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// 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")
}
}
}
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