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  }