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