2 * GIT - The information manager from hell
4 * Copyright (C) Linus Torvalds, 2005
6 * This handles basic git sha1 object files - packing, unpacking,
12 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
13 #define O_NOATIME 01000000
19 static unsigned int sha1_file_open_flag = O_NOATIME;
21 static unsigned hexval(char c)
23 if (c >= '0' && c <= '9')
25 if (c >= 'a' && c <= 'f')
27 if (c >= 'A' && c <= 'F')
32 int get_sha1_hex(const char *hex, unsigned char *sha1)
35 for (i = 0; i < 20; i++) {
36 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
45 static int get_sha1_file(const char *path, unsigned char *result)
48 int fd = open(path, O_RDONLY);
53 len = read(fd, buffer, sizeof(buffer));
57 return get_sha1_hex(buffer, result);
60 static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir;
61 static void setup_git_env(void)
63 git_dir = gitenv(GIT_DIR_ENVIRONMENT);
65 git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
66 git_object_dir = gitenv(DB_ENVIRONMENT);
67 if (!git_object_dir) {
68 git_object_dir = xmalloc(strlen(git_dir) + 9);
69 sprintf(git_object_dir, "%s/objects", git_dir);
71 git_refs_dir = xmalloc(strlen(git_dir) + 6);
72 sprintf(git_refs_dir, "%s/refs", git_dir);
73 git_index_file = gitenv(INDEX_ENVIRONMENT);
74 if (!git_index_file) {
75 git_index_file = xmalloc(strlen(git_dir) + 7);
76 sprintf(git_index_file, "%s/index", git_dir);
80 char *get_object_directory(void)
84 return git_object_dir;
87 char *get_refs_directory(void)
94 char *get_index_file(void)
98 return git_index_file;
101 int get_sha1(const char *str, unsigned char *sha1)
103 static char pathname[PATH_MAX];
104 static const char *prefix[] = {
114 if (!get_sha1_hex(str, sha1))
119 for (p = prefix; *p; p++) {
120 snprintf(pathname, sizeof(pathname), "%s/%s/%s",
122 if (!get_sha1_file(pathname, sha1))
129 char * sha1_to_hex(const unsigned char *sha1)
131 static char buffer[50];
132 static const char hex[] = "0123456789abcdef";
136 for (i = 0; i < 20; i++) {
137 unsigned int val = *sha1++;
138 *buf++ = hex[val >> 4];
139 *buf++ = hex[val & 0xf];
144 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
147 for (i = 0; i < 20; i++) {
148 static char hex[] = "0123456789abcdef";
149 unsigned int val = sha1[i];
150 char *pos = pathbuf + i*2 + (i > 0);
151 *pos++ = hex[val >> 4];
152 *pos = hex[val & 0xf];
157 * NOTE! This returns a statically allocated buffer, so you have to be
158 * careful about using it. Do a "strdup()" if you need to save the
161 * Also note that this returns the location for creating. Reading
162 * SHA1 file can happen from any alternate directory listed in the
163 * DB_ENVIRONMENT environment variable if it is not found in
164 * the primary object database.
166 char *sha1_file_name(const unsigned char *sha1)
168 static char *name, *base;
171 const char *sha1_file_directory = get_object_directory();
172 int len = strlen(sha1_file_directory);
173 base = xmalloc(len + 60);
174 memcpy(base, sha1_file_directory, len);
175 memset(base+len, 0, 60);
178 name = base + len + 1;
180 fill_sha1_path(name, sha1);
184 static struct alternate_object_database {
190 * Prepare alternate object database registry.
191 * alt_odb points at an array of struct alternate_object_database.
192 * This array is terminated with an element that has both its base
193 * and name set to NULL. alt_odb[n] comes from n'th non-empty
194 * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
195 * variable, and its base points at a statically allocated buffer
196 * that contains "/the/directory/corresponding/to/.git/objects/...",
197 * while its name points just after the slash at the end of
198 * ".git/objects/" in the example above, and has enough space to hold
199 * 40-byte hex SHA1, an extra slash for the first level indirection,
200 * and the terminating NUL.
