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_refs.h"
31 
32 #include "got_sha1_priv.h"
33 #include "got_path_priv.h"
34 #include "got_delta_priv.h"
35 #include "got_zb_priv.h"
36 #include "got_object_priv.h"
37 
38 /* A symbolic reference. */
39 struct got_symref {
40 	char *name;
41 	char *ref;
42 };
43 
44 /* A non-symbolic reference (there is no better designation). */
45 struct got_ref {
46 	char *name;
47 	u_int8_t sha1[SHA1_DIGEST_LENGTH];
48 };
49 
50 /* A reference which points to an arbitrary object. */
51 struct got_reference {
52 	unsigned int flags;
53 #define GOT_REF_IS_SYMBOLIC	0x01
54 
55 	union {
56 		struct got_ref ref;
57 		struct got_symref symref;
58 	} ref;
59 };
60 
61 static const struct got_error *
62 parse_symref(struct got_reference **ref, const char *name, const char *line)
63 {
64 	struct got_symref *symref;
65 	char *symref_name;
66 	char *symref_ref;
67 
68 	if (line[0] == '\0')
69 		return got_error(GOT_ERR_NOT_REF);
70 
71 	symref_name = strdup(name);
72 	if (symref_name == NULL)
73 		return got_error(GOT_ERR_NO_MEM);
74 	symref_ref = strdup(line);
75 	if (symref_ref == NULL) {
76 		free(symref_name);
77 		return got_error(GOT_ERR_NO_MEM);
78 	}
79 
80 	*ref = calloc(1, sizeof(**ref));
81 	if (*ref == NULL)
82 		return got_error(GOT_ERR_NO_MEM);
83 	(*ref)->flags |= GOT_REF_IS_SYMBOLIC;
84 	symref = &((*ref)->ref.symref);
85 	symref->name = symref_name;
86 	symref->ref = symref_ref;
87 	return NULL;
88 }
89 
90 static const struct got_error *
91 parse_ref_line(struct got_reference **ref, const char *name, const char *line)
92 {
93 	uint8_t digest[SHA1_DIGEST_LENGTH];
94 	char *ref_name;
95 
96 	if (strncmp(line, "ref: ", 5) == 0) {
97 		line += 5;
98 		return parse_symref(ref, name, line);
99 	}
100 
101 	ref_name = strdup(name);
102 	if (ref_name == NULL)
103 		return got_error(GOT_ERR_NO_MEM);
104 
105 	if (!got_parse_sha1_digest(digest, line))
106 		return got_error(GOT_ERR_NOT_REF);
107 
108 	*ref = calloc(1, sizeof(**ref));
109 	if (*ref == NULL)
110 		return got_error(GOT_ERR_NO_MEM);
111 	(*ref)->ref.ref.name = ref_name;
112 	memcpy(&(*ref)->ref.ref.sha1, digest, SHA1_DIGEST_LENGTH);
113 	return NULL;
114 }
115 
116 static const struct got_error *
117 parse_ref_file(struct got_reference **ref, const char *name,
118     const char *abspath)
119 {
120 	const struct got_error *err = NULL;
121 	FILE *f = fopen(abspath, "rb");
122 	char *line;
123 	size_t len;
124 	const char delim[3] = {'\0', '\0', '\0'};
125 
126 	if (f == NULL)
127 		return got_error(GOT_ERR_NOT_REF);
128 
129 	line = fparseln(f, &len, NULL, delim, 0);
130 	if (line == NULL) {
131 		err = got_error(GOT_ERR_NOT_REF);
132 		goto done;
133 	}
134 
135 	err = parse_ref_line(ref, name, line);
136 done:
137 	free(line);
138 	fclose(f);
139 	return err;
140 }
141 
142 static char *
143 get_refs_dir_path(struct got_repository *repo, const char *refname)
144 {
145 	if (strcmp(refname, GOT_REF_HEAD) == 0 ||
146 	    strcmp(refname, GOT_REF_ORIG_HEAD) == 0 ||
147 	    strcmp(refname, GOT_REF_MERGE_HEAD) == 0 ||
148 	    strcmp(refname, GOT_REF_FETCH_HEAD) == 0 ||
149 	    strncmp(refname, "refs/", 5) == 0)
150 		return got_repo_get_path_git_dir(repo);
151 
152 	return got_repo_get_path_refs(repo);
153 }
154 
155 const struct got_error *
156 got_ref_open(struct got_reference **ref, struct got_repository *repo,
157    const char *refname)
158 {
159 	const struct got_error *err = NULL;
160 	char *path_ref = NULL;
161 	char *normpath = NULL;
