read-cache.con commit Merge with http://members.cox.net/junkio/git-jc.git (f1a7eb3)
   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
   9struct cache_entry **active_cache = NULL;
  10unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
  11
  12int cache_match_stat(struct cache_entry *ce, struct stat *st)
  13{
  14        unsigned int changed = 0;
  15
  16        switch (ntohl(ce->ce_mode) & S_IFMT) {
  17        case S_IFREG:
  18                changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
  19                /* We consider only the owner x bit to be relevant for "mode changes" */
  20                if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
  21                        changed |= MODE_CHANGED;
  22                break;
  23        case S_IFLNK:
  24                changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
  25                break;
  26        default:
  27                die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
  28        }
  29        if (ce->ce_mtime.sec != htonl(st->st_mtime))
  30                changed |= MTIME_CHANGED;
  31        if (ce->ce_ctime.sec != htonl(st->st_ctime))
  32                changed |= CTIME_CHANGED;
  33
  34#ifdef NSEC
  35        /*
  36         * nsec seems unreliable - not all filesystems support it, so
  37         * as long as it is in the inode cache you get right nsec
  38         * but after it gets flushed, you get zero nsec.
  39         */
  40        if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
  41                changed |= MTIME_CHANGED;
  42        if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
  43                changed |= CTIME_CHANGED;
  44#endif  
  45
  46        if (ce->ce_uid != htonl(st->st_uid) ||
  47            ce->ce_gid != htonl(st->st_gid))
  48                changed |= OWNER_CHANGED;
  49        if (ce->ce_dev != htonl(st->st_dev) ||
  50            ce->ce_ino != htonl(st->st_ino))
  51                changed |= INODE_CHANGED;
  52        if (ce->ce_size != htonl(st->st_size))
  53                changed |= DATA_CHANGED;
  54        return changed;
  55}
  56
  57int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
  58{
  59        int len1 = flags1 & CE_NAMEMASK;
  60        int len2 = flags2 & CE_NAMEMASK;
  61        int len = len1 < len2 ? len1 : len2;
  62        int cmp;
  63
  64        cmp = memcmp(name1, name2, len);
  65        if (cmp)
  66                return cmp;
  67        if (len1 < len2)
  68                return -1;
  69        if (len1 > len2)
  70                return 1;
  71        if (flags1 < flags2)
  72                return -1;
  73        if (flags1 > flags2)
  74                return 1;
  75        return 0;
  76}
  77
  78int cache_name_pos(const char *name, int namelen)
  79{
  80        int first, last;
  81
  82        first = 0;
  83        last = active_nr;
  84        while (last > first) {
  85                int next = (last + first) >> 1;
  86                struct cache_entry *ce = active_cache[next];
  87                int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
  88                if (!cmp)
  89                        return next;
  90                if (cmp < 0) {
  91                        last = next;
  92                        continue;
  93                }
  94                first = next+1;
  95        }
  96        return -first-1;
  97}
  98
  99/* Remove entry, return true if there are more entries to go.. */
 100int remove_entry_at(int pos)
 101{
 102        active_cache_changed = 1;
 103        active_nr--;
 104        if (pos >= active_nr)
 105                return 0;
 106        memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
 107        return 1;
 108}
 109
 110int remove_file_from_cache(char *path)
 111{
 112        int pos = cache_name_pos(path, strlen(path));
 113        if (pos < 0)
 114                pos = -pos-1;
 115        while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
 116                remove_entry_at(pos);
 117        return 0;
 118}
 119
 120int same_name(struct cache_entry *a, struct cache_entry *b)
 121{
 122        int len = ce_namelen(a);
 123        return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
 124}
 125
 126/* We may be in a situation where we already have path/file and path
 127 * is being added, or we already have path and path/file is being
 128 * added.  Either one would result in a nonsense tree that has path
 129 * twice when git-write-tree tries to write it out.  Prevent it.
 130 * 
 131 * If ok-to-replace is specified, we remove the conflicting entries
 132 * from the cache so the caller should recompute the insert position.
 133 * When this happens, we return non-zero.
