code review 5298081: os: do not interpret 0-length read as EOF

os: do not interpret 0-length read as EOF

Fixes issue 2402.

[rsc, 2011-10-31 17:59:32]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://go.googlecode.com/hg/

[bradfitz, 2011-10-31 18:10:44]

LGTM
On Oct 31, 2011 10:59 AM, <rsc@golang.org> wrote:

> Reviewers: golang-dev_googlegroups.com,
>
> Message:
> Hello golang-dev@googlegroups.com,
>
> I'd like you to review this change to
> https://go.googlecode.com/hg/
>
>
> Description:
> os: do not interpret 0-length read as EOF
>
> Fixes issue 2402.
>
> Please review this at
http://codereview.appspot.com/**5298081/<http://codereview.appspot.com/5298081/>
>
> Affected files:
>  M src/pkg/os/file.go
>  M src/pkg/os/os_test.go
>
>
> Index: src/pkg/os/file.go
> ==============================**==============================**=======
> --- a/src/pkg/os/file.go
> +++ b/src/pkg/os/file.go
> @@ -69,7 +69,7 @@
>        if n < 0 {
>                n = 0
>        }
> -       if n == 0 && !iserror(e) {
> +       if n == 0 && len(b) > 0 && !iserror(e) {
>                return 0, EOF
>        }
>        if iserror(e) {
> Index: src/pkg/os/os_test.go
> ==============================**==============================**=======
> --- a/src/pkg/os/os_test.go
> +++ b/src/pkg/os/os_test.go
> @@ -165,6 +165,27 @@
>        }
>  }
>
> +// Read with length 0 should not return EOF.
> +func TestRead0(t *testing.T) {
> +       path := sfdir + "/" + sfname
> +       f, err := Open(path)
> +       if err != nil {
> +               t.Fatal("open failed:", err)
> +       }
> +       defer f.Close()
> +
> +       b := make([]byte, 0)
> +       n, err := f.Read(b)
> +       if n != 0 || err != nil {
> +               t.Errorf("Read(0) = %d, %v, want 0, nil", n, err)
> +       }
> +       b = make([]byte, 100)
> +       n, err = f.Read(b)
> +       if n <= 0 || err != nil {
> +               t.Errorf("Read(100) = %d, %v, want >0, nil", n, err)
> +       }
> +}
> +
>  func testReaddirnames(dir string, contents []string, t *testing.T) {
>        file, err := Open(dir)
>        defer file.Close()
>
>
>

[r, 2011-10-31 22:25:39]

LGTM

[rsc, 2011-11-01 04:17:12]

*** Submitted as http://code.google.com/p/go/source/detail?r=e77b8510ab73 ***

os: do not interpret 0-length read as EOF

Fixes issue 2402.

R=golang-dev, bradfitz, r
CC=golang-dev
http://codereview.appspot.com/5298081