66 lines
2.0 KiB
C++
66 lines
2.0 KiB
C++
/*
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* Copyright (C) 2021 The Android Open Source Project
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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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*/
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// File operations without libc. Most important is not touching thread-local errno.
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#ifndef BERBERIS_BASE_FD_H_
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#define BERBERIS_BASE_FD_H_
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#include <linux/unistd.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include "berberis/base/bit_util.h"
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#include "berberis/base/logging.h"
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#include "berberis/base/raw_syscall.h"
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// glibc in prebuilts does not have memfd_create
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#if defined(__linux__) && !defined(__NR_memfd_create)
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#if defined(__x86_64__)
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#define __NR_memfd_create 319
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#elif defined(__i386__)
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#define __NR_memfd_create 356
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#endif // defined(__i386__)
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#define MFD_CLOEXEC 0x0001U
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#endif // defined(__linux__) && !defined(__NR_memfd_create)
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namespace berberis {
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inline int CreateMemfdOrDie(const char* name) {
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// Use MFD_CLOEXEC to avoid leaking the file descriptor to child processes.
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int fd = RawSyscall(__NR_memfd_create, bit_cast<long>(name), MFD_CLOEXEC);
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CHECK(fd >= 0);
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return fd;
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}
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inline void WriteFullyOrDie(int fd, const void* data, size_t size) {
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auto* curr = reinterpret_cast<const uint8_t*>(data);
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auto* end = curr + size;
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while (curr < end) {
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auto written = RawSyscall(__NR_write, fd, bit_cast<long>(curr), end - curr);
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// It is not clear if write syscall can return 0 when writing more than 0 bytes.
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if (written >= 0) {
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curr += written;
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} else {
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CHECK(written == -EINTR);
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}
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}
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}
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} // namespace berberis
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#endif // BERBERIS_BASE_FD_H_
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