1 /*
2  * Copyright (c) 2018, 2019 Stefan Sperling <stsp@openbsd.org>
3  * Copyright (c) 2015 Theo de Raadt <deraadt@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <limits.h>
19 #include <stdlib.h>
20 #include <unistd.h>
21 #include <stdio.h>
22 #include <string.h>
23 
24 #include "got_error.h"
25 
26 #include "got_lib_path.h"
27 
28 #ifndef MIN
29 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
30 #endif
31 
32 int
33 got_path_is_absolute(const char *path)
34 {
35 	return path[0] == '/';
36 }
37 
38 char *
39 got_path_get_absolute(const char *relpath) 
40 {
41 	char cwd[PATH_MAX];
42 	char *abspath;
43 
44 	if (getcwd(cwd, sizeof(cwd)) == NULL)
45 		return NULL;
46 
47 	if (asprintf(&abspath, "%s/%s/", cwd, relpath) == -1)
48 		return NULL;
49 
50 	return abspath;
51 }
52 
53 char *
54 got_path_normalize(const char *path)
55 {
56 	char *resolved;
57 
58 	resolved = realpath(path, NULL);
59 	if (resolved == NULL)
60 		return NULL;
61 	
62 	if (!got_path_is_absolute(resolved)) {
63 		char *abspath = got_path_get_absolute(resolved);
64 		free(resolved);
65 		resolved = abspath;
66 	}
67 
68 	return resolved;
69 }
70 
71 /* based on canonpath() from kern_pledge.c */
72 const struct got_error *
73 got_canonpath(const char *input, char *buf, size_t bufsize)
74 {
75 	const char *p;
76 	char *q;
77 
78 	/* can't canon relative paths, don't bother */
79 	if (!got_path_is_absolute(input)) {
80 		if (strlcpy(buf, input, bufsize) >= bufsize)
81 			return got_error(GOT_ERR_NO_SPACE);
82 		return NULL;
83 	}
84 
85 	p = input;
86 	q = buf;
87 	while (*p && (q - buf < bufsize)) {
88 		if (p[0] == '/' && (p[1] == '/' || p[1] == '\0')) {
89 			p += 1;
90 
91 		} else if (p[0] == '/' && p[1] == '.' &&
92 		    (p[2] == '/' || p[2] == '\0')) {
93 			p += 2;
94 
95 		} else if (p[0] == '/' && p[1] == '.' && p[2] == '.' &&
96 		    (p[3] == '/' || p[3] == '\0')) {
97 			p += 3;
98 			if (q != buf)	/* "/../" at start of buf */
99 				while (*--q != '/')
100 					continue;
101 
102 		} else {
103 			*q++ = *p++;
104 		}
105 	}
106 	if ((*p == '\0') && (q - buf < bufsize)) {
107 		*q = 0;
108 		return NULL;
109 	} else
110 		return got_error(GOT_ERR_NO_SPACE);
111 }
112 
113 const struct got_error *
114 got_path_skip_common_ancestor(char **child, const char *parent_abspath,
115     const char *abspath)
116 {
117 	const struct got_error *err = NULL;
118 	size_t len_parent, len, bufsize;
119 
120 	len_parent = strlen(parent_abspath);
121 	len = strlen(abspath);
122 	if (len_parent >= len)
123 		return got_error(GOT_ERR_BAD_PATH);
124 	if (strncmp(parent_abspath, abspath, len_parent) != 0)
125 		return got_error(GOT_ERR_BAD_PATH);
126 	if (abspath[len_parent] != '/')
127 		return got_error(GOT_ERR_BAD_PATH);
128 	bufsize = len - len_parent + 1;
129 	*child = malloc(bufsize);
130 	if (*child == NULL)
131 		return got_error_from_errno();
132 	if (strlcpy(*child, abspath + len_parent, bufsize) >= bufsize) {
133 		err = got_error_from_errno();
134 		free(*child);
135 		*child = NULL;
136 		return err;
137 	}
138 	return NULL;
139 }
140 
141 int
142 got_path_is_root_dir(const char *path)
143 {
144 	return (path[0] == '/' && path[1] == '\0');
145 }
146 
147 int
148 got_path_is_child(const char *child, const char *parent, size_t parent_len)
149 {
150 	if (parent_len == 0)
151 		return 1;
152 
153 	if (strncmp(parent, child, parent_len) != 0)
154 		return 0;
155 	if (child[parent_len] != '/')
156 		return 0;
157 
158 	return 1;
159 }
160 
161 int
162 got_path_cmp(const char *path1, const char *path2)
163 {
164 	size_t len1 = strlen(path1);
165 	size_t len2 = strlen(path2);
166 	size_t min_len = MIN(len1, len2);
167 	size_t i = 0;
168 
169 	/* Skip over common prefix. */
170 	while (i < min_len && path1[i] == path2[i])
171 		i++;
172 
173 	/* Are the paths exactly equal? */
174 	if (len1 == len2 && i >= min_len)
175 		return 0;
176 
177 	/* Order children in subdirectories directly after their parents. */
178 	if (path1[i] == '/' && path2[i] == '\0')
179 		return 1;
180 	if (path2[i] == '/' && path1[i] == '\0')
181 		return -1;
182 	if (path1[i] == '/')
183 		return -1;
184 	if (path2[i] == '/')
185 		return 1;
186 
187 	/* Next character following the common prefix determines order. */
188 	return (unsigned char)path1[i] < (unsigned char)path2[i] ? -1 : 1;
189 }