1#include "refs.h"
2#include "cache.h"
3#include <errno.h>
5/* We allow "recursive" symbolic refs. Only within reason, though */
7#define MAXDEPTH 5
8const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
10{
11 int depth = MAXDEPTH, len;
12 char buffer[256];
13 for (;;) {
15 struct stat st;
16 char *buf;
17 int fd;
18 if (--depth < 0)
20 return NULL;
21 /* 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 /* 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 /*
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 /*
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}
72int 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#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 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}
109int read_ref(const char *filename, unsigned char *sha1)
111{
112 if (resolve_ref(filename, sha1, 1))
113 return 0;
114 return -1;
115}
116static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
118{
119 int retval = 0;
120 DIR *dir = opendir(git_path("%s", base));
121 if (dir) {
123 struct dirent *de;
124 int baselen = strlen(base);
125 char *path = xmalloc(baselen + 257);
126 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 while ((de = readdir(dir)) != NULL) {
136 unsigned char sha1[20];
137 struct stat st;
138 int namelen;
139 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, trim);
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 + trim, sha1);
164 if (retval)
165 break;
166 }
167 free(path);
168 closedir(dir);
169 }
170 return retval;
171}
172int 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}
180int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
182{
183 return do_for_each_ref("refs", fn, 0);
184}
185int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
187{
188 return do_for_each_ref("refs/tags", fn, 10);
189}
190int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
192{
193 return do_for_each_ref("refs/heads", fn, 11);
194}
195int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
197{
198 return do_for_each_ref("refs/remotes", fn, 13);
199}
200static char *ref_file_name(const char *ref)
202{
203 char *base = get_refs_directory();
204 int baselen = strlen(base);
205 int reflen = strlen(ref);
206 char *ret = xmalloc(baselen + 2 + reflen);
207 sprintf(ret, "%s/%s", base, ref);
208 return ret;
209}
210static char *ref_lock_file_name(const char *ref)
212{
213 char *base = get_refs_directory();
214 int baselen = strlen(base);
215 int reflen = strlen(ref);
216 char *ret = xmalloc(baselen + 7 + reflen);
217 sprintf(ret, "%s/%s.lock", base, ref);
218 return ret;
219}
220int get_ref_sha1(const char *ref, unsigned char *sha1)
222{
223 if (check_ref_format(ref))
224 return -1;
225 return read_ref(git_path("refs/%s", ref), sha1);
226}
227static int lock_ref_file(const char *filename, const char *lock_filename,
229 const unsigned char *old_sha1)
230{
231 int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
232 unsigned char current_sha1[20];
233 int retval;
234 if (fd < 0) {
235 return error("Couldn't open lock file for %s: %s",
236 filename, strerror(errno));
237 }
238 retval = read_ref(filename, current_sha1);
239 if (old_sha1) {
240 if (retval) {
241 close(fd);
242 unlink(lock_filename);
243 return error("Could not read the current value of %s",
244 filename);
245 }
246 if (memcmp(current_sha1, old_sha1, 20)) {
247 close(fd);
248 unlink(lock_filename);
249 error("The current value of %s is %s",
250 filename, sha1_to_hex(current_sha1));
251 return error("Expected %s",
252 sha1_to_hex(old_sha1));
253 }
254 } else {
255 if (!retval) {
256 close(fd);
257 unlink(lock_filename);
258 return error("Unexpectedly found a value of %s for %s",
259 sha1_to_hex(current_sha1), filename);
260 }
261 }
262 return fd;
263}
264int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
266{
267 char *filename;
268 char *lock_filename;
269 int retval;
270 if (check_ref_format(ref))
271 return -1;
272 filename = ref_file_name(ref);
273 lock_filename = ref_lock_file_name(ref);
274 retval = lock_ref_file(filename, lock_filename, old_sha1);
275 free(filename);
276 free(lock_filename);
277 return retval;
278}
279static int write_ref_file(const char *filename,
281 const char *lock_filename, int fd,
282 const unsigned char *sha1)
283{
284 char *hex = sha1_to_hex(sha1);
285 char term = '\n';
286 if (write(fd, hex, 40) < 40 ||
287 write(fd, &term, 1) < 1) {
288 error("Couldn't write %s", filename);
289 close(fd);
290 return -1;
291 }
292 close(fd);
293 rename(lock_filename, filename);
294 return 0;
295}
296int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
298{
299 char *filename;
300 char *lock_filename;
301 int retval;
302 if (fd < 0)
303 return -1;
304 if (check_ref_format(ref))
305 return -1;
306 filename = ref_file_name(ref);
307 lock_filename = ref_lock_file_name(ref);
308 if (safe_create_leading_directories(filename))
309 die("unable to create leading directory for %s", filename);
310 retval = write_ref_file(filename, lock_filename, fd, sha1);
311 free(filename);
312 free(lock_filename);
313 return retval;
314}
315/*
317 * Make sure "ref" is something reasonable to have under ".git/refs/";
318 * We do not like it if:
319 *
320 * - any path component of it begins with ".", or
321 * - it has double dots "..", or
322 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
323 * - it ends with a "/".
324 */
325static inline int bad_ref_char(int ch)
327{
328 return (((unsigned) ch) <= ' ' ||
329 ch == '~' || ch == '^' || ch == ':' ||
330 /* 2.13 Pattern Matching Notation */
331 ch == '?' || ch == '*' || ch == '[');
332}
333int check_ref_format(const char *ref)
335{
336 int ch, level;
337 const char *cp = ref;
338 level = 0;
340 while (1) {
341 while ((ch = *cp++) == '/')
342 ; /* tolerate duplicated slashes */
343 if (!ch)
344 return -1; /* should not end with slashes */
345 /* we are at the beginning of the path component */
347 if (ch == '.' || bad_ref_char(ch))
348 return -1;
349 /* scan the rest of the path component */
351 while ((ch = *cp++) != 0) {
352 if (bad_ref_char(ch))
353 return -1;
354 if (ch == '/')
355 break;
356 if (ch == '.' && *cp == '.')
357 return -1;
358 }
359 level++;
360 if (!ch) {
361 if (level < 2)
362 return -1; /* at least of form "heads/blah" */
363 return 0;
364 }
365 }
366}
367int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
369{
370 char *filename;
371 char *lock_filename;
372 int fd;
373 int retval;
374 if (check_ref_format(ref))
375 return -1;
376 filename = ref_file_name(ref);
377 lock_filename = ref_lock_file_name(ref);
378 if (safe_create_leading_directories(filename))
379 die("unable to create leading directory for %s", filename);
380 fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
381 if (fd < 0) {
382 error("Writing %s", lock_filename);
383 perror("Open");
384 }
385 retval = write_ref_file(filename, lock_filename, fd, sha1);
386 free(filename);
387 free(lock_filename);
388 return retval;
389}