Commit a5999b7b authored by George Gkirtsou's avatar George Gkirtsou Committed by Brad Fitzpatrick

os: more descriptive error for File.ReadAt and File.WriteAt with negative offset.

The existing implementation does not provide a useful error message
if a negative offset is passed in File.ReadAt or File.WriteAt. This
change is to return descriptive errors. An error of type *PathError
is returned to keep it consistent with rest of the code.

There is no need to add an exported error variable since it's used only
in one file.

Fixes #19031

Change-Id: Ib94cab0afae8c5fe4dd97ed2887018a09b9f4538
Reviewed-on: https://go-review.googlesource.com/39136Reviewed-by: 's avatarBrad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
parent 26c2926f
......@@ -37,6 +37,7 @@
package os
import (
"errors"
"io"
"syscall"
)
......@@ -117,6 +118,11 @@ func (f *File) ReadAt(b []byte, off int64) (n int, err error) {
if err := f.checkValid("read"); err != nil {
return 0, err
}
if off < 0 {
return 0, &PathError{"readat", f.name, errors.New("negative offset")}
}
for len(b) > 0 {
m, e := f.pread(b, off)
if e != nil {
......@@ -164,6 +170,11 @@ func (f *File) WriteAt(b []byte, off int64) (n int, err error) {
if err := f.checkValid("write"); err != nil {
return 0, err
}
if off < 0 {
return 0, &PathError{"writeat", f.name, errors.New("negative offset")}
}
for len(b) > 0 {
m, e := f.pwrite(b, off)
if e != nil {
......
......@@ -1451,6 +1451,26 @@ func TestReadAtOffset(t *testing.T) {
}
}
// Verify that ReadAt doesn't allow negative offset.
func TestReadAtNegativeOffset(t *testing.T) {
f := newFile("TestReadAtNegativeOffset", t)
defer Remove(f.Name())
defer f.Close()
const data = "hello, world\n"
io.WriteString(f, data)
f.Seek(0, 0)
b := make([]byte, 5)
n, err := f.ReadAt(b, -10)
const wantsub = "negative offset"
if !strings.Contains(fmt.Sprint(err), wantsub) || n != 0 {
t.Errorf("ReadAt(-10) = %v, %v; want 0, ...%q...", n, err, wantsub)
}
}
func TestWriteAt(t *testing.T) {
f := newFile("TestWriteAt", t)
defer Remove(f.Name())
......@@ -1473,6 +1493,20 @@ func TestWriteAt(t *testing.T) {
}
}
// Verify that WriteAt doesn't allow negative offset.
func TestWriteAtNegativeOffset(t *testing.T) {
f := newFile("TestWriteAtNegativeOffset", t)
defer Remove(f.Name())
defer f.Close()
n, err := f.WriteAt([]byte("WORLD"), -10)
const wantsub = "negative offset"
if !strings.Contains(fmt.Sprint(err), wantsub) || n != 0 {
t.Errorf("WriteAt(-10) = %v, %v; want 0, ...%q...", n, err, wantsub)
}
}
func writeFile(t *testing.T, fname string, flag int, text string) string {
f, err := OpenFile(fname, flag, 0666)
if err != nil {
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment