mirror of
https://github.com/git/git.git
synced 2024-11-24 18:33:43 +08:00
6e1c6c103c
Martin Langhoff noticed that ref^0 barfed correctly when we did not
have the commit in a broken repository, but ref^{commit} didn't.
Signed-off-by: Junio C Hamano <junkio@cox.net>
418 lines
9.2 KiB
C
418 lines
9.2 KiB
C
#include "cache.h"
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#include "tag.h"
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#include "commit.h"
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#include "tree.h"
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#include "blob.h"
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static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
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{
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struct alternate_object_database *alt;
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char hex[40];
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int found = 0;
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static struct alternate_object_database *fakeent;
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if (!fakeent) {
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const char *objdir = get_object_directory();
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int objdir_len = strlen(objdir);
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int entlen = objdir_len + 43;
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fakeent = xmalloc(sizeof(*fakeent) + entlen);
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memcpy(fakeent->base, objdir, objdir_len);
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fakeent->name = fakeent->base + objdir_len + 1;
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fakeent->name[-1] = '/';
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}
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fakeent->next = alt_odb_list;
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sprintf(hex, "%.2s", name);
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for (alt = fakeent; alt && found < 2; alt = alt->next) {
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struct dirent *de;
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DIR *dir;
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sprintf(alt->name, "%.2s/", name);
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dir = opendir(alt->base);
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if (!dir)
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continue;
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while ((de = readdir(dir)) != NULL) {
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if (strlen(de->d_name) != 38)
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continue;
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if (memcmp(de->d_name, name + 2, len - 2))
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continue;
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if (!found) {
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memcpy(hex + 2, de->d_name, 38);
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found++;
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}
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else if (memcmp(hex + 2, de->d_name, 38)) {
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found = 2;
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break;
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}
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}
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closedir(dir);
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}
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if (found == 1)
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return get_sha1_hex(hex, sha1) == 0;
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return found;
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}
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static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
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{
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do {
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if (*a != *b)
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return 0;
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a++;
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b++;
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len -= 2;
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} while (len > 1);
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if (len)
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if ((*a ^ *b) & 0xf0)
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return 0;
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return 1;
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}
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static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
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{
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struct packed_git *p;
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unsigned char found_sha1[20];
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int found = 0;
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prepare_packed_git();
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for (p = packed_git; p && found < 2; p = p->next) {
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unsigned num = num_packed_objects(p);
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unsigned first = 0, last = num;
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while (first < last) {
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unsigned mid = (first + last) / 2;
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unsigned char now[20];
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int cmp;
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nth_packed_object_sha1(p, mid, now);
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cmp = memcmp(match, now, 20);
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if (!cmp) {
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first = mid;
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break;
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}
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if (cmp > 0) {
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first = mid+1;
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continue;
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}
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last = mid;
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}
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if (first < num) {
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unsigned char now[20], next[20];
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nth_packed_object_sha1(p, first, now);
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if (match_sha(len, match, now)) {
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if (nth_packed_object_sha1(p, first+1, next) ||
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!match_sha(len, match, next)) {
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/* unique within this pack */
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if (!found) {
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memcpy(found_sha1, now, 20);
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found++;
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}
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else if (memcmp(found_sha1, now, 20)) {
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found = 2;
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break;
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}
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}
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else {
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/* not even unique within this pack */
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found = 2;
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break;
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}
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}
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}
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}
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if (found == 1)
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memcpy(sha1, found_sha1, 20);
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return found;
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}
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#define SHORT_NAME_NOT_FOUND (-1)
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#define SHORT_NAME_AMBIGUOUS (-2)
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static int find_unique_short_object(int len, char *canonical,
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unsigned char *res, unsigned char *sha1)
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{
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int has_unpacked, has_packed;
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unsigned char unpacked_sha1[20], packed_sha1[20];
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has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
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has_packed = find_short_packed_object(len, res, packed_sha1);
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if (!has_unpacked && !has_packed)
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return SHORT_NAME_NOT_FOUND;
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if (1 < has_unpacked || 1 < has_packed)
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return SHORT_NAME_AMBIGUOUS;
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if (has_unpacked != has_packed) {
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memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
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return 0;
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}
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/* Both have unique ones -- do they match? */
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if (memcmp(packed_sha1, unpacked_sha1, 20))
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return -2;
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memcpy(sha1, packed_sha1, 20);
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return 0;
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}
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static int get_short_sha1(const char *name, int len, unsigned char *sha1,
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int quietly)
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{
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int i, status;
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char canonical[40];
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unsigned char res[20];
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if (len < 4)
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return -1;
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memset(res, 0, 20);
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memset(canonical, 'x', 40);
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for (i = 0; i < len ;i++) {
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unsigned char c = name[i];
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unsigned char val;
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if (c >= '0' && c <= '9')
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val = c - '0';
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else if (c >= 'a' && c <= 'f')
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val = c - 'a' + 10;
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else if (c >= 'A' && c <='F') {
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val = c - 'A' + 10;
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c -= 'A' - 'a';
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}
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else
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return -1;
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canonical[i] = c;
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if (!(i & 1))
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val <<= 4;
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res[i >> 1] |= val;
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}
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status = find_unique_short_object(i, canonical, res, sha1);
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if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
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return error("short SHA1 %.*s is ambiguous.", len, canonical);
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return status;
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}
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const char *find_unique_abbrev(const unsigned char *sha1, int len)
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{
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int status;
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static char hex[41];
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memcpy(hex, sha1_to_hex(sha1), 40);
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while (len < 40) {
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unsigned char sha1_ret[20];
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status = get_short_sha1(hex, len, sha1_ret, 1);
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if (!status) {
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hex[len] = 0;
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return hex;
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}
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if (status != SHORT_NAME_AMBIGUOUS)
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return NULL;
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len++;
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}
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return NULL;
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}
