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 = p->pack_size - 20;
  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         while (offset < pack_sig_ofs) {
  65                 unsigned int remaining;
  66                 unsigned char *in = use_pack(p, w_curs, offset, &remaining);
  67                 offset += remaining;
  68                 if (offset > pack_sig_ofs)
  69                         remaining -= (unsigned int)(offset - pack_sig_ofs);
  70                 git_SHA1_Update(&ctx, in, remaining);
  71         }
  72         git_SHA1_Final(sha1, &ctx);
  73         pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
  74         if (hashcmp(sha1, pack_sig))
  75                 err = error("%s SHA1 checksum mismatch",
  76                             p->pack_name);
  77         if (hashcmp(index_base + index_size - 40, pack_sig))
  78                 err = error("%s SHA1 does not match its inddex",
  79                             p->pack_name);
  80         unuse_pack(w_curs);
  81
  82         /* Make sure everything reachable from idx is valid.  Since we
  83          * have verified that nr_objects matches between idx and pack,
  84          * we do not do scan-streaming check on the pack file.
  85          */
  86         nr_objects = p->num_objects;
  87         entries = xmalloc((nr_objects + 1) * sizeof(*entries));
  88         entries[nr_objects].offset = pack_sig_ofs;
  89         /* first sort entries by pack offset, since unpacking them is more efficient that way */
  90         for (i = 0; i < nr_objects; i++) {
  91                 entries[i].sha1 = nth_packed_object_sha1(p, i);
  92                 if (!entries[i].sha1)
  93                         die("internal error pack-check nth-packed-object");
  94                 entries[i].offset = nth_packed_object_offset(p, i);
  95                 entries[i].nr = i;
  96         }
  97         qsort(entries, nr_objects, sizeof(*entries), compare_entries);
  98
  99         for (i = 0; i < nr_objects; i++) {
 100                 void *data;
 101                 enum object_type type;
 102                 unsigned long size;
 103
 104                 if (p->index_version > 1) {
 105                         off_t offset = entries[i].offset;
 106                         off_t len = entries[i+1].offset - offset;
 107                         unsigned int nr = entries[i].nr;
 108                         if (check_pack_crc(p, w_curs, offset, len, nr))
 109                                 err = error("index CRC mismatch for object %s "
 110                                             "from %s at offset %"PRIuMAX"",
 111                                             sha1_to_hex(entries[i].sha1),
 112                                             p->pack_name, (uintmax_t)offset);
 113                 }
 114                 data = unpack_entry(p, entries[i].offset, &type, &size);
 115                 if (!data) {
 116                         err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
 117                                     sha1_to_hex(entries[i].sha1), p->pack_name,
 118                                     (uintmax_t)entries[i].offset);
 119                         break;
 120                 }
 121                 if (check_sha1_signature(entries[i].sha1, data, size, typename(type))) {
 122                         err = error("packed %s from %s is corrupt",
 123                                     sha1_to_hex(entries[i].sha1), p->pack_name);
 124                         free(data);
 125                         break;
 126                 }
 127                 free(data);
 128         }
 129         free(entries);
 130
 131         return err;
 132 }
 133
 134 int verify_pack(struct packed_git *p)
 135 {
 136         off_t index_size;
 137         const unsigned char *index_base;
 138         git_SHA_CTX ctx;
 139         unsigned char sha1[20];
 140         int err = 0;
 141         struct pack_window *w_curs = NULL;
 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
 156         /* Verify pack file */
 157         err |= verify_packfile(p, &w_curs);
 158         unuse_pack(&w_curs);
 159
 160         return err;
 161 }