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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 2006 Gabriel Somlo <somlo at cmu.edu>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
/* check if path points to an executable file;
* return 1 if found;
* return 0 otherwise;
*/
int FAST_FUNC file_is_executable(const char *name)
{
struct stat s;
return (!access(name, X_OK) && !stat(name, &s) && S_ISREG(s.st_mode));
}
/* search (*PATHp) for an executable file;
* return allocated string containing full path if found;
* PATHp points to the component after the one where it was found
* (or NULL if found in last component),
* you may call find_executable again with this PATHp to continue
* return NULL otherwise (PATHp is undefined)
*/
char* FAST_FUNC find_executable(const char *name, const char **PATHp)
{
/* About empty components in $PATH:
* http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
* 8.3 Other Environment Variables - PATH
* A zero-length prefix is a legacy feature that indicates the current
* working directory. It appears as two adjacent colons ( "::" ), as an
* initial colon preceding the rest of the list, or as a trailing colon
* following the rest of the list.
*/
char *p = (char*) *PATHp;
if (!p)
return NULL;
while (1) {
const char *end = strchrnul(p, ':');
int sz = end - p;
if (sz != 0) {
p = xasprintf("%.*s/%s", sz, p, name);
} else {
/* We have xxx::yyy in $PATH,
* it means "use current dir" */
p = xstrdup(name);
// A bit of discrepancy wrt the path used if file is found here.
// bash 5.2.15 "type" returns "./NAME".
// GNU which v2.21 returns "/CUR/DIR/NAME".
// With -a, both skip over all colons: xxx::::yyy is the same as xxx::yyy,
// current dir is not tried the second time.
}
if (file_is_executable(p)) {
*PATHp = (*end ? end+1 : NULL);
return p;
}
free(p);
if (*end == '\0')
return NULL;
p = (char *) end + 1;
}
}
/* search $PATH for an executable file;
* return 1 if found;
* return 0 otherwise;
*/
int FAST_FUNC executable_exists(const char *name)
{
const char *path = getenv("PATH");
char *ret = find_executable(name, &path);
free(ret);
return ret != NULL;
}
#if ENABLE_FEATURE_PREFER_APPLETS
/* just like the real execvp, but try to launch an applet named 'file' first */
int FAST_FUNC BB_EXECVP(const char *file, char *const argv[])
{
if (find_applet_by_name(file) >= 0)
execvp(bb_busybox_exec_path, argv);
return execvp(file, argv);
}
#endif
void FAST_FUNC BB_EXECVP_or_die(char **argv)
{
BB_EXECVP(argv[0], argv);
/* SUSv3-mandated exit codes */
xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
bb_perror_msg_and_die("can't execute '%s'", argv[0]);
}
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