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        if (ce->ce_mtime.sec != htonl(st->st_mtime))
  17                changed |= MTIME_CHANGED;
  18        if (ce->ce_ctime.sec != htonl(st->st_ctime))
  19                changed |= CTIME_CHANGED;
  20
  21#ifdef NSEC
  22        /*
  23         * nsec seems unreliable - not all filesystems support it, so
  24         * as long as it is in the inode cache you get right nsec
  25         * but after it gets flushed, you get zero nsec.
  26         */
  27        if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
  28                changed |= MTIME_CHANGED;
  29        if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
  30                changed |= CTIME_CHANGED;
  31#endif  
  32
  33        if (ce->ce_uid != htonl(st->st_uid) ||
  34            ce->ce_gid != htonl(st->st_gid))
  35                changed |= OWNER_CHANGED;
  36        /* We consider only the owner x bit to be relevant for "mode changes" */
  37        if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
  38                changed |= MODE_CHANGED;
  39        if (ce->ce_dev != htonl(st->st_dev) ||
  40            ce->ce_ino != htonl(st->st_ino))
  41                changed |= INODE_CHANGED;
  42        if (ce->ce_size != htonl(st->st_size))
  43                changed |= DATA_CHANGED;
  44        return changed;
  45}
  46
  47int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
  48{
  49        int len1 = flags1 & CE_NAMEMASK;
  50        int len2 = flags2 & CE_NAMEMASK;
  51        int len = len1 < len2 ? len1 : len2;
  52        int cmp;
  53
  54        cmp = memcmp(name1, name2, len);
  55        if (cmp)
  56                return cmp;
  57        if (len1 < len2)
  58                return -1;
  59        if (len1 > len2)
  60                return 1;
  61        if (flags1 < flags2)
  62                return -1;
  63        if (flags1 > flags2)
  64                return 1;
  65        return 0;
  66}
  67
  68int cache_name_pos(const char *name, int namelen)
  69{
  70        int first, last;
  71
  72        first = 0;
  73        last = active_nr;
  74        while (last > first) {
  75                int next = (last + first) >> 1;
  76                struct cache_entry *ce = active_cache[next];
  77                int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
  78                if (!cmp)
  79                        return next;
  80                if (cmp < 0) {
  81                        last = next;
  82                        continue;
  83                }
  84                first = next+1;
  85        }
  86        return -first-1;
  87}
  88
  89/* Remove entry, return true if there are more entries to go.. */
  90int remove_entry_at(int pos)
  91{
  92        active_nr--;
  93        if (pos >= active_nr)
  94                return 0;
  95        memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
  96        return 1;
  97}
  98
  99int remove_file_from_cache(char *path)
 100{
 101        int pos = cache_name_pos(path, strlen(path));
 102        if (pos < 0)
 103                pos = -pos-1;
 104        while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
 105                remove_entry_at(pos);
 106        return 0;
 107}
 108
 109int same_name(struct cache_entry *a, struct cache_entry *b)
 110{
 111        int len = ce_namelen(a);
 112        return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
 113}
 114
 115int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 116{
 117        int pos;
 118
 119        pos = cache_name_pos(ce->name, htons(ce->ce_flags));
 120
 121        /* existing match? Just replace it */
 122        if (pos >= 0) {
 123                active_cache[pos] = ce;
 124                return 0;
 125        }
 126        pos = -pos-1;
 127
 128        /*
 129         * Inserting a merged entry ("stage 0") into the index
 130         * will always replace all non-merged entries..
