pack-check.c

   1 #include "cache.h"
   2 #include "pack.h"
   3 #include "pack-revindex.h"
   4
   5 struct idx_entry {
   6         off_t                offset;
   7         const unsigned char *sha1;
   8         unsigned int nr;
   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 int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
  23                    off_t offset, off_t len, unsigned int nr)
  24 {
  25         const uint32_t *index_crc;
  26         uint32_t data_crc = crc32(0, NULL, 0);
  27
  28         do {
  29                 unsigned int avail;
  30                 void *data = use_pack(p, w_curs, offset, &avail);
  31                 if (avail > len)
  32                         avail = len;
  33                 data_crc = crc32(data_crc, data, avail);
  34                 offset += avail;
  35                 len -= avail;
  36         } while (len);
  37
  38         index_crc = p->index_data;
  39         index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
  40
  41         return data_crc != ntohl(*index_crc);
  42 }
  43
  44 static int verify_packfile(struct packed_git *p,
  45                 struct pack_window **w_curs)
  46 {
  47         off_t index_size = p->index_size;
  48         const unsigned char *index_base = p->index_data;
  49         git_SHA_CTX ctx;
  50         unsigned char sha1[20], *pack_sig;
  51         off_t offset = 0, pack_sig_ofs = 0;
  52         uint32_t nr_objects, i;
  53         int err = 0;
  54         struct idx_entry *entries;
  55
  56         /* Note that the pack header checks are actually performed by
  57          * use_pack when it first opens the pack file.  If anything
  58          * goes wrong during those checks then the call will die out
  59          * immediately.
  60          */
  61
  62         git_SHA1_Init(&ctx);
  63         do {
  64                 unsigned int remaining;
  65                 unsigned char *in = use_pack(p, w_curs, offset, &remaining);
  66                 offset += remaining;
  67                 if (!pack_sig_ofs)
  68                         pack_sig_ofs = p->pack_size - 20;
  69                 if (offset > pack_sig_ofs)
  70                         remaining -= (unsigned int)(offset - pack_sig_ofs);
  71                 git_SHA1_Update(&ctx, in, remaining);
  72         } while (offset < pack_sig_ofs);
  73         git_SHA1_Final(sha1, &ctx);
  74         pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
  75         if (hashcmp(sha1, pack_sig))
  76                 err = error("%s SHA1 checksum mismatch",
  77                             p->pack_name);
  78         if (hashcmp(index_base + index_size - 40, pack_sig))
  79                 err = error("%s SHA1 does not match its index",
  80                             p->pack_name);
  81         unuse_pack(w_curs);
  82
  83         /* Make sure everything reachable from idx is valid.  Since we
  84          * have verified that nr_objects matches between idx and pack,
  85          * we do not do scan-streaming check on the pack file.
  86          */
  87         nr_objects = p->num_objects;
  88         entries = xmalloc((nr_objects + 1) * sizeof(*entries));
  89         entries[nr_objects].offset = pack_sig_ofs;
  90         /* first sort entries by pack offset, since unpacking them is more efficient that way */
  91         for (i = 0; i < nr_objects; i++) {
  92                 entries[i].sha1 = nth_packed_object_sha1(p, i);
  93                 if (!entries[i].sha1)
  94                         die("internal error pack-check nth-packed-object");
  95                 entries[i].offset = nth_packed_object_offset(p, i);
  96                 entries[i].nr = i;
  97         }
  98         qsort(entries, nr_objects, sizeof(*entries), compare_entries);
  99
 100         for (i = 0; i < nr_objects; i++) {
 101                 void *data;
 102                 enum object_type type;
 103                 unsigned long size;
 104
 105                 if (p->index_version > 1) {
 106                         off_t offset = entries[i].offset;
 107                         off_t len = entries[i+1].offset - offset;
 108                         unsigned int nr = entries[i].nr;
 109                         if (check_pack_crc(p, w_curs, offset, len, nr))
 110                                 err = error("index CRC mismatch for object %s "
 111                                             "from %s at offset %"PRIuMAX"",
 112                                             sha1_to_hex(entries[i].sha1),
 113                                             p->pack_name, (uintmax_t)offset);
 114                 }
 115                 data = unpack_entry(p, entries[i].offset, &type, &size);
 116                 if (!data) {
 117                         err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
 118                                     sha1_to_hex(entries[i].sha1), p->pack_name,
 119                                     (uintmax_t)entries[i].offset);
 120                         break;
 121                 }
 122                 if (check_sha1_signature(entries[i].sha1, data, size, typename(type))) {
 123                         err = error("packed %s from %s is corrupt",
 124                                     sha1_to_hex(entries[i].sha1), p->pack_name);
 125                         free(data);
 126                         break;
 127                 }
 128                 free(data);
 129         }
 130         free(entries);
 131
 132         return err;
 133 }
 134
 135 int verify_pack_index(struct packed_git *p)
 136 {
 137         off_t index_size;
 138         const unsigned char *index_base;
 139         git_SHA_CTX ctx;
 140         unsigned char sha1[20];
 141         int err = 0;
 142
 143         if (open_pack_index(p))
 144                 return error("packfile %s index not opened", p->pack_name);
 145         index_size = p->index_size;
 146         index_base = p->index_data;
 147
 148         /* Verify SHA1 sum of the index file */
 149         git_SHA1_Init(&ctx);
 150         git_SHA1_Update(&ctx, index_base, (unsigned int)(index_size - 20));
 151         git_SHA1_Final(sha1, &ctx);
 152         if (hashcmp(sha1, index_base + index_size - 20))
 153                 err = error("Packfile index for %s SHA1 mismatch",
 154                             p->pack_name);
 155         return err;
 156 }
 157
 158 int verify_pack(struct packed_git *p)
 159 {
 160         int err = 0;
 161         struct pack_window *w_curs = NULL;
 162
 163         err |= verify_pack_index(p);
 164         if (!p->index_data)
 165                 return -1;
 166
 167         err |= verify_packfile(p, &w_curs);
 168         unuse_pack(&w_curs);
 169
 170         return err;
 171 }