1/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
4 *
5 * Copyright (C) 2006 Gabriel Somlo <somlo at cmu.edu>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
8 */
9
10#include "libbb.h"
11
12/* check if path points to an executable file;
13 * return 1 if found;
14 * return 0 otherwise;
15 */
16int FAST_FUNC execable_file(const char *name)
17{
18	struct stat s;
19	return (!access(name, X_OK) && !stat(name, &s) && S_ISREG(s.st_mode));
20}
21
22/* search (*PATHp) for an executable file;
23 * return allocated string containing full path if found;
24 *  PATHp points to the component after the one where it was found
25 *  (or NULL),
26 *  you may call find_execable again with this PATHp to continue
27 *  (if it's not NULL).
28 * return NULL otherwise; (PATHp is undefined)
29 * in all cases (*PATHp) contents will be trashed (s/:/NUL/).
30 */
31char* FAST_FUNC find_execable(const char *filename, char **PATHp)
32{
33	char *p, *n;
34
35	p = *PATHp;
36	while (p) {
37		n = strchr(p, ':');
38		if (n)
39			*n++ = '\0';
40		if (*p != '\0') { /* it's not a PATH="foo::bar" situation */
41			p = concat_path_file(p, filename);
42			if (execable_file(p)) {
43				*PATHp = n;
44				return p;
45			}
46			free(p);
47		}
48		p = n;
49	} /* on loop exit p == NULL */
50	return p;
51}
52
53/* search $PATH for an executable file;
54 * return 1 if found;
55 * return 0 otherwise;
56 */
57int FAST_FUNC exists_execable(const char *filename)
58{
59	char *path = xstrdup(getenv("PATH"));
60	char *tmp = path;
61	char *ret = find_execable(filename, &tmp);
62	free(path);
63	if (ret) {
64		free(ret);
65		return 1;
66	}
67	return 0;
68}
69
70#if ENABLE_FEATURE_PREFER_APPLETS
71/* just like the real execvp, but try to launch an applet named 'file' first
72 */
73int FAST_FUNC bb_execvp(const char *file, char *const argv[])
74{
75	return execvp(find_applet_by_name(file) >= 0 ? bb_busybox_exec_path : file,
76					argv);
77}
78#endif
79
80int FAST_FUNC BB_EXECVP_or_die(char **argv)
81{
82	BB_EXECVP(argv[0], argv);
83	/* SUSv3-mandated exit codes */
84	xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
85	bb_perror_msg_and_die("can't execute '%s'", argv[0]);
86}
87