lib/unistdio/ulc-vfprintf.c

/* Formatted output to a stream.
   Copyright (C) 2004, 2006-2026 Free Software Foundation, Inc.

   This file is free software.
   It is dual-licensed under "the GNU LGPLv3+ or the GNU GPLv2+".
   You can redistribute it and/or modify it under either
     - the terms of the GNU Lesser General Public License as published
       by the Free Software Foundation, either version 3, or (at your
       option) any later version, or
     - the terms of the GNU General Public License as published by the
       Free Software Foundation; either version 2, or (at your option)
       any later version, or
     - the same dual license "the GNU LGPLv3+ or the GNU GPLv2+".

   This file is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License and the GNU General Public License
   for more details.

   You should have received a copy of the GNU Lesser General Public
   License and of the GNU General Public License along with this
   program.  If not, see <https://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

/* Specification.  */
#include "unistdio.h"

#include <errno.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>

#include "fseterr.h"

/* Print formatted output to the stream FP.
   Return string length of formatted string.  On error, return a negative
   value.  */
int
ulc_vfprintf (FILE *fp, const char *format, va_list args)
{
  char buf[2000];
  size_t lenbuf = sizeof (buf);
  char *output = ulc_vasnprintf (buf, &lenbuf, format, args);
  size_t len = lenbuf;

  if (!output)
    {
      fseterr (fp);
      return -1;
    }

  if (fwrite (output, 1, len, fp) < len)
    {
      if (output != buf)
        {
          int saved_errno = errno;
          free (output);
          errno = saved_errno;
        }
      return -1;
    }

  if (len > INT_MAX)
    {
      errno = EOVERFLOW;
      fseterr (fp);
      return -1;
    }

  return len;
}