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![brian m. carlson](/assets/img/avatar_default.png)
Now that struct object_id has an algorithm field, we should populate it. This will allow us to handle object IDs in any supported algorithm and distinguish between them. Ensure that the field is written whenever we write an object ID by storing it explicitly every time we write an object. Set values for the empty blob and tree values as well. In addition, use the algorithm field to compare object IDs. Note that because we zero-initialize struct object_id in many places throughout the codebase, we default to the default algorithm in cases where the algorithm field is zero rather than explicitly initialize all of those locations. This leads to a branch on every comparison, but the alternative is to compare the entire buffer each time and padding the buffer for SHA-1. That alternative ranges up to 3.9% worse than this approach on the perf t0001, t1450, and t1451. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
159 lines
4.2 KiB
C
159 lines
4.2 KiB
C
#include "cache.h"
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const signed char hexval_table[256] = {
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-1, -1, -1, -1, -1, -1, -1, -1, /* 00-07 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 08-0f */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 10-17 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 18-1f */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 20-27 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 28-2f */
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0, 1, 2, 3, 4, 5, 6, 7, /* 30-37 */
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8, 9, -1, -1, -1, -1, -1, -1, /* 38-3f */
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-1, 10, 11, 12, 13, 14, 15, -1, /* 40-47 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 48-4f */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 50-57 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 58-5f */
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-1, 10, 11, 12, 13, 14, 15, -1, /* 60-67 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 68-67 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 70-77 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 78-7f */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 80-87 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 88-8f */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 90-97 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* 98-9f */
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-1, -1, -1, -1, -1, -1, -1, -1, /* a0-a7 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* a8-af */
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-1, -1, -1, -1, -1, -1, -1, -1, /* b0-b7 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* b8-bf */
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-1, -1, -1, -1, -1, -1, -1, -1, /* c0-c7 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* c8-cf */
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-1, -1, -1, -1, -1, -1, -1, -1, /* d0-d7 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* d8-df */
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-1, -1, -1, -1, -1, -1, -1, -1, /* e0-e7 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* e8-ef */
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-1, -1, -1, -1, -1, -1, -1, -1, /* f0-f7 */
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-1, -1, -1, -1, -1, -1, -1, -1, /* f8-ff */
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};
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int hex_to_bytes(unsigned char *binary, const char *hex, size_t len)
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{
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for (; len; len--, hex += 2) {
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unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
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if (val & ~0xff)
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return -1;
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*binary++ = val;
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}
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return 0;
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}
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static int get_hash_hex_algop(const char *hex, unsigned char *hash,
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const struct git_hash_algo *algop)
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{
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int i;
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for (i = 0; i < algop->rawsz; i++) {
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int val = hex2chr(hex);
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if (val < 0)
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return -1;
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*hash++ = val;
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hex += 2;
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}
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return 0;
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}
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int get_sha1_hex(const char *hex, unsigned char *sha1)
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{
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return get_hash_hex_algop(hex, sha1, the_hash_algo);
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}
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int get_oid_hex_algop(const char *hex, struct object_id *oid,
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const struct git_hash_algo *algop)
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{
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int ret = get_hash_hex_algop(hex, oid->hash, algop);
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if (!ret)
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oid_set_algo(oid, algop);
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return ret;
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}
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/*
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* NOTE: This function relies on hash algorithms being in order from shortest
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* length to longest length.
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*/
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int get_oid_hex_any(const char *hex, struct object_id *oid)
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{
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int i;
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for (i = GIT_HASH_NALGOS - 1; i > 0; i--) {
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if (!get_oid_hex_algop(hex, oid, &hash_algos[i]))
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return i;
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}
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return GIT_HASH_UNKNOWN;
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}
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int get_oid_hex(const char *hex, struct object_id *oid)
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{
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return get_oid_hex_algop(hex, oid, the_hash_algo);
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}
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int parse_oid_hex_algop(const char *hex, struct object_id *oid,
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const char **end,
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const struct git_hash_algo *algop)
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{
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int ret = get_oid_hex_algop(hex, oid, algop);
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if (!ret)
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*end = hex + algop->hexsz;
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return ret;
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}
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int parse_oid_hex_any(const char *hex, struct object_id *oid, const char **end)
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{
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int ret = get_oid_hex_any(hex, oid);
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if (ret)
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*end = hex + hash_algos[ret].hexsz;
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return ret;
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}
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int parse_oid_hex(const char *hex, struct object_id *oid, const char **end)
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{
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return parse_oid_hex_algop(hex, oid, end, the_hash_algo);
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}
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char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash,
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const struct git_hash_algo *algop)
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{
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static const char hex[] = "0123456789abcdef";
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char *buf = buffer;
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int i;
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for (i = 0; i < algop->rawsz; i++) {
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unsigned int val = *hash++;
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*buf++ = hex[val >> 4];
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*buf++ = hex[val & 0xf];
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}
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*buf = '\0';
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return buffer;
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}
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char *oid_to_hex_r(char *buffer, const struct object_id *oid)
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{
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return hash_to_hex_algop_r(buffer, oid->hash, the_hash_algo);
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}
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char *hash_to_hex_algop(const unsigned char *hash, const struct git_hash_algo *algop)
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{
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static int bufno;
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static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
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bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
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return hash_to_hex_algop_r(hexbuffer[bufno], hash, algop);
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}
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char *hash_to_hex(const unsigned char *hash)
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{
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return hash_to_hex_algop(hash, the_hash_algo);
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}
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char *oid_to_hex(const struct object_id *oid)
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{
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return hash_to_hex_algop(oid->hash, the_hash_algo);
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}
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