mirror of https://github.com/openXC7/prjxray.git
107 lines
2.6 KiB
C++
107 lines
2.6 KiB
C++
/*
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* Copyright (C) 2017-2020 The Project X-Ray Authors.
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*
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* Use of this source code is governed by a ISC-style
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* license that can be found in the LICENSE file or at
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* https://opensource.org/licenses/ISC
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*
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* SPDX-License-Identifier: ISC
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*/
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#include <prjxray/memory_mapped_file.h>
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#ifdef _WIN32
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#include <windows.h>
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#else
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#endif
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namespace prjxray {
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std::unique_ptr<MemoryMappedFile> MemoryMappedFile::InitWithFile(
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const std::string& path) {
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#ifdef _WIN32
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HANDLE file = CreateFileA(path.c_str(), GENERIC_READ, FILE_SHARE_READ,
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NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL,
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NULL);
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if (file == INVALID_HANDLE_VALUE)
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return nullptr;
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LARGE_INTEGER file_size;
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if (!GetFileSizeEx(file, &file_size)) {
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CloseHandle(file);
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return nullptr;
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}
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// A zero-length file cannot be mapped; return an object (to indicate
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// the file exists) with a nullptr and zero length.
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if (file_size.QuadPart == 0) {
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CloseHandle(file);
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return std::unique_ptr<MemoryMappedFile>(
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new MemoryMappedFile(nullptr, 0));
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}
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HANDLE mapping =
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CreateFileMappingA(file, NULL, PAGE_READONLY, 0, 0, NULL);
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// The view keeps the file/mapping alive, so the handles can be closed.
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CloseHandle(file);
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if (mapping == NULL)
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return nullptr;
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void* file_map = MapViewOfFile(mapping, FILE_MAP_READ, 0, 0, 0);
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CloseHandle(mapping);
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if (file_map == NULL)
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return nullptr;
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return std::unique_ptr<MemoryMappedFile>(new MemoryMappedFile(
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file_map, static_cast<size_t>(file_size.QuadPart)));
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#else
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int fd = open(path.c_str(), O_RDONLY, 0);
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if (fd == -1)
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return nullptr;
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struct stat statbuf;
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if (fstat(fd, &statbuf) < 0) {
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close(fd);
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return nullptr;
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}
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// mmap() will fail with EINVAL if length==0. If this file is
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// zero-length, return an object (to indicate the file exists) but
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// load it with a nullptr and zero length.
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if (statbuf.st_size == 0) {
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close(fd);
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return std::unique_ptr<MemoryMappedFile>(
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new MemoryMappedFile(nullptr, 0));
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}
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void* file_map =
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mmap(NULL, statbuf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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// If mmap() succeeded, the fd is no longer needed as the mapping will
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// keep the file open. If mmap() failed, the fd needs to be closed
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// anyway.
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close(fd);
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if (file_map == MAP_FAILED)
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return nullptr;
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return std::unique_ptr<MemoryMappedFile>(
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new MemoryMappedFile(file_map, statbuf.st_size));
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#endif
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}
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MemoryMappedFile::~MemoryMappedFile() {
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#ifdef _WIN32
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if (data_)
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UnmapViewOfFile(data_);
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#else
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munmap(data_, size_);
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#endif
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}
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} // namespace prjxray
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