pack-check.c

   1 #include "cache.h"
   2 #include "pack.h"
   3 #include "pack-revindex.h"
   4
   5 struct idx_entry
   6 {
   7         const unsigned char *sha1;
   8         off_t                offset;
   9 };
  10
  11 static int compare_entries(const void *e1, const void *e2)
  12 {
  13         const struct idx_entry *entry1 = e1;
  14         const struct idx_entry *entry2 = e2;
  15         if (entry1->offset < entry2->offset)
  16                 return -1;
  17         if (entry1->offset > entry2->offset)
  18                 return 1;
  19         return 0;
  20 }
  21
  22 static int verify_packfile(struct packed_git *p,
  23                 struct pack_window **w_curs)
  24 {
  25         off_t index_size = p->index_size;
  26         const unsigned char *index_base = p->index_data;
  27         SHA_CTX ctx;
  28         unsigned char sha1[20], *pack_sig;
  29         off_t offset = 0, pack_sig_ofs = p->pack_size - 20;
  30         uint32_t nr_objects, i;
  31         int err = 0;
  32         struct idx_entry *entries;
  33
  34         /* Note that the pack header checks are actually performed by
  35          * use_pack when it first opens the pack file.  If anything
  36          * goes wrong during those checks then the call will die out
  37          * immediately.
  38          */
  39
  40         SHA1_Init(&ctx);
  41         while (offset < pack_sig_ofs) {
  42                 unsigned int remaining;
  43                 unsigned char *in = use_pack(p, w_curs, offset, &remaining);
  44                 offset += remaining;
  45                 if (offset > pack_sig_ofs)
  46                         remaining -= (unsigned int)(offset - pack_sig_ofs);
  47                 SHA1_Update(&ctx, in, remaining);
  48         }
  49         SHA1_Final(sha1, &ctx);
  50         pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
  51         if (hashcmp(sha1, pack_sig))
  52                 err = error("%s SHA1 checksum mismatch",
  53                             p->pack_name);
  54         if (hashcmp(index_base + index_size - 40, pack_sig))
  55                 err = error("%s SHA1 does not match its inddex",
  56                             p->pack_name);
  57         unuse_pack(w_curs);
  58
  59         /* Make sure everything reachable from idx is valid.  Since we
  60          * have verified that nr_objects matches between idx and pack,
  61          * we do not do scan-streaming check on the pack file.
  62          */
  63         nr_objects = p->num_objects;
  64         entries = xmalloc(nr_objects * sizeof(*entries));
  65         /* first sort entries by pack offset, since unpacking them is more efficient that way */
  66         for (i = 0; i < nr_objects; i++) {
  67                 entries[i].sha1 = nth_packed_object_sha1(p, i);
  68                 if (!entries[i].sha1)
  69                         die("internal error pack-check nth-packed-object");
  70                 entries[i].offset = nth_packed_object_offset(p, i);
  71         }
  72         qsort(entries, nr_objects, sizeof(*entries), compare_entries);
  73
  74         for (i = 0; i < nr_objects; i++) {
  75                 void *data;
  76                 enum object_type type;
  77                 unsigned long size;
  78
  79                 data = unpack_entry(p, entries[i].offset, &type, &size);
  80                 if (!data) {
  81                         err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
  82                                     sha1_to_hex(entries[i].sha1), p->pack_name,
  83                                     (uintmax_t)entries[i].offset);
  84                         break;
  85                 }
  86                 if (check_sha1_signature(entries[i].sha1, data, size, typename(type))) {
  87                         err = error("packed %s from %s is corrupt",
  88                                     sha1_to_hex(entries[i].sha1), p->pack_name);
  89                         free(data);
  90                         break;
  91                 }
  92                 free(data);
  93         }
  94         free(entries);
  95
  96         return err;
  97 }
  98
  99 int verify_pack(struct packed_git *p)
 100 {
 101         off_t index_size;
 102         const unsigned char *index_base;
 103         SHA_CTX ctx;
 104         unsigned char sha1[20];
 105         int err = 0;
 106         struct pack_window *w_curs = NULL;
 107
 108         if (open_pack_index(p))
 109                 return error("packfile %s index not opened", p->pack_name);
 110         index_size = p->index_size;
 111         index_base = p->index_data;
 112
 113         /* Verify SHA1 sum of the index file */
 114         SHA1_Init(&ctx);
 115         SHA1_Update(&ctx, index_base, (unsigned int)(index_size - 20));
 116         SHA1_Final(sha1, &ctx);
 117         if (hashcmp(sha1, index_base + index_size - 20))
 118                 err = error("Packfile index for %s SHA1 mismatch",
 119                             p->pack_name);
 120
 121         /* Verify pack file */
 122         err |= verify_packfile(p, &w_curs);
 123         unuse_pack(&w_curs);
 124
 125         return err;
 126 }