pack-mtimes.c

   1 #include "cache.h"
   2 #include "gettext.h"
   3 #include "pack-mtimes.h"
   4 #include "object-store.h"
   5 #include "packfile.h"
   6
   7 static char *pack_mtimes_filename(struct packed_git *p)
   8 {
   9         size_t len;
  10         if (!strip_suffix(p->pack_name, ".pack", &len))
  11                 BUG("pack_name does not end in .pack");
  12         return xstrfmt("%.*s.mtimes", (int)len, p->pack_name);
  13 }
  14
  15 #define MTIMES_HEADER_SIZE (12)
  16
  17 struct mtimes_header {
  18         uint32_t signature;
  19         uint32_t version;
  20         uint32_t hash_id;
  21 };
  22
  23 static int load_pack_mtimes_file(char *mtimes_file,
  24                                  uint32_t num_objects,
  25                                  const uint32_t **data_p, size_t *len_p)
  26 {
  27         int fd, ret = 0;
  28         struct stat st;
  29         uint32_t *data = NULL;
  30         size_t mtimes_size, expected_size;
  31         struct mtimes_header header;
  32
  33         fd = git_open(mtimes_file);
  34
  35         if (fd < 0) {
  36                 ret = -1;
  37                 goto cleanup;
  38         }
  39         if (fstat(fd, &st)) {
  40                 ret = error_errno(_("failed to read %s"), mtimes_file);
  41                 goto cleanup;
  42         }
  43
  44         mtimes_size = xsize_t(st.st_size);
  45
  46         if (mtimes_size < MTIMES_HEADER_SIZE) {
  47                 ret = error(_("mtimes file %s is too small"), mtimes_file);
  48                 goto cleanup;
  49         }
  50
  51         data = xmmap(NULL, mtimes_size, PROT_READ, MAP_PRIVATE, fd, 0);
  52
  53         header.signature = ntohl(data[0]);
  54         header.version = ntohl(data[1]);
  55         header.hash_id = ntohl(data[2]);
  56
  57         if (header.signature != MTIMES_SIGNATURE) {
  58                 ret = error(_("mtimes file %s has unknown signature"), mtimes_file);
  59                 goto cleanup;
  60         }
  61
  62         if (header.version != 1) {
  63                 ret = error(_("mtimes file %s has unsupported version %"PRIu32),
  64                             mtimes_file, header.version);
  65                 goto cleanup;
  66         }
  67
  68         if (!(header.hash_id == 1 || header.hash_id == 2)) {
  69                 ret = error(_("mtimes file %s has unsupported hash id %"PRIu32),
  70                             mtimes_file, header.hash_id);
  71                 goto cleanup;
  72         }
  73
  74
  75         expected_size = MTIMES_HEADER_SIZE;
  76         expected_size = st_add(expected_size, st_mult(sizeof(uint32_t), num_objects));
  77         expected_size = st_add(expected_size, 2 * (header.hash_id == 1 ? GIT_SHA1_RAWSZ : GIT_SHA256_RAWSZ));
  78
  79         if (mtimes_size != expected_size) {
  80                 ret = error(_("mtimes file %s is corrupt"), mtimes_file);
  81                 goto cleanup;
  82         }
  83
  84 cleanup:
  85         if (ret) {
  86                 if (data)
  87                         munmap(data, mtimes_size);
  88         } else {
  89                 *len_p = mtimes_size;
  90                 *data_p = data;
  91         }
  92
  93         if (fd >= 0)
  94                 close(fd);
  95         return ret;
  96 }
  97
  98 int load_pack_mtimes(struct packed_git *p)
  99 {
 100         char *mtimes_name = NULL;
 101         int ret = 0;
 102
 103         if (!p->is_cruft)
 104                 return ret; /* not a cruft pack */
 105         if (p->mtimes_map)
 106                 return ret; /* already loaded */
 107
 108         ret = open_pack_index(p);
 109         if (ret < 0)
 110                 goto cleanup;
 111
 112         mtimes_name = pack_mtimes_filename(p);
 113         ret = load_pack_mtimes_file(mtimes_name,
 114                                     p->num_objects,
 115                                     &p->mtimes_map,
 116                                     &p->mtimes_size);
 117 cleanup:
 118         free(mtimes_name);
 119         return ret;
 120 }
 121
 122 uint32_t nth_packed_mtime(struct packed_git *p, uint32_t pos)
 123 {
 124         if (!p->mtimes_map)
 125                 BUG("pack .mtimes file not loaded for %s", p->pack_name);
 126         if (p->num_objects <= pos)
 127                 BUG("pack .mtimes out-of-bounds (%"PRIu32" vs %"PRIu32")",
 128                     pos, p->num_objects);
 129
 130         return get_be32(p->mtimes_map + pos + 3);
 131 }