code review 140050044: runtime: translate env*.c to Go

runtime: translate env*.c to Go

In an earlier CL I wrote a separate Go-only version, but that broke Plan 9,
because the Go-only version assumed a non-Plan 9 system.

Translate the real ones instead.

[rsc, 2014-08-30 18:10:37]

Hello golang-codereviews@googlegroups.com (cc: 0intro, iant, khr, r),

I'd like you to review this change to
https://code.google.com/p/go/

[r, 2014-08-30 18:23:41]

LGTM

[rsc, 2014-08-30 18:53:45]

*** Submitted as https://code.google.com/p/go/source/detail?r=0e9f269a9c70 ***

runtime: translate env*.c to Go

In an earlier CL I wrote a separate Go-only version, but that broke Plan 9,
because the Go-only version assumed a non-Plan 9 system.

Translate the real ones instead.

LGTM=r
R=golang-codereviews, r
CC=0intro, golang-codereviews, iant, khr
https://codereview.appspot.com/140050044

[0intro, 2014-08-30 19:00:34]

Thanks. I was working on a different approach, but this one is definitely
better.

https://codereview.appspot.com/140050044/diff/60001/src/pkg/runtime/env_plan9.go
File src/pkg/runtime/env_plan9.go (left):

https://codereview.appspot.com/140050044/diff/60001/src/pkg/runtime/env_plan9...
src/pkg/runtime/env_plan9.go:25: fd = runtime·open((int8*)file, OREAD, 0);
_OREAD is not defined.

[0intro, 2014-08-30 19:16:51]

https://codereview.appspot.com/140050044/diff/60001/src/pkg/runtime/env_plan9.go
File src/pkg/runtime/env_plan9.go (right):

https://codereview.appspot.com/140050044/diff/60001/src/pkg/runtime/env_plan9...
src/pkg/runtime/env_plan9.go:44: p = gomallocgc(uintptr(n+1), nil, 0)
Shouldn't it be flagNoScan?

[0intro, 2014-08-30 21:21:32]

LGTM with the changes.

I've sent CL 137030043 with the proposed changes.

https://codereview.appspot.com/140050044/diff/60001/src/pkg/runtime/env_plan9.go
File src/pkg/runtime/env_plan9.go (right):

https://codereview.appspot.com/140050044/diff/60001/src/pkg/runtime/env_plan9...
src/pkg/runtime/env_plan9.go:33: n := seek(fd, 0, 2)
Environment strings are usually null-terminated, so we really want -1 here.