read-cache.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6 #include <stdarg.h>
   7 #include "cache.h"
   8
   9 const char *sha1_file_directory = NULL;
  10 struct cache_entry **active_cache = NULL;
  11 unsigned int active_nr = 0, active_alloc = 0;
  12
  13 void usage(const char *err)
  14 {
  15         fprintf(stderr, "usage: %s\n", err);
  16         exit(1);
  17 }
  18
  19 static void report(const char *prefix, const char *err, va_list params)
  20 {
  21         fputs(prefix, stderr);
  22         vfprintf(stderr, err, params);
  23         fputs("\n", stderr);
  24 }
  25
  26 void die(const char *err, ...)
  27 {
  28         va_list params;
  29
  30         va_start(params, err);
  31         report("fatal: ", err, params);
  32         va_end(params);
  33         exit(1);
  34 }
  35
  36 int error(const char *err, ...)
  37 {
  38         va_list params;
  39
  40         va_start(params, err);
  41         report("error: ", err, params);
  42         va_end(params);
  43         return -1;
  44 }
  45
  46
  47 static unsigned hexval(char c)
  48 {
  49         if (c >= '0' && c <= '9')
  50                 return c - '0';
  51         if (c >= 'a' && c <= 'f')
  52                 return c - 'a' + 10;
  53         if (c >= 'A' && c <= 'F')
  54                 return c - 'A' + 10;
  55         return ~0;
  56 }
  57
  58 int get_sha1_hex(const char *hex, unsigned char *sha1)
  59 {
  60         int i;
  61         for (i = 0; i < 20; i++) {
  62                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  63                 if (val & ~0xff)
  64                         return -1;
  65                 *sha1++ = val;
  66                 hex += 2;
  67         }
  68         return 0;
  69 }
  70
  71 char * sha1_to_hex(const unsigned char *sha1)
  72 {
  73         static char buffer[50];
  74         static const char hex[] = "0123456789abcdef";
  75         char *buf = buffer;
  76         int i;
  77
  78         for (i = 0; i < 20; i++) {
  79                 unsigned int val = *sha1++;
  80                 *buf++ = hex[val >> 4];
  81                 *buf++ = hex[val & 0xf];
  82         }
  83         return buffer;
  84 }
  85
  86 /*
  87  * NOTE! This returns a statically allocated buffer, so you have to be
  88  * careful about using it. Do a "strdup()" if you need to save the
  89  * filename.
  90  */
  91 char *sha1_file_name(const unsigned char *sha1)
  92 {
  93         int i;
  94         static char *name, *base;
  95
  96         if (!base) {
  97                 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
  98                 int len = strlen(sha1_file_directory);
  99                 base = malloc(len + 60);
 100                 memcpy(base, sha1_file_directory, len);
 101                 memset(base+len, 0, 60);
 102                 base[len] = '/';
 103                 base[len+3] = '/';
 104                 name = base + len + 1;
 105         }
 106         for (i = 0; i < 20; i++) {
 107                 static char hex[] = "0123456789abcdef";
 108                 unsigned int val = sha1[i];
 109                 char *pos = name + i*2 + (i > 0);
 110                 *pos++ = hex[val >> 4];
 111                 *pos = hex[val & 0xf];
 112         }
 113         return base;
 114 }
 115
 116 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
 117 {
 118         unsigned char real_sha1[20];
 119         SHA_CTX c;
 120
 121         SHA1_Init(&c);
 122         SHA1_Update(&c, map, size);
 123         SHA1_Final(real_sha1, &c);
 124         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 125 }
 126
 127 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 128 {
 129         char *filename = sha1_file_name(sha1);
 130         int fd = open(filename, O_RDONLY);
 131         struct stat st;
 132         void *map;
 133
 134         if (fd < 0) {
 135                 perror(filename);
 136                 return NULL;
 137         }
 138         if (fstat(fd, &st) < 0) {
 139                 close(fd);
 140                 return NULL;
 141         }
 142         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 143         close(fd);
 144         if (-1 == (int)(long)map)
 145                 return NULL;
 146         *size = st.st_size;
 147         return map;
 148 }
 149
 150 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 151 {
 152         int ret, bytes;
 153         z_stream stream;
 154         char buffer[8192];
 155         char *buf;
 156
 157         /* Get the data stream */
 158         memset(&stream, 0, sizeof(stream));
 159         stream.next_in = map;
 160         stream.avail_in = mapsize;
 161         stream.next_out = buffer;
 162         stream.avail_out = sizeof(buffer);
 163
 164         inflateInit(&stream);
 165         ret = inflate(&stream, 0);
 166         if (sscanf(buffer, "%10s %lu", type, size) != 2)
 167                 return NULL;
 168
 169         bytes = strlen(buffer) + 1;
 170         buf = malloc(*size);
 171         if (!buf)
 172                 return NULL;
 173
 174         memcpy(buf, buffer + bytes, stream.total_out - bytes);
 175         bytes = stream.total_out - bytes;
