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 source tree.
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 */
file_is_executable(const char * name)16 int FAST_FUNC file_is_executable(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_executable 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 */
find_executable(const char * filename,char ** PATHp)31 char* FAST_FUNC find_executable(const char *filename, char **PATHp)
32 {
33 /* About empty components in $PATH:
34 * http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
35 * 8.3 Other Environment Variables - PATH
36 * A zero-length prefix is a legacy feature that indicates the current
37 * working directory. It appears as two adjacent colons ( "::" ), as an
38 * initial colon preceding the rest of the list, or as a trailing colon
39 * following the rest of the list.
40 */
41 char *p, *n;
42
43 p = *PATHp;
44 while (p) {
45 n = strchr(p, ':');
46 if (n)
47 *n++ = '\0';
48 p = concat_path_file(
49 p[0] ? p : ".", /* handle "::" case */
50 filename
51 );
52 if (file_is_executable(p)) {
53 *PATHp = n;
54 return p;
55 }
56 free(p);
57 p = n;
58 } /* on loop exit p == NULL */
59 return p;
60 }
61
62 /* search $PATH for an executable file;
63 * return 1 if found;
64 * return 0 otherwise;
65 */
executable_exists(const char * filename)66 int FAST_FUNC executable_exists(const char *filename)
67 {
68 char *path = xstrdup(getenv("PATH"));
69 char *tmp = path;
70 char *ret = find_executable(filename, &tmp);
71 free(path);
72 free(ret);
73 return ret != NULL;
74 }
75
76 #if ENABLE_FEATURE_PREFER_APPLETS
77 /* just like the real execvp, but try to launch an applet named 'file' first */
BB_EXECVP(const char * file,char * const argv[])78 int FAST_FUNC BB_EXECVP(const char *file, char *const argv[])
79 {
80 if (find_applet_by_name(file) >= 0)
81 execvp(bb_busybox_exec_path, argv);
82 return execvp(file, argv);
83 }
84 #endif
85
BB_EXECVP_or_die(char ** argv)86 void FAST_FUNC BB_EXECVP_or_die(char **argv)
87 {
88 BB_EXECVP(argv[0], argv);
89 /* SUSv3-mandated exit codes */
90 xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
91 bb_perror_msg_and_die("can't execute '%s'", argv[0]);
92 }
93
94 /* Typical idiom for applets which exec *optional* PROG [ARGS] */
exec_prog_or_SHELL(char ** argv)95 void FAST_FUNC exec_prog_or_SHELL(char **argv)
96 {
97 if (argv[0]) {
98 BB_EXECVP_or_die(argv);
99 }
100 run_shell(getenv("SHELL"), /*login:*/ 1, NULL);
101 }
102