github.com/neonyo/sys@v0.0.0-20230720094341-b1ee14be3ce8/unix/dup3_test.go (about) 1 // Copyright 2023 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 //go:build freebsd || linux || netbsd || openbsd 6 // +build freebsd linux netbsd openbsd 7 8 package unix_test 9 10 import ( 11 "os" 12 "runtime" 13 "testing" 14 15 "golang.org/x/sys/unix" 16 ) 17 18 func TestDup3(t *testing.T) { 19 tempFile, err := os.CreateTemp("", "TestDup") 20 if err != nil { 21 t.Fatalf("CreateTemp failed: %v", err) 22 } 23 defer os.Remove(tempFile.Name()) 24 defer tempFile.Close() 25 oldFd := int(tempFile.Fd()) 26 27 // On NetBSD, it is not an error if oldFd == newFd 28 if runtime.GOOS != "netbsd" { 29 if got, want := unix.Dup3(oldFd, oldFd, 0), unix.EINVAL; got != want { 30 t.Fatalf("Dup3: expected err %v, got %v", want, got) 31 } 32 } 33 34 // Create and reserve a file descriptor. 35 // Dup3 automatically closes it before reusing it. 36 nullFile, err := os.Open("/dev/null") 37 if err != nil { 38 t.Fatalf("Open failed: %v", err) 39 } 40 defer nullFile.Close() 41 newFd := int(nullFile.Fd()) 42 43 err = unix.Dup3(oldFd, newFd, 0) 44 if err != nil { 45 t.Fatalf("Dup3: %v", err) 46 } 47 48 b1 := []byte("Test123") 49 b2 := make([]byte, 7) 50 _, err = unix.Write(newFd, b1) 51 if err != nil { 52 t.Fatalf("Write to Dup3 fd failed: %v", err) 53 } 54 _, err = unix.Seek(oldFd, 0, 0) 55 if err != nil { 56 t.Fatalf("Seek failed: %v", err) 57 } 58 _, err = unix.Read(oldFd, b2) 59 if err != nil { 60 t.Fatalf("Read back failed: %v", err) 61 } 62 if string(b1) != string(b2) { 63 t.Errorf("Dup3: read %q from file, want %q", string(b2), string(b1)) 64 } 65 }