libc/src/unistd/linux/ftruncate.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-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