/* Variable-sized buffer with on-stack default allocation.

   Copyright (C) 2015-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library 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.

   The GNU C Library 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 the GNU C Library; if not, see

   <https://www.gnu.org/licenses/>.  */

#ifndef _LIBC

# include <libc-config.h>

#endif

#include <scratch_buffer.h>

#include <errno.h>

#include <string.h>

bool

__libc_scratch_buffer_grow_preserve (struct scratch_buffer *buffer)

{

  size_t new_length = 2 * buffer->length;

  void *new_ptr;

  if (buffer->data == buffer->__space)

    {

      /* Move buffer to the heap.  No overflow is possible because

	 buffer->length describes a small buffer on the stack.  */

      new_ptr = malloc (new_length);

      if (new_ptr == NULL)

	return false;

      memcpy (new_ptr, buffer->__space, buffer->length);

    }

  else

    {

      /* Buffer was already on the heap.  Check for overflow.  */

      if (__glibc_likely (new_length >= buffer->length))

	new_ptr = realloc (buffer->data, new_length);

      else

	{

	  __set_errno (ENOMEM);

	  new_ptr = NULL;

	}

      if (__glibc_unlikely (new_ptr == NULL))

	{

	  /* Deallocate, but buffer must remain valid to free.  */

	  free (buffer->data);

	  scratch_buffer_init (buffer);

	  return false;

	}

    }

  /* Install new heap-based buffer.  */

  buffer->data = new_ptr;

  buffer->length = new_length;

  return true;

}

libc_hidden_def (__libc_scratch_buffer_grow_preserve)