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
  12const char *sha1_file_directory = NULL;
  13
  14#ifndef O_NOATIME
  15#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  16#define O_NOATIME 01000000
  17#else
  18#define O_NOATIME 0
  19#endif
  20#endif
  21
  22static unsigned int sha1_file_open_flag = O_NOATIME;
  23
  24static unsigned hexval(char c)
  25{
  26        if (c >= '0' && c <= '9')
  27                return c - '0';
  28        if (c >= 'a' && c <= 'f')
  29                return c - 'a' + 10;
  30        if (c >= 'A' && c <= 'F')
  31                return c - 'A' + 10;
  32        return ~0;
  33}
  34
  35int get_sha1_hex(const char *hex, unsigned char *sha1)
  36{
  37        int i;
  38        for (i = 0; i < 20; i++) {
  39                unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  40                if (val & ~0xff)
  41                        return -1;
  42                *sha1++ = val;
  43                hex += 2;
  44        }
  45        return 0;
  46}
  47
  48int get_sha1_file(const char *path, unsigned char *result)
  49{
  50        char buffer[60];
  51        int fd = open(path, O_RDONLY);
  52        int len;
  53
  54        if (fd < 0)
  55                return -1;
  56        len = read(fd, buffer, sizeof(buffer));
  57        close(fd);
  58        if (len < 40)
  59                return -1;
  60        return get_sha1_hex(buffer, result);
  61}
  62
  63int get_sha1(const char *str, unsigned char *sha1)
  64{
  65        static char pathname[PATH_MAX];
  66        static const char *prefix[] = {
  67                "",
  68                "refs",
  69                "refs/tags",
  70                "refs/heads",
  71                "refs/snap",
  72                NULL
  73        };
  74        const char *gitdir;
  75        const char **p;
  76
  77        if (!get_sha1_hex(str, sha1))
  78                return 0;
  79
  80        gitdir = ".git";
  81        for (p = prefix; *p; p++) {
  82                snprintf(pathname, sizeof(pathname), "%s/%s/%s", gitdir, *p, str);
  83                if (!get_sha1_file(pathname, sha1))
  84                        return 0;
  85        }
  86
  87        return -1;
  88}
  89
  90char * sha1_to_hex(const unsigned char *sha1)
  91{
  92        static char buffer[50];
  93        static const char hex[] = "0123456789abcdef";
  94        char *buf = buffer;
  95        int i;
  96
  97        for (i = 0; i < 20; i++) {
  98                unsigned int val = *sha1++;
  99                *buf++ = hex[val >> 4];
 100                *buf++ = hex[val & 0xf];
 101        }
 102        return buffer;
 103}
 104
 105/*
 106 * NOTE! This returns a statically allocated buffer, so you have to be
 107 * careful about using it. Do a "strdup()" if you need to save the
 108 * filename.
 109 */
 110char *sha1_file_name(const unsigned char *sha1)
 111{
 112        int i;
 113        static char *name, *base;
 114
 115        if (!base) {
 116                char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
 117                int len = strlen(sha1_file_directory);
 118                base = xmalloc(len + 60);
 119                memcpy(base, sha1_file_directory, len);
 120                memset(base+len, 0, 60);
 121                base[len] = '/';
 122                base[len+3] = '/';
 123                name = base + len + 1;
 124        }
 125        for (i = 0; i < 20; i++) {
 126                static char hex[] = "0123456789abcdef";
 127                unsigned int val = sha1[i];
 128                char *pos = name + i*2 + (i > 0);
 129                *pos++ = hex[val >> 4];
 130                *pos = hex[val & 0xf];
 131        }
 132        return base;
 133}
 134
 135int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
 136{
 137        char header[100];
 138        unsigned char real_sha1[20];
 139        SHA_CTX c;
 140
 141        SHA1_Init(&c);
 142        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 143        SHA1_Update(&c, map, size);
 144        SHA1_Final(real_sha1, &c);
 145        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 146}
 147
 148void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 149{
 150        char *filename = sha1_file_name(sha1);
 151        struct stat st;
 152        void *map;
 153        int fd;
 154
 155        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 156        if (fd < 0) {
 157                /* See if it works without O_NOATIME */
 158                switch (sha1_file_open_flag) {
 159                default:
 160                        fd = open(filename, O_RDONLY);
 161                        if (fd >= 0)
 162                                break;
 163                /* Fallthrough */
 164                case 0:
 165                        perror(filename);
 166                        return NULL;
 167                }
 168
