1 /*
2  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/stat.h>
18 #include <sys/limits.h>
19 
20 #include <string.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <fcntl.h>
24 #include <errno.h>
25 #include <unistd.h>
26 
27 #include "got_error.h"
28 #include "got_repository.h"
29 #include "got_refs.h"
30 #include "got_worktree.h"
31 
32 #include "got_worktree_lib.h"
33 #include "got_path_lib.h"
34 #include "got_sha1_lib.h"
35 
36 static const struct got_error *
37 create_meta_file(const char *path_got, const char *name, const char *content)
38 {
39 	const struct got_error *err = NULL;
40 	char *path;
41 	int fd = -1;
42 	char buf[4];
43 	ssize_t n;
44 
45 	if (asprintf(&path, "%s/%s", path_got, name) == -1) {
46 		err = got_error(GOT_ERR_NO_MEM);
47 		path = NULL;
48 		goto done;
49 	}
50 
51 	fd = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW,
52 	    GOT_DEFAULT_FILE_MODE);
53 	if (fd == -1) {
54 		err = got_error_from_errno();
55 		goto done;
56 	}
57 
58 	/* The file should be empty. */
59 	n = read(fd, buf, sizeof(buf));
60 	if (n != 0) {
61 		err = (n == -1 ? got_error_from_errno() :
62 		    got_error(GOT_ERR_WORKTREE_EXISTS));
63 		goto done;
64 	}
65 
66 	if (content) {
67 		int len = dprintf(fd, "%s\n", content);
68 		if (len != strlen(content) + 1) {
69 			err = got_error_from_errno();
70 			goto done;
71 		}
72 	}
73 
74 done:
75 	if (fd != -1 && close(fd) == -1 && err == NULL)
76 		err = got_error_from_errno();
77 	free(path);
78 	return err;
79 }
80 
81 static const struct got_error *
82 read_meta_file(char **content, const char *path_got, const char *name)
83 {
84 	const struct got_error *err = NULL;
85 	char *path;
86 	int fd = -1;
87 	ssize_t n;
88 	struct stat sb;
89 
90 	*content = NULL;
91 
92 	if (asprintf(&path, "%s/%s", path_got, name) == -1) {
93 		err = got_error(GOT_ERR_NO_MEM);
94 		path = NULL;
95 		goto done;
96 	}
97 
98 	fd = open(path, O_RDONLY | O_NOFOLLOW);
99 	if (fd == -1) {
100 		err = got_error_from_errno();
101 		goto done;
102 	}
103 	if (flock(fd, LOCK_SH | LOCK_NB) == -1) {
104 		err = (errno == EWOULDBLOCK ? got_error(GOT_ERR_WORKTREE_BUSY)
105 		    : got_error_from_errno());
106 		goto done;
107 	}
108 
109 	stat(path, &sb);
110 	*content = calloc(1, sb.st_size);
111 	if (*content == NULL) {
112 		err = got_error(GOT_ERR_NO_MEM);
113 		goto done;
114 	}
115 
116 	n = read(fd, *content, sb.st_size);
117 	if (n != sb.st_size) {
118 		err = (n == -1 ? got_error_from_errno() :
119 		    got_error(GOT_ERR_WORKTREE_META));
120 		goto done;
121 	}
122 	if ((*content)[sb.st_size - 1] != '\n') {
123 		err = got_error(GOT_ERR_WORKTREE_META);
124 		goto done;
125 	}
126 	(*content)[sb.st_size - 1] = '\0';
127 
128 done:
129 	if (fd != -1 && close(fd) == -1 && err == NULL)
130 		err = got_error_from_errno();
131 	free(path);
132 	if (err) {
133 		free(*content);
134 		*content = NULL;
135 	}
136 	return err;
137 }
138 
139 const struct got_error *
140 got_worktree_init(const char *path, struct got_reference *head_ref,
141     const char *prefix, struct got_repository *repo)
142 {
143 	const struct got_error *err = NULL;
144 	char *path_got = NULL;
145 	char *refstr = NULL;
146 	char *repo_path = NULL;
147 	char *formatstr = NULL;
148 
149 	if (!got_path_is_absolute(prefix))
150 		return got_error(GOT_ERR_BAD_PATH);
151 
152 	/* Create top-level directory (may already exist). */
153 	if (mkdir(path, GOT_DEFAULT_DIR_MODE) == -1 && errno != EEXIST) {
154 		err = got_error_from_errno();
155 		goto done;
156 	}
157 
158 	/* Create .got directory (may already exist). */
159 	if (asprintf(&path_got, "%s/%s", path, GOT_WORKTREE_GOT_DIR) == -1) {
160 		err = got_error(GOT_ERR_NO_MEM);
161 		goto done;
162 	}
163 	if (mkdir(path_got, GOT_DEFAULT_DIR_MODE) == -1 && errno != EEXIST) {
164 		err = got_error_from_errno();
165 		goto done;
166 	}
167 
168 	/* Create an empty lock file. */
169 	err = create_meta_file(path_got, GOT_WORKTREE_LOCK, NULL);
170 	if (err)
171 		goto done;
172 
173 	/* Create an empty file index. */
174 	err = create_meta_file(path_got, GOT_WORKTREE_FILE_INDEX, NULL);
175 	if (err)
176 		goto done;
177 
178 	/* Save an invalid base commit hash. */
179 	err = create_meta_file(path_got, GOT_WORKTREE_BASE_COMMIT,
180 		GOT_WORKTREE_INVALID_COMMIT_ID);
181 	if (err)
182 		goto done;
183 
184 	/* Write the HEAD reference. */
