code review 4151043: syscall: do not use NULL for zero-length read, write

syscall: do not use NULL for zero-length read, write

Avoids problems running Linux binaries under QEMU.

[rsc, 2011-02-09 16:19:16]

Hello r (cc: golang-dev@googlegroups.com),

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

[gri, 2011-02-09 18:16:30]

FYI

http://codereview.appspot.com/4151043/diff/5001/src/pkg/syscall/zsyscall_darw...
File src/pkg/syscall/zsyscall_darwin_386.go (right):

http://codereview.appspot.com/4151043/diff/5001/src/pkg/syscall/zsyscall_darw...
src/pkg/syscall/zsyscall_darwin_386.go:121: var _p0 unsafe.Pointer
_p0 := unsafe.Pointer(&_zero)
and get rid of the else
apply everywhere

(if _p0 is explicitly initialized anyway, this ought to be better code)

[r, 2011-02-09 18:39:02]

LGTM but i'm curious how you figured it out

[rsc, 2011-02-09 19:09:19]

On Wed, Feb 9, 2011 at 13:39,  <r@golang.org> wrote:
> LGTM but i'm curious how you figured it out

Half luck.

When I saw that the zero-length write was the
one returning the EFAULT I knew why, because
the NaCl developers made the same mistake.
I fixed package syscall only for cleanliness.
I was surprised when it fixed godoc entirely.

Russ

[rsc, 2011-02-09 19:28:48]

*** Submitted as 5e1e2010ca05 ***

syscall: do not use NULL for zero-length read, write

Avoids problems running Linux binaries under QEMU.

R=r, gri
CC=golang-dev
http://codereview.appspot.com/4151043