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193088b246
Currently mmap returns an unsafe.Pointer that encodes OS errors as values less than 4096. In practice this is okay, but it borders on being really unsafe: for example, the value has to be checked immediately after return and if stack copying were ever to observe such a value, it would panic. It's also not remotely idiomatic. Fix this by making mmap return a separate pointer value and error, like a normal Go function. Updates #22218. Change-Id: Iefd965095ffc82cc91118872753a5d39d785c3a6 Reviewed-on: https://go-review.googlesource.com/71270 Run-TryBot: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
49 lines
1.7 KiB
Go
49 lines
1.7 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
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package runtime_test
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import (
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"runtime"
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"testing"
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"unsafe"
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)
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// Test that the error value returned by mmap is positive, as that is
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// what the code in mem_bsd.go, mem_darwin.go, and mem_linux.go expects.
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// See the uses of ENOMEM in sysMap in those files.
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func TestMmapErrorSign(t *testing.T) {
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p, err := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
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if p != nil || err != runtime.ENOMEM {
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t.Errorf("mmap = %v, %v, want nil, %v", p, err, runtime.ENOMEM)
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}
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}
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func TestPhysPageSize(t *testing.T) {
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// Mmap fails if the address is not page aligned, so we can
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// use this to test if the page size is the true page size.
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ps := runtime.GetPhysPageSize()
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// Get a region of memory to play with. This should be page-aligned.
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b, err := runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
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if err != 0 {
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t.Fatalf("Mmap: %v", err)
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}
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// Mmap should fail at a half page into the buffer.
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_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
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if err == 0 {
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t.Errorf("Mmap should have failed with half-page alignment %d, but succeeded: %v", ps/2, err)
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}
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// Mmap should succeed at a full page into the buffer.
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_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
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if err != 0 {
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t.Errorf("Mmap at full-page alignment %d failed: %v", ps, err)
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}
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}
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