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
8#ifndef USE_SYMLINK_HEAD
10#define USE_SYMLINK_HEAD 1
11#endif
12int validate_symref(const char *path)
14{
15 struct stat st;
16 char *buf, buffer[256];
17 int len, fd;
18 if (lstat(path, &st) < 0)
20 return -1;
21 /* Make sure it is a "refs/.." symlink */
23 if (S_ISLNK(st.st_mode)) {
24 len = readlink(path, buffer, sizeof(buffer)-1);
25 if (len >= 5 && !memcmp("refs/", buffer, 5))
26 return 0;
27 return -1;
28 }
29 /*
31 * Anything else, just open it and try to see if it is a symbolic ref.
32 */
33 fd = open(path, O_RDONLY);
34 if (fd < 0)
35 return -1;
36 len = read(fd, buffer, sizeof(buffer)-1);
37 close(fd);
38 /*
40 * Is it a symbolic ref?
41 */
42 if (len < 4 || memcmp("ref:", buffer, 4))
43 return -1;
44 buf = buffer + 4;
45 len -= 4;
46 while (len && isspace(*buf))
47 buf++, len--;
48 if (len >= 5 && !memcmp("refs/", buf, 5))
49 return 0;
50 return -1;
51}
52const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
54{
55 int depth = MAXDEPTH, len;
56 char buffer[256];
57 for (;;) {
59 struct stat st;
60 char *buf;
61 int fd;
62 if (--depth < 0)
64 return NULL;
65 /* Special case: non-existing file.
67 * Not having the refs/heads/new-branch is OK
68 * if we are writing into it, so is .git/HEAD
69 * that points at refs/heads/master still to be
70 * born. It is NOT OK if we are resolving for
71 * reading.
72 */
73 if (lstat(path, &st) < 0) {
74 if (reading || errno != ENOENT)
75 return NULL;
76 memset(sha1, 0, 20);
77 return path;
78 }
79 /* Follow "normalized" - ie "refs/.." symlinks by hand */
81 if (S_ISLNK(st.st_mode)) {
82 len = readlink(path, buffer, sizeof(buffer)-1);
83 if (len >= 5 && !memcmp("refs/", buffer, 5)) {
84 path = git_path("%.*s", len, buffer);
85 continue;
86 }
87 }
88 /*
90 * Anything else, just open it and try to use it as
91 * a ref
92 */
93 fd = open(path, O_RDONLY);
94 if (fd < 0)
95 return NULL;
96 len = read(fd, buffer, sizeof(buffer)-1);
97 close(fd);
98 /*
100 * Is it a symbolic ref?
101 */
102 if (len < 4 || memcmp("ref:", buffer, 4))
103 break;
104 buf = buffer + 4;
105 len -= 4;
106 while (len && isspace(*buf))
107 buf++, len--;
108 while (len && isspace(buf[len-1]))
109 buf[--len] = 0;
110 path = git_path("%.*s", len, buf);
111 }
112 if (len < 40 || get_sha1_hex(buffer, sha1))
113 return NULL;
114 return path;
115}
116int create_symref(const char *git_HEAD, const char *refs_heads_master)
118{
119#if USE_SYMLINK_HEAD
120 unlink(git_HEAD);
121 return symlink(refs_heads_master, git_HEAD);
122#else
123 const char *lockpath;
124 char ref[1000];
125 int fd, len, written;
126 len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
128 if (sizeof(ref) <= len) {
129 error("refname too long: %s", refs_heads_master);
130 return -1;
131 }
132 lockpath = mkpath("%s.lock", git_HEAD);
133 fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
134 written = write(fd, ref, len);
135 close(fd);
136 if (written != len) {
137 unlink(lockpath);
138 error("Unable to write to %s", lockpath);
139 return -2;
140 }
141 if (rename(lockpath, git_HEAD) < 0) {
142 unlink(lockpath);
143 error("Unable to create %s", git_HEAD);
144 return -3;
145 }
146 return 0;
147#endif
148}
149int read_ref(const char *filename, unsigned char *sha1)
151{
152 if (resolve_ref(filename, sha1, 1))
153 return 0;
154 return -1;
155}
156static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1))
158{
159 int retval = 0;
160 DIR *dir = opendir(git_path("%s", base));
161 if (dir) {
163 struct dirent *de;
164 int baselen = strlen(base);
165 char *path = xmalloc(baselen + 257);
166 if (!strncmp(base, "./", 2)) {
168 base += 2;
169 baselen -= 2;
170 }
171 memcpy(path, base, baselen);
172 if (baselen && base[baselen-1] != '/')
173 path[baselen++] = '/';
174 while ((de = readdir(dir)) != NULL) {
176 unsigned char sha1[20];
177 struct stat st;
178 int namelen;
179 if (de->d_name[0] == '.')
