runtime_mmap_test.go

Documentation: runtime

		 1  // Copyright 2016 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
		 6  // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
		 7  
		 8  package runtime_test
		 9  
		10  import (
		11  	"runtime"
		12  	"testing"
		13  	"unsafe"
		14  )
		15  
		16  // Test that the error value returned by mmap is positive, as that is
		17  // what the code in mem_bsd.go, mem_darwin.go, and mem_linux.go expects.
		18  // See the uses of ENOMEM in sysMap in those files.
		19  func TestMmapErrorSign(t *testing.T) {
		20  	p, err := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
		21  
		22  	if p != nil || err != runtime.ENOMEM {
		23  		t.Errorf("mmap = %v, %v, want nil, %v", p, err, runtime.ENOMEM)
		24  	}
		25  }
		26  
		27  func TestPhysPageSize(t *testing.T) {
		28  	// Mmap fails if the address is not page aligned, so we can
		29  	// use this to test if the page size is the true page size.
		30  	ps := runtime.GetPhysPageSize()
		31  
		32  	// Get a region of memory to play with. This should be page-aligned.
		33  	b, err := runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
		34  	if err != 0 {
		35  		t.Fatalf("Mmap: %v", err)
		36  	}
		37  
		38  	if runtime.GOOS == "aix" {
		39  		// AIX does not allow mapping a range that is already mapped.
		40  		runtime.Munmap(unsafe.Pointer(uintptr(b)), 2*ps)
		41  	}
		42  
		43  	// Mmap should fail at a half page into the buffer.
		44  	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
		45  	if err == 0 {
		46  		t.Errorf("Mmap should have failed with half-page alignment %d, but succeeded: %v", ps/2, err)
		47  	}
		48  
		49  	// Mmap should succeed at a full page into the buffer.
		50  	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
		51  	if err != 0 {
		52  		t.Errorf("Mmap at full-page alignment %d failed: %v", ps, err)
		53  	}
		54  }
		55
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