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1 office 1 /**
2 * @file find_program.h
3 * @author Ambroz Bizjak <ambrop7@gmail.com>
4 *
5 * @section LICENSE
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the author nor the
15 * names of its contributors may be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * @section DESCRIPTION
30 *
31 * Function that finds the absolute path of a program by checking a predefined
32 * list of directories.
33 */
34  
35 #ifndef BADVPN_FIND_PROGRAM_H
36 #define BADVPN_FIND_PROGRAM_H
37  
38 #include <stdlib.h>
39 #include <unistd.h>
40 #include <string.h>
41  
42 #include <misc/concat_strings.h>
43 #include <misc/debug.h>
44 #include <misc/balloc.h>
45  
46 static char * badvpn_find_program (const char *name);
47  
48 static char * badvpn_find_program (const char *name)
49 {
50 ASSERT(name)
51  
52 char *path = getenv("PATH");
53 if (path) {
54 while (1) {
55 size_t i = 0;
56 while (path[i] != ':' && path[i] != '\0') {
57 i++;
58 }
59 char const *src = path;
60 size_t src_len = i;
61 if (src_len == 0) {
62 src = ".";
63 src_len = 1;
64 }
65 size_t name_len = strlen(name);
66 char *entry = BAllocSize(bsize_add(bsize_fromsize(src_len), bsize_add(bsize_fromsize(name_len), bsize_fromsize(2))));
67 if (!entry) {
68 goto fail;
69 }
70 memcpy(entry, src, src_len);
71 entry[src_len] = '/';
72 strcpy(entry + (src_len + 1), name);
73 if (access(entry, X_OK) == 0) {
74 return entry;
75 }
76 free(entry);
77 if (path[i] == '\0') {
78 break;
79 }
80 path += i + 1;
81 }
82 }
83  
84 const char *dirs[] = {"/usr/sbin", "/usr/bin", "/sbin", "/bin", NULL};
85  
86 for (size_t i = 0; dirs[i]; i++) {
87 char *try_path = concat_strings(3, dirs[i], "/", name);
88 if (!try_path) {
89 goto fail;
90 }
91  
92 if (access(try_path, X_OK) == 0) {
93 return try_path;
94 }
95  
96 free(try_path);
97 }
98  
99 fail:
100 return NULL;
101 }
102  
103 #endif