42 lines · cpp
1//===-- Linux implementation of ftruncate ---------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "src/unistd/ftruncate.h"10 11#include "src/__support/OSUtil/syscall.h" // For internal syscall function.12#include "src/__support/common.h"13 14#include "hdr/stdint_proxy.h" // For uint64_t.15#include "hdr/unistd_macros.h"16#include "src/__support/libc_errno.h"17#include "src/__support/macros/config.h"18#include <sys/syscall.h> // For syscall numbers.19 20namespace LIBC_NAMESPACE_DECL {21 22LLVM_LIBC_FUNCTION(int, ftruncate, (int fd, off_t len)) {23#ifdef SYS_ftruncate24 int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_ftruncate, fd, len);25#elif defined(SYS_ftruncate64)26 // Same as ftruncate but can handle large offsets27 static_assert(sizeof(off_t) == 8);28 int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_ftruncate64, fd, (long)len,29 (long)(((uint64_t)(len)) >> 32));30#else31#error "ftruncate and ftruncate64 syscalls not available."32#endif33 34 if (ret < 0) {35 libc_errno = -ret;36 return -1;37 }38 return 0;39}40 41} // namespace LIBC_NAMESPACE_DECL42