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// +build amd64,linux
// Copyright 2018 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 cgotest
// Test that C.GoString uses IndexByte in safe manner.
/*
#include <sys/mman.h>
// Returns string with null byte at the last valid address
char* dangerousString1() {
int pageSize = 4096;
char *data = mmap(0, 2 * pageSize, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0);
mprotect(data + pageSize,pageSize,PROT_NONE);
int start = pageSize - 123 - 1; // last 123 bytes of first page + 1 null byte
int i = start;
for (; i < pageSize; i++) {
data[i] = 'x';
}
data[pageSize -1 ] = 0;
return data+start;
}
char* dangerousString2() {
int pageSize = 4096;
char *data = mmap(0, 3 * pageSize, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0);
mprotect(data + 2 * pageSize,pageSize,PROT_NONE);
int start = pageSize - 123 - 1; // last 123 bytes of first page + 1 null byte
int i = start;
for (; i < 2 * pageSize; i++) {
data[i] = 'x';
}
data[2*pageSize -1 ] = 0;
return data+start;
}
*/
import "C"
import (
"testing"
)
func test24206(t *testing.T) {
if l := len(C.GoString(C.dangerousString1())); l != 123 {
t.Errorf("Incorrect string length - got %d, want 123", l)
}
if l := len(C.GoString(C.dangerousString2())); l != 4096+123 {
t.Errorf("Incorrect string length - got %d, want %d", l, 4096+123)
}
}
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