pack-check.c

   1 #include "cache.h"
   2 #include "pack.h"
   3 #include "pack-revindex.h"
   4
   5 struct idx_entry
   6 {
   7         off_t                offset;
   8         const unsigned char *sha1;
   9         unsigned int nr;
  10 };
  11
  12 static int compare_entries(const void *e1, const void *e2)
  13 {
  14         const struct idx_entry *entry1 = e1;
  15         const struct idx_entry *entry2 = e2;
  16         if (entry1->offset < entry2->offset)
  17                 return -1;
  18         if (entry1->offset > entry2->offset)
  19                 return 1;
  20         return 0;
  21 }
  22
  23 int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
  24                    off_t offset, off_t len, unsigned int nr)
  25 {
  26         const uint32_t *index_crc;
  27         uint32_t data_crc = crc32(0, Z_NULL, 0);
  28
  29         do {
  30                 unsigned int avail;
  31                 void *data = use_pack(p, w_curs, offset, &avail);
  32                 if (avail > len)
  33                         avail = len;
  34                 data_crc = crc32(data_crc, data, avail);
  35                 offset += avail;
  36                 len -= avail;
  37         } while (len);
  38
  39         index_crc = p->index_data;
  40         index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
  41
  42         return data_crc != ntohl(*index_crc);
  43 }
  44
  45 static int verify_packfile(struct packed_git *p,
  46                 struct pack_window **w_curs)
  47 {
  48         off_t index_size = p->index_size;
  49         const unsigned char *index_base = p->index_data;
  50         git_SHA_CTX ctx;
  51         unsigned char sha1[20], *pack_sig;
  52         off_t offset = 0, pack_sig_ofs = 0;
  53         uint32_t nr_objects, i;
  54         int err = 0;
  55         struct idx_entry *entries;
  56
  57         /* Note that the pack header checks are actually performed by
  58          * use_pack when it first opens the pack file.  If anything
  59          * goes wrong during those checks then the call will die out
  60          * immediately.
  61          */
  62
  63         git_SHA1_Init(&ctx);
  64         do {
  65                 unsigned int remaining;
  66                 unsigned char *in = use_pack(p, w_curs, offset, &remaining);
  67                 offset += remaining;
  68                 if (!pack_sig_ofs)
  69                         pack_sig_ofs = p->pack_size - 20;
  70                 if (offset > pack_sig_ofs)
  71                         remaining -= (unsigned int)(offset - pack_sig_ofs);
  72                 git_SHA1_Update(&ctx, in, remaining);
  73         } while (offset < pack_sig_ofs);
  74         git_SHA1_Final(sha1, &ctx);
  75         pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
  76         if (hashcmp(sha1, pack_sig))
  77                 err = error("%s SHA1 checksum mismatch",
  78                             p->pack_name);
  79         if (hashcmp(index_base + index_size - 40, pack_sig))
  80                 err = error("%s SHA1 does not match its inddex",
  81                             p->pack_name);
  82         unuse_pack(w_curs);
  83
  84         /* Make sure everything reachable from idx is valid.  Since we
  85          * have verified that nr_objects matches between idx and pack,
  86          * we do not do scan-streaming check on the pack file.
  87          */
  88         nr_objects = p->num_objects;
  89         entries = xmalloc((nr_objects + 1) * sizeof(*entries));
  90         entries[nr_objects].offset = pack_sig_ofs;
  91         /* first sort entries by pack offset, since unpacking them is more efficient that way */
  92         for (i = 0; i < nr_objects; i++) {
  93                 entries[i].sha1 = nth_packed_object_sha1(p, i);
  94                 if (!entries[i].sha1)
  95                         die("internal error pack-check nth-packed-object");
  96                 entries[i].offset = nth_packed_object_offset(p, i);
  97                 entries[i].nr = i;
  98         }
  99         qsort(entries, nr_objects, sizeof(*entries), compare_entries);
 100
 101         for (i = 0; i < nr_objects; i++) {
 102                 void *data;
 103                 enum object_type type;
 104                 unsigned long size;
 105
 106                 if (p->index_version > 1) {
 107                         off_t offset = entries[i].offset;
 108                         off_t len = entries[i+1].offset - offset;
 109                         unsigned int nr = entries[i].nr;
 110                         if (check_pack_crc(p, w_curs, offset, len, nr))
 111                                 err = error("index CRC mismatch for object %s "
 112                                             "from %s at offset %"PRIuMAX"",
 113                                             sha1_to_hex(entries[i].sha1),
 114                                             p->pack_name, (uintmax_t)offset);
 115                 }
 116                 data = unpack_entry(p, entries[i].offset, &type, &size);
 117                 if (!data) {
 118                         err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
 119                                     sha1_to_hex(entries[i].sha1), p->pack_name,
 120                                     (uintmax_t)entries[i].offset);
 121                         break;
 122                 }
 123                 if (check_sha1_signature(entries[i].sha1, data, size, typename(type))) {
 124                         err = error("packed %s from %s is corrupt",
 125                                     sha1_to_hex(entries[i].sha1), p->pack_name);
 126                         free(data);
 127                         break;
 128                 }
 129                 free(data);
 130         }
 131         free(entries);
 132
 133         return err;
 134 }
 135
 136 int verify_pack(struct packed_git *p)
 137 {
 138         off_t index_size;
 139         const unsigned char *index_base;
 140         git_SHA_CTX ctx;
 141         unsigned char sha1[20];
 142         int err = 0;
 143         struct pack_window *w_curs = NULL;
 144
 145         if (open_pack_index(p))
 146                 return error("packfile %s index not opened", p->pack_name);
 147         index_size = p->index_size;
 148         index_base = p->index_data;
 149
 150         /* Verify SHA1 sum of the index file */
 151         git_SHA1_Init(&ctx);
 152         git_SHA1_Update(&ctx, index_base, (unsigned int)(index_size - 20));
 153         git_SHA1_Final(sha1, &ctx);
 154         if (hashcmp(sha1, index_base + index_size - 20))
 155                 err = error("Packfile index for %s SHA1 mismatch",
 156                             p->pack_name);
 157
 158         /* Verify pack file */
 159         err |= verify_packfile(p, &w_curs);
 160         unuse_pack(&w_curs);
 161
 162         return err;
 163 }