/* alloc - Convenience routines for safely allocating memory
 * Copyright (C) 2007-2009  Josh Coalson
 * Copyright (C) 2011-2016  Xiph.Org Foundation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Xiph.org Foundation nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef FLAC__SHARE__ALLOC_H
#define FLAC__SHARE__ALLOC_H

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

/* WATCHOUT: for c++ you may have to #define __STDC_LIMIT_MACROS 1 real early
 * before #including this file,  otherwise SIZE_MAX might not be defined
 */

#include <limits.h> /* for SIZE_MAX */
#include <stdint.h> /* for SIZE_MAX in case limits.h didn't get it */
#include <stdlib.h> /* for size_t, malloc(), etc */
#include "share/compat.h"

/* avoid malloc()ing 0 bytes, see:
 * https://www.securecoding.cert.org/confluence/display/seccode/MEM04-A.+Do+not+make+assumptions+about+the+result+of+allocating+0+bytes?focusedCommentId=5407003
*/
static inline void *safe_malloc_(size_t size)
{
	/* malloc(0) is undefined; FLAC src convention is to always allocate */
	if(!size)
		size++;
	return malloc(size);
}

static inline void *safe_calloc_(size_t nmemb, size_t size)
{
	if(!nmemb || !size)
		return malloc(1); /* malloc(0) is undefined; FLAC src convention is to always allocate */
	return calloc(nmemb, size);
}

/*@@@@ there's probably a better way to prevent overflows when allocating untrusted sums but this works for now */

static inline void *safe_malloc_add_2op_(size_t size1, size_t size2)
{
	size2 += size1;
	if(size2 < size1)
		return 0;
	return safe_malloc_(size2);
}

static inline void *safe_malloc_add_3op_(size_t size1, size_t size2, size_t size3)
{
	size2 += size1;
	if(size2 < size1)
		return 0;
	size3 += size2;
	if(size3 < size2)
		return 0;
	return safe_malloc_(size3);
}

static inline void *safe_malloc_add_4op_(size_t size1, size_t size2, size_t size3, size_t size4)
{
	size2 += size1;
	if(size2 < size1)
		return 0;
	size3 += size2;
	if(size3 < size2)
		return 0;
	size4 += size3;
	if(size4 < size3)
		return 0;
	return safe_malloc_(size4);
}

void *safe_malloc_mul_2op_(size_t size1, size_t size2) ;

static inline void *safe_malloc_mul_3op_(size_t size1, size_t size2, size_t size3)
{
	if(!size1 || !size2 || !size3)
		return malloc(1); /* malloc(0) is undefined; FLAC src convention is to always allocate */
	if(size1 > SIZE_MAX / size2)
		return 0;
	size1 *= size2;
	if(size1 > SIZE_MAX / size3)
		return 0;
	return malloc(size1*size3);
}

/* size1*size2 + size3 */
static inline void *safe_malloc_mul2add_(size_t size1, size_t size2, size_t size3)
{
	if(!size1 || !size2)
		return safe_malloc_(size3);
	if(size1 > SIZE_MAX / size2)
		return 0;
	return safe_malloc_add_2op_(size1*size2, size3);
}

/* size1 * (size2 + size3) */
static inline void *safe_malloc_muladd2_(size_t size1, size_t size2, size_t size3)
{
	if(!size1 || (!size2 && !size3))
		return malloc(1); /* malloc(0) is undefined; FLAC src convention is to always allocate */
	size2 += size3;
	if(size2 < size3)
		return 0;
	if(size1 > SIZE_MAX / size2)
		return 0;
	return malloc(size1*size2);
}

static inline void *safe_realloc_(void *ptr, size_t size)
{
	void *oldptr = ptr;
	void *newptr = realloc(ptr, size);
	if(size > 0 && newptr == 0)
		free(oldptr);
	return newptr;
}
static inline void *safe_realloc_add_2op_(void *ptr, size_t size1, size_t size2)
{
	size2 += size1;
	if(size2 < size1) {
		free(ptr);
		return 0;
	}
	return realloc(ptr, size2);
}

static inline void *safe_realloc_add_3op_(void *ptr, size_t size1, size_t size2, size_t size3)
{
	size2 += size1;
	if(size2 < size1)
		return 0;
	size3 += size2;
	if(size3 < size2)
		return 0;
	return realloc(ptr, size3);
}

static inline void *safe_realloc_add_4op_(void *ptr, size_t size1, size_t size2, size_t size3, size_t size4)
{
	size2 += size1;
	if(size2 < size1)
		return 0;
	size3 += size2;
	if(size3 < size2)
		return 0;
	size4 += size3;
	if(size4 < size3)
		return 0;
	return realloc(ptr, size4);
}

static inline void *safe_realloc_mul_2op_(void *ptr, size_t size1, size_t size2)
{
	if(!size1 || !size2)
		return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
	if(size1 > SIZE_MAX / size2)
		return 0;
	return safe_realloc_(ptr, size1*size2);
}

/* size1 * (size2 + size3) */
static inline void *safe_realloc_muladd2_(void *ptr, size_t size1, size_t size2, size_t size3)
{
	if(!size1 || (!size2 && !size3))
		return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
	size2 += size3;
	if(size2 < size3)
		return 0;
	return safe_realloc_mul_2op_(ptr, size1, size2);
}

#endif
