94 lines
2.4 KiB
C
94 lines
2.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) 2006 Gabriel Somlo <somlo at cmu.edu>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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/* check if path points to an executable file;
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* return 1 if found;
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* return 0 otherwise;
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*/
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int FAST_FUNC file_is_executable(const char *name)
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{
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struct stat s;
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return (!access(name, X_OK) && !stat(name, &s) && S_ISREG(s.st_mode));
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}
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/* search (*PATHp) for an executable file;
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* return allocated string containing full path if found;
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* PATHp points to the component after the one where it was found
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* (or NULL),
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* you may call find_executable again with this PATHp to continue
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* (if it's not NULL).
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* return NULL otherwise; (PATHp is undefined)
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* in all cases (*PATHp) contents are temporarily modified
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* but are restored on return (s/:/NUL/ and back).
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*/
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char* FAST_FUNC find_executable(const char *filename, char **PATHp)
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{
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/* About empty components in $PATH:
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* http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
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* 8.3 Other Environment Variables - PATH
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* A zero-length prefix is a legacy feature that indicates the current
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* working directory. It appears as two adjacent colons ( "::" ), as an
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* initial colon preceding the rest of the list, or as a trailing colon
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* following the rest of the list.
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*/
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char *p, *n;
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p = *PATHp;
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while (p) {
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int ex;
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n = strchr(p, ':');
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if (n) *n = '\0';
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p = concat_path_file(
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p[0] ? p : ".", /* handle "::" case */
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filename
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);
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ex = file_is_executable(p);
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if (n) *n++ = ':';
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if (ex) {
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*PATHp = n;
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return p;
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}
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free(p);
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p = n;
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} /* on loop exit p == NULL */
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return p;
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}
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/* search $PATH for an executable file;
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* return 1 if found;
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* return 0 otherwise;
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*/
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int FAST_FUNC executable_exists(const char *filename)
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{
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char *path = getenv("PATH");
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char *ret = find_executable(filename, &path);
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free(ret);
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return ret != NULL;
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}
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#if ENABLE_FEATURE_PREFER_APPLETS
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/* just like the real execvp, but try to launch an applet named 'file' first */
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int FAST_FUNC BB_EXECVP(const char *file, char *const argv[])
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{
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if (find_applet_by_name(file) >= 0)
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execvp(bb_busybox_exec_path, argv);
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return execvp(file, argv);
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}
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#endif
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void FAST_FUNC BB_EXECVP_or_die(char **argv)
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{
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BB_EXECVP(argv[0], argv);
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/* SUSv3-mandated exit codes */
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xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
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bb_perror_msg_and_die("can't execute '%s'", argv[0]);
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}
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