[PATCH] Allow reading "symbolic refs" that point to other refs
[git/git.git] / refs.c
CommitLineData
95fc7512
DB
1#include "refs.h"
2#include "cache.h"
3
4#include <errno.h>
ca8db142 5#include <ctype.h>
95fc7512 6
ca8db142
LT
7/* We allow "recursive" symbolic refs. Only within reason, though */
8#define MAXDEPTH 5
9
10int read_ref(const char *filename, unsigned char *sha1)
8a65ff76 11{
ca8db142
LT
12 int depth = 0;
13 int ret = -1, fd;
14
15 while ((fd = open(filename, O_RDONLY)) >= 0) {
16 char buffer[256];
17 int len = read(fd, buffer, sizeof(buffer)-1);
8a65ff76 18
8a65ff76 19 close(fd);
ca8db142
LT
20 if (len < 0)
21 break;
22
23 buffer[len] = 0;
24 while (len && isspace(buffer[len-1]))
25 buffer[--len] = 0;
26
27 if (!strncmp(buffer, "ref:", 4)) {
28 char *buf;
29 if (depth > MAXDEPTH)
30 break;
31 depth++;
32 buf = buffer + 4;
33 len -= 4;
34 while (len && isspace(*buf))
35 buf++, len--;
36 filename = git_path("%.*s", len, buf);
37 continue;
38 }
39 if (len >= 40)
40 ret = get_sha1_hex(buffer, sha1);
41 break;
8a65ff76
LT
42 }
43 return ret;
44}
45
944d8589 46static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1))
8a65ff76
LT
47{
48 int retval = 0;
4ec99bf0 49 DIR *dir = opendir(git_path("%s", base));
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LT
50
51 if (dir) {
52 struct dirent *de;
53 int baselen = strlen(base);
54 char *path = xmalloc(baselen + 257);
6cada6a9
LT
55
56 if (!strncmp(base, "./", 2)) {
57 base += 2;
58 baselen -= 2;
59 }
8a65ff76 60 memcpy(path, base, baselen);
944d8589
LT
61 if (baselen && base[baselen-1] != '/')
62 path[baselen++] = '/';
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LT
63
64 while ((de = readdir(dir)) != NULL) {
65 unsigned char sha1[20];
66 struct stat st;
67 int namelen;
68
69 if (de->d_name[0] == '.')
70 continue;
71 namelen = strlen(de->d_name);
72 if (namelen > 255)
73 continue;
74 memcpy(path + baselen, de->d_name, namelen+1);
a7e66ae3 75 if (stat(git_path("%s", path), &st) < 0)
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LT
76 continue;
77 if (S_ISDIR(st.st_mode)) {
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LT
78 retval = do_for_each_ref(path, fn);
79 if (retval)
80 break;
81 continue;
82 }
ca8db142 83 if (read_ref(git_path("%s", path), sha1) < 0)
8a65ff76
LT
84 continue;
85 if (!has_sha1_file(sha1))
86 continue;
87 retval = fn(path, sha1);
88 if (retval)
89 break;
90 }
91 free(path);
92 closedir(dir);
93 }
94 return retval;
95}
96
723c31fe
LT
97int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
98{
99 unsigned char sha1[20];
ca8db142 100 if (!read_ref(git_path("HEAD"), sha1))
99a0a6e0 101 return fn("HEAD", sha1);
2f34ba32 102 return 0;
723c31fe
LT
103}
104
944d8589 105int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
8a65ff76 106{
99a0a6e0 107 return do_for_each_ref("refs", fn);
8a65ff76
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108}
109
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DB
110static char *ref_file_name(const char *ref)
111{
112 char *base = get_refs_directory();
113 int baselen = strlen(base);
114 int reflen = strlen(ref);
115 char *ret = xmalloc(baselen + 2 + reflen);
116 sprintf(ret, "%s/%s", base, ref);
117 return ret;
118}
119
120static char *ref_lock_file_name(const char *ref)
121{
122 char *base = get_refs_directory();
123 int baselen = strlen(base);
124 int reflen = strlen(ref);
125 char *ret = xmalloc(baselen + 7 + reflen);
126 sprintf(ret, "%s/%s.lock", base, ref);