201 * This function allocates the alt_odb array and all the strings
202 * pointed by base fields of the array elements with one xmalloc();
203 * the string pool immediately follows the array.
205 static void prepare_alt_odb(void)
208 const char *cp, *last;
210 const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
212 /* The first pass counts how large an area to allocate to
213 * hold the entire alt_odb structure, including array of
214 * structs and path buffers for them. The second pass fills
215 * the structure and prepares the path buffers for use by
218 for (totlen = pass = 0; pass < 2; pass++) {
222 cp = strchr(last, ':') ? : last + strlen(last);
224 /* 43 = 40-byte + 2 '/' + terminating NUL */
225 int pfxlen = cp - last;
226 int entlen = pfxlen + 43;
230 alt_odb[i].base = op;
231 alt_odb[i].name = op + pfxlen + 1;
232 memcpy(op, last, pfxlen);
233 op[pfxlen] = op[pfxlen + 3] = '/';
239 while (*cp && *cp == ':')
245 alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
246 alt_odb[i].base = alt_odb[i].name = NULL;
247 op = (char*)(&alt_odb[i+1]);
251 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
254 char *name = sha1_file_name(sha1);
260 for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
261 fill_sha1_path(name, sha1);
262 if (!stat(alt_odb[i].base, st))
263 return alt_odb[i].base;
268 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
271 unsigned char real_sha1[20];
275 SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
276 SHA1_Update(&c, map, size);
277 SHA1_Final(real_sha1, &c);
278 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
281 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
286 char *filename = find_sha1_file(sha1, &st);
289 error("cannot map sha1 file %s", sha1_to_hex(sha1));
293 fd = open(filename, O_RDONLY | sha1_file_open_flag);
295 /* See if it works without O_NOATIME */
296 switch (sha1_file_open_flag) {
298 fd = open(filename, O_RDONLY);
307 /* If it failed once, it will probably fail again. Stop using O_NOATIME */
308 sha1_file_open_flag = 0;
310 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
312 if (-1 == (int)(long)map)
318 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
320 /* Get the data stream */
321 memset(stream, 0, sizeof(*stream));
322 stream->next_in = map;
323 stream->avail_in = mapsize;
324 stream->next_out = buffer;
325 stream->avail_out = size;
328 return inflate(stream, 0);
331 void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
333 int bytes = strlen(buffer) + 1;
334 unsigned char *buf = xmalloc(1+size);
336 memcpy(buf, buffer + bytes, stream->total_out - bytes);
337 bytes = stream->total_out - bytes;
339 stream->next_out = buf + bytes;
340 stream->avail_out = size - bytes;
341 while (inflate(stream, Z_FINISH) == Z_OK)
350 * We used to just use "sscanf()", but that's actually way
351 * too permissive for what we want to check. So do an anal
352 * object header parse by hand.
354 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
360 * The type can be at most ten bytes (including the
361 * terminating '\0' that we add), and is followed by
376 * The length must follow immediately, and be in canonical
377 * decimal format (ie "010" is not valid).