 169                /* If it failed once, it will probably fail again. Stop using O_NOATIME */
 170                sha1_file_open_flag = 0;
 171        }
 172        if (fstat(fd, &st) < 0) {
 173                close(fd);
 174                return NULL;
 175        }
 176        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 177        close(fd);
 178        if (-1 == (int)(long)map)
 179                return NULL;
 180        *size = st.st_size;
 181        return map;
 182}
 183
 184void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 185{
 186        int ret, bytes;
 187        z_stream stream;
 188        char buffer[8192];
 189        char *buf;
 190
 191        /* Get the data stream */
 192        memset(&stream, 0, sizeof(stream));
 193        stream.next_in = map;
 194        stream.avail_in = mapsize;
 195        stream.next_out = buffer;
 196        stream.avail_out = sizeof(buffer);
 197
 198        inflateInit(&stream);
 199        ret = inflate(&stream, 0);
 200        if (ret < Z_OK)
 201                return NULL;
 202        if (sscanf(buffer, "%10s %lu", type, size) != 2)
 203                return NULL;
 204
 205        bytes = strlen(buffer) + 1;
 206        buf = xmalloc(*size);
 207
 208        memcpy(buf, buffer + bytes, stream.total_out - bytes);
 209        bytes = stream.total_out - bytes;
 210        if (bytes < *size && ret == Z_OK) {
 211                stream.next_out = buf + bytes;
 212                stream.avail_out = *size - bytes;
 213                while (inflate(&stream, Z_FINISH) == Z_OK)
 214                        /* nothing */;
 215        }
 216        inflateEnd(&stream);
 217        return buf;
 218}
 219
 220void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 221{
 222        unsigned long mapsize;
 223        void *map, *buf;
 224
 225        map = map_sha1_file(sha1, &mapsize);
 226        if (map) {
 227                buf = unpack_sha1_file(map, mapsize, type, size);
 228                munmap(map, mapsize);
 229                return buf;
 230        }
 231        return NULL;
 232}
 233
 234void *read_object_with_reference(const unsigned char *sha1,
 235                                 const unsigned char *required_type,
 236                                 unsigned long *size,
 237                                 unsigned char *actual_sha1_return)
 238{
 239        char type[20];
 240        void *buffer;
 241        unsigned long isize;
 242        unsigned char actual_sha1[20];
 243
 244        memcpy(actual_sha1, sha1, 20);
 245        while (1) {
 246                int ref_length = -1;
 247                const char *ref_type = NULL;
 248
 249                buffer = read_sha1_file(actual_sha1, type, &isize);
 250                if (!buffer)
 251                        return NULL;
 252                if (!strcmp(type, required_type)) {
 253                        *size = isize;
 254                        if (actual_sha1_return)
 255                                memcpy(actual_sha1_return, actual_sha1, 20);
 256                        return buffer;
 257                }
 258                /* Handle references */
 259                else if (!strcmp(type, "commit"))
 260                        ref_type = "tree ";
 261                else if (!strcmp(type, "tag"))
 262                        ref_type = "object ";
 263                else {
 264                        free(buffer);
 265                        return NULL;
 266                }
 267                ref_length = strlen(ref_type);
 268
 269                if (memcmp(buffer, ref_type, ref_length) ||
 270                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
 271                        free(buffer);
 272                        return NULL;
 273                }
 274                /* Now we have the ID of the referred-to object in
 275                 * actual_sha1.  Check again. */
 276        }
 277}
 278
 279int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 280{
 281        int size;
 282        char *compressed;
 283        z_stream stream;
 284        unsigned char sha1[20];
 285        SHA_CTX c;
 286        char *filename;
 287        char hdr[50];
 288        int fd, hdrlen;
 289
 290        /* Generate the header */
 291        hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
 292
 293        /* Sha1.. */
 294        SHA1_Init(&c);
 295        SHA1_Update(&c, hdr, hdrlen);
 296        SHA1_Update(&c, buf, len);
 297        SHA1_Final(sha1, &c);
 298
 299        if (returnsha1)
 300                memcpy(returnsha1, sha1, 20);
 301
 302        filename = sha1_file_name(sha1);
 303        fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 304        if (fd < 0) {
 305                if (errno != EEXIST)
 306                        return -1;
 307
 308                /*
 309                 * We might do collision checking here, but we'd need to
 310                 * uncompress the old file and check it. Later.
