stdio-common/Xprintf_function_invoke.c

   1 /* Invoke a printf specifier handler.  Generic version.
   2    Copyright (C) 1991-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <array_length.h>
  20
  21 int
  22 Xprintf (function_invoke) (void *buf,
  23                            printf_function callback,
  24                            union printf_arg *args_value,
  25                            size_t ndata_args,
  26                            struct printf_info *info)
  27 {
  28   /* Most custom specifiers expect just one argument.  Use the heap
  29      for larger argument arrays.  */
  30   const void *onstack_args[4];
  31   const void **args;
  32   if (ndata_args <= array_length (onstack_args))
  33     args = onstack_args;
  34   else
  35     {
  36       args = calloc (ndata_args, sizeof (*args));
  37       if (args == NULL)
  38         return -1;
  39     }
  40
  41   for (unsigned int i = 0; i < ndata_args; ++i)
  42     args[i] = &args_value[i];
  43
  44   struct Xprintf (buffer_as_file) s;
  45   Xprintf (buffer_as_file_init) (&s, buf);
  46
  47   /* Call the function.  */
  48   int done = callback (Xprintf (buffer_as_file_get) (&s), info, args);
  49
  50   if (!Xprintf (buffer_as_file_terminate) (&s))
  51     done = -1;
  52
  53   if (args != onstack_args)
  54     free (args);
  55
  56   /* Potential error from the callback function.  */
  57   return done;
  58 }