libc/src/unistd/linux/truncate.cpp

   1 //===-- Linux implementation of truncate ----------------------------------===//
   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/truncate.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13 #include "src/__support/macros/config.h"
  14 #include "src/errno/libc_errno.h"
  15
  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, truncate, (const char *path, off_t len)) {
  23 #ifdef SYS_truncate
  24   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_truncate, path, len);
  25 #elif defined(SYS_truncate64)
  26   // Same as truncate but can handle large offsets
  27   static_assert(sizeof(off_t) == 8);
  28   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_truncate64, path, (long)len,
  29                                               (long)(((uint64_t)(len)) >> 32));
  30 #else
  31 #error "truncate and truncate64 syscalls not available."
  32 #endif
  33   if (ret < 0) {
  34     libc_errno = -ret;
  35     return -1;
  36   }
  37   return 0;
  38 }
  39
  40 } // namespace LIBC_NAMESPACE_DECL