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![Jeff King](/assets/img/avatar_default.png)
When checking the trailing checksum hash of a .idx file, we pass the
whole buffer (minus the trailing hash) into a single call to
the_hash_algo->update_fn(). But we cast it to an "unsigned int". This
comes from c4001d92be
(Use off_t when we really mean a file offset.,
2007-03-06). That commit started storing the index_size variable as an
off_t, but our mozilla-sha1 implementation from the time was limited to
a smaller size. Presumably the cast was a way of annotating that we
expected .idx files to be small, and so we didn't need to loop (as we do
for arbitrarily-large .pack files). Though as an aside it was still
wrong, because the mozilla function actually took a signed int.
These days our hash-update functions are defined to take a size_t, so we
can pass the whole buffer in directly. The cast is actually causing a
buggy truncation!
While we're here, though, let's drop the confusing off_t variable in the
first place. We're getting the size not from the filesystem anyway, but
from p->index_size, which is a size_t. In fact, we can make the code a
bit more readable by dropping our local variable duplicating
p->index_size, and instead have one that stores the size of the actual
index data, minus the trailing hash.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
203 lines
5.5 KiB
C
203 lines
5.5 KiB
C
#include "cache.h"
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#include "repository.h"
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#include "pack.h"
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#include "pack-revindex.h"
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#include "progress.h"
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#include "packfile.h"
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#include "object-store.h"
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struct idx_entry {
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off_t offset;
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unsigned int nr;
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};
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static int compare_entries(const void *e1, const void *e2)
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{
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const struct idx_entry *entry1 = e1;
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const struct idx_entry *entry2 = e2;
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if (entry1->offset < entry2->offset)
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return -1;
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if (entry1->offset > entry2->offset)
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return 1;
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return 0;
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}
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int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
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off_t offset, off_t len, unsigned int nr)
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{
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const uint32_t *index_crc;
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uint32_t data_crc = crc32(0, NULL, 0);
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do {
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unsigned long avail;
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void *data = use_pack(p, w_curs, offset, &avail);
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if (avail > len)
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avail = len;
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data_crc = crc32(data_crc, data, avail);
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offset += avail;
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len -= avail;
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} while (len);
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index_crc = p->index_data;
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index_crc += 2 + 256 + (size_t)p->num_objects * (the_hash_algo->rawsz/4) + nr;
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return data_crc != ntohl(*index_crc);
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}
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static int verify_packfile(struct repository *r,
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struct packed_git *p,
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struct pack_window **w_curs,
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verify_fn fn,
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struct progress *progress, uint32_t base_count)
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{
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off_t index_size = p->index_size;
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const unsigned char *index_base = p->index_data;
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git_hash_ctx ctx;
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unsigned char hash[GIT_MAX_RAWSZ], *pack_sig;
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off_t offset = 0, pack_sig_ofs = 0;
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uint32_t nr_objects, i;
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int err = 0;
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struct idx_entry *entries;
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if (!is_pack_valid(p))
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return error("packfile %s cannot be accessed", p->pack_name);
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r->hash_algo->init_fn(&ctx);
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do {
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unsigned long remaining;
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unsigned char *in = use_pack(p, w_curs, offset, &remaining);
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offset += remaining;
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if (!pack_sig_ofs)
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pack_sig_ofs = p->pack_size - r->hash_algo->rawsz;
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if (offset > pack_sig_ofs)
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remaining -= (unsigned int)(offset - pack_sig_ofs);
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r->hash_algo->update_fn(&ctx, in, remaining);
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} while (offset < pack_sig_ofs);
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r->hash_algo->final_fn(hash, &ctx);
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pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
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if (!hasheq(hash, pack_sig))
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err = error("%s pack checksum mismatch",
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p->pack_name);
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if (!hasheq(index_base + index_size - r->hash_algo->hexsz, pack_sig))
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err = error("%s pack checksum does not match its index",
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p->pack_name);
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unuse_pack(w_curs);
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/* Make sure everything reachable from idx is valid. Since we
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* have verified that nr_objects matches between idx and pack,
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* we do not do scan-streaming check on the pack file.
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*/
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nr_objects = p->num_objects;
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ALLOC_ARRAY(entries, nr_objects + 1);
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entries[nr_objects].offset = pack_sig_ofs;
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/* first sort entries by pack offset, since unpacking them is more efficient that way */
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for (i = 0; i < nr_objects; i++) {
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entries[i].offset = nth_packed_object_offset(p, i);
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entries[i].nr = i;
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}
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QSORT(entries, nr_objects, compare_entries);
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for (i = 0; i < nr_objects; i++) {
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void *data;
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struct object_id oid;
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enum object_type type;
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unsigned long size;
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off_t curpos;
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int data_valid;
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if (nth_packed_object_id(&oid, p, entries[i].nr) < 0)
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BUG("unable to get oid of object %lu from %s",
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(unsigned long)entries[i].nr, p->pack_name);
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if (p->index_version > 1) {
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off_t offset = entries[i].offset;
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off_t len = entries[i+1].offset - offset;
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unsigned int nr = entries[i].nr;
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if (check_pack_crc(p, w_curs, offset, len, nr))
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err = error("index CRC mismatch for object %s "
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"from %s at offset %"PRIuMAX"",
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oid_to_hex(&oid),
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p->pack_name, (uintmax_t)offset);
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}
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curpos = entries[i].offset;
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type = unpack_object_header(p, w_curs, &curpos, &size);
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unuse_pack(w_curs);
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if (type == OBJ_BLOB && big_file_threshold <= size) {
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/*
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* Let check_object_signature() check it with
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* the streaming interface; no point slurping
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* the data in-core only to discard.
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*/
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data = NULL;
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data_valid = 0;
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} else {
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data = unpack_entry(r, p, entries[i].offset, &type, &size);
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data_valid = 1;
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}
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if (data_valid && !data)
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err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
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oid_to_hex(&oid), p->pack_name,
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(uintmax_t)entries[i].offset);
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else if (check_object_signature(r, &oid, data, size, type_name(type)))
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err = error("packed %s from %s is corrupt",
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oid_to_hex(&oid), p->pack_name);
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else if (fn) {
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int eaten = 0;
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err |= fn(&oid, type, size, data, &eaten);
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if (eaten)
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data = NULL;
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}
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if (((base_count + i) & 1023) == 0)
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display_progress(progress, base_count + i);
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free(data);
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}
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display_progress(progress, base_count + i);
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free(entries);
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return err;
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}
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int verify_pack_index(struct packed_git *p)
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{
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size_t len;
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const unsigned char *index_base;
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git_hash_ctx ctx;
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unsigned char hash[GIT_MAX_RAWSZ];
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int err = 0;
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if (open_pack_index(p))
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return error("packfile %s index not opened", p->pack_name);
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index_base = p->index_data;
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len = p->index_size - the_hash_algo->rawsz;
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/* Verify SHA1 sum of the index file */
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the_hash_algo->init_fn(&ctx);
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the_hash_algo->update_fn(&ctx, index_base, len);
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the_hash_algo->final_fn(hash, &ctx);
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if (!hasheq(hash, index_base + len))
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err = error("Packfile index for %s hash mismatch",
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p->pack_name);
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return err;
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}
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int verify_pack(struct repository *r, struct packed_git *p, verify_fn fn,
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struct progress *progress, uint32_t base_count)
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{
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int err = 0;
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struct pack_window *w_curs = NULL;
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err |= verify_pack_index(p);
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if (!p->index_data)
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return -1;
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err |= verify_packfile(r, p, &w_curs, fn, progress, base_count);
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unuse_pack(&w_curs);
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return err;
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}
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