127 return ret;
128}
129
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DB
130int get_ref_sha1(const char *ref, unsigned char *sha1)
131{
ca8db142
LT
132 const char *filename;
133
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DB
134 if (check_ref_format(ref))
135 return -1;
ca8db142
LT
136 filename = git_path("refs/%s", ref);
137 return read_ref(filename, sha1);
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DB
138}
139
140static int lock_ref_file(const char *filename, const char *lock_filename,
141 const unsigned char *old_sha1)
142{
143 int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
144 unsigned char current_sha1[20];
145 int retval;
146 if (fd < 0) {
147 return error("Couldn't open lock file for %s: %s",
148 filename, strerror(errno));
149 }
ca8db142 150 retval = read_ref(filename, current_sha1);
95fc7512
DB
151 if (old_sha1) {
152 if (retval) {
153 close(fd);
154 unlink(lock_filename);
155 return error("Could not read the current value of %s",
156 filename);
157 }
158 if (memcmp(current_sha1, old_sha1, 20)) {
159 close(fd);
160 unlink(lock_filename);
161 error("The current value of %s is %s",
162 filename, sha1_to_hex(current_sha1));
163 return error("Expected %s",
164 sha1_to_hex(old_sha1));
165 }
166 } else {
167 if (!retval) {
168 close(fd);
169 unlink(lock_filename);
170 return error("Unexpectedly found a value of %s for %s",
171 sha1_to_hex(current_sha1), filename);
172 }
173 }
174 return fd;
175}
176
177int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
178{
179 char *filename;
180 char *lock_filename;
181 int retval;
182 if (check_ref_format(ref))
183 return -1;
184 filename = ref_file_name(ref);
185 lock_filename = ref_lock_file_name(ref);
186 retval = lock_ref_file(filename, lock_filename, old_sha1);
187 free(filename);
188 free(lock_filename);
189 return retval;
190}
191
192static int write_ref_file(const char *filename,
193 const char *lock_filename, int fd,
194 const unsigned char *sha1)
195{
196 char *hex = sha1_to_hex(sha1);
197 char term = '\n';
198 if (write(fd, hex, 40) < 40 ||
199 write(fd, &term, 1) < 1) {
200 error("Couldn't write %s\n", filename);
201 close(fd);
202 return -1;
203 }
204 close(fd);
205 rename(lock_filename, filename);
206 return 0;
207}
208
209int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
210{
211 char *filename;
212 char *lock_filename;
213 int retval;
214 if (fd < 0)
215 return -1;
216 if (check_ref_format(ref))
217 return -1;
218 filename = ref_file_name(ref);
219 lock_filename = ref_lock_file_name(ref);
220 retval = write_ref_file(filename, lock_filename, fd, sha1);
221 free(filename);
222 free(lock_filename);
223 return retval;
224}
225
226int check_ref_format(const char *ref)
227{
228 char *middle;
229 if (ref[0] == '.' || ref[0] == '/')
230 return -1;
231 middle = strchr(ref, '/');
232 if (!middle || !middle[1])
233 return -1;
234 if (strchr(middle + 1, '/'))
235 return -1;
236 return 0;
237}
238
239int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
240{
241 char *filename;
242 char *lock_filename;
243 int fd;
244 int retval;
245 if (check_ref_format(ref))
246 return -1;
247 filename = ref_file_name(ref);
248 lock_filename = ref_lock_file_name(ref);
249 fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
250 if (fd < 0) {
251 error("Writing %s", lock_filename);
252 perror("Open");
253 }
254 retval = write_ref_file(filename, lock_filename, fd, sha1);
255 free(filename);
256 free(lock_filename);
257 return retval;
258}