1 /*
2  * Copyright (c) 2017 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 <sha1.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <util.h>
23 #include <limits.h>
24 #include <errno.h>
25 
26 #include "got_error.h"
27 #include "got_object.h"
28 #include "got_repository.h"
29 #include "got_refs.h"
30 
31 #include "path.h"
32 
33 
34 static const struct got_error *
35 parse_symref(struct got_reference **ref, const char *name, const char *line)
36 {
37 	struct got_symref *symref;
38 	char *symref_name;
39 	char *symref_ref;
40 
41 	if (line[0] == '\0')
42 		return got_error(GOT_ERR_NOT_REF);
43 
44 	symref_name = strdup(name);
45 	if (symref_name == NULL)
46 		return got_error(GOT_ERR_NO_MEM);
47 	symref_ref = strdup(line);
48 	if (symref_ref == NULL) {
49 		free(symref_name);
50 		return got_error(GOT_ERR_NO_MEM);
51 	}
52 
53 	*ref = calloc(1, sizeof(**ref));
54 	(*ref)->flags |= GOT_REF_IS_SYMBOLIC;
55 	symref = &((*ref)->ref.symref);
56 	symref->name = symref_name;
57 	symref->ref = symref_ref;
58 	return NULL;
59 }
60 
61 static int
62 parse_xdigit(uint8_t *val, const char *hex)
63 {
64 	char *ep;
65 	long lval;
66 
67 	errno = 0;
68 	lval = strtol(hex, &ep, 16);
69 	if (hex[0] == '\0' || *ep != '\0')
70 		return 0;
71 	if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
72 		return 0;
73 
74 	*val = (uint8_t)lval;
75 	return 1;
76 }
77 
78 static int
79 parse_sha1_digest(uint8_t *digest, const char *line)
80 {
81 	uint8_t b = 0;
82 	char hex[3] = {'\0', '\0', '\0'};
83 	int i, j;
84 
85 	for (i = 0; i < SHA1_DIGEST_LENGTH; i++) {
86 		if (line[0] == '\0' || line[1] == '\0')
87 			return 0;
88 		for (j = 0; j < 2; j++) {
89 			hex[j] = *line;
90 			line++;
91 		}
92 		if (!parse_xdigit(&b, hex))
93 			return 0;
94 		digest[i] = b;
95 	}
96 
97 	return 1;
98 }
99 
100 static const struct got_error *
101 parse_ref_line(struct got_reference **ref, const char *name, const char *line)
102 {
103 	uint8_t digest[SHA1_DIGEST_LENGTH];
104 	char *ref_name;
105 
106 	if (strncmp(line, "ref: ", 5) == 0) {
107 		line += 5;
108 		return parse_symref(ref, name, line);
109 	}
110 
111 	ref_name = strdup(name);
112 	if (ref_name == NULL)
113 		return got_error(GOT_ERR_NO_MEM);
114 
115 	if (!parse_sha1_digest(digest, line))
116 		return got_error(GOT_ERR_NOT_REF);
117 
118 	*ref = calloc(1, sizeof(**ref));
119 	(*ref)->ref.ref.name = ref_name;
120 	memcpy(&(*ref)->ref.ref.sha1, digest, SHA1_DIGEST_LENGTH);
121 	return NULL;
122 }
123 
124 static const struct got_error *
125 parse_ref_file(struct got_reference **ref, const char *name,
126     const char *abspath)
127 {
128 	const struct got_error *err = NULL;
129 	FILE *f = fopen(abspath, "rb");
130 	char *line;
131 	size_t len;
132 	const char delim[3] = {'\0', '\0', '\0'};
133 
134 	if (f == NULL)
135 		return got_error(GOT_ERR_NOT_REF);
136 
137 	line = fparseln(f, &len, NULL, delim, 0);
138 	if (line == NULL) {
139 		err = got_error(GOT_ERR_NOT_REF);
140 		goto done;
141 	}
142 
143 	err = parse_ref_line(ref, name, line);
144 done:
145 	free(line);
146 	fclose(f);
147 	return err;
148 }
149 
150 static char *
151 get_refs_dir_path(struct got_repository *repo, const char *refname)
152 {
153 	if (strcmp(refname, GOT_REF_HEAD) == 0 ||
154 	    strcmp(refname, GOT_REF_ORIG_HEAD) == 0 ||
155 	    strcmp(refname, GOT_REF_MERGE_HEAD) == 0 ||
156 	    strcmp(refname, GOT_REF_FETCH_HEAD) == 0 ||
