src/cx/allocator.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. 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.
 *
 * 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 COPYRIGHT HOLDER 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.
 */
/**
 * \file allocator.h
 * Interface for custom allocators.
 */

#ifndef UCX_ALLOCATOR_H
#define UCX_ALLOCATOR_H

#include "common.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * The class definition for an allocator.
 */
typedef struct {
    /**
     * The allocator's malloc() implementation.
     */
    void *(*malloc)(
            void *data,
            size_t n
    );

    /**
     * The allocator's realloc() implementation.
     */
    void *(*realloc)(
            void *data,
            void *mem,
            size_t n
    )
    __attribute__((__warn_unused_result__));

    /**
     * The allocator's calloc() implementation.
     */
    void *(*calloc)(
            void *data,
            size_t nelem,
            size_t n
    );

    /**
     * The allocator's free() implementation.
     */
    void (*free)(
            void *data,
            void *mem
    )
    __attribute__((__nonnull__));
} cx_allocator_class;

/**
 * Structure holding the data for an allocator.
 */
struct cx_allocator_s {
    /**
     * A pointer to the instance of the allocator class.
     */
    cx_allocator_class *cl;
    /**
     * A pointer to the data this allocator uses.
     */
    void *data;
};

/**
 * High-Level type alias for the allocator type.
 */
typedef struct cx_allocator_s CxAllocator;

/**
 * A default allocator using standard library malloc() etc.
 */
extern CxAllocator *cxDefaultAllocator;

/**
 * Function pointer type for destructor functions.
 *
 * A destructor function deallocates possible contents and MAY free the memory
 * pointed to by \p memory. Read the documentation of the respective function
 * pointer to learn if a destructor SHALL, MAY, or MUST NOT free the memory in that
 * particular implementation.
 *
 * @param memory a pointer to the object to destruct
  */
typedef void (*cx_destructor_func)(void *memory) __attribute__((__nonnull__));

/**
 * Function pointer type for destructor functions.
 *
 * A destructor function deallocates possible contents and MAY free the memory
 * pointed to by \p memory. Read the documentation of the respective function
 * pointer to learn if a destructor SHALL, MAY, or MUST NOT free the memory in that
 * particular implementation.
 *
 * @param data an optional pointer to custom data
 * @param memory a pointer to the object to destruct
  */
typedef void (*cx_destructor_func2)(
        void *data,
        void *memory
) __attribute__((__nonnull__(2)));

/**
 * Allocate \p n bytes of memory.
 *
 * @param allocator the allocator
 * @param n the number of bytes
 * @return a pointer to the allocated memory
 */
void *cxMalloc(
        CxAllocator const *allocator,
        size_t n
)
__attribute__((__malloc__))
__attribute__((__alloc_size__(2)));

/**
 * Re-allocate the previously allocated block in \p mem, making the new block \p n bytes long.
 * This function may return the same pointer that was passed to it, if moving the memory
 * was not necessary.
 *
 * \note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @param allocator the allocator
 * @param mem pointer to the previously allocated block
 * @param n the new size in bytes
 * @return a pointer to the re-allocated memory
 */
void *cxRealloc(
        CxAllocator const *allocator,
        void *mem,
        size_t n
)
__attribute__((__warn_unused_result__))
__attribute__((__alloc_size__(3)));

/**
 * Re-allocate a previously allocated block and changes the pointer in-place, if necessary.
 * This function acts like cxRealloc() using the pointer pointed to by \p mem.
 * On success, the pointer is changed to the new location (in case the
 *
 * \note Re-allocating a block allocated by a different allocator is undefined.
 *
 * \par Error handling
 * \c errno will be set, if the underlying realloc function does so.
 *
 * @param allocator the allocator
 * @param mem pointer to the pointer to allocated block
 * @param n the new size in bytes
 * @return zero on success, non-zero on failure
 */
int cxReallocate(
        CxAllocator const *allocator,
        void **mem,
        size_t n
)
__attribute__((__nonnull__));

/**
 * Allocate \p nelem elements of \p n bytes each, all initialized to zero.
 *
 * @param allocator the allocator
 * @param nelem the number of elements
 * @param n the size of each element in bytes
 * @return a pointer to the allocated memory
 */
void *cxCalloc(
        CxAllocator const *allocator,
        size_t nelem,
        size_t n
)
__attribute__((__malloc__))
__attribute__((__alloc_size__(2, 3)));

/**
 * Free a block allocated by this allocator.
 *
 * \note Freeing a block of a different allocator is undefined.
 *
 * @param allocator the allocator
 * @param mem a pointer to the block to free
 */
void cxFree(
        CxAllocator const *allocator,
        void *mem
)
__attribute__((__nonnull__));

#ifdef __cplusplus
} // extern "C"
#endif

#endif // UCX_ALLOCATOR_H