/**
* slibc — Yet another C library
* Copyright © 2015 Mattias Andrée (maandree@member.fsf.org)
*
* 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 <stdlib.h>
#include <slibc-alloc.h>
#include <strings.h>
#include <sys/mman.h>
/**
* Create a new memory allocation on the heap.
* The allocation will not be initialised.
*
* @param size The size of the allocation.
* @return Pointer to the beginning of the new allocation.
* If `size` is zero, this function will either return
* `NULL` (that is what this implement does) or return
* a unique pointer that can later be freed with `free`.
* `NULL` is returned on error, and `errno` is set to
* indicate the error.
*
* @throws ENOMEM The process cannot allocate more memory.
*/
void* malloc(size_t size)
{
/* TODO implement implementation of malloc */
char* ptr;
if (size == 0)
return NULL;
ptr = mmap(NULL, sizeof(size_t) + size, (PROT_READ | PROT_WRITE),
(MAP_PRIVATE | MAP_ANONYMOUS), -1, 0);
*(size_t*)ptr = size;
return ptr + sizeof(size_t);
}
/**
* Variant of `malloc` that clears the allocation with zeroes.
*
* `p = calloc(n, m)` is equivalent to
* `(p = malloc(n * m), p ? (explicit_bzero(p, n * m), p) : NULL)`
*
* @param elem_count The number of elements to allocate.
* @param elem_size The size of each element.
* @return Pointer to the beginning of the new allocation.
* If `elem_count` or `elem_size` is zero, this function
* will either return `NULL` (that is what this implement
* does) or return a unique pointer that can later be
* freed with `free`. `NULL` is returned on error, and
* `errno` is set to indicate the error.
*
* @throws ENOMEM The process cannot allocate more memory.
*/
void* calloc(size_t elem_count, size_t elem_size)
{
void* ptr = malloc(elem_count * elem_size);
if (ptr != NULL)
explicit_bzero(ptr, elem_count * elem_size);
return ptr;
}
/**
* Variant of `malloc` that extends, or shrinks, an existing allocation,
* if beneficial and possible, or creates a new allocation with the new
* size, copies the data, and frees the old allocation.
*
* On error, `ptr` is not freed.
*
* @param ptr Pointer to the beginning of the old memory allocation.
* The process may crash if it does not point to the
* beginning of a memory allocation on the heap.
* However, if it is `NULL`, this function will behave
* like `malloc`.
* @param size The new allocation size. If zero, this function will
* behave like `free`, and will return `NULL`.
* @return Pointer to the beginning of the new allocation.
* If `size` is zero, `NULL` is returned. On error `NULL`
* is returned and `errno` is set to indicate the error.
*
* @throws ENOMEM The process cannot allocate more memory.
*/
void* realloc(void* ptr, size_t size)
{
return fast_realloc(ptr, size);
}
/**
* Free a memory allocation.
*
* @param ptr Pointer to the beginning of the memory allocation.
* The process may crash if it does not point to the
* beginning of a memory allocation on the heap.
* However, if it is `NULL`, nothing will happen.
*/
void free(void* ptr)
{
fast_free(ptr);
}
/**
* This function is identical to `free`.
* Any argument beyond the first argument, is ignored.
*
* This function uses variadic arguments because there
* there are multiple conflicting specifications for `cfree`.
*
* @param ptr Pointer to the beginning of the memory allocation.
* The process may crash if it does not point to the
* beginning of a memory allocation on the heap.
* However, if it is `NULL`, nothing will happen.
*/
void cfree(void* ptr, ...)
{
fast_free(ptr);
}
