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, 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
 126int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 127{
 128        int pos;
 129
 130        pos = cache_name_pos(ce->name, htons(ce->ce_flags));
 131
 132        /* existing match? Just replace it */
 133        if (pos >= 0) {
 134                active_cache_changed = 1;
 135                active_cache[pos] = ce;
 136                return 0;
 137        }
 138        pos = -pos-1;
 139
 140        /*
 141         * Inserting a merged entry ("stage 0") into the index
 142         * will always replace all non-merged entries..
 143         */
 144        if (pos < active_nr && ce_stage(ce) == 0) {
 145                while (same_name(active_cache[pos], ce)) {
 146                        ok_to_add = 1;
 147                        if (!remove_entry_at(pos))
 148                                break;
 149                }
 150        }
 151
 152        if (!ok_to_add)
 153                return -1;
 154
 155        /* Make sure the array is big enough .. */
 156        if (active_nr == active_alloc) {
 157                active_alloc = alloc_nr(active_alloc);
 158                active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 159        }
 160
 161        /* Add it in.. */
 162        active_nr++;
 163        if (active_nr > pos)
 164                memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 165        active_cache[pos] = ce;
 166        active_cache_changed = 1;
 167        return 0;
 168}
 169
 170static int verify_hdr(struct cache_header *hdr, unsigned long size)
 171{
 172        SHA_CTX c;
 173        unsigned char sha1[20];
 174
 175        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 176                return error("bad signature");
 177        if (hdr->hdr_version != htonl(2))
 178                return error("bad index version");
 179        SHA1_Init(&c);
 180        SHA1_Update(&c, hdr, size - 20);
 181        SHA1_Final(sha1, &c);
 182        if (memcmp(sha1, (void *)hdr + size - 20, 20))
 183                return error("bad index file sha1 signature");
 184        return 0;
 185}
 186
 187int read_cache(void)
 188{
 189        int fd, i;
 190        struct stat st;
 191        unsigned long size, offset;
 192        void *map;
 193        struct cache_header *hdr;
 194
 195        errno = EBUSY;
 196        if (active_cache)
 197                return error("more than one cachefile");
 198        errno = ENOENT;
 199        fd = open(get_index_file(), O_RDONLY);
 200        if (fd < 0)
 201                return (errno == ENOENT) ? 0 : error("open failed");
 202
 203        size = 0; // avoid gcc warning
 204        map = (void *)-1;
 205        if (!fstat(fd, &st)) {
 206                size = st.st_size;
 207                errno = EINVAL;
 208                if (size >= sizeof(struct cache_header) + 20)
 209                        map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
 210        }
 211        close(fd);
 212        if (-1 == (int)(long)map)
 213                return error("mmap failed");
 214
 215        hdr = map;
 216        if (verify_hdr(hdr, size) < 0)
 217                goto unmap;
 218
 219        active_nr = ntohl(hdr->hdr_entries);
 220        active_alloc = alloc_nr(active_nr);
 221        active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 222
 223        offset = sizeof(*hdr);
 224        for (i = 0; i < active_nr; i++) {
 225                struct cache_entry *ce = map + offset;
 226                offset = offset + ce_size(ce);
 227                active_cache[i] = ce;
 228        }
 229        return active_nr;
 230
 231unmap:
 232        munmap(map, size);
 233        errno = EINVAL;
 234        return error("verify header failed");
 235}
 236
 237#define WRITE_BUFFER_SIZE 8192
 238static char write_buffer[WRITE_BUFFER_SIZE];
 239static unsigned long write_buffer_len;
 240
 241static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
 242{
 243        while (len) {
 244                unsigned int buffered = write_buffer_len;
 245                unsigned int partial = WRITE_BUFFER_SIZE - buffered;
 246                if (partial > len)
 247                        partial = len;
 248                memcpy(write_buffer + buffered, data, partial);
 249                buffered += partial;
 250                if (buffered == WRITE_BUFFER_SIZE) {
 251                        SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
 252                        if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
 253                                return -1;
 254                        buffered = 0;
 255                }
 256                write_buffer_len = buffered;
 257                len -= partial;
 258                data += partial;
 259        }
 260        return 0;
 261}
 262
 263static int ce_flush(SHA_CTX *context, int fd)
 264{
 265        unsigned int left = write_buffer_len;
 266
 267        if (left) {
 268                write_buffer_len = 0;
 269                SHA1_Update(context, write_buffer, left);
 270        }
 271
 272        /* Append the SHA1 signature at the end */
 273        SHA1_Final(write_buffer + left, context);
 274        left += 20;
 275        if (write(fd, write_buffer, left) != left)
 276                return -1;
 277        return 0;
 278}
 279
 280int write_cache(int newfd, struct cache_entry **cache, int entries)
 281{
 282        SHA_CTX c;
 283        struct cache_header hdr;
 284        int i;
 285
 286        hdr.hdr_signature = htonl(CACHE_SIGNATURE);
 287        hdr.hdr_version = htonl(2);
 288        hdr.hdr_entries = htonl(entries);
 289
 290        SHA1_Init(&c);
 291        if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
 292                return -1;
 293
 294        for (i = 0; i < entries; i++) {
 295                struct cache_entry *ce = cache[i];
 296                if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
 297                        return -1;
 298        }
 299        return ce_flush(&c, newfd);
 300}