Add a conversion tool to migrate remote information into the config
[git.git] / refs.c
1 #include "refs.h"
2 #include "cache.h"
3
4 #include <errno.h>
5
6 /* We allow "recursive" symbolic refs. Only within reason, though */
7 #define MAXDEPTH 5
8
9 const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
10 {
11         int depth = MAXDEPTH, len;
12         char buffer[256];
13
14         for (;;) {
15                 struct stat st;
16                 char *buf;
17                 int fd;
18
19                 if (--depth < 0)
20                         return NULL;
21
22                 /* Special case: non-existing file.
23                  * Not having the refs/heads/new-branch is OK
24                  * if we are writing into it, so is .git/HEAD
25                  * that points at refs/heads/master still to be
26                  * born.  It is NOT OK if we are resolving for
27                  * reading.
28                  */
29                 if (lstat(path, &st) < 0) {
30                         if (reading || errno != ENOENT)
31                                 return NULL;
32                         memset(sha1, 0, 20);
33                         return path;
34                 }
35
36                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
37                 if (S_ISLNK(st.st_mode)) {
38                         len = readlink(path, buffer, sizeof(buffer)-1);
39                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
40                                 path = git_path("%.*s", len, buffer);
41                                 continue;
42                         }
43                 }
44
45                 /*
46                  * Anything else, just open it and try to use it as
47                  * a ref
48                  */
49                 fd = open(path, O_RDONLY);
50                 if (fd < 0)
51                         return NULL;
52                 len = read(fd, buffer, sizeof(buffer)-1);
53                 close(fd);
54
55                 /*
56                  * Is it a symbolic ref?
57                  */
58                 if (len < 4 || memcmp("ref:", buffer, 4))
59                         break;
60                 buf = buffer + 4;
61                 len -= 4;
62                 while (len && isspace(*buf))
63                         buf++, len--;
64                 while (len && isspace(buf[len-1]))
65                         buf[--len] = 0;
66                 path = git_path("%.*s", len, buf);
67         }
68         if (len < 40 || get_sha1_hex(buffer, sha1))
69                 return NULL;
70         return path;
71 }
72
73 int create_symref(const char *git_HEAD, const char *refs_heads_master)
74 {
75         const char *lockpath;
76         char ref[1000];
77         int fd, len, written;
78
79 #ifndef NO_SYMLINK_HEAD
80         if (prefer_symlink_refs) {
81                 unlink(git_HEAD);
82                 if (!symlink(refs_heads_master, git_HEAD))
83                         return 0;
84                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
85         }
86 #endif
87
88         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
89         if (sizeof(ref) <= len) {
90                 error("refname too long: %s", refs_heads_master);
91                 return -1;
92         }
93         lockpath = mkpath("%s.lock", git_HEAD);
94         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666); 
95         written = write(fd, ref, len);
96         close(fd);
97         if (written != len) {
98                 unlink(lockpath);
99                 error("Unable to write to %s", lockpath);
100                 return -2;
101         }
102         if (rename(lockpath, git_HEAD) < 0) {
103                 unlink(lockpath);
104                 error("Unable to create %s", git_HEAD);
105                 return -3;
106         }
107         return 0;
108 }
109
110 int read_ref(const char *filename, unsigned char *sha1)
111 {
112         if (resolve_ref(filename, sha1, 1))
113                 return 0;
114         return -1;
115 }
116
117 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1))
118 {
119         int retval = 0;
120         DIR *dir = opendir(git_path("%s", base));
121
122         if (dir) {
123                 struct dirent *de;
124                 int baselen = strlen(base);
125                 char *path = xmalloc(baselen + 257);
126
127                 if (!strncmp(base, "./", 2)) {
128                         base += 2;
129                         baselen -= 2;
130                 }
131                 memcpy(path, base, baselen);
132                 if (baselen && base[baselen-1] != '/')
133                         path[baselen++] = '/';
134
135                 while ((de = readdir(dir)) != NULL) {
136                         unsigned char sha1[20];
137                         struct stat st;
138                         int namelen;
139
140                         if (de->d_name[0] == '.')
