Andrew's git / gitweb.git / sha1_file.c
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sha1_file.con commit Fix thinko in the logic to refuse unmerged path fed to git-apply-patch-script. (e4f5b8c)
   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
 103static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 104{
 105        int i;
 106        for (i = 0; i < 20; i++) {
 107                static char hex[] = "0123456789abcdef";
 108                unsigned int val = sha1[i];
 109                char *pos = pathbuf + i*2 + (i > 0);
 110                *pos++ = hex[val >> 4];
 111                *pos = hex[val & 0xf];
 112        }
 113}
 114
 115/*
 116 * NOTE! This returns a statically allocated buffer, so you have to be
 117 * careful about using it. Do a "strdup()" if you need to save the
 118 * filename.
 119 *
 120 * Also note that this returns the location for creating.  Reading
 121 * SHA1 file can happen from any alternate directory listed in the
 122 * SHA1_FILE_DIRECTORIES environment variable if it is not found in
 123 * the primary object database.
 124 */
 125char *sha1_file_name(const unsigned char *sha1)
 126{
 127        static char *name, *base;
 128
 129        if (!base) {
 130                char *sha1_file_directory = get_object_directory();
 131                int len = strlen(sha1_file_directory);
 132                base = xmalloc(len + 60);
 133                memcpy(base, sha1_file_directory, len);
 134                memset(base+len, 0, 60);
 135                base[len] = '/';
 136                base[len+3] = '/';
 137                name = base + len + 1;
 138        }
 139        fill_sha1_path(name, sha1);
 140        return base;
 141}
 142
 143static struct alternate_object_database
 144{
 145        char *base;
 146        char *name;
 147} *alt_odb;
 148
 149static void prepare_alt_odb(void)
 150{
 151        int pass, totlen, i;
 152        void *buf;
 153        const char *cp, *last;
 154        char *op = 0;
 155        const char *alt = getenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
 156
 157        for (totlen = pass = 0; pass < 2; pass++) {
 158                last = alt;
 159                i = 0;
 160                do {
 161                        cp = strchr(last, ':') ? : last + strlen(last);
 162                        if (last != cp) {
 163                                /* 43 = 40-byte + 2 '/' + terminating NUL */
 164                                int pfxlen = cp - last;
 165                                int entlen = pfxlen + 43;
 166                                if (pass == 0)
 167                                        totlen += entlen;
 168                                else {
 169                                        alt_odb[i].base = op;
 170                                        alt_odb[i].name = op + pfxlen + 1;
 171                                        memcpy(op, last, pfxlen);
 172                                        op[pfxlen] = op[pfxlen + 3] = '/';
 173                                        op[entlen-1] = 0;
 174                                        op += entlen;
 175                                }
 176                                i++;
 177                        }
 178                        while (*cp && *cp == ':')
 179                                cp++;
 180                        last = cp;
 181                } while (*cp);
 182                if (pass)
 183                        break;
 184                alt_odb = buf = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
 185                alt_odb[i].base = alt_odb[i].name = 0;
 186                op = (char*)(&alt_odb[i+1]);
 187        }
 188}
 189
 190static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 191{
 192        int i;
 193        char *name = sha1_file_name(sha1);
 194
 195        if (!stat(name, st))
 196                return name;
 197        if (!alt_odb)
 198                prepare_alt_odb();
 199        for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
 200                fill_sha1_path(name, sha1);
 201                if (!stat(alt_odb[i].base, st))
 202                        return alt_odb[i].base;
 203        }
 204        return NULL;
 205}
 206
 207int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
 208{
 209        char header[100];
 210        unsigned char real_sha1[20];
 211        SHA_CTX c;
 212
 213        SHA1_Init(&c);
 214        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 215        SHA1_Update(&c, map, size);
 216        SHA1_Final(real_sha1, &c);
 217        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 218}
 219
 220void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 221{
 222        struct stat st;
 223        void *map;
 224        int fd;
 225        char *filename = find_sha1_file(sha1, &st);
 226
 227        if (!filename) {
 228                error("cannot map sha1 file %s", sha1_to_hex(sha1));
 229                return NULL;
 230        }
 231
 232        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 233        if (fd < 0) {
 234                /* See if it works without O_NOATIME */
 235                switch (sha1_file_open_flag) {
