2 * GIT - The information manager from hell
4 * Copyright (C) Linus Torvalds, 2005
6 * This handles basic git sha1 object files - packing, unpacking,
13 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
14 #define O_NOATIME 01000000
20 static unsigned int sha1_file_open_flag = O_NOATIME;
22 static unsigned hexval(char c)
24 if (c >= '0' && c <= '9')
26 if (c >= 'a' && c <= 'f')
28 if (c >= 'A' && c <= 'F')
33 int get_sha1_hex(const char *hex, unsigned char *sha1)
36 for (i = 0; i < 20; i++) {
37 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
46 static int get_sha1_file(const char *path, unsigned char *result)
49 int fd = open(path, O_RDONLY);
54 len = read(fd, buffer, sizeof(buffer));
58 return get_sha1_hex(buffer, result);
61 static char *git_dir, *git_object_dir, *git_index_file;
62 static void setup_git_env(void)
64 git_dir = gitenv(GIT_DIR_ENVIRONMENT);
66 git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
67 git_object_dir = gitenv(DB_ENVIRONMENT);
68 if (!git_object_dir) {
69 git_object_dir = xmalloc(strlen(git_dir) + 9);
70 sprintf(git_object_dir, "%s/objects", git_dir);
72 git_index_file = gitenv(INDEX_ENVIRONMENT);
73 if (!git_index_file) {
74 git_index_file = xmalloc(strlen(git_dir) + 7);
75 sprintf(git_index_file, "%s/index", git_dir);
79 char *get_object_directory(void)
83 return git_object_dir;
86 char *get_index_file(void)
90 return git_index_file;
93 int get_sha1(const char *str, unsigned char *sha1)
95 static char pathname[PATH_MAX];
96 static const char *prefix[] = {
106 if (!get_sha1_hex(str, sha1))
111 for (p = prefix; *p; p++) {
112 snprintf(pathname, sizeof(pathname), "%s/%s/%s",
114 if (!get_sha1_file(pathname, sha1))
121 char * sha1_to_hex(const unsigned char *sha1)
123 static char buffer[50];
124 static const char hex[] = "0123456789abcdef";
128 for (i = 0; i < 20; i++) {
129 unsigned int val = *sha1++;
130 *buf++ = hex[val >> 4];
131 *buf++ = hex[val & 0xf];
136 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
139 for (i = 0; i < 20; i++) {
140 static char hex[] = "0123456789abcdef";
141 unsigned int val = sha1[i];
142 char *pos = pathbuf + i*2 + (i > 0);
143 *pos++ = hex[val >> 4];
144 *pos = hex[val & 0xf];
149 * NOTE! This returns a statically allocated buffer, so you have to be
150 * careful about using it. Do a "strdup()" if you need to save the
153 * Also note that this returns the location for creating. Reading
154 * SHA1 file can happen from any alternate directory listed in the
155 * DB_ENVIRONMENT environment variable if it is not found in
156 * the primary object database.
158 char *sha1_file_name(const unsigned char *sha1)
160 static char *name, *base;
163 const char *sha1_file_directory = get_object_directory();
164 int len = strlen(sha1_file_directory);
165 base = xmalloc(len + 60);
166 memcpy(base, sha1_file_directory, len);
167 memset(base+len, 0, 60);
170 name = base + len + 1;
172 fill_sha1_path(name, sha1);
176 static struct alternate_object_database {
182 * Prepare alternate object database registry.
183 * alt_odb points at an array of struct alternate_object_database.
184 * This array is terminated with an element that has both its base
185 * and name set to NULL. alt_odb[n] comes from n'th non-empty
186 * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
187 * variable, and its base points at a statically allocated buffer
188 * that contains "/the/directory/corresponding/to/.git/objects/...",
189 * while its name points just after the slash at the end of
190 * ".git/objects/" in the example above, and has enough space to hold
191 * 40-byte hex SHA1, an extra slash for the first level indirection,
192 * and the terminating NUL.
