2 * GIT - The information manager from hell
4 * Copyright (C) Linus Torvalds, 2005
6 * This handles basic git sha1 object files - packing, unpacking,
15 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
16 #define O_NOATIME 01000000
22 static unsigned int sha1_file_open_flag = O_NOATIME;
24 static unsigned hexval(char c)
26 if (c >= '0' && c <= '9')
28 if (c >= 'a' && c <= 'f')
30 if (c >= 'A' && c <= 'F')
35 int get_sha1_hex(const char *hex, unsigned char *sha1)
38 for (i = 0; i < 20; i++) {
39 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
48 static int get_sha1_file(const char *path, unsigned char *result)
51 int fd = open(path, O_RDONLY);
56 len = read(fd, buffer, sizeof(buffer));
60 return get_sha1_hex(buffer, result);
63 static char *git_dir, *git_object_dir, *git_index_file;
64 static void setup_git_env(void)
66 git_dir = gitenv(GIT_DIR_ENVIRONMENT);
68 git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
69 git_object_dir = gitenv(DB_ENVIRONMENT);
70 if (!git_object_dir) {
71 git_object_dir = xmalloc(strlen(git_dir) + 9);
72 sprintf(git_object_dir, "%s/objects", git_dir);
74 git_index_file = gitenv(INDEX_ENVIRONMENT);
75 if (!git_index_file) {
76 git_index_file = xmalloc(strlen(git_dir) + 7);
77 sprintf(git_index_file, "%s/index", git_dir);
81 char *get_object_directory(void)
85 return git_object_dir;
88 char *get_index_file(void)
92 return git_index_file;
95 int get_sha1(const char *str, unsigned char *sha1)
97 static char pathname[PATH_MAX];
98 static const char *prefix[] = {
108 if (!get_sha1_hex(str, sha1))
113 for (p = prefix; *p; p++) {
114 snprintf(pathname, sizeof(pathname), "%s/%s/%s",
116 if (!get_sha1_file(pathname, sha1))
123 char * sha1_to_hex(const unsigned char *sha1)
125 static char buffer[50];
126 static const char hex[] = "0123456789abcdef";
130 for (i = 0; i < 20; i++) {
131 unsigned int val = *sha1++;
132 *buf++ = hex[val >> 4];
133 *buf++ = hex[val & 0xf];
138 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
141 for (i = 0; i < 20; i++) {
142 static char hex[] = "0123456789abcdef";
143 unsigned int val = sha1[i];
144 char *pos = pathbuf + i*2 + (i > 0);
145 *pos++ = hex[val >> 4];
146 *pos = hex[val & 0xf];
151 * NOTE! This returns a statically allocated buffer, so you have to be
152 * careful about using it. Do a "strdup()" if you need to save the
155 * Also note that this returns the location for creating. Reading
156 * SHA1 file can happen from any alternate directory listed in the
157 * DB_ENVIRONMENT environment variable if it is not found in
158 * the primary object database.
160 char *sha1_file_name(const unsigned char *sha1)
162 static char *name, *base;
165 const char *sha1_file_directory = get_object_directory();
166 int len = strlen(sha1_file_directory);
167 base = xmalloc(len + 60);
168 memcpy(base, sha1_file_directory, len);
169 memset(base+len, 0, 60);
172 name = base + len + 1;
174 fill_sha1_path(name, sha1);
178 static struct alternate_object_database {
184 * Prepare alternate object database registry.
185 * alt_odb points at an array of struct alternate_object_database.
186 * This array is terminated with an element that has both its base
187 * and name set to NULL. alt_odb[n] comes from n'th non-empty
188 * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
189 * variable, and its base points at a statically allocated buffer
190 * that contains "/the/directory/corresponding/to/.git/objects/...",
191 * while its name points just after the slash at the end of
192 * ".git/objects/" in the example above, and has enough space to hold
193 * 40-byte hex SHA1, an extra slash for the first level indirection,
194 * and the terminating NUL.