384 unsigned long c = *hdr - '0';
388 size = size * 10 + c;
394 * The length must be followed by a zero byte
396 return *hdr ? -1 : 0;
399 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
405 ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
406 if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
409 return unpack_sha1_rest(&stream, hdr, *size);
412 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
415 unsigned long mapsize, size;
420 map = map_sha1_file(sha1, &mapsize);
422 return error("unable to map %s", sha1_to_hex(sha1));
423 if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
424 status = error("unable to unpack %s header",
426 if (parse_sha1_header(hdr, type, &size) < 0)
427 status = error("unable to parse %s header", sha1_to_hex(sha1));
433 munmap(map, mapsize);
437 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
439 unsigned long mapsize;
442 map = map_sha1_file(sha1, &mapsize);
444 buf = unpack_sha1_file(map, mapsize, type, size);
445 munmap(map, mapsize);
451 void *read_object_with_reference(const unsigned char *sha1,
452 const char *required_type,
454 unsigned char *actual_sha1_return)
459 unsigned char actual_sha1[20];
461 memcpy(actual_sha1, sha1, 20);
464 const char *ref_type = NULL;
466 buffer = read_sha1_file(actual_sha1, type, &isize);
469 if (!strcmp(type, required_type)) {
471 if (actual_sha1_return)
472 memcpy(actual_sha1_return, actual_sha1, 20);
475 /* Handle references */
476 else if (!strcmp(type, "commit"))
478 else if (!strcmp(type, "tag"))
479 ref_type = "object ";
484 ref_length = strlen(ref_type);
486 if (memcmp(buffer, ref_type, ref_length) ||
487 get_sha1_hex(buffer + ref_length, actual_sha1)) {
491 /* Now we have the ID of the referred-to object in
492 * actual_sha1. Check again. */
496 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
499 unsigned char *compressed;
501 unsigned char sha1[20];
504 static char tmpfile[PATH_MAX];
505 unsigned char hdr[50];
508 /* Generate the header */
509 hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
513 SHA1_Update(&c, hdr, hdrlen);
514 SHA1_Update(&c, buf, len);
515 SHA1_Final(sha1, &c);
518 memcpy(returnsha1, sha1, 20);
520 filename = sha1_file_name(sha1);
521 fd = open(filename, O_RDONLY);
524 * FIXME!!! We might do collision checking here, but we'd
525 * need to uncompress the old file and check it. Later.
531 if (errno != ENOENT) {
532 fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
536 snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
538 fd = mkstemp(tmpfile);
540 fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
545 memset(&stream, 0, sizeof(stream));
546 deflateInit(&stream, Z_BEST_COMPRESSION);
547 size = deflateBound(&stream, len+hdrlen);
548 compressed = xmalloc(size);
551 stream.next_out = compressed;
552 stream.avail_out = size;
555 stream.next_in = hdr;
556 stream.avail_in = hdrlen;
557 while (deflate(&stream, 0) == Z_OK)
560 /* Then the data itself.. */
561 stream.next_in = buf;
562 stream.avail_in = len;
563 while (deflate(&stream, Z_FINISH) == Z_OK)
566 size = stream.total_out;
568 if (write(fd, compressed, size) != size)
569 die("unable to write file");
574 ret = link(tmpfile, filename);
579 * Coda hack - coda doesn't like cross-directory links,
580 * so we fall back to a rename, which will mean that it
581 * won't be able to check collisions, but that's not a
584 * When this succeeds, we just return 0. We have nothing
587 if (ret == EXDEV && !rename(tmpfile, filename))
593 fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
596 /* FIXME!!! Collision check here ? */
602 int write_sha1_from_fd(const unsigned char *sha1, int fd)
604 char *filename = sha1_file_name(sha1);
608 unsigned char real_sha1[20];
609 unsigned char buf[4096];
610 unsigned char discard[4096];
614 local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
617 return error("Couldn't open %s\n", filename);
619 memset(&stream, 0, sizeof(stream));
621 inflateInit(&stream);
627 size = read(fd, buf, 4096);
632 return error("Connection closed?");
633 perror("Reading from connection");
636 write(local, buf, size);
637 stream.avail_in = size;
638 stream.next_in = buf;
640 stream.next_out = discard;
641 stream.avail_out = sizeof(discard);
642 ret = inflate(&stream, Z_SYNC_FLUSH);
643 SHA1_Update(&c, discard, sizeof(discard) -
645 } while (stream.avail_in && ret == Z_OK);
647 } while (ret == Z_OK);
651 SHA1_Final(real_sha1, &c);
652 if (ret != Z_STREAM_END) {
654 return error("File %s corrupted", sha1_to_hex(sha1));
656 if (memcmp(sha1, real_sha1, 20)) {
658 return error("File %s has bad hash\n", sha1_to_hex(sha1));
664 int has_sha1_file(const unsigned char *sha1)
667 return !!find_sha1_file(sha1, &st);
670 int index_fd(unsigned char *sha1, int fd, struct stat *st)
672 unsigned long size = st->st_size;
678 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
680 if ((int)(long)buf == -1)
683 ret = write_sha1_file(buf, size, "blob", sha1);