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/*
* Copyright (C) 2021 The Android Open Source Project
*
* 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.
*/
// File operations without libc. Most important is not touching thread-local errno.
#ifndef BERBERIS_BASE_FD_H_
#define BERBERIS_BASE_FD_H_
#include <linux/unistd.h>
#include <sys/mman.h>
#include <unistd.h>
#include "berberis/base/bit_util.h"
#include "berberis/base/logging.h"
#include "berberis/base/raw_syscall.h"
// glibc in prebuilts does not have memfd_create
#if defined(__linux__) && !defined(__NR_memfd_create)
#if defined(__x86_64__)
#define __NR_memfd_create 319
#elif defined(__i386__)
#define __NR_memfd_create 356
#endif // defined(__i386__)
#define MFD_CLOEXEC 0x0001U
#endif // defined(__linux__) && !defined(__NR_memfd_create)
namespace berberis {
inline int CreateMemfdOrDie(const char* name) {
// Use MFD_CLOEXEC to avoid leaking the file descriptor to child processes.
int fd = static_cast<int>(RawSyscall(__NR_memfd_create, bit_cast<long>(name), MFD_CLOEXEC));
CHECK(fd >= 0);
return fd;
}
inline void FtruncateOrDie(int fd, off64_t size) {
// Call libc instead of syscall because we want 64 version and do not want to
// do ifdefs for 32/64/glibc/bionic in order to get the correct one.
CHECK_EQ(ftruncate64(fd, size), 0);
}
inline void WriteFullyOrDie(int fd, const void* data, size_t size) {
auto* curr = reinterpret_cast<const uint8_t*>(data);
auto* end = curr + size;
while (curr < end) {
auto written = RawSyscall(__NR_write, fd, bit_cast<long>(curr), end - curr);
// It is not clear if write syscall can return 0 when writing more than 0 bytes.
if (written >= 0) {
curr += written;
} else {
CHECK(written == -EINTR);
}
}
}
inline void CloseUnsafe(int fd) {
RawSyscall(__NR_close, fd);
}
} // namespace berberis
#endif // BERBERIS_BASE_FD_H_
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