36972fd6df63b3c4eebdcf89238df8ade60d53c3
[git/git.git] / path.c
1 /*
2 * I'm tired of doing "vsnprintf()" etc just to open a
3 * file, so here's a "return static buffer with printf"
4 * interface for paths.
5 *
6 * It's obviously not thread-safe. Sue me. But it's quite
7 * useful for doing things like
8 *
9 * f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
10 *
11 * which is what it's designed for.
12 */
13 #include "cache.h"
14 #include <pwd.h>
15
16 static char pathname[PATH_MAX];
17 static char bad_path[] = "/bad-path/";
18
19 static char *cleanup_path(char *path)
20 {
21 /* Clean it up */
22 if (!memcmp(path, "./", 2)) {
23 path += 2;
24 while (*path == '/')
25 path++;
26 }
27 return path;
28 }
29
30 char *mkpath(const char *fmt, ...)
31 {
32 va_list args;
33 unsigned len;
34
35 va_start(args, fmt);
36 len = vsnprintf(pathname, PATH_MAX, fmt, args);
37 va_end(args);
38 if (len >= PATH_MAX)
39 return bad_path;
40 return cleanup_path(pathname);
41 }
42
43 char *git_path(const char *fmt, ...)
44 {
45 const char *git_dir = get_git_dir();
46 va_list args;
47 unsigned len;
48
49 len = strlen(git_dir);
50 if (len > PATH_MAX-100)
51 return bad_path;
52 memcpy(pathname, git_dir, len);
53 if (len && git_dir[len-1] != '/')
54 pathname[len++] = '/';
55 va_start(args, fmt);
56 len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
57 va_end(args);
58 if (len >= PATH_MAX)
59 return bad_path;
60 return cleanup_path(pathname);
61 }
62
63
64 /* git_mkstemp() - create tmp file honoring TMPDIR variable */
65 int git_mkstemp(char *path, size_t len, const char *template)
66 {
67 char *env, *pch = path;
68
69 if ((env = getenv("TMPDIR")) == NULL) {
70 strcpy(pch, "/tmp/");
71 len -= 5;
72 pch += 5;
73 } else {
74 size_t n = snprintf(pch, len, "%s/", env);
75
76 len -= n;
77 pch += n;
78 }
79
80 safe_strncpy(pch, template, len);
81
82 return mkstemp(path);
83 }
84
85
86 size_t safe_strncpy(char *dest, const char *src, size_t size)
87 {
88 size_t ret = strlen(src);
89
90 if (size) {
91 size_t len = (ret >= size) ? size - 1 : ret;
92 memcpy(dest, src, len);
93 dest[len] = '\0';
94 }
95 return ret;
96 }
97
98
99 int validate_symref(const char *path)
100 {
101 struct stat st;
102 char *buf, buffer[256];
103 int len, fd;
104
105 if (lstat(path, &st) < 0)
106 return -1;
107
108 /* Make sure it is a "refs/.." symlink */
109 if (S_ISLNK(st.st_mode)) {
110 len = readlink(path, buffer, sizeof(buffer)-1);
111 if (len >= 5 && !memcmp("refs/", buffer, 5))
112 return 0;
113 return -1;
114 }
115
116 /*
117 * Anything else, just open it and try to see if it is a symbolic ref.
118 */
119 fd = open(path, O_RDONLY);
120 if (fd < 0)
121 return -1;
122 len = read(fd, buffer, sizeof(buffer)-1);
123 close(fd);
124
125 /*
126 * Is it a symbolic ref?
