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