monado/src/xrt/auxiliary/util/u_misc.h

// Copyright 2019, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Very small misc utils.
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @ingroup aux_util
 */

#pragma once

#include <stdlib.h> // for calloc
#include <string.h> // for memset

#ifdef __cplusplus
extern "C" {
#endif


/*!
 * Allocate and zero the give size and casts the memory into a pointer of the
 * given type.
 *
 * Use instead of a bare calloc, but only when U_TYPED_CALLOC and
 * U_TYPED_ARRAY_CALLOC do not meet your needs.
 *
 * - If you are using `U_CALLOC_WITH_CAST(struct MyStruct, sizeof(MyStruct))` to
 *   allocate a single structure of fixed size, you should actually use
 *   `U_TYPED_CALLOC(struct MyStruct)`.
 *
 * - If you are using `U_CALLOC_WITH_CAST(struct MyStruct, sizeof(MyStruct) *
 *   n)` to allocate an array, you should actually use
 *   `U_TYPED_ARRAY_CALLOC(struct MyStruct, n)`.
 *
 * @ingroup aux_util
 */
#define U_CALLOC_WITH_CAST(TYPE, SIZE) ((TYPE *)calloc(1, SIZE))

/*!
 * Allocate and zero the space required for some type, and cast the return type
 * appropriately.
 *
 * Use instead of a bare calloc when allocating a single structure.
 *
 * @ingroup aux_util
 */
#define U_TYPED_CALLOC(TYPE) ((TYPE *)calloc(1, sizeof(TYPE)))

/*!
 * Allocate and zero the space required for some type, and cast the return type
 * appropriately.
 *
 * Use instead of a bare calloc when allocating an array of a type.
 * This includes allocating C strings: pass char as the type.
 *
 * @ingroup aux_util
 */
#define U_TYPED_ARRAY_CALLOC(TYPE, COUNT) ((TYPE *)calloc((COUNT), sizeof(TYPE)))

/*!
 * Zeroes the correct amount of memory based on the type pointed-to by the
 * argument.
 *
 * Use instead of memset(..., 0, ...) on a structure or pointer to structure.
 *
 * @ingroup aux_util
 */
#define U_ZERO(PTR) memset((PTR), 0, sizeof(*(PTR)))

/*!
 * Zeroes the correct amount of memory based on the type and size of the static
 * array named in the argument.
 *
 * Use instead of memset(..., 0, ...) on an array.
 *
 * @ingroup aux_util
 */
#define U_ZERO_ARRAY(ARRAY) memset((ARRAY), 0, sizeof(ARRAY))

/*!
 * Reallocates or frees dynamically-allocated memory.
 *
 * Just wraps realloc with a return value check, freeing the provided memory if
 * it is NULL, to avoid leaks. Use U_ARRAY_REALLOC_OR_FREE() instead.
 *
 * @ingroup aux_util
 */
static inline void *
u_realloc_or_free(void *ptr, size_t new_size)
{
	void *ret = realloc(ptr, new_size);
	if (ret == NULL) {
		free(ptr);
	}
	return ret;
}

/*!
 * Re-allocate the space required for some type, and update the pointer -
 * freeing the allocation instead if it can't be resized.
 *
 * Use instead of a bare realloc when allocating an array of a type.
 * This includes reallocating C strings: pass char as the type.
 *
 * Be sure not to parenthesize the type! It will cause an error like "expression
 * expected".
 *
 * On the other hand, if you get an incompatible types error in assignment,
 * that's a type mismatch, a real bug.
 *
 * @ingroup aux_util
 */
#define U_ARRAY_REALLOC_OR_FREE(VAR, TYPE, COUNT) (VAR) = ((TYPE *)u_realloc_or_free((VAR), sizeof(TYPE) * (COUNT)))

#ifdef __cplusplus
}
#endif