os/File: add stubs for os.File Deadlines (#4465)

os/File: add stubs for os.File Deadlines
* add os.SetDeadline, os.SetReadDeadline, os.SetWriteDeadline stubs for
posix files.
* deadline: add tests

Signed-off-by: leongross <[email protected]>

Author: leongross

src/os/deadline_test.go

@@ -0,0 +1,50 @@
+//go:build posix && !baremetal && !js
+
+package os_test
+
+import (
+	"errors"
+	. "os"
+	"testing"
+)
+
+func TestDeadlines(t *testing.T) {
+	// Create a handle to a known-good, existing file
+	f, err := Open("/dev/null")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := f.SetDeadline(0); err == nil {
+		if err != nil {
+			t.Errorf("wanted nil, got %v", err)
+		}
+	}
+
+	if err := f.SetDeadline(1); err == nil {
+		if !errors.Is(err, ErrNotImplemented) {
+			t.Errorf("wanted ErrNotImplemented, got %v", err)
+		}
+	}
+
+	if err := f.SetReadDeadline(1); err == nil {
+		if !errors.Is(err, ErrNotImplemented) {
+			t.Errorf("wanted ErrNotImplemented, got %v", err)
+		}
+	}
+
+	if err := f.SetWriteDeadline(1); err == nil {
+		if !errors.Is(err, ErrNotImplemented) {
+			t.Errorf("wanted ErrNotImplemented, got %v", err)
+		}
+	}
+
+	// Closed files must return an error
+	f.Close()
+
+	if err := f.SetDeadline(0); err == nil {
+		if err != ErrClosed {
+			t.Errorf("wanted ErrClosed, got %v", err)
+		}
+	}
+}

src/os/file.go

@@ -257,12 +257,29 @@ func (f *File) SyscallConn() (conn syscall.RawConn, err error) {
 	return
 }
 
+// SetDeadline sets the read and write deadlines for a File.
+// Calls to SetDeadline for files that do not support deadlines will return ErrNoDeadline
+// This stub always returns ErrNoDeadline.
+// A zero value for t means I/O operations will not time out.
+func (f *File) SetDeadline(t time.Time) error {
+	if f.handle == nil {
+		return ErrClosed
+	}
+	return f.setDeadline(t)
+}
+
 // SetReadDeadline sets the deadline for future Read calls and any
 // currently-blocked Read call.
 func (f *File) SetReadDeadline(t time.Time) error {
 	return f.setReadDeadline(t)
 }
 
+// SetWriteDeadline sets the deadline for any future Write calls and any
+// currently-blocked Write call.
+func (f *File) SetWriteDeadline(t time.Time) error {
+	return f.setWriteDeadline(t)
+}
+
 // fd is an internal interface that is used to try a type assertion in order to
 // call the Fd() method of the underlying file handle if it is implemented.
 type fd interface {

src/os/file_posix.go

@@ -4,12 +4,35 @@ import (
 	"time"
 )
 
+//TODO: re-implement the ErrNoDeadline error in the correct code path
+
 // Chtimes is a stub, not yet implemented
 func Chtimes(name string, atime time.Time, mtime time.Time) error {
 	return ErrNotImplemented
 }
 
+// setDeadline sets the read and write deadline.
+func (f *File) setDeadline(t time.Time) error {
+	if t.IsZero() {
+		return nil
+	}
+	return ErrNotImplemented
+}
+
 // setReadDeadline sets the read deadline, not yet implemented
-func (f *File) setReadDeadline(_ time.Time) error {
+// A zero value for t means Read will not time out.
+func (f *File) setReadDeadline(t time.Time) error {
+	if t.IsZero() {
+		return nil
+	}
+	return ErrNotImplemented
+}
+
+// setWriteDeadline sets the write deadline, not yet implemented
+// A zero value for t means Read will not time out.
+func (f *File) setWriteDeadline(t time.Time) error {
+	if t.IsZero() {
+		return nil
+	}
 	return ErrNotImplemented
 }