193 * This function allocates the alt_odb array and all the strings
194 * pointed by base fields of the array elements with one xmalloc();
195 * the string pool immediately follows the array.
197 static void prepare_alt_odb(void)
200 const char *cp, *last;
202 const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
204 /* The first pass counts how large an area to allocate to
205 * hold the entire alt_odb structure, including array of
206 * structs and path buffers for them. The second pass fills
207 * the structure and prepares the path buffers for use by
210 for (totlen = pass = 0; pass < 2; pass++) {
214 cp = strchr(last, ':') ? : last + strlen(last);
216 /* 43 = 40-byte + 2 '/' + terminating NUL */
217 int pfxlen = cp - last;
218 int entlen = pfxlen + 43;
222 alt_odb[i].base = op;
223 alt_odb[i].name = op + pfxlen + 1;
224 memcpy(op, last, pfxlen);
225 op[pfxlen] = op[pfxlen + 3] = '/';
231 while (*cp && *cp == ':')
237 alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
238 alt_odb[i].base = alt_odb[i].name = NULL;
239 op = (char*)(&alt_odb[i+1]);
243 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
246 char *name = sha1_file_name(sha1);
252 for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
253 fill_sha1_path(name, sha1);
254 if (!stat(alt_odb[i].base, st))
255 return alt_odb[i].base;
260 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
263 unsigned char real_sha1[20];
267 SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
268 SHA1_Update(&c, map, size);
269 SHA1_Final(real_sha1, &c);
270 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
273 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
278 char *filename = find_sha1_file(sha1, &st);
281 error("cannot map sha1 file %s", sha1_to_hex(sha1));
285 fd = open(filename, O_RDONLY | sha1_file_open_flag);
287 /* See if it works without O_NOATIME */
288 switch (sha1_file_open_flag) {
290 fd = open(filename, O_RDONLY);
299 /* If it failed once, it will probably fail again. Stop using O_NOATIME */
300 sha1_file_open_flag = 0;
302 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
304 if (-1 == (int)(long)map)
310 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
312 /* Get the data stream */
313 memset(stream, 0, sizeof(*stream));
314 stream->next_in = map;
315 stream->avail_in = mapsize;
316 stream->next_out = buffer;
317 stream->avail_out = size;
320 return inflate(stream, 0);
323 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
330 ret = unpack_sha1_header(&stream, map, mapsize, buffer, sizeof(buffer));
331 if (ret < Z_OK || sscanf(buffer, "%10s %lu", type, size) != 2)
334 bytes = strlen(buffer) + 1;
335 buf = xmalloc(1+*size);
337 memcpy(buf, buffer + bytes, stream.total_out - bytes);
338 bytes = stream.total_out - bytes;
339 if (bytes < *size && ret == Z_OK) {
340 stream.next_out = buf + bytes;
341 stream.avail_out = *size - bytes;
342 while (inflate(&stream, Z_FINISH) == Z_OK)
350 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
352 unsigned long mapsize;
355 map = map_sha1_file(sha1, &mapsize);
357 buf = unpack_sha1_file(map, mapsize, type, size);
358 munmap(map, mapsize);
359 if (buf && !strcmp(type, "delta")) {
360 void *ref = NULL, *delta = buf;
361 unsigned long ref_size, delta_size = *size;
364 ref = read_sha1_file(delta, type, &ref_size);
366 buf = patch_delta(ref, ref_size,
367 delta+20, delta_size-20,
377 void *read_object_with_reference(const unsigned char *sha1,
378 const char *required_type,
380 unsigned char *actual_sha1_return)
385 unsigned char actual_sha1[20];
387 memcpy(actual_sha1, sha1, 20);
390 const char *ref_type = NULL;
392 buffer = read_sha1_file(actual_sha1, type, &isize);
395 if (!strcmp(type, required_type)) {
397 if (actual_sha1_return)
398 memcpy(actual_sha1_return, actual_sha1, 20);
401 /* Handle references */
402 else if (!strcmp(type, "commit"))
404 else if (!strcmp(type, "tag"))
405 ref_type = "object ";
410 ref_length = strlen(ref_type);
412 if (memcmp(buffer, ref_type, ref_length) ||
413 get_sha1_hex(buffer + ref_length, actual_sha1)) {
417 /* Now we have the ID of the referred-to object in
418 * actual_sha1. Check again. */
422 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
425 unsigned char *compressed;
427 unsigned char sha1[20];
430 static char tmpfile[PATH_MAX];
431 unsigned char hdr[50];
434 /* Generate the header */
435 hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
439 SHA1_Update(&c, hdr, hdrlen);
440 SHA1_Update(&c, buf, len);
441 SHA1_Final(sha1, &c);
444 memcpy(returnsha1, sha1, 20);
446 filename = sha1_file_name(sha1);
447 fd = open(filename, O_RDONLY);
450 * FIXME!!! We might do collision checking here, but we'd
451 * need to uncompress the old file and check it. Later.