 236                default:
 237                        fd = open(filename, O_RDONLY);
 238                        if (fd >= 0)
 239                                break;
 240                /* Fallthrough */
 241                case 0:
 242                        perror(filename);
 243                        return NULL;
 244                }
 245
 246                /* If it failed once, it will probably fail again. Stop using O_NOATIME */
 247                sha1_file_open_flag = 0;
 248        }
 249        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 250        close(fd);
 251        if (-1 == (int)(long)map)
 252                return NULL;
 253        *size = st.st_size;
 254        return map;
 255}
 256
 257void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 258{
 259        int ret, bytes;
 260        z_stream stream;
 261        char buffer[8192];
 262        char *buf;
 263
 264        /* Get the data stream */
 265        memset(&stream, 0, sizeof(stream));
 266        stream.next_in = map;
 267        stream.avail_in = mapsize;
 268        stream.next_out = buffer;
 269        stream.avail_out = sizeof(buffer);
 270
 271        inflateInit(&stream);
 272        ret = inflate(&stream, 0);
 273        if (ret < Z_OK)
 274                return NULL;
 275        if (sscanf(buffer, "%10s %lu", type, size) != 2)
 276                return NULL;
 277
 278        bytes = strlen(buffer) + 1;
 279        buf = xmalloc(*size);
 280
 281        memcpy(buf, buffer + bytes, stream.total_out - bytes);
 282        bytes = stream.total_out - bytes;
 283        if (bytes < *size && ret == Z_OK) {
 284                stream.next_out = buf + bytes;
 285                stream.avail_out = *size - bytes;
 286                while (inflate(&stream, Z_FINISH) == Z_OK)
 287                        /* nothing */;
 288        }
 289        inflateEnd(&stream);
 290        return buf;
 291}
 292
 293void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 294{
 295        unsigned long mapsize;
 296        void *map, *buf;
 297
 298        map = map_sha1_file(sha1, &mapsize);
 299        if (map) {
 300                buf = unpack_sha1_file(map, mapsize, type, size);
 301                munmap(map, mapsize);
 302                return buf;
 303        }
 304        return NULL;
 305}
 306
 307void *read_object_with_reference(const unsigned char *sha1,
 308                                 const unsigned char *required_type,
 309                                 unsigned long *size,
 310                                 unsigned char *actual_sha1_return)
 311{
 312        char type[20];
 313        void *buffer;
 314        unsigned long isize;
 315        unsigned char actual_sha1[20];
 316
 317        memcpy(actual_sha1, sha1, 20);
 318        while (1) {
 319                int ref_length = -1;
 320                const char *ref_type = NULL;
 321
 322                buffer = read_sha1_file(actual_sha1, type, &isize);
 323                if (!buffer)
 324                        return NULL;
 325                if (!strcmp(type, required_type)) {
 326                        *size = isize;
 327                        if (actual_sha1_return)
 328                                memcpy(actual_sha1_return, actual_sha1, 20);
 329                        return buffer;
 330                }
 331                /* Handle references */
 332                else if (!strcmp(type, "commit"))
 333                        ref_type = "tree ";
 334                else if (!strcmp(type, "tag"))
 335                        ref_type = "object ";
 336                else {
 337                        free(buffer);
 338                        return NULL;
 339                }
 340                ref_length = strlen(ref_type);
 341
 342                if (memcmp(buffer, ref_type, ref_length) ||
 343                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
 344                        free(buffer);
 345                        return NULL;
 346                }
 347                /* Now we have the ID of the referred-to object in
 348                 * actual_sha1.  Check again. */
 349        }
 350}
 351
 352int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 353{
 354        int size;
 355        char *compressed;
 356        z_stream stream;
 357        unsigned char sha1[20];
 358        SHA_CTX c;
 359        char *filename;
 360        static char tmpfile[PATH_MAX];
 361        char hdr[50];
 362        int fd, hdrlen, ret;
 363
 364        /* Generate the header */
 365        hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
 366
 367        /* Sha1.. */
 368        SHA1_Init(&c);
 369        SHA1_Update(&c, hdr, hdrlen);
 370        SHA1_Update(&c, buf, len);
 371        SHA1_Final(sha1, &c);
 372
 373        if (returnsha1)
 374                memcpy(returnsha1, sha1, 20);
 375
 376        filename = sha1_file_name(sha1);
 377        fd = open(filename, O_RDONLY);
 378        if (fd >= 0) {
 379                /*
 380                 * FIXME!!! We might do collision checking here, but we'd
 381                 * need to uncompress the old file and check it. Later.
