зеркало из https://github.com/microsoft/git.git
packfile: abstract away hash constant values
There are several instances of the constant 20 and 20-based values in the packfile code. Abstract away dependence on SHA-1 by using the values from the_hash_algo instead. Use unsigned values for temporary constants to provide the compiler with more information about what kinds of values it should expect. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
brian m. carlson
Junio C Hamano
Родитель
544443cb3c
Коммит
37fec86a83
66
packfile.c
66
packfile.c
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@ -84,6 +84,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
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uint32_t version, nr, i, *index;
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int fd = git_open(path);
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struct stat st;
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const unsigned int hashsz = the_hash_algo->rawsz;
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if (fd < 0)
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return -1;
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@ -92,7 +93,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
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return -1;
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}
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idx_size = xsize_t(st.st_size);
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if (idx_size < 4 * 256 + 20 + 20) {
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if (idx_size < 4 * 256 + hashsz + hashsz) {
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close(fd);
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return error("index file %s is too small", path);
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}
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@ -129,11 +130,11 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
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/*
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* Total size:
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* - 256 index entries 4 bytes each
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* - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
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* - 20-byte SHA1 of the packfile
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* - 20-byte SHA1 file checksum
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* - 24-byte entries * nr (object ID + 4-byte offset)
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* - hash of the packfile
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* - file checksum
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*/
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if (idx_size != 4*256 + nr * 24 + 20 + 20) {
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if (idx_size != 4*256 + nr * (hashsz + 4) + hashsz + hashsz) {
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munmap(idx_map, idx_size);
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return error("wrong index v1 file size in %s", path);
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}
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@ -142,16 +143,16 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
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* Minimum size:
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* - 8 bytes of header
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* - 256 index entries 4 bytes each
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* - 20-byte sha1 entry * nr
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* - object ID entry * nr
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* - 4-byte crc entry * nr
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* - 4-byte offset entry * nr
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* - 20-byte SHA1 of the packfile
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* - 20-byte SHA1 file checksum
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* - hash of the packfile
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* - file checksum
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* And after the 4-byte offset table might be a
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* variable sized table containing 8-byte entries
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* for offsets larger than 2^31.
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*/
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unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
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unsigned long min_size = 8 + 4*256 + nr*(hashsz + 4 + 4) + hashsz + hashsz;
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unsigned long max_size = min_size;
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if (nr)
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max_size += (nr - 1)*8;
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@ -444,10 +445,11 @@ static int open_packed_git_1(struct packed_git *p)
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{
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struct stat st;
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struct pack_header hdr;
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unsigned char sha1[20];
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unsigned char *idx_sha1;
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unsigned char hash[GIT_MAX_RAWSZ];
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unsigned char *idx_hash;
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long fd_flag;
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ssize_t read_result;
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const unsigned hashsz = the_hash_algo->rawsz;
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if (!p->index_data && open_pack_index(p))
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return error("packfile %s index unavailable", p->pack_name);
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@ -507,15 +509,15 @@ static int open_packed_git_1(struct packed_git *p)
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" while index indicates %"PRIu32" objects",
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p->pack_name, ntohl(hdr.hdr_entries),
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p->num_objects);
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if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
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if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)
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return error("end of packfile %s is unavailable", p->pack_name);
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read_result = read_in_full(p->pack_fd, sha1, sizeof(sha1));
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read_result = read_in_full(p->pack_fd, hash, hashsz);
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if (read_result < 0)
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return error_errno("error reading from %s", p->pack_name);
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if (read_result != sizeof(sha1))
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if (read_result != hashsz)
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return error("packfile %s signature is unavailable", p->pack_name);
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idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
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if (hashcmp(sha1, idx_sha1))
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idx_hash = ((unsigned char *)p->index_data) + p->index_size - hashsz * 2;
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if (hashcmp(hash, idx_hash))
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return error("packfile %s does not match index", p->pack_name);
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return 0;
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}
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@ -530,7 +532,7 @@ static int open_packed_git(struct packed_git *p)
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static int in_window(struct pack_window *win, off_t offset)
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{
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/* We must promise at least 20 bytes (one hash) after the
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/* We must promise at least one full hash after the
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* offset is available from this window, otherwise the offset
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* is not actually in this window and a different window (which
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* has that one hash excess) must be used. This is to support
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@ -538,7 +540,7 @@ static int in_window(struct pack_window *win, off_t offset)
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*/
