libc/src/stdio/generic/ftell.cpp

   1 //===-- Implementation of ftell -------------------------------------------===//
   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/stdio/ftell.h"
  10 #include "src/__support/File/file.h"
  11
  12 #include "src/__support/macros/config.h"
  13 #include "src/errno/libc_errno.h"
  14
  15 namespace LIBC_NAMESPACE_DECL {
  16
  17 LLVM_LIBC_FUNCTION(long, ftell, (::FILE * stream)) {
  18   auto result = reinterpret_cast<LIBC_NAMESPACE::File *>(stream)->tell();
  19   if (!result.has_value()) {
  20     libc_errno = result.error();
  21     return -1;
  22   }
  23   // tell() returns an off_t (64-bit signed integer), but this function returns
  24   // a long (32-bit signed integer in 32-bit systems). We add a cast here to
  25   // silence a "implicit conversion loses integer precision" warning when
  26   // compiling for 32-bit systems.
  27   return static_cast<long>(result.value());
  28 }
  29
  30 } // namespace LIBC_NAMESPACE_DECL