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/types.h>
18 #include <sys/queue.h>
19 
20 #include <sha1.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <util.h>
25 #include <zlib.h>
26 #include <time.h>
27 
28 #include "got_error.h"
29 #include "got_object.h"
30 #include "got_repository.h"
31 #include "got_reference.h"
32 
33 #include "got_lib_sha1.h"
34 #include "got_lib_path.h"
35 #include "got_lib_delta.h"
36 #include "got_lib_inflate.h"
37 #include "got_lib_object.h"
38 
39 #define GOT_REF_HEADS	"heads"
40 #define GOT_REF_TAGS	"tags"
41 #define GOT_REF_REMOTES	"remotes"
42 
43 /* A symbolic reference. */
44 struct got_symref {
45 	char *name;
46 	char *ref;
47 };
48 
49 /* A non-symbolic reference (there is no better designation). */
50 struct got_ref {
51 	char *name;
52 	u_int8_t sha1[SHA1_DIGEST_LENGTH];
53 };
54 
55 /* A reference which points to an arbitrary object. */
56 struct got_reference {
57 	unsigned int flags;
58 #define GOT_REF_IS_SYMBOLIC	0x01
59 
60 	union {
61 		struct got_ref ref;
62 		struct got_symref symref;
63 	} ref;
64 };
65 
66 static const struct got_error *
67 parse_symref(struct got_reference **ref, const char *name, const char *line)
68 {
69 	struct got_symref *symref;
70 	char *symref_name;
71 	char *symref_ref;
72 
73 	if (line[0] == '\0')
74 		return got_error(GOT_ERR_NOT_REF);
75 
76 	symref_name = strdup(name);
77 	if (symref_name == NULL)
78 		return got_error_from_errno();
79 	symref_ref = strdup(line);
80 	if (symref_ref == NULL) {
81 		const struct got_error *err = got_error_from_errno();
82 		free(symref_name);
83 		return err;
84 	}
85 
86 	*ref = calloc(1, sizeof(**ref));
87 	if (*ref == NULL)
88 		return got_error_from_errno();
89 	(*ref)->flags |= GOT_REF_IS_SYMBOLIC;
90 	symref = &((*ref)->ref.symref);
91 	symref->name = symref_name;
92 	symref->ref = symref_ref;
93 	return NULL;
94 }
95 
96 static const struct got_error *
97 parse_ref_line(struct got_reference **ref, const char *name, const char *line)
98 {
99 	uint8_t digest[SHA1_DIGEST_LENGTH];
100 	char *ref_name;
101 
102 	if (strncmp(line, "ref: ", 5) == 0) {
103 		line += 5;
104 		return parse_symref(ref, name, line);
105 	}
106 
107 	ref_name = strdup(name);
108 	if (ref_name == NULL)
109 		return got_error_from_errno();
110 
111 	if (!got_parse_sha1_digest(digest, line))
112 		return got_error(GOT_ERR_NOT_REF);
113 
114 	*ref = calloc(1, sizeof(**ref));
115 	if (*ref == NULL)
116 		return got_error_from_errno();
117 	(*ref)->ref.ref.name = ref_name;
118 	memcpy(&(*ref)->ref.ref.sha1, digest, SHA1_DIGEST_LENGTH);
119 	return NULL;
120 }
121 
122 static const struct got_error *
123 parse_ref_file(struct got_reference **ref, const char *name,
124     const char *abspath)
125 {
126 	const struct got_error *err = NULL;
127 	FILE *f = fopen(abspath, "rb");
128 	char *line;
129 	size_t len;
130 	const char delim[3] = {'\0', '\0', '\0'};
131 
132 	if (f == NULL)
133 		return got_error(GOT_ERR_NOT_REF);
134 
135 	line = fparseln(f, &len, NULL, delim, 0);
136 	if (line == NULL) {
137 		err = got_error(GOT_ERR_NOT_REF);
138 		goto done;
139 	}
140 
141 	err = parse_ref_line(ref, name, line);
142 done:
143 	free(line);
144 	fclose(f);
145 	return err;
146 }
147 
148 static char *
149 get_refs_dir_path(struct got_repository *repo, const char *refname)
150 {
151 	if (strcmp(refname, GOT_REF_HEAD) == 0 ||
152 	    strcmp(refname, GOT_REF_ORIG_HEAD) == 0 ||
153 	    strcmp(refname, GOT_REF_MERGE_HEAD) == 0 ||
154 	    strcmp(refname, GOT_REF_FETCH_HEAD) == 0 ||
155 	    strncmp(refname, "refs/", 5) == 0)
156 		return got_repo_get_path_git_dir(repo);
157 
158 	return got_repo_get_path_refs(repo);
159 }
160 
161 static const struct got_error *
162 open_ref(struct got_reference **ref, const char *path_refs, const char *subdir,
163     const char *refname)
164 {
165 	const struct got_error *err = NULL;
166 	char *path_ref;
167 	char *normpath;
168 