 131         */
 132        if (pos < active_nr && ce_stage(ce) == 0) {
 133                while (same_name(active_cache[pos], ce)) {
 134                        ok_to_add = 1;
 135                        if (!remove_entry_at(pos))
 136                                break;
 137                }
 138        }
 139
 140        if (!ok_to_add)
 141                return -1;
 142
 143        /* Make sure the array is big enough .. */
 144        if (active_nr == active_alloc) {
 145                active_alloc = alloc_nr(active_alloc);
 146                active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 147        }
 148
 149        /* Add it in.. */
 150        active_nr++;
 151        if (active_nr > pos)
 152                memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 153        active_cache[pos] = ce;
 154        return 0;
 155}
 156
 157static int verify_hdr(struct cache_header *hdr, unsigned long size)
 158{
 159        SHA_CTX c;
 160        unsigned char sha1[20];
 161
 162        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 163                return error("bad signature");
 164        if (hdr->hdr_version != htonl(2))
 165                return error("bad index version");
 166        SHA1_Init(&c);
 167        SHA1_Update(&c, hdr, size - 20);
 168        SHA1_Final(sha1, &c);
 169        if (memcmp(sha1, (void *)hdr + size - 20, 20))
 170                return error("bad index file sha1 signature");
 171        return 0;
 172}
 173
 174int read_cache(void)
 175{
 176        int fd, i;
 177        struct stat st;
 178        unsigned long size, offset;
 179        void *map;
 180        struct cache_header *hdr;
 181
 182        errno = EBUSY;
 183        if (active_cache)
 184                return error("more than one cachefile");
 185        errno = ENOENT;
 186        sha1_file_directory = getenv(DB_ENVIRONMENT);
 187        if (!sha1_file_directory)
 188                sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 189        if (access(sha1_file_directory, X_OK) < 0)
 190                return error("no access to SHA1 file directory");
 191        fd = open(get_index_file(), O_RDONLY);
 192        if (fd < 0)
 193                return (errno == ENOENT) ? 0 : error("open failed");
 194
 195        size = 0; // avoid gcc warning
 196        map = (void *)-1;
 197        if (!fstat(fd, &st)) {
 198                size = st.st_size;
 199                errno = EINVAL;
 200                if (size >= sizeof(struct cache_header) + 20)
 201                        map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 202        }
 203        close(fd);
 204        if (-1 == (int)(long)map)
 205                return error("mmap failed");
 206
 207        hdr = map;
 208        if (verify_hdr(hdr, size) < 0)
 209                goto unmap;
 210
 211        active_nr = ntohl(hdr->hdr_entries);
 212        active_alloc = alloc_nr(active_nr);
 213        active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 214
 215        offset = sizeof(*hdr);
 216        for (i = 0; i < active_nr; i++) {
 217                struct cache_entry *ce = map + offset;
 218                offset = offset + ce_size(ce);
 219                active_cache[i] = ce;
 220        }
 221        return active_nr;
 222
 223unmap:
 224        munmap(map, size);
 225        errno = EINVAL;
 226        return error("verify header failed");
 227}
 228
 229#define WRITE_BUFFER_SIZE 8192
 230static char write_buffer[WRITE_BUFFER_SIZE];
 231static unsigned long write_buffer_len;
 232
 233static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
 234{
 235        while (len) {
 236                unsigned int buffered = write_buffer_len;
 237                unsigned int partial = WRITE_BUFFER_SIZE - buffered;
 238                if (partial > len)
 239                        partial = len;
 240                memcpy(write_buffer + buffered, data, partial);
 241                buffered += partial;
 242                if (buffered == WRITE_BUFFER_SIZE) {
 243                        SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
 244                        if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
 245                                return -1;
 246                        buffered = 0;
 247                }
 248                write_buffer_len = buffered;
 249                len -= partial;
 250                data += partial;
 251        }
 252        return 0;
 253}
 254
 255static int ce_flush(SHA_CTX *context, int fd)
 256{
 257        unsigned int left = write_buffer_len;
 258
 259        if (left) {
 260                write_buffer_len = 0;
 261                SHA1_Update(context, write_buffer, left);
 262        }
 263
 264        /* Append the SHA1 signature at the end */
 265        SHA1_Final(write_buffer + left, context);
 266        left += 20;
 267        if (write(fd, write_buffer, left) != left)
 268                return -1;
 269        return 0;
 270}
 271
 272int write_cache(int newfd, struct cache_entry **cache, int entries)
 273{
 274        SHA_CTX c;
 275        struct cache_header hdr;
 276        int i;
 277
 278        hdr.hdr_signature = htonl(CACHE_SIGNATURE);
 279        hdr.hdr_version = htonl(2);
 280        hdr.hdr_entries = htonl(entries);
 281
 282        SHA1_Init(&c);
 283        if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
 284                return -1;
 285
 286        for (i = 0; i < entries; i++) {
 287                struct cache_entry *ce = cache[i];
 288                if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
 289                        return -1;
 290        }
 291        return ce_flush(&c, newfd);
 292}