1 files changed, 92 insertions, 0 deletions
diff --git a/libbb/executable.c b/libbb/executable.c
new file mode 100644
index 0000000..85ecc3e
--- /dev/null
+++ b/libbb/executable.c
@@ -0,0 +1,92 @@
+/* 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 will be trashed (s/:/NUL/).
+ */
+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) {
+		n = strchr(p, ':');
+		if (n)
+			*n++ = '\0';
+		p = concat_path_file(
+			p[0] ? p : ".", /* handle "::" case */
+			filename
+		);
+		if (file_is_executable(p)) {
+			*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 = xstrdup(getenv("PATH"));
+	char *tmp = path;
+	char *ret = find_executable(filename, &tmp);
+	free(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
+
+int 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]);
+}