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-exception 6 // 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 "src/errno/libc_errno.h" 15 #include <stdint.h> // For uint64_t. 16 #include <sys/syscall.h> // For syscall numbers. 17 #include <unistd.h> 18 19 namespace LIBC_NAMESPACE { 20 21 LLVM_LIBC_FUNCTION(int, ftruncate, (int fd, off_t len)) { 22 #ifdef SYS_ftruncate 23 int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_ftruncate, fd, len); 24 #elif defined(SYS_ftruncate64) 25 // Same as ftruncate but can handle large offsets 26 static_assert(sizeof(off_t) == 8); 27 int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_ftruncate64, fd, (long)len, 28 (long)(((uint64_t)(len)) >> 32)); 29 #else 30 #error "ftruncate and ftruncate64 syscalls not available." 31 #endif 32 33 if (ret < 0) { 34 libc_errno = -ret; 35 return -1; 36 } 37 return 0; 38 } 39 40 } // namespace LIBC_NAMESPACE 41