 176         if (bytes < *size && ret == Z_OK) {
 177                 stream.next_out = buf + bytes;
 178                 stream.avail_out = *size - bytes;
 179                 while (inflate(&stream, Z_FINISH) == Z_OK)
 180                         /* nothing */;
 181         }
 182         inflateEnd(&stream);
 183         return buf;
 184 }
 185
 186 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 187 {
 188         unsigned long mapsize;
 189         void *map, *buf;
 190
 191         map = map_sha1_file(sha1, &mapsize);
 192         if (map) {
 193                 buf = unpack_sha1_file(map, mapsize, type, size);
 194                 munmap(map, mapsize);
 195                 return buf;
 196         }
 197         return NULL;
 198 }
 199
 200 int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
 201 {
 202         int size;
 203         char *compressed;
 204         z_stream stream;
 205         unsigned char sha1[20];
 206         SHA_CTX c;
 207
 208         /* Set it up */
 209         memset(&stream, 0, sizeof(stream));
 210         deflateInit(&stream, Z_BEST_COMPRESSION);
 211         size = deflateBound(&stream, len);
 212         compressed = malloc(size);
 213
 214         /* Compress it */
 215         stream.next_in = buf;
 216         stream.avail_in = len;
 217         stream.next_out = compressed;
 218         stream.avail_out = size;
 219         while (deflate(&stream, Z_FINISH) == Z_OK)
 220                 /* nothing */;
 221         deflateEnd(&stream);
 222         size = stream.total_out;
 223
 224         /* Sha1.. */
 225         SHA1_Init(&c);
 226         SHA1_Update(&c, compressed, size);
 227         SHA1_Final(sha1, &c);
 228
 229         if (write_sha1_buffer(sha1, compressed, size) < 0)
 230                 return -1;
 231         if (returnsha1)
 232                 memcpy(returnsha1, sha1, 20);
 233         return 0;
 234 }
 235
 236 int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
 237 {
 238         char *filename = sha1_file_name(sha1);
 239         int fd;
 240
 241         fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 242         if (fd < 0) {
 243                 void *map;
 244
 245                 if (errno != EEXIST)
 246                         return -1;
 247 #ifndef COLLISION_CHECK
 248                 fd = open(filename, O_RDONLY);
 249                 if (fd < 0)
 250                         return -1;
 251                 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 252                 if (map == MAP_FAILED)
 253                         return -1;
 254                 if (memcmp(buf, map, size))
 255                         return error("SHA1 collision detected!"
 256                                         " This is bad, bad, BAD!\a\n");
 257 #endif
 258                 return 0;
 259         }
 260         write(fd, buf, size);
 261         close(fd);
 262         return 0;
 263 }
 264
 265 int cache_match_stat(struct cache_entry *ce, struct stat *st)
 266 {
 267         unsigned int changed = 0;
 268
 269         /* nsec seems unreliable - not all filesystems support it, so
 270          * as long as it is in the inode cache you get right nsec
 271          * but after it gets flushed, you get zero nsec. */
 272         if (ce->mtime.sec  != (unsigned int)st->st_mtim.tv_sec
 273 #ifdef NSEC
 274             || ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec
 275 #endif
 276             )
 277                 changed |= MTIME_CHANGED;
 278         if (ce->ctime.sec  != (unsigned int)st->st_ctim.tv_sec
 279 #ifdef NSEC
 280             || ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec
 281 #endif
 282             )
 283                 changed |= CTIME_CHANGED;
 284         if (ce->st_uid != (unsigned int)st->st_uid ||
 285             ce->st_gid != (unsigned int)st->st_gid)
 286                 changed |= OWNER_CHANGED;
 287         if (ce->st_mode != (unsigned int)st->st_mode)
 288                 changed |= MODE_CHANGED;
 289         if (ce->st_dev != (unsigned int)st->st_dev ||
 290             ce->st_ino != (unsigned int)st->st_ino)
 291                 changed |= INODE_CHANGED;
 292         if (ce->st_size != (unsigned int)st->st_size)
 293                 changed |= DATA_CHANGED;
 294         return changed;
 295 }
 296
 297 int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
 298 {
 299         int len = len1 < len2 ? len1 : len2;
 300         int cmp;
 301
 302         cmp = memcmp(name1, name2, len);
 303         if (cmp)
 304                 return cmp;
 305         if (len1 < len2)
 306                 return -1;
 307         if (len1 > len2)
 308                 return 1;
 309         return 0;
 310 }
 311
 312 int cache_name_pos(const char *name, int namelen)
 313 {
 314         int first, last;
 315
 316         first = 0;
 317         last = active_nr;
 318         while (last > first) {
 319                 int next = (last + first) >> 1;
 320                 struct cache_entry *ce = active_cache[next];
 321                 int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen);
 322                 if (!cmp)
