1 files changed, 50 insertions, 0 deletions
diff --git a/util.c b/util.c
new file mode 100644
index 0000000..e0f6177
--- /dev/null
+++ b/util.c
@@ -0,0 +1,50 @@
+/*********************************************************************
+ * bfs                                                               *
+ * Copyright (C) 2016 Tavian Barnes <tavianator@tavianator.com>      *
+ *                                                                   *
+ * This program is free software. It comes without any warranty, to  *
+ * the extent permitted by applicable law. You can redistribute it   *
+ * and/or modify it under the terms of the Do What The Fuck You Want *
+ * To Public License, Version 2, as published by Sam Hocevar. See    *
+ * the COPYING file or http://www.wtfpl.net/ for more details.       *
+ *********************************************************************/
+
+#include "util.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <stdarg.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+bool isopen(int fd) {
+	return fcntl(fd, F_GETFD) >= 0 || errno != EBADF;
+}
+
+int redirect(int fd, const char *path, int flags, ...) {
+	close(fd);
+
+	mode_t mode = 0;
+	if (flags & O_CREAT) {
+		va_list args;
+		va_start(args, flags);
+
+		// Use int rather than mode_t, because va_arg must receive a
+		// fully-promoted type
+		mode = va_arg(args, int);
+
+		va_end(args);
+	}
+
+	int ret = open(path, flags, mode);
+
+	if (ret >= 0 && ret != fd) {
+		int other = ret;
+		ret = dup2(other, fd);
+		if (close(other) != 0) {
+			ret = -1;
+		}
+	}
+
+	return ret;
+}