syscall: prlimit argument error for Getrlimit and Setrlimit on Linux 32-bit

The rlimit arguments for prlimit are reversed for linux 32-bit (386 and arm).
Getrlimit becomes Setrlimit and vice versa.
Fixes #5949.

R=iant, mikioh.mikioh, rsc
CC=golang-dev
https://golang.org/cl/11803043

src/pkg/syscall/rlimit_linux_test.go

+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package syscall_test
+
+import (
+	"syscall"
+	"testing"
+)
+
+func TestRlimit(t *testing.T) {
+	var rlimit, zero syscall.Rlimit
+	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit)
+	if err != nil {
+		t.Fatalf("Getrlimit: save failed: %v", err)
+	}
+	if zero == rlimit {
+		t.Fatalf("Getrlimit: save failed: got zero value %#v", rlimit)
+	}
+	set := rlimit
+	set.Cur = set.Max - 1
+	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &set)
+	if err != nil {
+		t.Fatalf("Setrlimit: set failed: %#v %v", set, err)
+	}
+	var get syscall.Rlimit
+	err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &get)
+	if err != nil {
+		t.Fatalf("Getrlimit: get failed: %v", err)
+	}
+	set = rlimit
+	set.Cur = set.Max - 1
+	if set != get {
+		t.Fatalf("Rlimit: change failed: wanted %#v got %#v", set, get)
+	}
+	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit)
+	if err != nil {
+		t.Fatalf("Setrlimit: restore failed: %#v %v", rlimit, err)
+	}
+}

src/pkg/syscall/syscall_linux_386.go

@@ -78,7 +78,7 @@ const rlimInf32 = ^uint32(0)
 const rlimInf64 = ^uint64(0)
 
 func Getrlimit(resource int, rlim *Rlimit) (err error) {
-	err = prlimit(0, resource, rlim, nil)
+	err = prlimit(0, resource, nil, rlim)
 	if err != ENOSYS {
 		return err
 	}
@@ -106,7 +106,7 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 //sysnb setrlimit(resource int, rlim *rlimit32) (err error) = SYS_SETRLIMIT
 
 func Setrlimit(resource int, rlim *Rlimit) (err error) {
-	err = prlimit(0, resource, nil, rlim)
+	err = prlimit(0, resource, rlim, nil)
 	if err != ENOSYS {
 		return err
 	}

src/pkg/syscall/syscall_linux_arm.go

@@ -119,7 +119,7 @@ const rlimInf32 = ^uint32(0)
 const rlimInf64 = ^uint64(0)
 
 func Getrlimit(resource int, rlim *Rlimit) (err error) {
-	err = prlimit(0, resource, rlim, nil)
+	err = prlimit(0, resource, nil, rlim)
 	if err != ENOSYS {
 		return err
 	}
@@ -147,7 +147,7 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 //sysnb setrlimit(resource int, rlim *rlimit32) (err error) = SYS_SETRLIMIT
 
 func Setrlimit(resource int, rlim *Rlimit) (err error) {
-	err = prlimit(0, resource, nil, rlim)
+	err = prlimit(0, resource, rlim, nil)
 	if err != ENOSYS {
 		return err
 	}