195 * This function allocates the alt_odb array and all the strings
196 * pointed by base fields of the array elements with one xmalloc();
197 * the string pool immediately follows the array.
199 static void prepare_alt_odb(void)
202 const char *cp, *last;
204 const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
206 /* The first pass counts how large an area to allocate to
207 * hold the entire alt_odb structure, including array of
208 * structs and path buffers for them. The second pass fills
209 * the structure and prepares the path buffers for use by
212 for (totlen = pass = 0; pass < 2; pass++) {
216 cp = strchr(last, ':') ? : last + strlen(last);
218 /* 43 = 40-byte + 2 '/' + terminating NUL */
219 int pfxlen = cp - last;
220 int entlen = pfxlen + 43;
224 alt_odb[i].base = op;
225 alt_odb[i].name = op + pfxlen + 1;
226 memcpy(op, last, pfxlen);
227 op[pfxlen] = op[pfxlen + 3] = '/';
233 while (*cp && *cp == ':')
239 alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
240 alt_odb[i].base = alt_odb[i].name = NULL;
241 op = (char*)(&alt_odb[i+1]);
245 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
248 char *name = sha1_file_name(sha1);
254 for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
255 fill_sha1_path(name, sha1);
256 if (!stat(alt_odb[i].base, st))
257 return alt_odb[i].base;
262 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
265 unsigned char real_sha1[20];
269 SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
270 SHA1_Update(&c, map, size);
271 SHA1_Final(real_sha1, &c);
272 return memcmp(sha1, real_sha1, 20) ? -1 : 0;
275 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
280 char *filename = find_sha1_file(sha1, &st);
283 error("cannot map sha1 file %s", sha1_to_hex(sha1));
287 fd = open(filename, O_RDONLY | sha1_file_open_flag);
289 /* See if it works without O_NOATIME */
290 switch (sha1_file_open_flag) {
292 fd = open(filename, O_RDONLY);
301 /* If it failed once, it will probably fail again. Stop using O_NOATIME */
302 sha1_file_open_flag = 0;
304 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
306 if (-1 == (int)(long)map)
312 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
319 /* Get the data stream */
320 memset(&stream, 0, sizeof(stream));
321 stream.next_in = map;
322 stream.avail_in = mapsize;
323 stream.next_out = (unsigned char *)buffer;
324 stream.avail_out = sizeof(buffer);
326 inflateInit(&stream);
327 ret = inflate(&stream, 0);
330 if (sscanf(buffer, "%10s %lu", type, size) != 2)
333 bytes = strlen(buffer) + 1;
334 buf = xmalloc(*size);
336 memcpy(buf, buffer + bytes, stream.total_out - bytes);
337 bytes = stream.total_out - bytes;
338 if (bytes < *size && ret == Z_OK) {
339 stream.next_out = buf + bytes;
340 stream.avail_out = *size - bytes;
341 while (inflate(&stream, Z_FINISH) == Z_OK)
348 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
350 unsigned long mapsize;
353 map = map_sha1_file(sha1, &mapsize);
355 buf = unpack_sha1_file(map, mapsize, type, size);
356 munmap(map, mapsize);
357 if (buf && !strcmp(type, "delta")) {
358 void *ref = NULL, *delta = buf;
359 unsigned long ref_size, delta_size = *size;
362 ref = read_sha1_file(delta, type, &ref_size);
364 buf = patch_delta(ref, ref_size,
365 delta+20, delta_size-20,
375 void *read_object_with_reference(const unsigned char *sha1,
376 const char *required_type,
378 unsigned char *actual_sha1_return)
383 unsigned char actual_sha1[20];
385 memcpy(actual_sha1, sha1, 20);
388 const char *ref_type = NULL;
390 buffer = read_sha1_file(actual_sha1, type, &isize);
393 if (!strcmp(type, required_type)) {
395 if (actual_sha1_return)
396 memcpy(actual_sha1_return, actual_sha1, 20);
399 /* Handle references */
400 else if (!strcmp(type, "commit"))
402 else if (!strcmp(type, "tag"))
403 ref_type = "object ";
408 ref_length = strlen(ref_type);
410 if (memcmp(buffer, ref_type, ref_length) ||
411 get_sha1_hex(buffer + ref_length, actual_sha1)) {
415 /* Now we have the ID of the referred-to object in
416 * actual_sha1. Check again. */
420 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
423 unsigned char *compressed;
425 unsigned char sha1[20];
428 static char tmpfile[PATH_MAX];
429 unsigned char hdr[50];
432 /* Generate the header */
433 hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
437 SHA1_Update(&c, hdr, hdrlen);
438 SHA1_Update(&c, buf, len);
439 SHA1_Final(sha1, &c);
442 memcpy(returnsha1, sha1, 20);
444 filename = sha1_file_name(sha1);
445 fd = open(filename, O_RDONLY);
448 * FIXME!!! We might do collision checking here, but we'd
449 * need to uncompress the old file and check it. Later.
455 if (errno != ENOENT) {
456 fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
460 snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
462 fd = mkstemp(tmpfile);
464 fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
469 memset(&stream, 0, sizeof(stream));
470 deflateInit(&stream, Z_BEST_COMPRESSION);
471 size = deflateBound(&stream, len+hdrlen);
472 compressed = xmalloc(size);
475 stream.next_out = compressed;
476 stream.avail_out = size;
479 stream.next_in = hdr;
480 stream.avail_in = hdrlen;
481 while (deflate(&stream, 0) == Z_OK)
484 /* Then the data itself.. */
485 stream.next_in = buf;
486 stream.avail_in = len;
487 while (deflate(&stream, Z_FINISH) == Z_OK)
490 size = stream.total_out;
492 if (write(fd, compressed, size) != size)
493 die("unable to write file");
498 ret = link(tmpfile, filename);
503 * Coda hack - coda doesn't like cross-directory links,
504 * so we fall back to a rename, which will mean that it
505 * won't be able to check collisions, but that's not a
508 * When this succeeds, we just return 0. We have nothing
511 if (ret == EXDEV && !rename(tmpfile, filename))
517 fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
520 /* FIXME!!! Collision check here ? */
526 int write_sha1_from_fd(const unsigned char *sha1, int fd)
528 char *filename = sha1_file_name(sha1);
532 unsigned char real_sha1[20];
533 unsigned char buf[4096];
534 unsigned char discard[4096];
538 local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
541 return error("Couldn't open %s\n", filename);
543 memset(&stream, 0, sizeof(stream));
545 inflateInit(&stream);
551 size = read(fd, buf, 4096);
556 return error("Connection closed?");
557 perror("Reading from connection");
560 write(local, buf, size);
561 stream.avail_in = size;
562 stream.next_in = buf;
564 stream.next_out = discard;
565 stream.avail_out = sizeof(discard);
566 ret = inflate(&stream, Z_SYNC_FLUSH);
567 SHA1_Update(&c, discard, sizeof(discard) -
569 } while (stream.avail_in && ret == Z_OK);
571 } while (ret == Z_OK);
575 SHA1_Final(real_sha1, &c);
576 if (ret != Z_STREAM_END) {
578 return error("File %s corrupted", sha1_to_hex(sha1));
580 if (memcmp(sha1, real_sha1, 20)) {
582 return error("File %s has bad hash\n", sha1_to_hex(sha1));
588 int has_sha1_file(const unsigned char *sha1)
591 return !!find_sha1_file(sha1, &st);
594 int index_fd(unsigned char *sha1, int fd, struct stat *st)
596 unsigned long size = st->st_size;
602 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
604 if ((int)(long)buf == -1)
607 ret = write_sha1_file(buf, size, "blob", sha1);