Andrew's git - gitweb.git/blob

   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;
  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                break;
  20        case S_IFLNK:
  21                changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
  22                break;
  23        default:
  24                die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
  25        }
  26        if (ce->ce_mtime.sec != htonl(st->st_mtime))
  27                changed |= MTIME_CHANGED;
  28        if (ce->ce_ctime.sec != htonl(st->st_ctime))
  29                changed |= CTIME_CHANGED;
  30
  31#ifdef NSEC
  32        /*
  33         * nsec seems unreliable - not all filesystems support it, so
  34         * as long as it is in the inode cache you get right nsec
  35         * but after it gets flushed, you get zero nsec.
  36         */
  37        if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
  38                changed |= MTIME_CHANGED;
  39        if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
  40                changed |= CTIME_CHANGED;
  41#endif  
  42
  43        if (ce->ce_uid != htonl(st->st_uid) ||
  44            ce->ce_gid != htonl(st->st_gid))
  45                changed |= OWNER_CHANGED;
  46        /* We consider only the owner x bit to be relevant for "mode changes" */
  47        if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
  48                changed |= MODE_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_nr--;
 103        if (pos >= active_nr)
 104                return 0;
 105        memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
 106        return 1;
 107}
 108
 109int remove_file_from_cache(char *path)
 110{
 111        int pos = cache_name_pos(path, strlen(path));
 112        if (pos < 0)
 113                pos = -pos-1;
 114        while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
 115                remove_entry_at(pos);
 116        return 0;
 117}
 118
 119int same_name(struct cache_entry *a, struct cache_entry *b)
 120{
 121        int len = ce_namelen(a);
 122        return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
 123}
 124
 125int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 126{
 127        int pos;
 128
 129        pos = cache_name_pos(ce->name, htons(ce->ce_flags));
 130
 131        /* existing match? Just replace it */
 132        if (pos >= 0) {
 133                active_cache[pos] = ce;
 134                return 0;
 135        }
 136        pos = -pos-1;
 137
 138        /*
 139         * Inserting a merged entry ("stage 0") into the index
 140         * will always replace all non-merged entries..
 141         */
 142        if (pos < active_nr && ce_stage(ce) == 0) {
 143                while (same_name(active_cache[pos], ce)) {
 144                        ok_to_add = 1;
 145                        if (!remove_entry_at(pos))
 146                                break;
 147                }
 148        }
 149
 150        if (!ok_to_add)
 151                return -1;
 152
 153        /* Make sure the array is big enough .. */
 154        if (active_nr == active_alloc) {
 155                active_alloc = alloc_nr(active_alloc);
 156                active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 157        }
 158
 159        /* Add it in.. */
 160        active_nr++;
 161        if (active_nr > pos)
 162                memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 163        active_cache[pos] = ce;
 164        return 0;
 165}
 166
 167static int verify_hdr(struct cache_header *hdr, unsigned long size)
 168{
 169        SHA_CTX c;
 170        unsigned char sha1[20];
 171
 172        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 173                return error("bad signature");
 174        if (hdr->hdr_version != htonl(2))
 175                return error("bad index version");
 176        SHA1_Init(&c);
 177        SHA1_Update(&c, hdr, size - 20);
 178        SHA1_Final(sha1, &c);
 179        if (memcmp(sha1, (void *)hdr + size - 20, 20))
 180                return error("bad index file sha1 signature");
 181        return 0;
 182}
 183
 184int read_cache(void)
 185{
 186        int fd, i;
 187        struct stat st;
 188        unsigned long size, offset;
 189        void *map;
 190        struct cache_header *hdr;
 191
 192        errno = EBUSY;
 193        if (active_cache)
 194                return error("more than one cachefile");
 195        errno = ENOENT;
 196        sha1_file_directory = getenv(DB_ENVIRONMENT);
 197        if (!sha1_file_directory)
 198                sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 199        if (access(sha1_file_directory, X_OK) < 0)
 200                return error("no access to SHA1 file directory");
 201        fd = open(get_index_file(), O_RDONLY);
 202        if (fd < 0)
 203                return (errno == ENOENT) ? 0 : error("open failed");
 204
 205        size = 0; // avoid gcc warning
 206        map = (void *)-1;
 207        if (!fstat(fd, &st)) {
 208                size = st.st_size;
 209                errno = EINVAL;
 210                if (size >= sizeof(struct cache_header) + 20)
 211                        map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
 212        }
 213        close(fd);
 214        if (-1 == (int)(long)map)
 215                return error("mmap failed");
 216
 217        hdr = map;
 218        if (verify_hdr(hdr, size) < 0)
 219                goto unmap;
 220
 221        active_nr = ntohl(hdr->hdr_entries);
 222        active_alloc = alloc_nr(active_nr);
 223        active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 224
 225        offset = sizeof(*hdr);
 226        for (i = 0; i < active_nr; i++) {
 227                struct cache_entry *ce = map + offset;
 228                offset = offset + ce_size(ce);
 229                active_cache[i] = ce;
 230        }
 231        return active_nr;
 232
 233unmap:
 234        munmap(map, size);
 235        errno = EINVAL;
 236        return error("verify header failed");
 237}
 238
 239#define WRITE_BUFFER_SIZE 8192
 240static char write_buffer[WRITE_BUFFER_SIZE];
 241static unsigned long write_buffer_len;
 242
 243static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
 244{
 245        while (len) {
 246                unsigned int buffered = write_buffer_len;
 247                unsigned int partial = WRITE_BUFFER_SIZE - buffered;
 248                if (partial > len)
 249                        partial = len;
 250                memcpy(write_buffer + buffered, data, partial);
 251                buffered += partial;
 252                if (buffered == WRITE_BUFFER_SIZE) {
 253                        SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
 254                        if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
 255                                return -1;
 256                        buffered = 0;
 257                }
 258                write_buffer_len = buffered;
 259                len -= partial;
 260                data += partial;
 261        }
 262        return 0;
 263}
 264
 265static int ce_flush(SHA_CTX *context, int fd)
 266{
 267        unsigned int left = write_buffer_len;
 268
 269        if (left) {
 270                write_buffer_len = 0;
 271                SHA1_Update(context, write_buffer, left);
 272        }
 273
 274        /* Append the SHA1 signature at the end */
 275        SHA1_Final(write_buffer + left, context);
 276        left += 20;
 277        if (write(fd, write_buffer, left) != left)
 278                return -1;
 279        return 0;
 280}
 281
 282int write_cache(int newfd, struct cache_entry **cache, int entries)
 283{
 284        SHA_CTX c;
 285        struct cache_header hdr;
 286        int i;
 287
 288        hdr.hdr_signature = htonl(CACHE_SIGNATURE);
 289        hdr.hdr_version = htonl(2);
 290        hdr.hdr_entries = htonl(entries);
 291
 292        SHA1_Init(&c);
 293        if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
 294                return -1;
 295
 296        for (i = 0; i < entries; i++) {
 297                struct cache_entry *ce = cache[i];
 298                if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
 299                        return -1;
 300        }
 301        return ce_flush(&c, newfd);
 302}