157 	    strncmp(refname, "refs/", 5) == 0)
158 		return got_repo_get_path_git_dir(repo);
159 
160 	return got_repo_get_path_refs(repo);
161 }
162 
163 const struct got_error *
164 got_ref_open(struct got_reference **ref, struct got_repository *repo,
165    const char *refname)
166 {
167 	const struct got_error *err = NULL;
168 	char *path_ref = NULL;
169 	char *normpath = NULL;
170 	const char *parent_dir;
171 	char *path_refs = get_refs_dir_path(repo, refname);
172 
173 	if (path_refs == NULL) {
174 		err = got_error(GOT_ERR_NO_MEM);
175 		goto done;
176 	}
177 	
178 	/* XXX For now, this assumes that refs exist in the filesystem. */
179 
180 	if (asprintf(&path_ref, "%s/%s", path_refs, refname) == -1) {
181 		err = got_error(GOT_ERR_NO_MEM);
182 		goto done;
183 	}
184 
185 	normpath = got_path_normalize(path_ref);
186 	if (normpath == NULL) {
187 		err = got_error(GOT_ERR_NOT_REF);
188 		goto done;
189 	}
190 
191 	err = parse_ref_file(ref, refname, normpath);
192 done:
193 	free(normpath);
194 	free(path_ref);
195 	free(path_refs);
196 	return err;
197 }
198 
199 void
200 got_ref_close(struct got_reference *ref)
201 {
202 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
203 		free(ref->ref.symref.name);
204 	else
205 		free(ref->ref.ref.name);
206 	free(ref);
207 }
208 
209 struct got_reference *
210 got_ref_dup(struct got_reference *ref)
211 {
212 	struct got_reference *ret = calloc(1, sizeof(*ret));
213 	char *name = NULL;
214 	char *symref = NULL;
215 
216 	if (ret == NULL)
217 		return NULL;
218 
219 	ret->flags = ref->flags;
220 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
221 		ret->ref.symref.name = strdup(ref->ref.symref.name);
222 		if (ret->ref.symref.name == NULL) {
223 			free(ret);
224 			return NULL;
225 		}
226 		ret->ref.symref.ref = strdup(ref->ref.symref.ref);
227 		if (ret->ref.symref.ref == NULL) {
228 			free(ret->ref.symref.name);
229 			free(ret);
230 			return NULL;
231 		}
232 	} else {
233 		ref->ref.ref.name = strdup(ref->ref.ref.name);
234 		if (ref->ref.ref.name == NULL) {
235 			free(ret);
236 			return NULL;
237 		}
238 		memcpy(ret->ref.ref.sha1, ref->ref.ref.sha1,
239 		    SHA1_DIGEST_LENGTH);
240 	}
241 
242 	return ret;
243 }
244 
245 static const struct got_error *
246 resolve_symbolic_ref(struct got_reference **resolved,
247     struct got_repository *repo, struct got_reference *ref)
248 {
249 	struct got_reference *nextref;
250 	const struct got_error *err;
251 
252 	err = got_ref_open(&nextref, repo, ref->ref.symref.ref);
253 	if (err)
254 		return err;
255 
256 	if (nextref->flags & GOT_REF_IS_SYMBOLIC)
257 		err = resolve_symbolic_ref(resolved, repo, nextref);
258 	else
259 		*resolved = got_ref_dup(nextref);
260 
261 	got_ref_close(nextref);
262 	return err;
263 }
264 
265 const struct got_error *
266 got_ref_resolve(struct got_object_id **id, struct got_repository *repo,
267     struct got_reference *ref)
268 {
269 	const struct got_error *err;
270 
271 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
272 		struct got_reference *resolved = NULL;
273 		err = resolve_symbolic_ref(&resolved, repo, ref);
274 		if (err == NULL)
275 			err = got_ref_resolve(id, repo, resolved);
276 		free(resolved);
277 		return err;
278 	}
279 
280 	*id = calloc(1, sizeof(**id));
281 	if (*id == NULL)
282 		return got_error(GOT_ERR_NO_MEM);
283 	memcpy((*id)->sha1, ref->ref.ref.sha1, SHA1_DIGEST_LENGTH);
284 	return NULL;
285 }