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/__support/macros/config.h" 15 #include "src/errno/libc_errno.h" 16 #include <stdint.h> // For uint64_t. 17 #include <sys/syscall.h> // For syscall numbers. 18 #include <unistd.h> 19 20 namespace LIBC_NAMESPACE_DECL { 21 22 LLVM_LIBC_FUNCTION(int, ftruncate, (int fd, off_t len)) { 23 #ifdef SYS_ftruncate 24 int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_ftruncate, fd, len); 25 #elif defined(SYS_ftruncate64) 26 // Same as ftruncate but can handle large offsets 27 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 #else 31 #error "ftruncate and ftruncate64 syscalls not available." 32 #endif 33 34 if (ret < 0) { 35 libc_errno = -ret; 36 return -1; 37 } 38 return 0; 39 } 40 41 } // namespace LIBC_NAMESPACE_DECL 42