pack-check.c

   1 #include "cache.h"
   2 #include "pack.h"
   3 #include "pack-revindex.h"
   4 #include "progress.h"
   5
   6 struct idx_entry {
   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, NULL, 0);
  28
  29         do {
  30                 unsigned long 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                            verify_fn fn,
  48                            struct progress *progress, uint32_t base_count)
  49
  50 {
  51         off_t index_size = p->index_size;
  52         const unsigned char *index_base = p->index_data;
  53         git_SHA_CTX ctx;
  54         unsigned char sha1[20], *pack_sig;
  55         off_t offset = 0, pack_sig_ofs = 0;
  56         uint32_t nr_objects, i;
  57         int err = 0;
  58         struct idx_entry *entries;
  59
  60         if (!is_pack_valid(p))
  61                 return error("packfile %s cannot be accessed", p->pack_name);
  62
  63         git_SHA1_Init(&ctx);
  64         do {
  65                 unsigned long 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 index",
  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         ALLOC_ARRAY(entries, nr_objects + 1);
  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, compare_entries);
 100
 101         for (i = 0; i < nr_objects; i++) {
 102                 void *data;
 103                 enum object_type type;
 104                 unsigned long size;
 105                 off_t curpos;
 106                 int data_valid;
 107
 108                 if (p->index_version > 1) {
 109                         off_t offset = entries[i].offset;
 110                         off_t len = entries[i+1].offset - offset;
 111                         unsigned int nr = entries[i].nr;
 112                         if (check_pack_crc(p, w_curs, offset, len, nr))
 113                                 err = error("index CRC mismatch for object %s "
 114                                             "from %s at offset %"PRIuMAX"",
 115                                             sha1_to_hex(entries[i].sha1),
 116                                             p->pack_name, (uintmax_t)offset);
 117                 }
 118
 119                 curpos = entries[i].offset;
 120                 type = unpack_object_header(p, w_curs, &curpos, &size);
 121                 unuse_pack(w_curs);
 122
 123                 if (type == OBJ_BLOB && big_file_threshold <= size) {
 124                         /*
 125                          * Let check_sha1_signature() check it with
 126                          * the streaming interface; no point slurping
 127                          * the data in-core only to discard.
 128                          */
 129                         data = NULL;
 130                         data_valid = 0;
 131                 } else {
 132                         data = unpack_entry(p, entries[i].offset, &type, &size);
 133                         data_valid = 1;
 134                 }
 135
 136                 if (data_valid && !data)
 137                         err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
 138                                     sha1_to_hex(entries[i].sha1), p->pack_name,
 139                                     (uintmax_t)entries[i].offset);
 140                 else if (check_sha1_signature(entries[i].sha1, data, size, typename(type)))
 141                         err = error("packed %s from %s is corrupt",
 142                                     sha1_to_hex(entries[i].sha1), p->pack_name);
 143                 else if (fn) {
 144                         int eaten = 0;
 145                         err |= fn(entries[i].sha1, type, size, data, &eaten);
 146                         if (eaten)
 147                                 data = NULL;
 148                 }
 149                 if (((base_count + i) & 1023) == 0)
 150                         display_progress(progress, base_count + i);
 151                 free(data);
 152
 153         }
 154         display_progress(progress, base_count + i);
 155         free(entries);
 156
 157         return err;
 158 }
 159
 160 int verify_pack_index(struct packed_git *p)
 161 {
 162         off_t index_size;
 163         const unsigned char *index_base;
 164         git_SHA_CTX ctx;
 165         unsigned char sha1[20];
 166         int err = 0;
 167
 168         if (open_pack_index(p))
 169                 return error("packfile %s index not opened", p->pack_name);
 170         index_size = p->index_size;
 171         index_base = p->index_data;
 172
 173         /* Verify SHA1 sum of the index file */
 174         git_SHA1_Init(&ctx);
 175         git_SHA1_Update(&ctx, index_base, (unsigned int)(index_size - 20));
 176         git_SHA1_Final(sha1, &ctx);
 177         if (hashcmp(sha1, index_base + index_size - 20))
 178                 err = error("Packfile index for %s SHA1 mismatch",
 179                             p->pack_name);
 180         return err;
 181 }
 182
 183 int verify_pack(struct packed_git *p, verify_fn fn,
 184                 struct progress *progress, uint32_t base_count)
 185 {
 186         int err = 0;
 187         struct pack_window *w_curs = NULL;
 188
 189         err |= verify_pack_index(p);
 190         if (!p->index_data)
 191                 return -1;
 192
 193         err |= verify_packfile(p, &w_curs, fn, progress, base_count);
 194         unuse_pack(&w_curs);
 195
 196         return err;
 197 }