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off_t win_off = win->offset;
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return win_off <= offset
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&& (offset + 20) <= (win_off + win->len);
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&& (offset + the_hash_algo->rawsz) <= (win_off + win->len);
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}
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unsigned char *use_pack(struct packed_git *p,
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@ -555,7 +557,7 @@ unsigned char *use_pack(struct packed_git *p,
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*/
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if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
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die("packfile %s cannot be accessed", p->pack_name);
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if (offset > (p->pack_size - 20))
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if (offset > (p->pack_size - the_hash_algo->rawsz))
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die("offset beyond end of packfile (truncated pack?)");
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if (offset < 0)
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die(_("offset before end of packfile (broken .idx?)"));
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@ -675,7 +677,8 @@ struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
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p->pack_size = st.st_size;
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p->pack_local = local;
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p->mtime = st.st_mtime;
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if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
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if (path_len < the_hash_algo->hexsz ||
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get_sha1_hex(path + path_len - the_hash_algo->hexsz, p->sha1))
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hashclr(p->sha1);
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return p;
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}
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@ -1028,7 +1031,8 @@ const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
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for (p = the_repository->objects->packed_git; p; p = p->next)
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for (i = 0; i < p->num_bad_objects; i++)
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if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
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if (!hashcmp(sha1,
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p->bad_object_sha1 + the_hash_algo->rawsz * i))
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return p;
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return NULL;
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}
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@ -1066,7 +1070,7 @@ static off_t get_delta_base(struct packed_git *p,
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} else if (type == OBJ_REF_DELTA) {
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/* The base entry _must_ be in the same pack */
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base_offset = find_pack_entry_one(base_info, p);
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*curpos += 20;
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*curpos += the_hash_algo->rawsz;
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} else
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die("I am totally screwed");
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return base_offset;
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@ -1671,6 +1675,7 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
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{
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const unsigned char *index_fanout = p->index_data;
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const unsigned char *index_lookup;
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const unsigned int hashsz = the_hash_algo->rawsz;
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int index_lookup_width;
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if (!index_fanout)
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@ -1678,10 +1683,10 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
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index_lookup = index_fanout + 4 * 256;
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if (p->index_version == 1) {
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index_lookup_width = 24;
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index_lookup_width = hashsz + 4;
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index_lookup += 4;
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} else {
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index_lookup_width = 20;
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index_lookup_width = hashsz;
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index_fanout += 8;
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index_lookup += 8;
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}
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@ -1694,6 +1699,7 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
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uint32_t n)
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{
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const unsigned char *index = p->index_data;
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const unsigned int hashsz = the_hash_algo->rawsz;
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if (!index) {
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if (open_pack_index(p))
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return NULL;
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@ -1703,10 +1709,10 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
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return NULL;
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index += 4 * 256;
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if (p->index_version == 1) {
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return index + 24 * n + 4;
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return index + (hashsz + 4) * n + 4;
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} else {
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index += 8;
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return index + 20 * n;
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return index + hashsz * n;
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}
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}
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@ -1738,12 +1744,13 @@ void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
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off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
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{
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const unsigned char *index = p->index_data;
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const unsigned int hashsz = the_hash_algo->rawsz;
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index += 4 * 256;
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if (p->index_version == 1) {
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return ntohl(*((uint32_t *)(index + 24 * n)));
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return ntohl(*((uint32_t *)(index + (hashsz + 4) * n)));
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} else {
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uint32_t off;
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index += 8 + p->num_objects * (20 + 4);
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index += 8 + p->num_objects * (hashsz + 4);
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off = ntohl(*((uint32_t *)(index + 4 * n)));
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if (!(off & 0x80000000))
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return off;
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@ -1814,7 +1821,8 @@ static int fill_pack_entry(const struct object_id *oid,
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if (p->num_bad_objects) {
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unsigned i;
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for (i = 0; i < p->num_bad_objects; i++)
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if (!hashcmp(oid->hash, p->bad_object_sha1 + 20 * i))
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if (!hashcmp(oid->hash,
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p->bad_object_sha1 + the_hash_algo->rawsz * i))
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return 0;
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}
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