 382                 */
 383                close(fd);
 384                return 0;
 385        }
 386
 387        if (errno != ENOENT) {
 388                fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
 389                return -1;
 390        }
 391
 392        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
 393
 394        fd = mkstemp(tmpfile);
 395        if (fd < 0) {
 396                fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
 397                return -1;
 398        }
 399
 400        /* Set it up */
 401        memset(&stream, 0, sizeof(stream));
 402        deflateInit(&stream, Z_BEST_COMPRESSION);
 403        size = deflateBound(&stream, len+hdrlen);
 404        compressed = xmalloc(size);
 405
 406        /* Compress it */
 407        stream.next_out = compressed;
 408        stream.avail_out = size;
 409
 410        /* First header.. */
 411        stream.next_in = hdr;
 412        stream.avail_in = hdrlen;
 413        while (deflate(&stream, 0) == Z_OK)
 414                /* nothing */
 415
 416        /* Then the data itself.. */
 417        stream.next_in = buf;
 418        stream.avail_in = len;
 419        while (deflate(&stream, Z_FINISH) == Z_OK)
 420                /* nothing */;
 421        deflateEnd(&stream);
 422        size = stream.total_out;
 423
 424        if (write(fd, compressed, size) != size)
 425                die("unable to write file");
 426        fchmod(fd, 0444);
 427        close(fd);
 428
 429        ret = link(tmpfile, filename);
 430        if (ret < 0) {
 431                ret = errno;
 432
 433                /*
 434                 * Coda hack - coda doesn't like cross-directory links,
 435                 * so we fall back to a rename, which will mean that it
 436                 * won't be able to check collisions, but that's not a
 437                 * big deal.
 438                 *
 439                 * When this succeeds, we just return 0. We have nothing
 440                 * left to unlink.
 441                 */
 442                if (ret == EXDEV && !rename(tmpfile, filename))
 443                        return 0;
 444        }
 445        unlink(tmpfile);
 446        if (ret) {
 447                if (ret != EEXIST) {
 448                        fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
 449                        return -1;
 450                }
 451                /* FIXME!!! Collision check here ? */
 452        }
 453
 454        return 0;
 455}
 456
 457int write_sha1_from_fd(const unsigned char *sha1, int fd)
 458{
 459        char *filename = sha1_file_name(sha1);
 460
 461        int local;
 462        z_stream stream;
 463        unsigned char real_sha1[20];
 464        char buf[4096];
 465        char discard[4096];
 466        int ret;
 467        SHA_CTX c;
 468
 469        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 470
 471        if (local < 0)
 472                return error("Couldn't open %s\n", filename);
 473
 474        memset(&stream, 0, sizeof(stream));
 475
 476        inflateInit(&stream);
 477
 478        SHA1_Init(&c);
 479
 480        do {
 481                ssize_t size;
 482                size = read(fd, buf, 4096);
 483                if (size <= 0) {
 484                        close(local);
 485                        unlink(filename);
 486                        if (!size)
 487                                return error("Connection closed?");
 488                        perror("Reading from connection");
 489                        return -1;
 490                }
 491                write(local, buf, size);
 492                stream.avail_in = size;
 493                stream.next_in = buf;
 494                do {
 495                        stream.next_out = discard;
 496                        stream.avail_out = sizeof(discard);
 497                        ret = inflate(&stream, Z_SYNC_FLUSH);
 498                        SHA1_Update(&c, discard, sizeof(discard) -
 499                                    stream.avail_out);
 500                } while (stream.avail_in && ret == Z_OK);
 501                
 502        } while (ret == Z_OK);
 503        inflateEnd(&stream);
 504
 505        close(local);
 506        SHA1_Final(real_sha1, &c);
 507        if (ret != Z_STREAM_END) {
 508                unlink(filename);
 509                return error("File %s corrupted", sha1_to_hex(sha1));
 510        }
 511        if (memcmp(sha1, real_sha1, 20)) {
 512                unlink(filename);
 513                return error("File %s has bad hash\n", sha1_to_hex(sha1));
 514        }
 515        
 516        return 0;
 517}
 518
 519int has_sha1_file(const unsigned char *sha1)
 520{
 521        struct stat st;
 522        return !!find_sha1_file(sha1, &st);
 523}
 524
 525int index_fd(unsigned char *sha1, int fd, struct stat *st)
 526{
 527        unsigned long size = st->st_size;
 528        void *buf;
 529        int ret;
 530
 531        buf = "";
 532        if (size)
 533                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 534        close(fd);
 535        if ((int)(long)buf == -1)
 536                return -1;
 537
 538        ret = write_sha1_file(buf, size, "blob", sha1);
 539        if (size)
 540                munmap(buf, size);
 541        return ret;
 542}