 323                         return next;
 324                 if (cmp < 0) {
 325                         last = next;
 326                         continue;
 327                 }
 328                 first = next+1;
 329         }
 330         return -first-1;
 331 }
 332
 333 int remove_file_from_cache(char *path)
 334 {
 335         int pos = cache_name_pos(path, strlen(path));
 336         if (pos >= 0) {
 337                 active_nr--;
 338                 if (pos < active_nr)
 339                         memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
 340         }
 341         return 0;
 342 }
 343
 344 int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 345 {
 346         int pos;
 347
 348         pos = cache_name_pos(ce->name, ce->namelen);
 349
 350         /* existing match? Just replace it */
 351         if (pos >= 0) {
 352                 active_cache[pos] = ce;
 353                 return 0;
 354         }
 355         pos = -pos-1;
 356
 357         if (!ok_to_add)
 358                 return -1;
 359
 360         /* Make sure the array is big enough .. */
 361         if (active_nr == active_alloc) {
 362                 active_alloc = alloc_nr(active_alloc);
 363                 active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 364         }
 365
 366         /* Add it in.. */
 367         active_nr++;
 368         if (active_nr > pos)
 369                 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 370         active_cache[pos] = ce;
 371         return 0;
 372 }
 373
 374 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 375 {
 376         SHA_CTX c;
 377         unsigned char sha1[20];
 378
 379         if (hdr->signature != CACHE_SIGNATURE)
 380                 return error("bad signature");
 381         if (hdr->version != 1)
 382                 return error("bad version");
 383         SHA1_Init(&c);
 384         SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
 385         SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
 386         SHA1_Final(sha1, &c);
 387         if (memcmp(sha1, hdr->sha1, 20))
 388                 return error("bad header sha1");
 389         return 0;
 390 }
 391
 392 int read_cache(void)
 393 {
 394         int fd, i;
 395         struct stat st;
 396         unsigned long size, offset;
 397         void *map;
 398         struct cache_header *hdr;
 399
 400         errno = EBUSY;
 401         if (active_cache)
 402                 return error("more than one cachefile");
 403         errno = ENOENT;
 404         sha1_file_directory = getenv(DB_ENVIRONMENT);
 405         if (!sha1_file_directory)
 406                 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 407         if (access(sha1_file_directory, X_OK) < 0)
 408                 return error("no access to SHA1 file directory");
 409         fd = open(".git/index", O_RDONLY);
 410         if (fd < 0)
 411                 return (errno == ENOENT) ? 0 : error("open failed");
 412
 413         size = 0; // avoid gcc warning
 414         map = (void *)-1;
 415         if (!fstat(fd, &st)) {
 416                 size = st.st_size;
 417                 errno = EINVAL;
 418                 if (size >= sizeof(struct cache_header))
 419                         map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 420         }
 421         close(fd);
 422         if (-1 == (int)(long)map)
 423                 return error("mmap failed");
 424
 425         hdr = map;
 426         if (verify_hdr(hdr, size) < 0)
 427                 goto unmap;
 428
 429         active_nr = hdr->entries;
 430         active_alloc = alloc_nr(active_nr);
 431         active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 432
 433         offset = sizeof(*hdr);
 434         for (i = 0; i < hdr->entries; i++) {
 435                 struct cache_entry *ce = map + offset;
 436                 offset = offset + ce_size(ce);
 437                 active_cache[i] = ce;
 438         }
 439         return active_nr;
 440
 441 unmap:
 442         munmap(map, size);
 443         errno = EINVAL;
 444         return error("verify header failed");
 445 }
 446
 447 int write_cache(int newfd, struct cache_entry **cache, int entries)
 448 {
 449         SHA_CTX c;
 450         struct cache_header hdr;
 451         int i;
 452
 453         hdr.signature = CACHE_SIGNATURE;
 454         hdr.version = 1;
 455         hdr.entries = entries;
 456
 457         SHA1_Init(&c);
 458         SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
 459         for (i = 0; i < entries; i++) {
 460                 struct cache_entry *ce = cache[i];
 461                 int size = ce_size(ce);
 462                 SHA1_Update(&c, ce, size);
 463         }
 464         SHA1_Final(hdr.sha1, &c);
 465
 466         if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
 467                 return -1;
 468
 469         for (i = 0; i < entries; i++) {
 470                 struct cache_entry *ce = cache[i];
 471                 int size = ce_size(ce);
 472                 if (write(newfd, ce, size) != size)
 473                         return -1;
 474         }
 475         return 0;
 476 }