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_lib.h"
33 #include "got_path_lib.h"
34 #include "got_delta_lib.h"
35 #include "got_zbuf_lib.h"
36 #include "got_object_lib.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 	char *path_refs = get_refs_dir_path(repo, refname);
163 
164 	if (path_refs == NULL) {
165 		err = got_error(GOT_ERR_NO_MEM);
166 		goto done;
167 	}
168 	
169 	/* XXX For now, this assumes that refs exist in the filesystem. */
170 
171 	if (asprintf(&path_ref, "%s/%s", path_refs, refname) == -1) {
172 		err = got_error(GOT_ERR_NO_MEM);
173 		goto done;
174 	}
175 
176 	normpath = got_path_normalize(path_ref);
177 	if (normpath == NULL) {
178 		err = got_error(GOT_ERR_NOT_REF);
179 		goto done;
180 	}
181 
182 	err = parse_ref_file(ref, refname, normpath);
183 done:
184 	free(normpath);
185 	free(path_ref);
186 	free(path_refs);
187 	return err;
188 }
189 
190 void
191 got_ref_close(struct got_reference *ref)
192 {
193 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
194 		free(ref->ref.symref.name);
195 	else
196 		free(ref->ref.ref.name);
197 	free(ref);
198 }
199 
200 struct got_reference *
201 got_ref_dup(struct got_reference *ref)
202 {
203 	struct got_reference *ret;
204 
205 	ret = calloc(1, sizeof(*ret));
206 	if (ret == NULL)
207 		return NULL;
208 
209 	ret->flags = ref->flags;
210 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
211 		ret->ref.symref.name = strdup(ref->ref.symref.name);
212 		if (ret->ref.symref.name == NULL) {
213 			free(ret);
214 			return NULL;
215 		}
216 		ret->ref.symref.ref = strdup(ref->ref.symref.ref);
217 		if (ret->ref.symref.ref == NULL) {
218 			free(ret->ref.symref.name);
219 			free(ret);
220 			return NULL;
221 		}
222 	} else {
223 		ref->ref.ref.name = strdup(ref->ref.ref.name);
224 		if (ref->ref.ref.name == NULL) {
225 			free(ret);
226 			return NULL;
227 		}
228 		memcpy(ret->ref.ref.sha1, ref->ref.ref.sha1,
229 		    SHA1_DIGEST_LENGTH);
230 	}
231 
232 	return ret;
233 }
234 
235 static const struct got_error *
236 resolve_symbolic_ref(struct got_reference **resolved,
237     struct got_repository *repo, struct got_reference *ref)
238 {
239 	struct got_reference *nextref;
240 	const struct got_error *err;
241 
242 	err = got_ref_open(&nextref, repo, ref->ref.symref.ref);
243 	if (err)
244 		return err;
245 
246 	if (nextref->flags & GOT_REF_IS_SYMBOLIC)
247 		err = resolve_symbolic_ref(resolved, repo, nextref);
248 	else
249 		*resolved = got_ref_dup(nextref);
250 
251 	got_ref_close(nextref);
252 	return err;
253 }
254 
255 const struct got_error *
256 got_ref_resolve(struct got_object_id **id, struct got_repository *repo,
257     struct got_reference *ref)
258 {
259 	const struct got_error *err;
260 
261 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
262 		struct got_reference *resolved = NULL;
263 		err = resolve_symbolic_ref(&resolved, repo, ref);
264 		if (err == NULL)
265 			err = got_ref_resolve(id, repo, resolved);
266 		free(resolved);
267 		return err;
268 	}
269 
270 	*id = calloc(1, sizeof(**id));
271 	if (*id == NULL)
272 		return got_error(GOT_ERR_NO_MEM);
273 	memcpy((*id)->sha1, ref->ref.ref.sha1, SHA1_DIGEST_LENGTH);
274 	return NULL;
275 }
276 
277 char *
278 got_ref_to_str(struct got_reference *ref)
279 {
280 	char *str;
281 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
282 		if (asprintf(&str, "ref: %s", ref->ref.symref.ref) == -1)
283 			return NULL;
284 	} else {
285 		str = calloc(1, SHA1_DIGEST_STRING_LENGTH);
286 		if (str == NULL)
287 			return NULL;
288 		str = got_sha1_digest_to_str(ref->ref.ref.sha1, str,
289 		    SHA1_DIGEST_STRING_LENGTH);
290 	}
291 
292 	return str;
293 }