libc: add issetugid()

issetugid() returns 1 if the process environment or memory address space
is considered tainted, and returns 0 otherwise.  This happens, for example,
when a process's privileges are elevated by the setuid or setgid flags on
an executable belonging to root.  This function first appeard in OpenBSD 2.0
and is needed for the LibreSSL.

This patch follows the same logic as the equivalent musl commit.  For more
information see the commit message at

http://git.musl-libc.org/cgit/musl/commit/?id=ddddec106fd17c3aca3287005d21e92f742aa9d4

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/libc/misc/file/issetugid.c b/libc/misc/file/issetugid.c
new file mode 100644
index 000000000..6756a1e85
--- /dev/null
+++ b/libc/misc/file/issetugid.c
@@ -0,0 +1,10 @@
+/* Copyright (C) 2013 Gentoo Foundation
+ * Licensed under LGPL v2.1 or later, see the file COPYING.LIB in this tarball.
+ */
+
+#include <unistd.h>
+
+int issetugid(void)
+{
+	return _pe_secure;
+}