| // Copyright 2022 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "base/memory/platform_shared_memory_mapper.h" |
| |
| #include "base/logging.h" |
| #include "base/numerics/safe_conversions.h" |
| |
| #include <sys/mman.h> |
| |
| namespace base { |
| |
| absl::optional<span<uint8_t>> PlatformSharedMemoryMapper::Map( |
| subtle::PlatformSharedMemoryHandle handle, |
| bool write_allowed, |
| uint64_t offset, |
| size_t size) { |
| // IMPORTANT: Even if the mapping is readonly and the mapped data is not |
| // changing, the region must ALWAYS be mapped with MAP_SHARED, otherwise with |
| // ashmem the mapping is equivalent to a private anonymous mapping. |
| void* address = |
| mmap(nullptr, size, PROT_READ | (write_allowed ? PROT_WRITE : 0), |
| MAP_SHARED, handle, checked_cast<off_t>(offset)); |
| |
| if (address == MAP_FAILED) { |
| DPLOG(ERROR) << "mmap " << handle << " failed"; |
| return absl::nullopt; |
| } |
| |
| return make_span(reinterpret_cast<uint8_t*>(address), size); |
| } |
| |
| void PlatformSharedMemoryMapper::Unmap(span<uint8_t> mapping) { |
| if (munmap(mapping.data(), mapping.size()) < 0) |
| DPLOG(ERROR) << "munmap"; |
| } |
| |
| } // namespace base |