"errno = %d\n", from, errno);
- return(-1);
+ return -1;
}
*slash = '/';
- if(getcwd(to, size) == NULL){
+ if (getcwd(to, size) == NULL) {
cow_printf("absolutize : unable to get cwd of '%s' - "
"errno = %d\n", from, errno);
- return(-1);
+ return -1;
}
remaining = size - strlen(to);
- if(strlen(slash) + 1 > remaining){
+ if (strlen(slash) + 1 > remaining) {
cow_printf("absolutize : unable to fit '%s' into %d "
"chars\n", from, size);
- return(-1);
+ return -1;
}
strcat(to, slash);
}
else {
- if(strlen(save_cwd) + 1 + strlen(from) + 1 > size){
+ if (strlen(save_cwd) + 1 + strlen(from) + 1 > size) {
cow_printf("absolutize : unable to fit '%s' into %d "
"chars\n", from, size);
- return(-1);
+ return -1;
}
strcpy(to, save_cwd);
strcat(to, "/");
strcat(to, from);
}
chdir(save_cwd);
- return(0);
+ return 0;
}
int write_cow_header(char *cow_file, int fd, char *backing_file,
int err;
err = cow_seek_file(fd, 0);
- if(err < 0){
+ if (err < 0) {
cow_printf("write_cow_header - lseek failed, err = %d\n", -err);
goto out;
}
err = -ENOMEM;
header = cow_malloc(sizeof(*header));
- if(header == NULL){
- cow_printf("Failed to allocate COW V3 header\n");
+ if (header == NULL) {
+ cow_printf("write_cow_header - failed to allocate COW V3 "
+ "header\n");
goto out;
}
header->magic = htonl(COW_MAGIC);
header->version = htonl(COW_VERSION);
err = -EINVAL;
- if(strlen(backing_file) > sizeof(header->backing_file) - 1){
+ 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 %d characters\n", backing_file,
+ "limited to %zd characters\n", backing_file,
sizeof(header->backing_file) - 1);
goto out_free;
}
- if(absolutize(header->backing_file, sizeof(header->backing_file),
+ if (absolutize(header->backing_file, sizeof(header->backing_file),
backing_file))
goto out_free;
err = os_file_modtime(header->backing_file, &modtime);
- if(err < 0){
- cow_printf("Backing file '%s' mtime request failed, "
- "err = %d\n", header->backing_file, -err);
+ if (err < 0) {
+ cow_printf("write_cow_header - backing file '%s' mtime "
+ "request failed, err = %d\n", header->backing_file,
+ -err);
goto out_free;
}
err = cow_file_size(header->backing_file, size);
- if(err < 0){
- cow_printf("Couldn't get size of backing file '%s', "
- "err = %d\n", header->backing_file, -err);
+ if (err < 0) {
+ cow_printf("write_cow_header - couldn't get size of "
+ "backing file '%s', err = %d\n",
+ header->backing_file, -err);
goto out_free;
}
header->alignment = htonl(alignment);
header->cow_format = COW_BITMAP;
- err = os_write_file(fd, header, sizeof(*header));
- if(err != sizeof(*header)){
- cow_printf("Write of header to new COW file '%s' failed, "
- "err = %d\n", cow_file, -err);
+ err = cow_write_file(fd, header, sizeof(*header));
+ if (err != sizeof(*header)) {
+ cow_printf("write_cow_header - write of header to "
+ "new COW file '%s' failed, err = %d\n", cow_file,
+ -err);
goto out_free;
}
err = 0;
out_free:
cow_free(header);
out:
- return(err);
+ return err;
}
int file_reader(__u64 offset, char *buf, int len, void *arg)
{
int fd = *((int *) arg);
- return(pread(fd, buf, len, offset));
+ return pread(fd, buf, len, offset);
}
/* XXX Need to sanity-check the values read from the header */
unsigned long version, magic;
header = cow_malloc(sizeof(*header));
- if(header == NULL){
+ if (header == NULL) {
cow_printf("read_cow_header - Failed to allocate header\n");
- return(-ENOMEM);
+ return -ENOMEM;
}
err = -EINVAL;
n = (*reader)(0, (char *) header, sizeof(*header), arg);
- if(n < offsetof(typeof(header->v1), backing_file)){
+ if (n < offsetof(typeof(header->v1), backing_file)) {
cow_printf("read_cow_header - short header\n");
goto out;
}
magic = header->v1.magic;
- if(magic == COW_MAGIC) {
+ if (magic == COW_MAGIC)
version = header->v1.version;
- }
- else if(magic == ntohl(COW_MAGIC)){
+ else if (magic == ntohl(COW_MAGIC))
version = ntohl(header->v1.version);
- }
/* No error printed because the non-COW case comes through here */
else goto out;
*version_out = version;
- if(version == 1){
- if(n < sizeof(header->v1)){
+ if (version == 1) {
+ if (n < sizeof(header->v1)) {
cow_printf("read_cow_header - failed to read V1 "
"header\n");
goto out;
*align_out = *sectorsize_out;
file = header->v1.backing_file;
}
- else if(version == 2){
- if(n < sizeof(header->v2)){
+ else if (version == 2) {
+ if (n < sizeof(header->v2)) {
cow_printf("read_cow_header - failed to read V2 "
"header\n");
goto out;
*align_out = *sectorsize_out;
file = header->v2.backing_file;
}
- else if(version == 3){
- if(n < sizeof(header->v3)){
- cow_printf("read_cow_header - failed to read V2 "
+ /* This is very subtle - see above at union cow_header definition */
+ else if (version == 3 && (*((int*)header->v3.backing_file) != 0)) {
+ if (n < sizeof(header->v3)) {
+ cow_printf("read_cow_header - failed to read V3 "
"header\n");
goto out;
}
*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;
}
err = -ENOMEM;
*backing_file_out = cow_strdup(file);
- if(*backing_file_out == NULL){
+ if (*backing_file_out == NULL) {
cow_printf("read_cow_header - failed to allocate backing "
"file\n");
goto out;
err = 0;
out:
cow_free(header);
- return(err);
+ return err;
}
int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize,
err = write_cow_header(cow_file, fd, backing_file, sectorsize,
alignment, &size);
- if(err)
+ if (err)
goto out;
*bitmap_offset_out = ROUND_UP(sizeof(struct cow_header_v3), alignment);
offset = *data_offset_out + size - sizeof(zero);
err = cow_seek_file(fd, offset);
- if(err < 0){
+ if (err < 0) {
cow_printf("cow bitmap lseek failed : err = %d\n", -err);
goto out;
}
- /* does not really matter how much we write it is just to set EOF
+ /*
+ * does not really matter how much we write it is just to set EOF
* this also sets the entire COW bitmap
* to zero without having to allocate it
*/
err = cow_write_file(fd, &zero, sizeof(zero));
- if(err != sizeof(zero)){
+ if (err != sizeof(zero)) {
cow_printf("Write of bitmap to new COW file '%s' failed, "
"err = %d\n", cow_file, -err);
- err = -EINVAL;
+ if (err >= 0)
+ err = -EINVAL;
goto out;
}
- return(0);
-
+ return 0;
out:
- return(err);
+ return err;
}
-
-/*
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff