Andrew's git - gitweb.git/blob

   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 *
   6 * This handles basic git sha1 object files - packing, unpacking,
   7 * creation etc.
   8 */
   9#include <stdarg.h>
  10#include "cache.h"
  11
  12#ifndef O_NOATIME
  13#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  14#define O_NOATIME 01000000
  15#else
  16#define O_NOATIME 0
  17#endif
  18#endif
  19
  20static unsigned int sha1_file_open_flag = O_NOATIME;
  21
  22static unsigned hexval(char c)
  23{
  24        if (c >= '0' && c <= '9')
  25                return c - '0';
  26        if (c >= 'a' && c <= 'f')
  27                return c - 'a' + 10;
  28        if (c >= 'A' && c <= 'F')
  29                return c - 'A' + 10;
  30        return ~0;
  31}
  32
  33int get_sha1_hex(const char *hex, unsigned char *sha1)
  34{
  35        int i;
  36        for (i = 0; i < 20; i++) {
  37                unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  38                if (val & ~0xff)
  39                        return -1;
  40                *sha1++ = val;
  41                hex += 2;
  42        }
  43        return 0;
  44}
  45
  46int get_sha1_file(const char *path, unsigned char *result)
  47{
  48        char buffer[60];
  49        int fd = open(path, O_RDONLY);
  50        int len;
  51
  52        if (fd < 0)
  53                return -1;
  54        len = read(fd, buffer, sizeof(buffer));
  55        close(fd);
  56        if (len < 40)
  57                return -1;
  58        return get_sha1_hex(buffer, result);
  59}
  60
  61int get_sha1(const char *str, unsigned char *sha1)
  62{
  63        static char pathname[PATH_MAX];
  64        static const char *prefix[] = {
  65                "",
  66                "refs",
  67                "refs/tags",
  68                "refs/heads",
  69                "refs/snap",
  70                NULL
  71        };
  72        const char *gitdir;
  73        const char **p;
  74
  75        if (!get_sha1_hex(str, sha1))
  76                return 0;
  77
  78        gitdir = ".git";
  79        for (p = prefix; *p; p++) {
  80                snprintf(pathname, sizeof(pathname), "%s/%s/%s", gitdir, *p, str);
  81                if (!get_sha1_file(pathname, sha1))
  82                        return 0;
  83        }
  84
  85        return -1;
  86}
  87
  88char * sha1_to_hex(const unsigned char *sha1)
  89{
  90        static char buffer[50];
  91        static const char hex[] = "0123456789abcdef";
  92        char *buf = buffer;
  93        int i;
  94
  95        for (i = 0; i < 20; i++) {
  96                unsigned int val = *sha1++;
  97                *buf++ = hex[val >> 4];
  98                *buf++ = hex[val & 0xf];
  99        }
 100        return buffer;
 101}
 102
 103/*
 104 * NOTE! This returns a statically allocated buffer, so you have to be
 105 * careful about using it. Do a "strdup()" if you need to save the
 106 * filename.
 107 */
 108char *sha1_file_name(const unsigned char *sha1)
 109{
 110        int i;
 111        static char *name, *base;
 112
 113        if (!base) {
 114                char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
 115                int len = strlen(sha1_file_directory);
 116                base = xmalloc(len + 60);
 117                memcpy(base, sha1_file_directory, len);
 118                memset(base+len, 0, 60);
 119                base[len] = '/';
 120                base[len+3] = '/';
 121                name = base + len + 1;
 122        }
 123        for (i = 0; i < 20; i++) {
 124                static char hex[] = "0123456789abcdef";
 125                unsigned int val = sha1[i];
 126                char *pos = name + i*2 + (i > 0);
 127                *pos++ = hex[val >> 4];
 128                *pos = hex[val & 0xf];
 129        }
 130        return base;
 131}
 132
 133int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
 134{
 135        char header[100];
 136        unsigned char real_sha1[20];
 137        SHA_CTX c;
 138
 139        SHA1_Init(&c);
 140        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 141        SHA1_Update(&c, map, size);
 142        SHA1_Final(real_sha1, &c);
 143        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 144}
 145
 146void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 147{
 148        char *filename = sha1_file_name(sha1);
 149        struct stat st;
 150        void *map;
 151        int fd;
 152
 153        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 154        if (fd < 0) {
 155                /* See if it works without O_NOATIME */
 156                switch (sha1_file_open_flag) {
 157                default:
 158                        fd = open(filename, O_RDONLY);
 159                        if (fd >= 0)
 160                                break;
 161                /* Fallthrough */
 162                case 0:
 163                        perror(filename);
 164                        return NULL;
 165                }
 166
 167                /* If it failed once, it will probably fail again. Stop using O_NOATIME */
 168                sha1_file_open_flag = 0;
 169        }
 170        if (fstat(fd, &st) < 0) {
 171                close(fd);
 172                return NULL;
 173        }
 174        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 175        close(fd);
 176        if (-1 == (int)(long)map)
 177                return NULL;
 178        *size = st.st_size;
 179        return map;
 180}
 181
 182void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 183{
 184        int ret, bytes;
 185        z_stream stream;
 186        char buffer[8192];
 187        char *buf;
 188
 189        /* Get the data stream */
 190        memset(&stream, 0, sizeof(stream));
 191        stream.next_in = map;
 192        stream.avail_in = mapsize;
 193        stream.next_out = buffer;
 194        stream.avail_out = sizeof(buffer);
 195
 196        inflateInit(&stream);
 197        ret = inflate(&stream, 0);
 198        if (ret < Z_OK)
 199                return NULL;
 200        if (sscanf(buffer, "%10s %lu", type, size) != 2)
 201                return NULL;
 202
 203        bytes = strlen(buffer) + 1;
 204        buf = xmalloc(*size);
 205
 206        memcpy(buf, buffer + bytes, stream.total_out - bytes);
 207        bytes = stream.total_out - bytes;
 208        if (bytes < *size && ret == Z_OK) {
 209                stream.next_out = buf + bytes;
 210                stream.avail_out = *size - bytes;
 211                while (inflate(&stream, Z_FINISH) == Z_OK)
 212                        /* nothing */;
 213        }
 214        inflateEnd(&stream);
 215        return buf;
 216}
 217
 218void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 219{
 220        unsigned long mapsize;
 221        void *map, *buf;
 222
 223        map = map_sha1_file(sha1, &mapsize);
 224        if (map) {
 225                buf = unpack_sha1_file(map, mapsize, type, size);
 226                munmap(map, mapsize);
 227                return buf;
 228        }
 229        return NULL;
 230}
 231
 232void *read_object_with_reference(const unsigned char *sha1,
 233                                 const unsigned char *required_type,
 234                                 unsigned long *size,
 235                                 unsigned char *actual_sha1_return)
 236{
 237        char type[20];
 238        void *buffer;
 239        unsigned long isize;
 240        unsigned char actual_sha1[20];
 241
 242        memcpy(actual_sha1, sha1, 20);
 243        while (1) {
 244                int ref_length = -1;
 245                const char *ref_type = NULL;
 246
 247                buffer = read_sha1_file(actual_sha1, type, &isize);
 248                if (!buffer)
 249                        return NULL;
 250                if (!strcmp(type, required_type)) {
 251                        *size = isize;
 252                        if (actual_sha1_return)
 253                                memcpy(actual_sha1_return, actual_sha1, 20);
 254                        return buffer;
 255                }
 256                /* Handle references */
 257                else if (!strcmp(type, "commit"))
 258                        ref_type = "tree ";
 259                else if (!strcmp(type, "tag"))
 260                        ref_type = "object ";
 261                else {
 262                        free(buffer);
 263                        return NULL;
 264                }
 265                ref_length = strlen(ref_type);
 266
 267                if (memcmp(buffer, ref_type, ref_length) ||
 268                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
 269                        free(buffer);
 270                        return NULL;
 271                }
 272                /* Now we have the ID of the referred-to object in
 273                 * actual_sha1.  Check again. */
 274        }
 275}
 276
 277int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 278{
 279        int size;
 280        char *compressed;
 281        z_stream stream;
 282        unsigned char sha1[20];
 283        SHA_CTX c;
 284        char *filename;
 285        static char tmpfile[PATH_MAX];
 286        char hdr[50];
 287        int fd, hdrlen, ret;
 288
 289        /* Generate the header */
 290        hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
 291
 292        /* Sha1.. */
 293        SHA1_Init(&c);
 294        SHA1_Update(&c, hdr, hdrlen);
 295        SHA1_Update(&c, buf, len);
 296        SHA1_Final(sha1, &c);
 297
 298        if (returnsha1)
 299                memcpy(returnsha1, sha1, 20);
 300
 301        filename = sha1_file_name(sha1);
 302        fd = open(filename, O_RDONLY);
 303        if (fd >= 0) {
 304                /*
 305                 * FIXME!!! We might do collision checking here, but we'd
 306                 * need to uncompress the old file and check it. Later.
 307                 */
 308                close(fd);
 309                return 0;
 310        }
 311
 312        if (errno != ENOENT) {
 313                fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
 314                return -1;
 315        }
 316
 317        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
 318        fd = mkstemp(tmpfile);
 319        if (fd < 0) {
 320                fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
 321                return -1;
 322        }
 323
 324        /* Set it up */
 325        memset(&stream, 0, sizeof(stream));
 326        deflateInit(&stream, Z_BEST_COMPRESSION);
 327        size = deflateBound(&stream, len+hdrlen);
 328        compressed = xmalloc(size);
 329
 330        /* Compress it */
 331        stream.next_out = compressed;
 332        stream.avail_out = size;
 333
 334        /* First header.. */
 335        stream.next_in = hdr;
 336        stream.avail_in = hdrlen;
 337        while (deflate(&stream, 0) == Z_OK)
 338                /* nothing */
 339
 340        /* Then the data itself.. */
 341        stream.next_in = buf;
 342        stream.avail_in = len;
 343        while (deflate(&stream, Z_FINISH) == Z_OK)
 344                /* nothing */;
 345        deflateEnd(&stream);
 346        size = stream.total_out;
 347
 348        if (write(fd, compressed, size) != size)
 349                die("unable to write file");
 350        fchmod(fd, 0444);
 351        close(fd);
 352
 353        ret = link(tmpfile, filename);
 354        if (ret < 0) {
 355                ret = errno;
 356
 357                /*
 358                 * Coda hack - coda doesn't like cross-directory links,
 359                 * so we fall back to a rename, which will mean that it
 360                 * won't be able to check collisions, but that's not a
 361                 * big deal.
 362                 *
 363                 * When this succeeds, we just return 0. We have nothing
 364                 * left to unlink.
 365                 */
 366                if (ret == EXDEV && !rename(tmpfile, filename))
 367                        return 0;
 368        }
 369        unlink(tmpfile);
 370        if (ret) {
 371                if (ret != EEXIST) {
 372                        fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
 373                        return -1;
 374                }
 375                /* FIXME!!! Collision check here ? */
 376        }
 377
 378        return 0;
 379}
 380
 381int write_sha1_from_fd(const unsigned char *sha1, int fd)
 382{
 383        char *filename = sha1_file_name(sha1);
 384
 385        int local;
 386        z_stream stream;
 387        unsigned char real_sha1[20];
 388        char buf[4096];
 389        char discard[4096];
 390        int ret;
 391        SHA_CTX c;
 392
 393        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 394
 395        if (local < 0)
 396                return error("Couldn't open %s\n", filename);
 397
 398        memset(&stream, 0, sizeof(stream));
 399
 400        inflateInit(&stream);
 401
 402        SHA1_Init(&c);
 403
 404        do {
 405                ssize_t size;
 406                size = read(fd, buf, 4096);
 407                if (size <= 0) {
 408                        close(local);
 409                        unlink(filename);
 410                        if (!size)
 411                                return error("Connection closed?");
 412                        perror("Reading from connection");
 413                        return -1;
 414                }
 415                write(local, buf, size);
 416                stream.avail_in = size;
 417                stream.next_in = buf;
 418                do {
 419                        stream.next_out = discard;
 420                        stream.avail_out = sizeof(discard);
 421                        ret = inflate(&stream, Z_SYNC_FLUSH);
 422                        SHA1_Update(&c, discard, sizeof(discard) -
 423                                    stream.avail_out);
 424                } while (stream.avail_in && ret == Z_OK);
 425                
 426        } while (ret == Z_OK);
 427        inflateEnd(&stream);
 428
 429        close(local);
 430        SHA1_Final(real_sha1, &c);
 431        if (ret != Z_STREAM_END) {
 432                unlink(filename);
 433                return error("File %s corrupted", sha1_to_hex(sha1));
 434        }
 435        if (memcmp(sha1, real_sha1, 20)) {
 436                unlink(filename);
 437                return error("File %s has bad hash\n", sha1_to_hex(sha1));
 438        }
 439        
 440        return 0;
 441}
 442
 443int has_sha1_file(const unsigned char *sha1)
 444{
 445        char *filename = sha1_file_name(sha1);
 446        struct stat st;
 447
 448        if (!stat(filename, &st))
 449                return 1;
 450        return 0;
 451}
 452
 453int index_fd(unsigned char *sha1, int fd, struct stat *st)
 454{
 455        unsigned long size = st->st_size;
 456        void *buf;
 457        int ret;
 458
 459        buf = "";
 460        if (size)
 461                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 462        close(fd);
 463        if ((int)(long)buf == -1)
 464                return -1;
 465
 466        ret = write_sha1_file(buf, size, "blob", sha1);
 467        if (size)
 468                munmap(buf, size);
 469        return ret;
 470}