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 #include "libbb.h"
10
11 /* check if path points to an executable file;
12 * return 1 if found;
13 * return 0 otherwise;
14 */
file_is_executable(const char * name)15 int FAST_FUNC file_is_executable(const char *name)
16 {
17 struct stat s;
18 return (!access(name, X_OK) && !stat(name, &s) && S_ISREG(s.st_mode));
19 }
20
21 /* search (*PATHp) for an executable file;
22 * return allocated string containing full path if found;
23 * PATHp points to the component after the one where it was found
24 * (or NULL),
25 * you may call find_executable again with this PATHp to continue
26 * (if it's not NULL).
27 * return NULL otherwise; (PATHp is undefined)
28 * in all cases (*PATHp) contents are temporarily modified
29 * but are restored on return (s/:/NUL/ and back).
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 int ex;
46
47 n = strchr(p, ':');
48 if (n) *n = '\0';
49 p = concat_path_file(
50 p[0] ? p : ".", /* handle "::" case */
51 filename
52 );
53 ex = file_is_executable(p);
54 if (n) *n++ = ':';
55 if (ex) {
56 *PATHp = n;
57 return p;
58 }
59 free(p);
60 p = n;
61 } /* on loop exit p == NULL */
62 return p;
63 }
64
65 /* search $PATH for an executable file;
66 * return 1 if found;
67 * return 0 otherwise;
68 */
executable_exists(const char * filename)69 int FAST_FUNC executable_exists(const char *filename)
70 {
71 char *path = getenv("PATH");
72 char *ret = find_executable(filename, &path);
73 free(ret);
74 return ret != NULL;
75 }
76
77 #if ENABLE_FEATURE_PREFER_APPLETS
78 /* just like the real execvp, but try to launch an applet named 'file' first */
BB_EXECVP(const char * file,char * const argv[])79 int FAST_FUNC BB_EXECVP(const char *file, char *const argv[])
80 {
81 if (find_applet_by_name(file) >= 0)
82 execvp(bb_busybox_exec_path, argv);
83 return execvp(file, argv);
84 }
85 #endif
86
BB_EXECVP_or_die(char ** argv)87 void FAST_FUNC BB_EXECVP_or_die(char **argv)
88 {
89 BB_EXECVP(argv[0], argv);
90 /* SUSv3-mandated exit codes */
91 xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
92 bb_perror_msg_and_die("can't execute '%s'", argv[0]);
93 }
94