Externals: Add libLZMA.

Externals/liblzma/tuklib/tuklib_open_stdxxx.c

@@ -0,0 +1,57 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       tuklib_open_stdxxx.c
+/// \brief      Make sure that file descriptors 0, 1, and 2 are open
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "tuklib_open_stdxxx.h"
+
+#ifndef TUKLIB_DOSLIKE
+#	include <stdlib.h>
+#	include <errno.h>
+#	include <fcntl.h>
+#	include <unistd.h>
+#endif
+
+
+extern void
+tuklib_open_stdxxx(int err_status)
+{
+#ifdef TUKLIB_DOSLIKE
+	// Do nothing, just silence warnings.
+	(void)err_status;
+
+#else
+	for (int i = 0; i <= 2; ++i) {
+		// We use fcntl() to check if the file descriptor is open.
+		if (fcntl(i, F_GETFD) == -1 && errno == EBADF) {
+			// With stdin, we could use /dev/full so that
+			// writing to stdin would fail. However, /dev/full
+			// is Linux specific, and if the program tries to
+			// write to stdin, there's already a problem anyway.
+			const int fd = open("/dev/null", O_NOCTTY
+					| (i == 0 ? O_WRONLY : O_RDONLY));
+
+			if (fd != i) {
+				if (fd != -1)
+					(void)close(fd);
+
+				// Something went wrong. Exit with the
+				// exit status we were given. Don't try
+				// to print an error message, since stderr
+				// may very well be non-existent. This
+				// error should be extremely rare.
+				exit(err_status);
+			}
+		}
+	}
+#endif
+
+	return;
+}