pack-mtimes.c

   1 #include "git-compat-util.h"
   2 #include "gettext.h"
   3 #include "pack-mtimes.h"
   4 #include "object-file.h"
   5 #include "object-store.h"
   6 #include "packfile.h"
   7
   8 static char *pack_mtimes_filename(struct packed_git *p)
   9 {
  10         size_t len;
  11         if (!strip_suffix(p->pack_name, ".pack", &len))
  12                 BUG("pack_name does not end in .pack");
  13         return xstrfmt("%.*s.mtimes", (int)len, p->pack_name);
  14 }
  15
  16 #define MTIMES_HEADER_SIZE (12)
  17
  18 struct mtimes_header {
  19         uint32_t signature;
  20         uint32_t version;
  21         uint32_t hash_id;
  22 };
  23
  24 static int load_pack_mtimes_file(char *mtimes_file,
  25                                  uint32_t num_objects,
  26                                  const uint32_t **data_p, size_t *len_p)
  27 {
  28         int fd, ret = 0;
  29         struct stat st;
  30         uint32_t *data = NULL;
  31         size_t mtimes_size, expected_size;
  32         struct mtimes_header header;
  33
  34         fd = git_open(mtimes_file);
  35
  36         if (fd < 0) {
  37                 ret = -1;
  38                 goto cleanup;
  39         }
  40         if (fstat(fd, &st)) {
  41                 ret = error_errno(_("failed to read %s"), mtimes_file);
  42                 goto cleanup;
  43         }
  44
  45         mtimes_size = xsize_t(st.st_size);
  46
  47         if (mtimes_size < MTIMES_HEADER_SIZE) {
  48                 ret = error(_("mtimes file %s is too small"), mtimes_file);
  49                 goto cleanup;
  50         }
  51
  52         data = xmmap(NULL, mtimes_size, PROT_READ, MAP_PRIVATE, fd, 0);
  53
  54         header.signature = ntohl(data[0]);
  55         header.version = ntohl(data[1]);
  56         header.hash_id = ntohl(data[2]);
  57
  58         if (header.signature != MTIMES_SIGNATURE) {
  59                 ret = error(_("mtimes file %s has unknown signature"), mtimes_file);
  60                 goto cleanup;
  61         }
  62
  63         if (header.version != 1) {
  64                 ret = error(_("mtimes file %s has unsupported version %"PRIu32),
  65                             mtimes_file, header.version);
  66                 goto cleanup;
  67         }
  68
  69         if (!(header.hash_id == 1 || header.hash_id == 2)) {
  70                 ret = error(_("mtimes file %s has unsupported hash id %"PRIu32),
  71                             mtimes_file, header.hash_id);
  72                 goto cleanup;
  73         }
  74
  75
  76         expected_size = MTIMES_HEADER_SIZE;
  77         expected_size = st_add(expected_size, st_mult(sizeof(uint32_t), num_objects));
  78         expected_size = st_add(expected_size, 2 * (header.hash_id == 1 ? GIT_SHA1_RAWSZ : GIT_SHA256_RAWSZ));
  79
  80         if (mtimes_size != expected_size) {
  81                 ret = error(_("mtimes file %s is corrupt"), mtimes_file);
  82                 goto cleanup;
  83         }
  84
  85 cleanup:
  86         if (ret) {
  87                 if (data)
  88                         munmap(data, mtimes_size);
  89         } else {
  90                 *len_p = mtimes_size;
  91                 *data_p = data;
  92         }
  93
  94         if (fd >= 0)
  95                 close(fd);
  96         return ret;
  97 }
  98
  99 int load_pack_mtimes(struct packed_git *p)
 100 {
 101         char *mtimes_name = NULL;
 102         int ret = 0;
 103
 104         if (!p->is_cruft)
 105                 return ret; /* not a cruft pack */
 106         if (p->mtimes_map)
 107                 return ret; /* already loaded */
 108
 109         ret = open_pack_index(p);
 110         if (ret < 0)
 111                 goto cleanup;
 112
 113         mtimes_name = pack_mtimes_filename(p);
 114         ret = load_pack_mtimes_file(mtimes_name,
 115                                     p->num_objects,
 116                                     &p->mtimes_map,
 117                                     &p->mtimes_size);
 118 cleanup:
 119         free(mtimes_name);
 120         return ret;
 121 }
 122
 123 uint32_t nth_packed_mtime(struct packed_git *p, uint32_t pos)
 124 {
 125         if (!p->mtimes_map)
 126                 BUG("pack .mtimes file not loaded for %s", p->pack_name);
 127         if (p->num_objects <= pos)
 128                 BUG("pack .mtimes out-of-bounds (%"PRIu32" vs %"PRIu32")",
 129                     pos, p->num_objects);
 130
 131         return get_be32(p->mtimes_map + pos + 3);
 132 }