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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 freebsd || linux || netbsd || openbsd
package unix_test
import (
"os"
"path/filepath"
"runtime"
"testing"
"golang.org/x/sys/unix"
)
func TestDup3(t *testing.T) {
tempFile, err := os.Create(filepath.Join(t.TempDir(), "TestDup"))
if err != nil {
t.Fatal(err)
}
defer tempFile.Close()
oldFd := int(tempFile.Fd())
// On NetBSD, it is not an error if oldFd == newFd
if runtime.GOOS != "netbsd" {
if got, want := unix.Dup3(oldFd, oldFd, 0), unix.EINVAL; got != want {
t.Fatalf("Dup3: expected err %v, got %v", want, got)
}
}
// Create and reserve a file descriptor.
// Dup3 automatically closes it before reusing it.
nullFile, err := os.Open("/dev/null")
if err != nil {
t.Fatalf("Open failed: %v", err)
}
defer nullFile.Close()
newFd := int(nullFile.Fd())
err = unix.Dup3(oldFd, newFd, 0)
if err != nil {
t.Fatalf("Dup3: %v", err)
}
b1 := []byte("Test123")
b2 := make([]byte, 7)
_, err = unix.Write(newFd, b1)
if err != nil {
t.Fatalf("Write to Dup3 fd failed: %v", err)
}
_, err = unix.Seek(oldFd, 0, 0)
if err != nil {
t.Fatalf("Seek failed: %v", err)
}
_, err = unix.Read(oldFd, b2)
if err != nil {
t.Fatalf("Read back failed: %v", err)
}
if string(b1) != string(b2) {
t.Errorf("Dup3: read %q from file, want %q", string(b2), string(b1))
}
}
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