185 	refstr = got_ref_to_str(head_ref);
186 	if (refstr == NULL) {
187 		err = got_error(GOT_ERR_NO_MEM);
188 		goto done;
189 	}
190 	err = create_meta_file(path_got, GOT_WORKTREE_HEAD, refstr);
191 	if (err)
192 		goto done;
193 
194 	/* Store path to repository. */
195 	repo_path = got_repo_get_path(repo);
196 	if (repo_path == NULL) {
197 		err = got_error(GOT_ERR_NO_MEM);
198 		goto done;
199 	}
200 	err = create_meta_file(path_got, GOT_WORKTREE_REPOSITORY, repo_path);
201 	if (err)
202 		goto done;
203 
204 	/* Store in-repository path prefix. */
205 	err = create_meta_file(path_got, GOT_WORKTREE_PATH_PREFIX, prefix);
206 	if (err)
207 		goto done;
208 
209 	/* Stamp work tree with format file. */
210 	if (asprintf(&formatstr, "%d", GOT_WORKTREE_FORMAT_VERSION) == -1) {
211 		err = got_error(GOT_ERR_NO_MEM);
212 		goto done;
213 	}
214 	err = create_meta_file(path_got, GOT_WORKTREE_FORMAT, formatstr);
215 	if (err)
216 		goto done;
217 
218 done:
219 	free(path_got);
220 	free(formatstr);
221 	free(refstr);
222 	free(repo_path);
223 	return err;
224 }
225 
226 const struct got_error *
227 got_worktree_open(struct got_worktree **worktree, const char *path)
228 {
229 	const struct got_error *err = NULL;
230 	char *path_got;
231 	char *refstr = NULL;
232 	char *formatstr = NULL;
233 	char *path_lock = NULL;
234 	int version, fd = -1;
235 	const char *errstr;
236 
237 	*worktree = NULL;
238 
239 	if (asprintf(&path_got, "%s/%s", path, GOT_WORKTREE_GOT_DIR) == -1) {
240 		err = got_error(GOT_ERR_NO_MEM);
241 		path_got = NULL;
242 		goto done;
243 	}
244 
245 	if (asprintf(&path_lock, "%s/%s", path_got, GOT_WORKTREE_LOCK) == -1) {
246 		err = got_error(GOT_ERR_NO_MEM);
247 		path_lock = NULL;
248 		goto done;
249 	}
250 
251 	fd = open(path_lock, O_RDWR | O_EXLOCK | O_NONBLOCK);
252 	if (fd == -1) {
253 		err = (errno == EWOULDBLOCK ? got_error(GOT_ERR_WORKTREE_BUSY)
254 		    : got_error_from_errno());
255 		goto done;
256 	}
257 
258 	err = read_meta_file(&formatstr, path_got, GOT_WORKTREE_FORMAT);
259 	if (err)
260 		goto done;
261 
262 	version = strtonum(formatstr, 1, INT_MAX, &errstr);
263 	if (errstr) {
264 		err = got_error(GOT_ERR_WORKTREE_META);
265 		goto done;
266 	}
267 	if (version != GOT_WORKTREE_FORMAT_VERSION) {
268 		err = got_error(GOT_ERR_WORKTREE_VERS);
269 		goto done;
270 	}
271 
272 	*worktree = calloc(1, sizeof(**worktree));
273 	if (*worktree == NULL) {
274 		err = got_error(GOT_ERR_NO_MEM);
275 		goto done;
276 	}
277 	(*worktree)->lockfd = -1;
278 
279 	(*worktree)->root_path = strdup(path);
280 	if ((*worktree)->root_path == NULL) {
281 		err = got_error(GOT_ERR_NO_MEM);
282 		goto done;
283 	}
284 	err = read_meta_file(&(*worktree)->repo_path, path_got,
285 	    GOT_WORKTREE_REPOSITORY);
286 	if (err)
287 		goto done;
288 	err = read_meta_file(&(*worktree)->path_prefix, path_got,
289 	    GOT_WORKTREE_PATH_PREFIX);
290 	if (err)
291 		goto done;
292 
293 	err = read_meta_file(&(*worktree)->base_commit, path_got,
294 	    GOT_WORKTREE_BASE_COMMIT);
295 	if (err)
296 		goto done;
297 
298 	err = read_meta_file(&(*worktree)->head_ref, path_got,
299 	    GOT_WORKTREE_HEAD);
300 	if (err)
301 		goto done;
302 
303 done:
304 	free(path_got);
305 	free(path_lock);
306 	if (err) {
307 		if (fd != -1)
308 			close(fd);
309 		if (*worktree != NULL)
310 			got_worktree_close(*worktree);
311 		*worktree = NULL;
312 	} else
313 		(*worktree)->lockfd = fd;
314 
315 	return err;
316 }
317 
318 void
319 got_worktree_close(struct got_worktree *worktree)
320 {
321 	free(worktree->root_path);
322 	free(worktree->repo_path);
323 	free(worktree->path_prefix);
324 	free(worktree->base_commit);
325 	free(worktree->head_ref);
326 	if (worktree->lockfd != -1)
327 		close(worktree->lockfd);
328 	free(worktree);
329 }
330 
331 char *
332 got_worktree_get_repo_path(struct got_worktree *worktree)
333 {
334 	return strdup(worktree->repo_path);
335 }
336 
337 struct got_reference *
338 got_worktree_get_head(struct got_worktree *worktree)
339 {
340 	return NULL;
341 }
342 
343 const struct got_error *
344 got_worktree_change_head(struct got_worktree *worktree, struct got_reference *head,
345     struct got_repository *repo)
346 {
347 	return NULL;
348 }
349 
350 const struct got_error *
351 got_worktree_checkout_files(struct got_worktree *worktree,
352     struct got_repository *repo)
353 {
354 	return NULL;
355 }