169 	if (asprintf(&path_ref, "%s/%s/%s", path_refs, subdir, refname) == -1)
170 		return got_error_from_errno();
171 
172 	normpath = got_path_normalize(path_ref);
173 	if (normpath == NULL) {
174 		err = got_error(GOT_ERR_NOT_REF);
175 		goto done;
176 	}
177 
178 	err = parse_ref_file(ref, refname, normpath);
179 done:
180 	free(path_ref);
181 	free(normpath);
182 	return err;
183 }
184 
185 const struct got_error *
186 got_ref_open(struct got_reference **ref, struct got_repository *repo,
187    const char *refname)
188 {
189 	const struct got_error *err = NULL;
190 	char *path_refs = get_refs_dir_path(repo, refname);
191 
192 	if (path_refs == NULL) {
193 		err = got_error_from_errno();
194 		goto done;
195 	}
196 	
197 	/* XXX For now, this assumes that refs exist in the filesystem. */
198 
199 	err = open_ref(ref, path_refs, GOT_REF_HEADS, refname);
200 	if (err != NULL)
201 		err = open_ref(ref, path_refs, GOT_REF_TAGS, refname);
202 	if (err != NULL)
203 		err = open_ref(ref, path_refs, GOT_REF_REMOTES, refname);
204 	if (err != NULL)
205 		err = open_ref(ref, path_refs, "", refname);
206 done:
207 	free(path_refs);
208 	return err;
209 }
210 
211 void
212 got_ref_close(struct got_reference *ref)
213 {
214 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
215 		free(ref->ref.symref.name);
216 	else
217 		free(ref->ref.ref.name);
218 	free(ref);
219 }
220 
221 struct got_reference *
222 got_ref_dup(struct got_reference *ref)
223 {
224 	struct got_reference *ret;
225 
226 	ret = calloc(1, sizeof(*ret));
227 	if (ret == NULL)
228 		return NULL;
229 
230 	ret->flags = ref->flags;
231 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
232 		ret->ref.symref.name = strdup(ref->ref.symref.name);
233 		if (ret->ref.symref.name == NULL) {
234 			free(ret);
235 			return NULL;
236 		}
237 		ret->ref.symref.ref = strdup(ref->ref.symref.ref);
238 		if (ret->ref.symref.ref == NULL) {
239 			free(ret->ref.symref.name);
240 			free(ret);
241 			return NULL;
242 		}
243 	} else {
244 		ref->ref.ref.name = strdup(ref->ref.ref.name);
245 		if (ref->ref.ref.name == NULL) {
246 			free(ret);
247 			return NULL;
248 		}
249 		memcpy(ret->ref.ref.sha1, ref->ref.ref.sha1,
250 		    SHA1_DIGEST_LENGTH);
251 	}
252 
253 	return ret;
254 }
255 
256 static const struct got_error *
257 resolve_symbolic_ref(struct got_reference **resolved,
258     struct got_repository *repo, struct got_reference *ref)
259 {
260 	struct got_reference *nextref;
261 	const struct got_error *err;
262 
263 	err = got_ref_open(&nextref, repo, ref->ref.symref.ref);
264 	if (err)
265 		return err;
266 
267 	if (nextref->flags & GOT_REF_IS_SYMBOLIC)
268 		err = resolve_symbolic_ref(resolved, repo, nextref);
269 	else
270 		*resolved = got_ref_dup(nextref);
271 
272 	got_ref_close(nextref);
273 	return err;
274 }
275 
276 const struct got_error *
277 got_ref_resolve(struct got_object_id **id, struct got_repository *repo,
278     struct got_reference *ref)
279 {
280 	const struct got_error *err;
281 
282 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
283 		struct got_reference *resolved = NULL;
284 		err = resolve_symbolic_ref(&resolved, repo, ref);
285 		if (err == NULL)
286 			err = got_ref_resolve(id, repo, resolved);
287 		free(resolved);
288 		return err;
289 	}
290 
291 	*id = calloc(1, sizeof(**id));
292 	if (*id == NULL)
293 		return got_error_from_errno();
294 	memcpy((*id)->sha1, ref->ref.ref.sha1, SHA1_DIGEST_LENGTH);
295 	return NULL;
296 }
297 
298 char *
299 got_ref_to_str(struct got_reference *ref)
300 {
301 	char *str;
302 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
303 		if (asprintf(&str, "ref: %s", ref->ref.symref.ref) == -1)
304 			return NULL;
305 	} else {
306 		str = calloc(1, SHA1_DIGEST_STRING_LENGTH);
307 		if (str == NULL)
308 			return NULL;
309 		str = got_sha1_digest_to_str(ref->ref.ref.sha1, str,
310 		    SHA1_DIGEST_STRING_LENGTH);
311 	}
312 
313 	return str;
314 }