diff options
Diffstat (limited to 'read-cache.c')
| -rw-r--r-- | read-cache.c | 39 |
1 files changed, 28 insertions, 11 deletions
diff --git a/read-cache.c b/read-cache.c index e3d3ddb..8e90d2c 100644 --- a/read-cache.c +++ b/read-cache.c @@ -233,6 +233,33 @@ int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1) return 0; } +static inline int collision_check(char *filename, void *buf, unsigned int size) +{ +#ifdef COLLISION_CHECK + void *map; + int fd = open(filename, O_RDONLY); + struct stat st; + int cmp; + + /* Unreadable object, or object went away? Strange. */ + if (fd < 0) + return -1; + + if (fstat(fd, &st) < 0 || size != st.st_size) + return -1; + + map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); + close(fd); + if (map == MAP_FAILED) + return -1; + cmp = memcmp(buf, map, size); + munmap(map, size); + if (cmp) + return -1; +#endif + return 0; +} + int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size) { char *filename = sha1_file_name(sha1); @@ -240,21 +267,11 @@ int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size) fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666); if (fd < 0) { - void *map; - if (errno != EEXIST) return -1; -#ifndef COLLISION_CHECK - fd = open(filename, O_RDONLY); - if (fd < 0) - return -1; - map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); - if (map == MAP_FAILED) - return -1; - if (memcmp(buf, map, size)) + if (collision_check(filename, buf, size)) return error("SHA1 collision detected!" " This is bad, bad, BAD!\a\n"); -#endif return 0; } write(fd, buf, size); |