457 if (errno != ENOENT) {
458 fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
462 snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
464 fd = mkstemp(tmpfile);
466 fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
471 memset(&stream, 0, sizeof(stream));
472 deflateInit(&stream, Z_BEST_COMPRESSION);
473 size = deflateBound(&stream, len+hdrlen);
474 compressed = xmalloc(size);
477 stream.next_out = compressed;
478 stream.avail_out = size;
481 stream.next_in = hdr;
482 stream.avail_in = hdrlen;
483 while (deflate(&stream, 0) == Z_OK)
486 /* Then the data itself.. */
487 stream.next_in = buf;
488 stream.avail_in = len;
489 while (deflate(&stream, Z_FINISH) == Z_OK)
492 size = stream.total_out;
494 if (write(fd, compressed, size) != size)
495 die("unable to write file");
500 ret = link(tmpfile, filename);
505 * Coda hack - coda doesn't like cross-directory links,
506 * so we fall back to a rename, which will mean that it
507 * won't be able to check collisions, but that's not a
510 * When this succeeds, we just return 0. We have nothing
513 if (ret == EXDEV && !rename(tmpfile, filename))
519 fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
522 /* FIXME!!! Collision check here ? */
528 int write_sha1_from_fd(const unsigned char *sha1, int fd)
530 char *filename = sha1_file_name(sha1);
534 unsigned char real_sha1[20];
535 unsigned char buf[4096];
536 unsigned char discard[4096];
540 local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
543 return error("Couldn't open %s\n", filename);
545 memset(&stream, 0, sizeof(stream));
547 inflateInit(&stream);
553 size = read(fd, buf, 4096);
558 return error("Connection closed?");
559 perror("Reading from connection");
562 write(local, buf, size);
563 stream.avail_in = size;
564 stream.next_in = buf;
566 stream.next_out = discard;
567 stream.avail_out = sizeof(discard);
568 ret = inflate(&stream, Z_SYNC_FLUSH);
569 SHA1_Update(&c, discard, sizeof(discard) -
571 } while (stream.avail_in && ret == Z_OK);
573 } while (ret == Z_OK);
577 SHA1_Final(real_sha1, &c);
578 if (ret != Z_STREAM_END) {
580 return error("File %s corrupted", sha1_to_hex(sha1));
582 if (memcmp(sha1, real_sha1, 20)) {
584 return error("File %s has bad hash\n", sha1_to_hex(sha1));
590 int has_sha1_file(const unsigned char *sha1)
593 return !!find_sha1_file(sha1, &st);
596 int index_fd(unsigned char *sha1, int fd, struct stat *st)
598 unsigned long size = st->st_size;
604 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
606 if ((int)(long)buf == -1)
609 ret = write_sha1_file(buf, size, "blob", sha1);