 134 */
 135static int check_file_directory_conflict(const struct cache_entry *ce,
 136                                         int ok_to_replace)
 137{
 138        int pos, replaced = 0;
 139        const char *path = ce->name;
 140        int namelen = strlen(path);
 141        int stage = ce_stage(ce);
 142        char *pathbuf = xmalloc(namelen + 1);
 143        char *cp;
 144
 145        memcpy(pathbuf, path, namelen + 1);
 146
 147        /*
 148         * We are inserting path/file.  Do they have path registered at
 149         * the same stage?  We need to do this for all the levels of our
 150         * subpath.
 151         */
 152        cp = pathbuf;
 153        while (1) {
 154                char *ep = strchr(cp, '/');
 155                if (!ep)
 156                        break;
 157                *ep = 0;    /* first cut it at slash */
 158                pos = cache_name_pos(pathbuf,
 159                                     htons(create_ce_flags(ep-cp, stage)));
 160                if (0 <= pos) {
 161                        /* Our leading path component is registered as a file,
 162                         * and we are trying to make it a directory.  This is
 163                         * bad.
 164                         */
 165                        if (!ok_to_replace) {
 166                                free(pathbuf);
 167                                return -1;
 168                        }
 169                        fprintf(stderr, "removing file '%s' to replace it with a directory to create '%s'.\n", pathbuf, path);
 170                        remove_entry_at(pos);
 171                        replaced = 1;
 172                }
 173                *ep = '/';  /* then restore it and go downwards */
 174                cp = ep + 1;
 175        }
 176        free(pathbuf);
 177
 178        /* Do we have an entry in the cache that makes our path a prefix
 179         * of it?  That is, are we creating a file where they already expect
 180         * a directory there?
 181         */
 182        pos = cache_name_pos(path,
 183                             htons(create_ce_flags(namelen, stage)));
 184
 185        /* (0 <= pos) cannot happen because add_cache_entry()
 186         * should have taken care of that case.
 187         */
 188        pos = -pos-1;
 189
 190        /* pos would point at an existing entry that would come immediately
 191         * after our path.  It could be the same as our path in higher stage,
 192         * or different path but in a lower stage.
 193         *
 194         * E.g. when we are inserting path at stage 2,
 195         *
 196         *        1 path
 197         * pos->  3 path
 198         *        2 path/file1
 199         *        3 path/file1
 200         *        2 path/file2
 201         *        2 patho
 202         *
 203         * We need to examine pos, ignore it because it is at different
 204         * stage, examine next to find the path/file at stage 2, and
 205         * complain.  We need to do this until we are not the leading
 206         * path of an existing entry anymore.
 207         */
 208
 209        while (pos < active_nr) {
 210                struct cache_entry *other = active_cache[pos];
 211                if (strncmp(other->name, path, namelen))
 212                        break; /* it is not our "subdirectory" anymore */
 213                if ((ce_stage(other) == stage) &&
 214                    other->name[namelen] == '/') {
 215                        if (!ok_to_replace)
 216                                return -1;
 217                        fprintf(stderr, "removing file '%s' under '%s' to be replaced with a file\n", other->name, path);
 218                        remove_entry_at(pos);
 219                        replaced = 1;
 220                        continue; /* cycle without updating pos */
 221                }
 222                pos++;
 223        }
 224        return replaced;
 225}
 226
 227int add_cache_entry(struct cache_entry *ce, int option)
 228{
 229        int pos;
 230        int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
 231        int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
 232        pos = cache_name_pos(ce->name, htons(ce->ce_flags));
 233
 234        /* existing match? Just replace it */
 235        if (pos >= 0) {
 236                active_cache_changed = 1;
 237                active_cache[pos] = ce;
 238                return 0;
 239        }
 240        pos = -pos-1;
 241
 242        /*
 243         * Inserting a merged entry ("stage 0") into the index
 244         * will always replace all non-merged entries..
