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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef GVISOR_TEST_UTIL_MEMORY_UTIL_H_
#define GVISOR_TEST_UTIL_MEMORY_UTIL_H_
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/mman.h>
#include "absl/strings/str_format.h"
#include "absl/strings/string_view.h"
#include "test/util/logging.h"
#include "test/util/posix_error.h"
#include "test/util/save_util.h"
#include "test/util/test_util.h"
namespace gvisor {
namespace testing {
// RAII type for mmap'ed memory. Only usable in tests due to use of a test-only
// macro that can't be named without invoking the presubmit's wrath.
class Mapping {
public:
// Constructs a mapping that owns nothing.
Mapping() = default;
// Constructs a mapping that owns the mmapped memory [ptr, ptr+len). Most
// users should use Mmap or MmapAnon instead.
Mapping(void* ptr, size_t len) : ptr_(ptr), len_(len) {}
Mapping(Mapping&& orig) : ptr_(orig.ptr_), len_(orig.len_) { orig.release(); }
Mapping& operator=(Mapping&& orig) {
ptr_ = orig.ptr_;
len_ = orig.len_;
orig.release();
return *this;
}
Mapping(Mapping const&) = delete;
Mapping& operator=(Mapping const&) = delete;
~Mapping() { reset(); }
void* ptr() const { return ptr_; }
size_t len() const { return len_; }
// Returns a pointer to the end of the mapping. Useful for when the mapping
// is used as a thread stack.
void* endptr() const { return reinterpret_cast<void*>(addr() + len_); }
// Returns the start of this mapping cast to uintptr_t for ease of pointer
// arithmetic.
uintptr_t addr() const { return reinterpret_cast<uintptr_t>(ptr_); }
// Returns the end of this mapping cast to uintptr_t for ease of pointer
// arithmetic.
uintptr_t endaddr() const { return reinterpret_cast<uintptr_t>(endptr()); }
// Returns this mapping as a StringPiece for ease of comparison.
//
// This function is named view in anticipation of the eventual replacement of
// StringPiece with std::string_view.
absl::string_view view() const {
return absl::string_view(static_cast<char const*>(ptr_), len_);
}
// These are both named reset for consistency with standard smart pointers.
void reset(void* ptr, size_t len) {
if (len_) {
TEST_PCHECK(munmap(ptr_, len_) == 0);
}
ptr_ = ptr;
len_ = len;
}
void reset() { reset(nullptr, 0); }
void release() {
ptr_ = nullptr;
len_ = 0;
}
private:
void* ptr_ = nullptr;
size_t len_ = 0;
};
// Wrapper around mmap(2) that returns a Mapping.
inline PosixErrorOr<Mapping> Mmap(void* addr, size_t length, int prot,
int flags, int fd, off_t offset) {
void* ptr = mmap(addr, length, prot, flags, fd, offset);
if (ptr == MAP_FAILED) {
return PosixError(
errno, absl::StrFormat("mmap(%p, %d, %x, %x, %d, %d)", addr, length,
prot, flags, fd, offset));
}
MaybeSave();
return Mapping(ptr, length);
}
// Convenience wrapper around Mmap for anonymous mappings.
inline PosixErrorOr<Mapping> MmapAnon(size_t length, int prot, int flags) {
return Mmap(nullptr, length, prot, flags | MAP_ANONYMOUS, -1, 0);
}
} // namespace testing
} // namespace gvisor
#endif // GVISOR_TEST_UTIL_MEMORY_UTIL_H_
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