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