libc/src/stdio/printf_core/vasprintf_internal.h

   1 //===-- Internal Implementation of asprintf ---------------------*- 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 "hdr/func/free.h"
  10 #include "hdr/func/malloc.h"
  11 #include "hdr/func/realloc.h"
  12 #include "src/__support/arg_list.h"
  13 #include "src/stdio/printf.h"
  14 #include "src/stdio/printf_core/core_structs.h"
  15 #include "src/stdio/printf_core/printf_main.h"
  16 #include "src/stdio/printf_core/writer.h"
  17
  18 namespace LIBC_NAMESPACE_DECL {
  19 namespace printf_core {
  20
  21 LIBC_INLINE int resize_overflow_hook(cpp::string_view new_str, void *target) {
  22   printf_core::WriteBuffer *wb =
  23       reinterpret_cast<printf_core::WriteBuffer *>(target);
  24   size_t new_size = new_str.size() + wb->buff_cur;
  25   const bool isBuffOnStack = (wb->buff == wb->init_buff);
  26   char *new_buff = static_cast<char *>(
  27       isBuffOnStack ? malloc(new_size + 1)
  28                     : realloc(wb->buff, new_size + 1)); // +1 for null
  29   if (new_buff == nullptr) {
  30     if (wb->buff != wb->init_buff)
  31       free(wb->buff);
  32     return printf_core::ALLOCATION_ERROR;
  33   }
  34   if (isBuffOnStack)
  35     inline_memcpy(new_buff, wb->buff, wb->buff_cur);
  36   wb->buff = new_buff;
  37   inline_memcpy(wb->buff + wb->buff_cur, new_str.data(), new_str.size());
  38   wb->buff_cur = new_size;
  39   wb->buff_len = new_size;
  40   return printf_core::WRITE_OK;
  41 }
  42
  43 constexpr size_t DEFAULT_BUFFER_SIZE = 200;
  44
  45 LIBC_INLINE int vasprintf_internal(char **ret, const char *__restrict format,
  46                                    internal::ArgList args) {
  47   char init_buff_on_stack[DEFAULT_BUFFER_SIZE];
  48   printf_core::WriteBuffer wb(init_buff_on_stack, DEFAULT_BUFFER_SIZE,
  49                               resize_overflow_hook);
  50   printf_core::Writer writer(&wb);
  51
  52   auto ret_val = printf_core::printf_main(&writer, format, args);
  53   if (ret_val < 0) {
  54     *ret = nullptr;
  55     return -1;
  56   }
  57   if (wb.buff == init_buff_on_stack) {
  58     *ret = static_cast<char *>(malloc(ret_val + 1));
  59     if (ret == nullptr)
  60       return printf_core::ALLOCATION_ERROR;
  61     inline_memcpy(*ret, wb.buff, ret_val);
  62   } else {
  63     *ret = wb.buff;
  64   }
  65   (*ret)[ret_val] = '\0';
  66   return ret_val;
  67 }
  68 } // namespace printf_core
  69 } // namespace LIBC_NAMESPACE_DECL