Fix minor DOS in rev-list.
[git/git.git] / sha1_name.c
CommitLineData
9938af6a
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1#include "cache.h"
2#include "commit.h"
3
4static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
5{
6 static char dirname[PATH_MAX];
7 char hex[40];
8 DIR *dir;
9 int found;
10
11 snprintf(dirname, sizeof(dirname), "%s/%.2s", get_object_directory(), name);
12 dir = opendir(dirname);
13 sprintf(hex, "%.2s", name);
14 found = 0;
15 if (dir) {
16 struct dirent *de;
17 while ((de = readdir(dir)) != NULL) {
18 if (strlen(de->d_name) != 38)
19 continue;
20 if (memcmp(de->d_name, name + 2, len-2))
21 continue;
22 memcpy(hex + 2, de->d_name, 38);
23 if (++found > 1)
24 break;
25 }
26 closedir(dir);
27 }
28 if (found == 1)
29 return get_sha1_hex(hex, sha1) == 0;
30 return 0;
31}
32
33static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
34{
35 do {
36 if (*a != *b)
37 return 0;
38 a++;
39 b++;
40 len -= 2;
41 } while (len > 1);
42 if (len)
43 if ((*a ^ *b) & 0xf0)
44 return 0;
45 return 1;
46}
47
48static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
49{
50 struct packed_git *p;
51
52 prepare_packed_git();
53 for (p = packed_git; p; p = p->next) {
54 unsigned num = num_packed_objects(p);
55 unsigned first = 0, last = num;
56 while (first < last) {
57 unsigned mid = (first + last) / 2;
58 unsigned char now[20];
59 int cmp;
60
61 nth_packed_object_sha1(p, mid, now);
62 cmp = memcmp(match, now, 20);
63 if (!cmp) {
64 first = mid;
65 break;
66 }
67 if (cmp > 0) {
68 first = mid+1;
69 continue;
70 }
71 last = mid;
72 }
73 if (first < num) {
74 unsigned char now[20], next[20];
75 nth_packed_object_sha1(p, first, now);
76 if (match_sha(len, match, now)) {
77 if (nth_packed_object_sha1(p, first+1, next) || !match_sha(len, match, next)) {
78 memcpy(sha1, now, 20);
79 return 1;
80 }
81 }
82 }
83 }
84 return 0;
85}
86
af61c6e0 87static int get_short_sha1(const char *name, int len, unsigned char *sha1)
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88{
89 int i;
90 char canonical[40];
91 unsigned char res[20];
92
af61c6e0
LT
93 if (len < 4)
94 return -1;
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JH
95 memset(res, 0, 20);
96 memset(canonical, 'x', 40);
af61c6e0 97 for (i = 0; i < len ;i++) {
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98 unsigned char c = name[i];
99 unsigned char val;
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100 if (c >= '0' && c <= '9')
101 val = c - '0';
102 else if (c >= 'a' && c <= 'f')
103 val = c - 'a' + 10;
104 else if (c >= 'A' && c <='F') {
105 val = c - 'A' + 10;
106 c -= 'A' - 'a';
107 }
108 else
109 return -1;
110 canonical[i] = c;
111 if (!(i & 1))
112 val <<= 4;
113 res[i >> 1] |= val;
114 }
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JH
115 if (find_short_object_filename(i, canonical, sha1))
116 return 0;
117 if (find_short_packed_object(i, res, sha1))
118 return 0;
119 return -1;
120}
121
9938af6a
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122static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
123{
124 static const char *prefix[] = {
125 "",
126 "refs",
127 "refs/tags",
128 "refs/heads",
9938af6a
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129 NULL
130 };
131 const char **p;
132
3c3852e3 133 if (len == 40 && !get_sha1_hex(str, sha1))
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134 return 0;
135
136 for (p = prefix; *p; p++) {
137 char *pathname = git_path("%s/%.*s", *p, len, str);
ca8db142 138 if (!read_ref(pathname, sha1))
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139 return 0;
140 }
141
142 return -1;
143}
144
145static int get_sha1_1(const char *name, int len, unsigned char *sha1);
146
147static int get_parent(const char *name, int len,
148 unsigned char *result, int idx)
149{
150 unsigned char sha1[20];
151 int ret = get_sha1_1(name, len, sha1);
152 struct commit *commit;
153 struct commit_list *p;
154
155 if (ret)
156 return ret;
157 commit = lookup_commit_reference(sha1);
158 if (!commit)
159 return -1;
160 if (parse_commit(commit))
161 return -1;
162 if (!idx) {
163 memcpy(result, commit->object.sha1, 20);
164 return 0;
165 }
166 p = commit->parents;
167 while (p) {
168 if (!--idx) {
169 memcpy(result, p->item->object.sha1, 20);
170 return 0;
171 }
172 p = p->next;
173 }
174 return -1;
175}
176
4f7599ac
JH
177static int get_nth_ancestor(const char *name, int len,
178 unsigned char *result, int generation)
179{
180 unsigned char sha1[20];
181 int ret = get_sha1_1(name, len, sha1);
182 if (ret)
183 return ret;
184
185 while (generation--) {
186 struct commit *commit = lookup_commit_reference(sha1);
187
188 if (!commit || parse_commit(commit) || !commit->parents)
189 return -1;
190 memcpy(sha1, commit->parents->item->object.sha1, 20);
191 }
192 memcpy(result, sha1, 20);
193 return 0;
194}
195
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196static int get_sha1_1(const char *name, int len, unsigned char *sha1)
197{
198 int parent, ret;
4f7599ac 199 const char *cp;
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200
201 /* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
202 if (len > 2 && name[len-2] == '^' &&
203 name[len-1] >= '0' && name[len-1] <= '9') {
204 parent = name[len-1] - '0';
205 len -= 2;
206 }
ef0bd2e6 207 else if (len > 1 && name[len-1] == '^') {
9938af6a 208 parent = 1;
ef0bd2e6
JS
209 len--;
210 } else
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211 parent = -1;
212
02a4a32c
LT
213 if (parent >= 0)
214 return get_parent(name, len, sha1, parent);
215
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216 /* "name~3" is "name^^^",
217 * "name~12" is "name^^^^^^^^^^^^", and
218 * "name~" and "name~0" are name -- not "name^0"!
219 */
220 parent = 0;
221 for (cp = name + len - 1; name <= cp; cp--) {
222 int ch = *cp;
223 if ('0' <= ch && ch <= '9')
224 continue;
225 if (ch != '~')
226 parent = -1;
227 break;
228 }
229 if (!parent && *cp == '~') {
230 int len1 = cp - name;
231 cp++;
232 while (cp < name + len)
233 parent = parent * 10 + *cp++ - '0';
234 return get_nth_ancestor(name, len1, sha1, parent);
235 }
236
9938af6a
JH
237 ret = get_sha1_basic(name, len, sha1);
238 if (!ret)
239 return 0;
af61c6e0 240 return get_short_sha1(name, len, sha1);
9938af6a
JH
241}
242
243/*
244 * This is like "get_sha1_basic()", except it allows "sha1 expressions",
245 * notably "xyz^" for "parent of xyz"
246 */
247int get_sha1(const char *name, unsigned char *sha1)
248{
249 return get_sha1_1(name, strlen(name), sha1);
250}