1 files changed, 45 insertions, 0 deletions
diff --git a/src/runtime/fds_unix.go b/src/runtime/fds_unix.go
new file mode 100644
index 0000000..7182ef0
--- /dev/null
+++ b/src/runtime/fds_unix.go
@@ -0,0 +1,45 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+package runtime
+
+func checkfds() {
+	if islibrary || isarchive {
+		// If the program is actually a library, presumably being consumed by
+		// another program, we don't want to mess around with the file
+		// descriptors.
+		return
+	}
+
+	const (
+		// F_GETFD, EBADF, O_RDWR are standard across all unixes we support, so
+		// we define them here rather than in each of the OS specific files.
+		F_GETFD = 0x01
+		EBADF   = 0x09
+		O_RDWR  = 0x02
+	)
+
+	devNull := []byte("/dev/null\x00")
+	for i := 0; i < 3; i++ {
+		ret, errno := fcntl(int32(i), F_GETFD, 0)
+		if ret >= 0 {
+			continue
+		}
+
+		if errno != EBADF {
+			print("runtime: unexpected error while checking standard file descriptor ", i, ", errno=", errno, "\n")
+			throw("cannot open standard fds")
+		}
+
+		if ret := open(&devNull[0], O_RDWR, 0); ret < 0 {
+			print("runtime: standard file descriptor ", i, " closed, unable to open /dev/null, errno=", errno, "\n")
+			throw("cannot open standard fds")
+		} else if ret != int32(i) {
+			print("runtime: opened unexpected file descriptor ", ret, " when attempting to open ", i, "\n")
+			throw("cannot open standard fds")
+		}
+	}
+}