181 continue;
182 namelen = strlen(de->d_name);
183 if (namelen > 255)
184 continue;
185 memcpy(path + baselen, de->d_name, namelen+1);
186 if (stat(git_path("%s", path), &st) < 0)
187 continue;
188 if (S_ISDIR(st.st_mode)) {
189 retval = do_for_each_ref(path, fn);
190 if (retval)
191 break;
192 continue;
193 }
194 if (read_ref(git_path("%s", path), sha1) < 0)
195 continue;
196 if (!has_sha1_file(sha1))
197 continue;
198 retval = fn(path, sha1);
199 if (retval)
200 break;
201 }
202 free(path);
203 closedir(dir);
204 }
205 return retval;
206}
207int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
209{
210 unsigned char sha1[20];
211 if (!read_ref(git_path("HEAD"), sha1))
212 return fn("HEAD", sha1);
213 return 0;
214}
215int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
217{
218 return do_for_each_ref("refs", fn);
219}
220static char *ref_file_name(const char *ref)
222{
223 char *base = get_refs_directory();
224 int baselen = strlen(base);
225 int reflen = strlen(ref);
226 char *ret = xmalloc(baselen + 2 + reflen);
227 sprintf(ret, "%s/%s", base, ref);
228 return ret;
229}
230static char *ref_lock_file_name(const char *ref)
232{
233 char *base = get_refs_directory();
234 int baselen = strlen(base);
235 int reflen = strlen(ref);
236 char *ret = xmalloc(baselen + 7 + reflen);
237 sprintf(ret, "%s/%s.lock", base, ref);
238 return ret;
239}
240int get_ref_sha1(const char *ref, unsigned char *sha1)
242{
243 const char *filename;
244 if (check_ref_format(ref))
246 return -1;
247 filename = git_path("refs/%s", ref);
248 return read_ref(filename, sha1);
249}
250static int lock_ref_file(const char *filename, const char *lock_filename,
252 const unsigned char *old_sha1)
253{
254 int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
255 unsigned char current_sha1[20];
256 int retval;
257 if (fd < 0) {
258 return error("Couldn't open lock file for %s: %s",
259 filename, strerror(errno));
260 }
261 retval = read_ref(filename, current_sha1);
262 if (old_sha1) {
263 if (retval) {
264 close(fd);
265 unlink(lock_filename);
266 return error("Could not read the current value of %s",
267 filename);
268 }
269 if (memcmp(current_sha1, old_sha1, 20)) {
270 close(fd);
271 unlink(lock_filename);
272 error("The current value of %s is %s",
273 filename, sha1_to_hex(current_sha1));
274 return error("Expected %s",
275 sha1_to_hex(old_sha1));
276 }
277 } else {
278 if (!retval) {
279 close(fd);
280 unlink(lock_filename);
281 return error("Unexpectedly found a value of %s for %s",
282 sha1_to_hex(current_sha1), filename);
283 }
284 }
285 return fd;
286}
287int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
289{
290 char *filename;
291 char *lock_filename;
292 int retval;
293 if (check_ref_format(ref))
294 return -1;
295 filename = ref_file_name(ref);
296 lock_filename = ref_lock_file_name(ref);
297 retval = lock_ref_file(filename, lock_filename, old_sha1);
298 free(filename);
299 free(lock_filename);
300 return retval;
301}
302static int write_ref_file(const char *filename,
304 const char *lock_filename, int fd,
305 const unsigned char *sha1)
306{
307 char *hex = sha1_to_hex(sha1);
308 char term = '\n';
309 if (write(fd, hex, 40) < 40 ||
310 write(fd, &term, 1) < 1) {
311 error("Couldn't write %s\n", filename);
312 close(fd);
313 return -1;
314 }
315 close(fd);
316 rename(lock_filename, filename);
317 return 0;
318}
319int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
321{
322 char *filename;
323 char *lock_filename;
324 int retval;
325 if (fd < 0)
326 return -1;
327 if (check_ref_format(ref))
328 return -1;
329 filename = ref_file_name(ref);
330 lock_filename = ref_lock_file_name(ref);
331 retval = write_ref_file(filename, lock_filename, fd, sha1);
332 free(filename);
333 free(lock_filename);
334 return retval;
335}
336/*
338 * Make sure "ref" is something reasonable to have under ".git/refs/";
339 * We do not like it if:
340 *
341 * - any path component of it begins with ".", or
342 * - it has double dots "..", or
343 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
344 * - it ends with a "/".
345 */
346static inline int bad_ref_char(int ch)
348{
349 return (((unsigned) ch) <= ' ' ||
350 ch == '~' || ch == '^' || ch == ':');
351}
352int check_ref_format(const char *ref)
354{
355 int ch, level;
356 const char *cp = ref;
357 level = 0;
359 while (1) {
360 while ((ch = *cp++) == '/')
361 ; /* tolerate duplicated slashes */
362 if (!ch)
363 return -1; /* should not end with slashes */
364 /* we are at the beginning of the path component */
366 if (ch == '.' || bad_ref_char(ch))
367 return -1;
368 /* scan the rest of the path component */
370 while ((ch = *cp++) != 0) {
371 if (bad_ref_char(ch))
372 return -1;
373 if (ch == '/')
374 break;
375 if (ch == '.' && *cp == '.')
376 return -1;
377 }
378 level++;
379 if (!ch) {
380 if (level < 2)
381 return -1; /* at least of form "heads/blah" */
382 return 0;
383 }
384 }
385}
386int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
388{
389 char *filename;
390 char *lock_filename;
391 int fd;
392 int retval;
393 if (check_ref_format(ref))
394 return -1;
395 filename = ref_file_name(ref);
396 lock_filename = ref_lock_file_name(ref);
397 fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
398 if (fd < 0) {
399 error("Writing %s", lock_filename);
400 perror("Open");
401 }
402 retval = write_ref_file(filename, lock_filename, fd, sha1);
403 free(filename);
404 free(lock_filename);
405 return retval;
406}