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>
brian m. carlson committed
May 2, 2018 at 00:25 UTC
37fec86a8353106dad000d498df8251ea3547855
1 file changed
+37
-29
packfile.c
+37
-29
@@ -84,6 +84,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
84
uint32_t version, nr, i, *index;
85
int fd = git_open(path);
86
struct stat st;
87
+ const unsigned int hashsz = the_hash_algo->rawsz;
88
89
if (fd < 0)
90
return -1;
@@ -92,7 +93,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
93
return -1;
94
}
95
idx_size = xsize_t(st.st_size);
95
- if (idx_size < 4 * 256 + 20 + 20) {
96
+ if (idx_size < 4 * 256 + hashsz + hashsz) {
97
close(fd);
98
return error("index file %s is too small", path);
99
}
@@ -129,11 +130,11 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
130
/*
131
* Total size:
132
* - 256 index entries 4 bytes each
132
- * - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
133
- * - 20-byte SHA1 of the packfile
134
- * - 20-byte SHA1 file checksum
133
+ * - 24-byte entries * nr (object ID + 4-byte offset)
134
+ * - hash of the packfile
135
+ * - file checksum
136
*/
136
- if (idx_size != 4*256 + nr * 24 + 20 + 20) {
137
+ if (idx_size != 4*256 + nr * (hashsz + 4) + hashsz + hashsz) {
138
munmap(idx_map, idx_size);
139
return error("wrong index v1 file size in %s", path);
140
}
@@ -142,16 +143,16 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
143
* Minimum size:
144
* - 8 bytes of header
145
* - 256 index entries 4 bytes each
145
- * - 20-byte sha1 entry * nr
146
+ * - object ID entry * nr
147
* - 4-byte crc entry * nr
148
* - 4-byte offset entry * nr
148
- * - 20-byte SHA1 of the packfile
149
- * - 20-byte SHA1 file checksum
149
+ * - hash of the packfile
150
+ * - file checksum
151
* And after the 4-byte offset table might be a
152
* variable sized table containing 8-byte entries
153
* for offsets larger than 2^31.
154
*/
154
- unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
155
+ unsigned long min_size = 8 + 4*256 + nr*(hashsz + 4 + 4) + hashsz + hashsz;
156
unsigned long max_size = min_size;
157
if (nr)
158
max_size += (nr - 1)*8;
@@ -444,10 +445,11 @@ static int open_packed_git_1(struct packed_git *p)
445
{
446
struct stat st;
447
struct pack_header hdr;
447
- unsigned char sha1[20];
448
- unsigned char *idx_sha1;
448
+ unsigned char hash[GIT_MAX_RAWSZ];
449
+ unsigned char *idx_hash;
450
long fd_flag;
451
ssize_t read_result;
452
+ const unsigned hashsz = the_hash_algo->rawsz;
453
454
if (!p->index_data && open_pack_index(p))
455
return error("packfile %s index unavailable", p->pack_name);
@@ -507,15 +509,15 @@ static int open_packed_git_1(struct packed_git *p)
509
" while index indicates %"PRIu32" objects",
510
p->pack_name, ntohl(hdr.hdr_entries),
511
p->num_objects);
510
- if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
512
+ if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)
513
return error("end of packfile %s is unavailable", p->pack_name);
512
- read_result = read_in_full(p->pack_fd, sha1, sizeof(sha1));
514
+ read_result = read_in_full(p->pack_fd, hash, hashsz);
515
if (read_result < 0)
516
return error_errno("error reading from %s", p->pack_name);
515
- if (read_result != sizeof(sha1))
517
+ if (read_result != hashsz)
518
return error("packfile %s signature is unavailable", p->pack_name);
517
- idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
518
- if (hashcmp(sha1, idx_sha1))
519
+ idx_hash = ((unsigned char *)p->index_data) + p->index_size - hashsz * 2;
520
+ if (hashcmp(hash, idx_hash))
521
return error("packfile %s does not match index", p->pack_name);
522
return 0;
523
}
@@ -530,7 +532,7 @@ static int open_packed_git(struct packed_git *p)
532
533
static int in_window(struct pack_window *win, off_t offset)
534
{
533
- /* We must promise at least 20 bytes (one hash) after the
535
+ /* We must promise at least one full hash after the
536
* offset is available from this window, otherwise the offset
537
* is not actually in this window and a different window (which
538
* has that one hash excess) must be used. This is to support
@@ -538,7 +540,7 @@ static int in_window(struct pack_window *win, off_t offset)