 311                 */
 312                return 0;
 313        }
 314
 315        /* Set it up */
 316        memset(&stream, 0, sizeof(stream));
 317        deflateInit(&stream, Z_BEST_COMPRESSION);
 318        size = deflateBound(&stream, len+hdrlen);
 319        compressed = xmalloc(size);
 320
 321        /* Compress it */
 322        stream.next_out = compressed;
 323        stream.avail_out = size;
 324
 325        /* First header.. */
 326        stream.next_in = hdr;
 327        stream.avail_in = hdrlen;
 328        while (deflate(&stream, 0) == Z_OK)
 329                /* nothing */
 330
 331        /* Then the data itself.. */
 332        stream.next_in = buf;
 333        stream.avail_in = len;
 334        while (deflate(&stream, Z_FINISH) == Z_OK)
 335                /* nothing */;
 336        deflateEnd(&stream);
 337        size = stream.total_out;
 338
 339        if (write(fd, compressed, size) != size)
 340                die("unable to write file");
 341        close(fd);
 342                
 343        return 0;
 344}
 345
 346static inline int collision_check(char *filename, void *buf, unsigned int size)
 347{
 348#ifdef COLLISION_CHECK
 349        void *map;
 350        int fd = open(filename, O_RDONLY);
 351        struct stat st;
 352        int cmp;
 353
 354        /* Unreadable object, or object went away? Strange. */
 355        if (fd < 0)
 356                return -1;
 357
 358        if (fstat(fd, &st) < 0 || size != st.st_size)
 359                return -1;
 360
 361        map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 362        close(fd);
 363        if (map == MAP_FAILED)
 364                return -1;
 365        cmp = memcmp(buf, map, size);
 366        munmap(map, size);
 367        if (cmp)
 368                return -1;
 369#endif
 370        return 0;
 371}
 372
 373int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
 374{
 375        char *filename = sha1_file_name(sha1);
 376        int fd;
 377
 378        fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 379        if (fd < 0) {
 380                if (errno != EEXIST)
 381                        return -1;
 382                if (collision_check(filename, buf, size))
 383                        return error("SHA1 collision detected!"
 384                                        " This is bad, bad, BAD!\a\n");
 385                return 0;
 386        }
 387        write(fd, buf, size);
 388        close(fd);
 389        return 0;
 390}
 391
 392int write_sha1_from_fd(const unsigned char *sha1, int fd)
 393{
 394        char *filename = sha1_file_name(sha1);
 395
 396        int local;
 397        z_stream stream;
 398        unsigned char real_sha1[20];
 399        char buf[4096];
 400        char discard[4096];
 401        int ret;
 402        SHA_CTX c;
 403
 404        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 405
 406        if (local < 0)
 407                return error("Couldn't open %s\n", filename);
 408
 409        memset(&stream, 0, sizeof(stream));
 410
 411        inflateInit(&stream);
 412
 413        SHA1_Init(&c);
 414
 415        do {
 416                ssize_t size;
 417                size = read(fd, buf, 4096);
 418                if (size <= 0) {
 419                        close(local);
 420                        unlink(filename);
 421                        if (!size)
 422                                return error("Connection closed?");
 423                        perror("Reading from connection");
 424                        return -1;
 425                }
 426                write(local, buf, size);
 427                stream.avail_in = size;
 428                stream.next_in = buf;
 429                do {
 430                        stream.next_out = discard;
 431                        stream.avail_out = sizeof(discard);
 432                        ret = inflate(&stream, Z_SYNC_FLUSH);
 433                        SHA1_Update(&c, discard, sizeof(discard) -
 434                                    stream.avail_out);
 435                } while (stream.avail_in && ret == Z_OK);
 436                
 437        } while (ret == Z_OK);
 438        inflateEnd(&stream);
 439
 440        close(local);
 441        SHA1_Final(real_sha1, &c);
 442        if (ret != Z_STREAM_END) {
 443                unlink(filename);
 444                return error("File %s corrupted", sha1_to_hex(sha1));
 445        }
 446        if (memcmp(sha1, real_sha1, 20)) {
 447                unlink(filename);
 448                return error("File %s has bad hash\n", sha1_to_hex(sha1));
 449        }
 450        
 451        return 0;
 452}
 453
 454int has_sha1_file(const unsigned char *sha1)
 455{
 456        char *filename = sha1_file_name(sha1);
 457        struct stat st;
 458
 459        if (!stat(filename, &st))
 460                return 1;
 461        return 0;
 462}