X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fum%2Fdrivers%2Fcow_user.c;h=0ec4052db9c5bbb183714a44012ef07fc388b026;hb=43bc926fffd92024b46cafaf7350d669ba9ca884;hp=a8ce6fc3ef26b1ca8db782fe93f26fd301cc3aa0;hpb=cee37fe97739d85991964371c1f3a745c00dd236;p=linux-2.6.git diff --git a/arch/um/drivers/cow_user.c b/arch/um/drivers/cow_user.c index a8ce6fc3e..0ec4052db 100644 --- a/arch/um/drivers/cow_user.c +++ b/arch/um/drivers/cow_user.c @@ -9,7 +9,6 @@ #include #include #include -#include #include "os.h" @@ -18,30 +17,34 @@ #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; -}; - -/* 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 + __s32 sectorsize; +} __attribute__((packed)); /* Changes from V2 - * PATH_LEN_V3 as described above @@ -67,6 +70,15 @@ struct cow_header_v2 { * 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; @@ -76,6 +88,18 @@ struct cow_header_v3 { __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 */ @@ -85,6 +109,7 @@ union cow_header { 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 */ @@ -177,7 +202,7 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, err = -ENOMEM; header = cow_malloc(sizeof(*header)); if(header == NULL){ - cow_printf("Failed to allocate COW V3 header\n"); + cow_printf("write_cow_header - failed to allocate COW V3 header\n"); goto out; } header->magic = htonl(COW_MAGIC); @@ -185,8 +210,9 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, 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 %d characters\n", backing_file, + "limited to %zd characters\n", backing_file, sizeof(header->backing_file) - 1); goto out_free; } @@ -197,15 +223,17 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, 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); + 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); + cow_printf("write_cow_header - couldn't get size of " + "backing file '%s', err = %d\n", + header->backing_file, -err); goto out_free; } @@ -215,10 +243,11 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, header->alignment = htonl(alignment); header->cow_format = COW_BITMAP; - err = os_write_file(fd, header, sizeof(*header)); + err = cow_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); + 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; @@ -298,9 +327,10 @@ int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg, *align_out = *sectorsize_out; file = header->v2.backing_file; } - else if(version == 3){ + /* 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 V2 " + cow_printf("read_cow_header - failed to read V3 " "header\n"); goto out; } @@ -308,9 +338,43 @@ int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg, *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; @@ -360,7 +424,8 @@ int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize, 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; }