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static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
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{
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static const char *prefix[] = {
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"",
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"refs",
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"refs/tags",
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"refs/heads",
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NULL
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};
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const char **p;
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if (len == 40 && !get_sha1_hex(str, sha1))
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return 0;
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for (p = prefix; *p; p++) {
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char *pathname = git_path("%s/%.*s", *p, len, str);
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if (!read_ref(pathname, sha1))
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return 0;
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}
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return -1;
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}
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static int get_sha1_1(const char *name, int len, unsigned char *sha1);
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static int get_parent(const char *name, int len,
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unsigned char *result, int idx)
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{
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unsigned char sha1[20];
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int ret = get_sha1_1(name, len, sha1);
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struct commit *commit;
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struct commit_list *p;
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if (ret)
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return ret;
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commit = lookup_commit_reference(sha1);
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if (!commit)
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return -1;
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if (parse_commit(commit))
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return -1;
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if (!idx) {
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memcpy(result, commit->object.sha1, 20);
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return 0;
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}
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p = commit->parents;
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while (p) {
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if (!--idx) {
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memcpy(result, p->item->object.sha1, 20);
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return 0;
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}
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p = p->next;
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}
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return -1;
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}
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static int get_nth_ancestor(const char *name, int len,
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unsigned char *result, int generation)
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{
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unsigned char sha1[20];
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int ret = get_sha1_1(name, len, sha1);
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if (ret)
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return ret;
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while (generation--) {
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struct commit *commit = lookup_commit_reference(sha1);
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if (!commit || parse_commit(commit) || !commit->parents)
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return -1;
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memcpy(sha1, commit->parents->item->object.sha1, 20);
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}
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memcpy(result, sha1, 20);
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return 0;
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}
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static int peel_onion(const char *name, int len, unsigned char *sha1)
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{
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unsigned char outer[20];
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const char *sp;
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const char *type_string = NULL;
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struct object *o;
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/*
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* "ref^{type}" dereferences ref repeatedly until you cannot
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* dereference anymore, or you get an object of given type,
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* whichever comes first. "ref^{}" means just dereference
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* tags until you get a non-tag. "ref^0" is a shorthand for
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* "ref^{commit}". "commit^{tree}" could be used to find the
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* top-level tree of the given commit.
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*/
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if (len < 4 || name[len-1] != '}')
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return -1;
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for (sp = name + len - 1; name <= sp; sp--) {
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int ch = *sp;
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if (ch == '{' && name < sp && sp[-1] == '^')
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break;
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}
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if (sp <= name)
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return -1;
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sp++; /* beginning of type name, or closing brace for empty */
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if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
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type_string = commit_type;
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else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
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type_string = tree_type;
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else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
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type_string = blob_type;
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else if (sp[0] == '}')
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type_string = NULL;
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else
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return -1;
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if (get_sha1_1(name, sp - name - 2, outer))
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return -1;
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o = parse_object(outer);
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if (!o)
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return -1;
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if (!type_string) {
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o = deref_tag(o);
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if (!o || (!o->parsed && !parse_object(o->sha1)))
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return -1;
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memcpy(sha1, o->sha1, 20);
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}
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else {
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/* At this point, the syntax look correct, so
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* if we do not get the needed object, we should
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* barf.
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*/
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while (1) {
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if (!o || (!o->parsed && !parse_object(o->sha1)))
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return -1;
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if (o->type == type_string) {
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memcpy(sha1, o->sha1, 20);
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return 0;
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}
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if (o->type == tag_type)
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o = ((struct tag*) o)->tagged;
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else if (o->type == commit_type)
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o = &(((struct commit *) o)->tree->object);
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else
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return error("%.*s: expected %s type, but the object dereferences to %s type",
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len, name, type_string,
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o->type);
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if (!o->parsed)
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parse_object(o->sha1);
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}
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}
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return 0;
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}
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static int get_sha1_1(const char *name, int len, unsigned char *sha1)
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{
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int parent, ret;
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const char *cp;
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/* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
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if (len > 2 && name[len-2] == '^' &&
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name[len-1] >= '0' && name[len-1] <= '9') {
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parent = name[len-1] - '0';
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len -= 2;
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}
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else if (len > 1 && name[len-1] == '^') {
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parent = 1;
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len--;
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} else
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parent = -1;
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if (parent >= 0)
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return get_parent(name, len, sha1, parent);
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/* "name~3" is "name^^^",
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* "name~12" is "name^^^^^^^^^^^^", and
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* "name~" and "name~0" are name -- not "name^0"!
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*/
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parent = 0;
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for (cp = name + len - 1; name <= cp; cp--) {
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int ch = *cp;
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if ('0' <= ch && ch <= '9')
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continue;
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if (ch != '~')
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parent = -1;
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break;
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}
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if (!parent && *cp == '~') {
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int len1 = cp - name;
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cp++;
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while (cp < name + len)
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parent = parent * 10 + *cp++ - '0';
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return get_nth_ancestor(name, len1, sha1, parent);
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}
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ret = peel_onion(name, len, sha1);
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if (!ret)
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return 0;
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ret = get_sha1_basic(name, len, sha1);
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if (!ret)
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return 0;
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return get_short_sha1(name, len, sha1, 0);
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}
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/*
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* This is like "get_sha1_basic()", except it allows "sha1 expressions",
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* notably "xyz^" for "parent of xyz"
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*/
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int get_sha1(const char *name, unsigned char *sha1)
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{
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prepare_alt_odb();
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return get_sha1_1(name, strlen(name), sha1);
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}
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