/* vasprintf and asprintf with out-of-memory checking.

   Copyright (C) 1999, 2002-2004, 2006-2017 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include "xvasprintf.h"

#include <errno.h>

#include <limits.h>

#include <string.h>

#include <stdio.h>

#include "xalloc.h"

/* Checked size_t computations.  */

#include "xsize.h"

static char *

xstrcat (size_t argcount, va_list args)

{

  char *result;

  va_list ap;

  size_t totalsize;

  size_t i;

  char *p;

  /* Determine the total size.  */

  totalsize = 0;

  va_copy (ap, args);

  for (i = argcount; i > 0; i--)

    {

      const char *next = va_arg (ap, const char *);

      totalsize = xsum (totalsize, strlen (next));

    }

  va_end (ap);

  /* Test for overflow in the summing pass above or in (totalsize + 1) below.

     Also, don't return a string longer than INT_MAX, for consistency with

     vasprintf().  */

  if (totalsize == SIZE_MAX || totalsize > INT_MAX)

    {

      errno = EOVERFLOW;

      return NULL;

    }

  /* Allocate and fill the result string.  */

  result = XNMALLOC (totalsize + 1, char);

  p = result;

  for (i = argcount; i > 0; i--)

    {

      const char *next = va_arg (args, const char *);

      size_t len = strlen (next);

      memcpy (p, next, len);

      p += len;

    }

  *p = '\0';

  return result;

}

char *

xvasprintf (const char *format, va_list args)

{

  char *result;

  /* Recognize the special case format = "%s...%s".  It is a frequently used

     idiom for string concatenation and needs to be fast.  We don't want to

     have a separate function xstrcat() for this purpose.  */

  {

    size_t argcount = 0;

    const char *f;

    for (f = format;;)

      {

        if (*f == '\0')

          /* Recognized the special case of string concatenation.  */

          return xstrcat (argcount, args);

        if (*f != '%')

          break;

        f++;

        if (*f != 's')

          break;

        f++;

        argcount++;

      }

  }

  if (vasprintf (&result, format, args) < 0)

    {

      if (errno == ENOMEM)

        xalloc_die ();

      return NULL;

    }

  return result;

}