 245         */
 246        if (pos < active_nr && ce_stage(ce) == 0) {
 247                while (same_name(active_cache[pos], ce)) {
 248                        ok_to_add = 1;
 249                        if (!remove_entry_at(pos))
 250                                break;
 251                }
 252        }
 253
 254        if (!ok_to_add)
 255                return -1;
 256
 257        if (check_file_directory_conflict(ce, ok_to_replace)) {
 258                if (!ok_to_replace)
 259                        return -1;
 260                pos = cache_name_pos(ce->name, htons(ce->ce_flags));
 261                pos = -pos-1;
 262        }
 263
 264        /* Make sure the array is big enough .. */
 265        if (active_nr == active_alloc) {
 266                active_alloc = alloc_nr(active_alloc);
 267                active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 268        }
 269
 270        /* Add it in.. */
 271        active_nr++;
 272        if (active_nr > pos)
 273                memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 274        active_cache[pos] = ce;
 275        active_cache_changed = 1;
 276        return 0;
 277}
 278
 279static int verify_hdr(struct cache_header *hdr, unsigned long size)
 280{
 281        SHA_CTX c;
 282        unsigned char sha1[20];
 283
 284        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 285                return error("bad signature");
 286        if (hdr->hdr_version != htonl(2))
 287                return error("bad index version");
 288        SHA1_Init(&c);
 289        SHA1_Update(&c, hdr, size - 20);
 290        SHA1_Final(sha1, &c);
 291        if (memcmp(sha1, (void *)hdr + size - 20, 20))
 292                return error("bad index file sha1 signature");
 293        return 0;
 294}
 295
 296int read_cache(void)
 297{
 298        int fd, i;
 299        struct stat st;
 300        unsigned long size, offset;
 301        void *map;
 302        struct cache_header *hdr;
 303
 304        errno = EBUSY;
 305        if (active_cache)
 306                return error("more than one cachefile");
 307        errno = ENOENT;
 308        fd = open(get_index_file(), O_RDONLY);
 309        if (fd < 0)
 310                return (errno == ENOENT) ? 0 : error("open failed");
 311
 312        size = 0; // avoid gcc warning
 313        map = (void *)-1;
 314        if (!fstat(fd, &st)) {
 315                size = st.st_size;
 316                errno = EINVAL;
 317                if (size >= sizeof(struct cache_header) + 20)
 318                        map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
 319        }
 320        close(fd);
 321        if (-1 == (int)(long)map)
 322                return error("mmap failed");
 323
 324        hdr = map;
 325        if (verify_hdr(hdr, size) < 0)
 326                goto unmap;
 327
 328        active_nr = ntohl(hdr->hdr_entries);
 329        active_alloc = alloc_nr(active_nr);
 330        active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 331
 332        offset = sizeof(*hdr);
 333        for (i = 0; i < active_nr; i++) {
 334                struct cache_entry *ce = map + offset;
 335                offset = offset + ce_size(ce);
 336                active_cache[i] = ce;
 337        }
 338        return active_nr;
 339
 340unmap:
 341        munmap(map, size);
 342        errno = EINVAL;
 343        return error("verify header failed");
 344}
 345
 346#define WRITE_BUFFER_SIZE 8192
 347static char write_buffer[WRITE_BUFFER_SIZE];
 348static unsigned long write_buffer_len;
 349
 350static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
 351{
 352        while (len) {
 353                unsigned int buffered = write_buffer_len;
 354                unsigned int partial = WRITE_BUFFER_SIZE - buffered;
 355                if (partial > len)
 356                        partial = len;
 357                memcpy(write_buffer + buffered, data, partial);
 358                buffered += partial;
 359                if (buffered == WRITE_BUFFER_SIZE) {
 360                        SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
 361                        if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
 362                                return -1;
 363                        buffered = 0;
 364                }
 365                write_buffer_len = buffered;
 366                len -= partial;
 367                data += partial;
 368        }
 369        return 0;
 370}
 371
 372static int ce_flush(SHA_CTX *context, int fd)
 373{
 374        unsigned int left = write_buffer_len;
 375
 376        if (left) {
 377                write_buffer_len = 0;
 378                SHA1_Update(context, write_buffer, left);
 379        }
 380
 381        /* Append the SHA1 signature at the end */
 382        SHA1_Final(write_buffer + left, context);
 383        left += 20;
 384        if (write(fd, write_buffer, left) != left)
 385                return -1;
 386        return 0;
 387}
 388
 389int write_cache(int newfd, struct cache_entry **cache, int entries)
 390{
 391        SHA_CTX c;
 392        struct cache_header hdr;
 393        int i;
 394
 395        hdr.hdr_signature = htonl(CACHE_SIGNATURE);
 396        hdr.hdr_version = htonl(2);
 397        hdr.hdr_entries = htonl(entries);
 398
 399        SHA1_Init(&c);
 400        if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
 401                return -1;
 402
 403        for (i = 0; i < entries; i++) {
 404                struct cache_entry *ce = cache[i];
 405                if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
 406                        return -1;
 407        }
 408        return ce_flush(&c, newfd);
 409}