libc/src/stdlib/strfromd.cpp

//===-- Implementation of strfromd ------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "src/stdlib/strfromd.h"
#include "src/__support/CPP/limits.h"
#include "src/__support/macros/config.h"
#include "src/__support/printf_core/core_structs.h"
#include "src/__support/printf_core/error_mapper.h"
#include "src/stdlib/str_from_util.h"

namespace LIBC_NAMESPACE_DECL {

LLVM_LIBC_FUNCTION(int, strfromd,
                   (char *__restrict s, size_t n, const char *__restrict format,
                    double fp)) {
  LIBC_ASSERT(s != nullptr);

  printf_core::Writer writer =
      printf_core::make_drop_overflow_writer(s, (n > 0 ? n - 1 : 0));
  int result = internal::strfromfloat_convert(&writer, format, fp);
  if (result < 0)
    return result;

  if (n > 0) {
    printf_core::WriteBuffer<char> &wb = writer.get_write_buffer();
    wb.buff[wb.buff_cur] = '\0';
  }

  if (writer.get_chars_written() >
      static_cast<size_t>(cpp::numeric_limits<int>::max())) {
    libc_errno =
        printf_core::internal_error_to_errno(-printf_core::OVERFLOW_ERROR);
    return -1;
  }
  return static_cast<int>(writer.get_chars_written());
}

} // namespace LIBC_NAMESPACE_DECL