540
*/
541
off_t win_off = win->offset;
542
return win_off <= offset
541
- && (offset + 20) <= (win_off + win->len);
543
+ && (offset + the_hash_algo->rawsz) <= (win_off + win->len);
544
}
545
546
unsigned char *use_pack(struct packed_git *p,
@@ -555,7 +557,7 @@ unsigned char *use_pack(struct packed_git *p,
557
*/
558
if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
559
die("packfile %s cannot be accessed", p->pack_name);
558
- if (offset > (p->pack_size - 20))
560
+ if (offset > (p->pack_size - the_hash_algo->rawsz))
561
die("offset beyond end of packfile (truncated pack?)");
562
if (offset < 0)
563
die(_("offset before end of packfile (broken .idx?)"));
@@ -675,7 +677,8 @@ struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
677
p->pack_size = st.st_size;
678
p->pack_local = local;
679
p->mtime = st.st_mtime;
678
- if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
680
+ if (path_len < the_hash_algo->hexsz ||
681
+ get_sha1_hex(path + path_len - the_hash_algo->hexsz, p->sha1))
682
hashclr(p->sha1);
683
return p;
684
}
@@ -1028,7 +1031,8 @@ const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1031
1032
for (p = the_repository->objects->packed_git; p; p = p->next)
1033
for (i = 0; i < p->num_bad_objects; i++)
1031
- if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1034
+ if (!hashcmp(sha1,
1035
+ p->bad_object_sha1 + the_hash_algo->rawsz * i))
1036
return p;
1037
return NULL;
1038
}
@@ -1066,7 +1070,7 @@ static off_t get_delta_base(struct packed_git *p,
1070
} else if (type == OBJ_REF_DELTA) {
1071
/* The base entry _must_ be in the same pack */
1072
base_offset = find_pack_entry_one(base_info, p);
1069
- *curpos += 20;
1073
+ *curpos += the_hash_algo->rawsz;
1074
} else
1075
die("I am totally screwed");
1076
return base_offset;
@@ -1671,6 +1675,7 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
1675
{
1676
const unsigned char *index_fanout = p->index_data;
1677
const unsigned char *index_lookup;
1678
+ const unsigned int hashsz = the_hash_algo->rawsz;
1679
int index_lookup_width;
1680
1681
if (!index_fanout)
@@ -1678,10 +1683,10 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
1683
1684
index_lookup = index_fanout + 4 * 256;
1685
if (p->index_version == 1) {
1681
- index_lookup_width = 24;
1686
+ index_lookup_width = hashsz + 4;
1687
index_lookup += 4;
1688
} else {
1684
- index_lookup_width = 20;
1689
+ index_lookup_width = hashsz;
1690
index_fanout += 8;
1691
index_lookup += 8;
1692
}
@@ -1694,6 +1699,7 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1699
uint32_t n)
1700
{
1701
const unsigned char *index = p->index_data;
1702
+ const unsigned int hashsz = the_hash_algo->rawsz;
1703
if (!index) {
1704
if (open_pack_index(p))
1705
return NULL;
@@ -1703,10 +1709,10 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1709
return NULL;
1710
index += 4 * 256;
1711
if (p->index_version == 1) {
1706
- return index + 24 * n + 4;
1712
+ return index + (hashsz + 4) * n + 4;
1713
} else {
1714
index += 8;
1709
- return index + 20 * n;
1715
+ return index + hashsz * n;
1716
}
1717
}
1718
@@ -1738,12 +1744,13 @@ void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1744
off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1745
{
1746
const unsigned char *index = p->index_data;
1747
+ const unsigned int hashsz = the_hash_algo->rawsz;
1748
index += 4 * 256;
1749
if (p->index_version == 1) {
1743
- return ntohl(*((uint32_t *)(index + 24 * n)));
1750
+ return ntohl(*((uint32_t *)(index + (hashsz + 4) * n)));
1751
} else {
1752
uint32_t off;
1746
- index += 8 + p->num_objects * (20 + 4);
1753
+ index += 8 + p->num_objects * (hashsz + 4);
1754
off = ntohl(*((uint32_t *)(index + 4 * n)));
1755
if (!(off & 0x80000000))
1756
return off;
@@ -1814,7 +1821,8 @@ static int fill_pack_entry(const struct object_id *oid,
1821
if (p->num_bad_objects) {
1822
unsigned i;
1823
for (i = 0; i < p->num_bad_objects; i++)
1817
- if (!hashcmp(oid->hash, p->bad_object_sha1 + 20 * i))
1824
+ if (!hashcmp(oid->hash,
1825
+ p->bad_object_sha1 + the_hash_algo->rawsz * i))
1826
return 0;
1827
}
1828