/* 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), * you may call find_executable again with this PATHp to continue * (if it's not NULL). * return NULL otherwise; (PATHp is undefined) * in all cases (*PATHp) contents are temporarily modified * but are restored on return (s/:/NUL/ and back). */ char* FAST_FUNC find_executable(const char *filename, 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, *n; p = *PATHp; while (p) { int ex; n = strchr(p, ':'); if (n) *n = '\0'; p = concat_path_file( p[0] ? p : ".", /* handle "::" case */ filename ); ex = file_is_executable(p); if (n) *n++ = ':'; if (ex) { *PATHp = n; return p; } free(p); p = n; } /* on loop exit p == NULL */ return p; } /* search $PATH for an executable file; * return 1 if found; * return 0 otherwise; */ int FAST_FUNC executable_exists(const char *filename) { char *path = getenv("PATH"); char *ret = find_executable(filename, &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]); } /* Typical idiom for applets which exec *optional* PROG [ARGS] */ void FAST_FUNC exec_prog_or_SHELL(char **argv) { if (argv[0]) { BB_EXECVP_or_die(argv); } run_shell(getenv("SHELL"), /*login:*/ 1, NULL); }