X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=arch%2Fum%2Fdrivers%2Fcow_user.c;h=93f227a25ba42f5742d1343c1fc7e0bb34a9ea74;hb=20ebc0073b0fb63ce4a27ca761418ecfdecaadb7;hp=61951b721268f1c030279cff98b2a25213708ca8;hpb=2e1ca21d46aaef95101723fa402f39d3a95aba59;p=linux-2.6-omap-h63xx.git diff --git a/arch/um/drivers/cow_user.c b/arch/um/drivers/cow_user.c index 61951b72126..93f227a25ba 100644 --- a/arch/um/drivers/cow_user.c +++ b/arch/um/drivers/cow_user.c @@ -1,48 +1,55 @@ -#include -#include -#include -/* _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 #include -#include -#include -#include - -#include "os.h" - +#include +#include +#include +#include #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 @@ -66,6 +73,16 @@ 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; @@ -75,6 +92,18 @@ 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 */ @@ -84,6 +113,7 @@ 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 */ @@ -96,7 +126,7 @@ void cow_sizes(int version, __u64 size, int sectorsize, int align, 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; @@ -118,46 +148,46 @@ static int absolutize(char *to, int size, char *from) 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, @@ -168,34 +198,36 @@ 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("write_cow_header - 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){ + if (err < 0) { cow_printf("write_cow_header - backing file '%s' mtime " "request failed, err = %d\n", header->backing_file, -err); @@ -203,7 +235,7 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, } err = cow_file_size(header->backing_file, size); - if(err < 0){ + if (err < 0) { cow_printf("write_cow_header - couldn't get size of " "backing file '%s', err = %d\n", header->backing_file, -err); @@ -217,7 +249,7 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, header->cow_format = COW_BITMAP; err = cow_write_file(fd, header, sizeof(*header)); - if(err != 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); @@ -227,14 +259,14 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, 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 */ @@ -251,31 +283,29 @@ int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg, 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; @@ -287,8 +317,8 @@ int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg, *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; @@ -300,8 +330,9 @@ 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){ - if(n < sizeof(header->v3)){ + /* 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; @@ -310,16 +341,51 @@ 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; } 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; @@ -327,7 +393,7 @@ int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg, err = 0; out: cow_free(header); - return(err); + return err; } int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize, @@ -340,7 +406,7 @@ 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); @@ -349,17 +415,18 @@ int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize, 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); if (err >= 0) @@ -367,15 +434,7 @@ int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize, goto out; } - return(0); - + return 0; out: - return(err); + return err; } - -/* - * --------------------------------------------------------------------------- - * Local variables: - * c-file-style: "linux" - * End: - */