162 	const char *parent_dir;
163 	char *path_refs = get_refs_dir_path(repo, refname);
164 
165 	if (path_refs == NULL) {
166 		err = got_error(GOT_ERR_NO_MEM);
167 		goto done;
168 	}
169 	
170 	/* XXX For now, this assumes that refs exist in the filesystem. */
171 
172 	if (asprintf(&path_ref, "%s/%s", path_refs, refname) == -1) {
173 		err = got_error(GOT_ERR_NO_MEM);
174 		goto done;
175 	}
176 
177 	normpath = got_path_normalize(path_ref);
178 	if (normpath == NULL) {
179 		err = got_error(GOT_ERR_NOT_REF);
180 		goto done;
181 	}
182 
183 	err = parse_ref_file(ref, refname, normpath);
184 done:
185 	free(normpath);
186 	free(path_ref);
187 	free(path_refs);
188 	return err;
189 }
190 
191 void
192 got_ref_close(struct got_reference *ref)
193 {
194 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
195 		free(ref->ref.symref.name);
196 	else
197 		free(ref->ref.ref.name);
198 	free(ref);
199 }
200 
201 struct got_reference *
202 got_ref_dup(struct got_reference *ref)
203 {
204 	struct got_reference *ret;
205 	char *name = NULL;
206 	char *symref = NULL;
207 
208 	ret = calloc(1, sizeof(*ret));
209 	if (ret == NULL)
210 		return NULL;
211 
212 	ret->flags = ref->flags;
213 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
214 		ret->ref.symref.name = strdup(ref->ref.symref.name);
215 		if (ret->ref.symref.name == NULL) {
216 			free(ret);
217 			return NULL;
218 		}
219 		ret->ref.symref.ref = strdup(ref->ref.symref.ref);
220 		if (ret->ref.symref.ref == NULL) {
221 			free(ret->ref.symref.name);
222 			free(ret);
223 			return NULL;
224 		}
225 	} else {
226 		ref->ref.ref.name = strdup(ref->ref.ref.name);
227 		if (ref->ref.ref.name == NULL) {
228 			free(ret);
229 			return NULL;
230 		}
231 		memcpy(ret->ref.ref.sha1, ref->ref.ref.sha1,
232 		    SHA1_DIGEST_LENGTH);
233 	}
234 
235 	return ret;
236 }
237 
238 static const struct got_error *
239 resolve_symbolic_ref(struct got_reference **resolved,
240     struct got_repository *repo, struct got_reference *ref)
241 {
242 	struct got_reference *nextref;
243 	const struct got_error *err;
244 
245 	err = got_ref_open(&nextref, repo, ref->ref.symref.ref);
246 	if (err)
247 		return err;
248 
249 	if (nextref->flags & GOT_REF_IS_SYMBOLIC)
250 		err = resolve_symbolic_ref(resolved, repo, nextref);
251 	else
252 		*resolved = got_ref_dup(nextref);
253 
254 	got_ref_close(nextref);
255 	return err;
256 }
257 
258 const struct got_error *
259 got_ref_resolve(struct got_object_id **id, struct got_repository *repo,
260     struct got_reference *ref)
261 {
262 	const struct got_error *err;
263 
264 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
265 		struct got_reference *resolved = NULL;
266 		err = resolve_symbolic_ref(&resolved, repo, ref);
267 		if (err == NULL)
268 			err = got_ref_resolve(id, repo, resolved);
269 		free(resolved);
270 		return err;
271 	}
272 
273 	*id = calloc(1, sizeof(**id));
274 	if (*id == NULL)
275 		return got_error(GOT_ERR_NO_MEM);
276 	memcpy((*id)->sha1, ref->ref.ref.sha1, SHA1_DIGEST_LENGTH);
277 	return NULL;
278 }
279 
280 char *
281 got_ref_to_str(struct got_reference *ref)
282 {
283 	char *str;
284 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
285 		if (asprintf(&str, "ref: %s", ref->ref.symref.ref) == -1)
286 			return NULL;
287 	} else {
288 		str = calloc(1, SHA1_DIGEST_STRING_LENGTH);
289 		if (str == NULL)
290 			return NULL;
291 		str = got_sha1_digest_to_str(ref->ref.ref.sha1, str,
292 		    SHA1_DIGEST_STRING_LENGTH);
293 	}
294 
295 	return str;
296 }