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//===-- Linux implementation of pwrite ------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "src/unistd/pwrite.h"
#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
#include "src/__support/common.h"
#include "hdr/stdint_proxy.h" // For uint64_t.
#include "src/__support/libc_errno.h"
#include "src/__support/macros/config.h"
#include <sys/syscall.h> // For syscall numbers.
namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(ssize_t, pwrite,
(int fd, const void *buf, size_t count, off_t offset)) {
ssize_t ret;
if constexpr (sizeof(long) == sizeof(uint32_t) &&
sizeof(off_t) == sizeof(uint64_t)) {
// This is a 32-bit system with a 64-bit offset, offset must be split.
const uint64_t bits = cpp::bit_cast<uint64_t>(offset);
const uint32_t lo = bits & UINT32_MAX;
const uint32_t hi = bits >> 32;
const long offset_low = cpp::bit_cast<long>(static_cast<long>(lo));
const long offset_high = cpp::bit_cast<long>(static_cast<long>(hi));
ret = LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_pwrite64, fd, buf, count,
offset_low, offset_high);
} else {
ret = LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_pwrite64, fd, buf, count,
offset);
}
if (ret < 0) {
libc_errno = static_cast<int>(-ret);
return -1;
}
return ret;
}
} // namespace LIBC_NAMESPACE_DECL
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