libc/src/stdio/vsnprintf.cpp

   1 //===-- Implementation of vsnprintf -----------------------------*- C++ -*-===//
   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/vsnprintf.h"
  10
  11 #include "src/__support/arg_list.h"
  12 #include "src/__support/macros/config.h"
  13 #include "src/stdio/printf_core/printf_main.h"
  14 #include "src/stdio/printf_core/writer.h"
  15
  16 #include <stdarg.h>
  17 #include <stddef.h>
  18
  19 namespace LIBC_NAMESPACE_DECL {
  20
  21 LLVM_LIBC_FUNCTION(int, vsnprintf,
  22                    (char *__restrict buffer, size_t buffsz,
  23                     const char *__restrict format, va_list vlist)) {
  24   internal::ArgList args(vlist); // This holder class allows for easier copying
  25                                  // and pointer semantics, as well as handling
  26                                  // destruction automatically.
  27   printf_core::WriteBuffer wb(buffer, (buffsz > 0 ? buffsz - 1 : 0));
  28   printf_core::Writer writer(&wb);
  29
  30   int ret_val = printf_core::printf_main(&writer, format, args);
  31   if (buffsz > 0) // if the buffsz is 0 the buffer may be a null pointer.
  32     wb.buff[wb.buff_cur] = '\0';
  33   return ret_val;
  34 }
  35
  36 } // namespace LIBC_NAMESPACE_DECL