141                                 continue;
142                         namelen = strlen(de->d_name);
143                         if (namelen > 255)
144                                 continue;
145                         memcpy(path + baselen, de->d_name, namelen+1);
146                         if (stat(git_path("%s", path), &st) < 0)
147                                 continue;
148                         if (S_ISDIR(st.st_mode)) {
149                                 retval = do_for_each_ref(path, fn);
150                                 if (retval)
151                                         break;
152                                 continue;
153                         }
154                         if (read_ref(git_path("%s", path), sha1) < 0) {
155                                 error("%s points nowhere!", path);
156                                 continue;
157                         }
158                         if (!has_sha1_file(sha1)) {
159                                 error("%s does not point to a valid "
160                                       "commit object!", path);
161                                 continue;
162                         }
163                         retval = fn(path, sha1);
164                         if (retval)
165                                 break;
166                 }
167                 free(path);
168                 closedir(dir);
169         }
170         return retval;
171 }
172
173 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
174 {
175         unsigned char sha1[20];
176         if (!read_ref(git_path("HEAD"), sha1))
177                 return fn("HEAD", sha1);
178         return 0;
179 }
180
181 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
182 {
183         return do_for_each_ref("refs", fn);
184 }
185
186 static char *ref_file_name(const char *ref)
187 {
188         char *base = get_refs_directory();
189         int baselen = strlen(base);
190         int reflen = strlen(ref);
191         char *ret = xmalloc(baselen + 2 + reflen);
192         sprintf(ret, "%s/%s", base, ref);
193         return ret;
194 }
195
196 static char *ref_lock_file_name(const char *ref)
197 {
198         char *base = get_refs_directory();
199         int baselen = strlen(base);
200         int reflen = strlen(ref);
201         char *ret = xmalloc(baselen + 7 + reflen);
202         sprintf(ret, "%s/%s.lock", base, ref);
203         return ret;
204 }
205
206 int get_ref_sha1(const char *ref, unsigned char *sha1)
207 {
208         const char *filename;
209
210         if (check_ref_format(ref))
211                 return -1;
212         filename = git_path("refs/%s", ref);
213         return read_ref(filename, sha1);
214 }
215
216 static int lock_ref_file(const char *filename, const char *lock_filename,
217                          const unsigned char *old_sha1)
218 {
219         int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
220         unsigned char current_sha1[20];
221         int retval;
222         if (fd < 0) {
223                 return error("Couldn't open lock file for %s: %s",
224                              filename, strerror(errno));
225         }
226         retval = read_ref(filename, current_sha1);
227         if (old_sha1) {
228                 if (retval) {
229                         close(fd);
230                         unlink(lock_filename);
231                         return error("Could not read the current value of %s",
232                                      filename);
233                 }
234                 if (memcmp(current_sha1, old_sha1, 20)) {
235                         close(fd);
236                         unlink(lock_filename);
237                         error("The current value of %s is %s",
238                               filename, sha1_to_hex(current_sha1));
239                         return error("Expected %s",
240                                      sha1_to_hex(old_sha1));
241                 }
242         } else {
243                 if (!retval) {
244                         close(fd);
245                         unlink(lock_filename);
246                         return error("Unexpectedly found a value of %s for %s",
247                                      sha1_to_hex(current_sha1), filename);
248                 }
249         }
250         return fd;
251 }
252
253 int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
254 {
255         char *filename;
256         char *lock_filename;
257         int retval;
258         if (check_ref_format(ref))
259                 return -1;
260         filename = ref_file_name(ref);
261         lock_filename = ref_lock_file_name(ref);
262         retval = lock_ref_file(filename, lock_filename, old_sha1);
263         free(filename);
264         free(lock_filename);
265         return retval;
266 }
267
268 static int write_ref_file(const char *filename,
269                           const char *lock_filename, int fd,
270                           const unsigned char *sha1)
271 {
272         char *hex = sha1_to_hex(sha1);
273         char term = '\n';
274         if (write(fd, hex, 40) < 40 ||
275             write(fd, &term, 1) < 1) {
276                 error("Couldn't write %s", filename);
277                 close(fd);
278                 return -1;
279         }
280         close(fd);
281         rename(lock_filename, filename);
282         return 0;
283 }
284
285 int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
286 {
287         char *filename;
288         char *lock_filename;
289         int retval;
290         if (fd < 0)
291                 return -1;
292         if (check_ref_format(ref))
293                 return -1;
294         filename = ref_file_name(ref);
295         lock_filename = ref_lock_file_name(ref);
296         if (safe_create_leading_directories(filename))
297                 die("unable to create leading directory for %s", filename);
298         retval = write_ref_file(filename, lock_filename, fd, sha1);
299         free(filename);
300         free(lock_filename);
301         return retval;
302 }
303
304 /*
305  * Make sure "ref" is something reasonable to have under ".git/refs/";
306  * We do not like it if:
307  *
308  * - any path component of it begins with ".", or
309  * - it has double dots "..", or
310  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
311  * - it ends with a "/".
312  */
313
314 static inline int bad_ref_char(int ch)
315 {
316         return (((unsigned) ch) <= ' ' ||
317                 ch == '~' || ch == '^' || ch == ':' ||
318                 /* 2.13 Pattern Matching Notation */
319                 ch == '?' || ch == '*' || ch == '[');
320 }
321
322 int check_ref_format(const char *ref)
323 {
324         int ch, level;
325         const char *cp = ref;
326
327         level = 0;
328         while (1) {
329                 while ((ch = *cp++) == '/')
330                         ; /* tolerate duplicated slashes */
331                 if (!ch)
332                         return -1; /* should not end with slashes */
333
334                 /* we are at the beginning of the path component */
335                 if (ch == '.' || bad_ref_char(ch))
336                         return -1;
337
338                 /* scan the rest of the path component */
339                 while ((ch = *cp++) != 0) {
340                         if (bad_ref_char(ch))
341                                 return -1;
342                         if (ch == '/')
343                                 break;
344                         if (ch == '.' && *cp == '.')
345                                 return -1;
346                 }
347                 level++;
348                 if (!ch) {
349                         if (level < 2)
350                                 return -1; /* at least of form "heads/blah" */
351                         return 0;
352                 }
353         }
354 }
355
356 int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
357 {
358         char *filename;
359         char *lock_filename;
360         int fd;
361         int retval;
362         if (check_ref_format(ref))
363                 return -1;
364         filename = ref_file_name(ref);
365         lock_filename = ref_lock_file_name(ref);
366         if (safe_create_leading_directories(filename))
367                 die("unable to create leading directory for %s", filename);
368         fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
369         if (fd < 0) {
370                 error("Writing %s", lock_filename);
371                 perror("Open");
372         }
373         retval = write_ref_file(filename, lock_filename, fd, sha1);
374         free(filename);
375         free(lock_filename);
376         return retval;
377 }