127 */
128 if (len < 4 || memcmp("ref:", buffer, 4))
129 return -1;
130 buf = buffer + 4;
131 len -= 4;
132 while (len && isspace(*buf))
133 buf++, len--;
134 if (len >= 5 && !memcmp("refs/", buf, 5))
135 return 0;
136 return -1;
137 }
138
139 static char *user_path(char *buf, char *path, int sz)
140 {
141 struct passwd *pw;
142 char *slash;
143 int len, baselen;
144
145 if (!path || path[0] != '~')
146 return NULL;
147 path++;
148 slash = strchr(path, '/');
149 if (path[0] == '/' || !path[0]) {
150 pw = getpwuid(getuid());
151 }
152 else {
153 if (slash) {
154 *slash = 0;
155 pw = getpwnam(path);
156 *slash = '/';
157 }
158 else
159 pw = getpwnam(path);
160 }
161 if (!pw || !pw->pw_dir || sz <= strlen(pw->pw_dir))
162 return NULL;
163 baselen = strlen(pw->pw_dir);
164 memcpy(buf, pw->pw_dir, baselen);
165 while ((1 < baselen) && (buf[baselen-1] == '/')) {
166 buf[baselen-1] = 0;
167 baselen--;
168 }
169 if (slash && slash[1]) {
170 len = strlen(slash);
171 if (sz <= baselen + len)
172 return NULL;
173 memcpy(buf + baselen, slash, len + 1);
174 }
175 return buf;
176 }
177
178 /*
179 * First, one directory to try is determined by the following algorithm.
180 *
181 * (0) If "strict" is given, the path is used as given and no DWIM is
182 * done. Otherwise:
183 * (1) "~/path" to mean path under the running user's home directory;
184 * (2) "~user/path" to mean path under named user's home directory;
185 * (3) "relative/path" to mean cwd relative directory; or
186 * (4) "/absolute/path" to mean absolute directory.
187 *
188 * Unless "strict" is given, we try access() for existence of "%s.git/.git",
189 * "%s/.git", "%s.git", "%s" in this order. The first one that exists is
190 * what we try.
191 *
192 * Second, we try chdir() to that. Upon failure, we return NULL.
193 *
194 * Then, we try if the current directory is a valid git repository.
195 * Upon failure, we return NULL.
196 *
197 * If all goes well, we return the directory we used to chdir() (but
198 * before ~user is expanded), avoiding getcwd() resolving symbolic
199 * links. User relative paths are also returned as they are given,
200 * except DWIM suffixing.
201 */
202 char *enter_repo(char *path, int strict)
203 {
204 static char used_path[PATH_MAX];
205 static char validated_path[PATH_MAX];
206
207 if (!path)
208 return NULL;
209
210 if (!strict) {
211 static const char *suffix[] = {
212 ".git/.git", "/.git", ".git", "", NULL,
213 };
214 int len = strlen(path);
215 int i;
216 while ((1 < len) && (path[len-1] == '/')) {
217 path[len-1] = 0;
218 len--;
219 }
220 if (PATH_MAX <= len)
221 return NULL;
222 if (path[0] == '~') {
223 if (!user_path(used_path, path, PATH_MAX))
224 return NULL;
225 strcpy(validated_path, path);
226 path = used_path;
227 }
228 else if (PATH_MAX - 10 < len)
229 return NULL;
230 else {
231 path = strcpy(used_path, path);
232 strcpy(validated_path, path);
233 }
234 len = strlen(path);
235 for (i = 0; suffix[i]; i++) {
236 strcpy(path + len, suffix[i]);
237 if (!access(path, F_OK)) {
238 strcat(validated_path, suffix[i]);
239 break;
240 }
241 }
242 if (!suffix[i] || chdir(path))
243 return NULL;
244 path = validated_path;
245 }
246 else if (chdir(path))
247 return NULL;
248
249 if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
250 validate_symref("HEAD") == 0) {
251 putenv("GIT_DIR=.");
252 check_repository_format();
253 return path;
254 }
255
256 return NULL;
257 }
258
259 int adjust_shared_perm(const char *path)
260 {
261 struct stat st;
262 int mode;
263
264 if (!shared_repository)
265 return 0;
266 if (lstat(path, &st) < 0)
267 return -1;
268 mode = st.st_mode;
269 if (mode & S_IRUSR)
270 mode |= (shared_repository == PERM_GROUP
271 ? S_IRGRP
272 : (shared_repository == PERM_EVERYBODY
273 ? (S_IRGRP|S_IROTH)
274 : 0));
275
276 if (mode & S_IWUSR)
277 mode |= S_IWGRP;
278
279 if (mode & S_IXUSR)
280 mode |= (shared_repository == PERM_GROUP
281 ? S_IXGRP
282 : (shared_repository == PERM_EVERYBODY
283 ? (S_IXGRP|S_IXOTH)
284 : 0));
285 if (S_ISDIR(mode))
286 mode |= S_ISGID;
287 if (chmod(path, mode) < 0)
288 return -2;
289 return 0;
290 }