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Diffstat (limited to 'src/stdlib')
| -rw-r--r-- | src/stdlib/malloc.c | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/src/stdlib/malloc.c b/src/stdlib/malloc.c new file mode 100644 index 0000000..82a6f54 --- /dev/null +++ b/src/stdlib/malloc.c @@ -0,0 +1,134 @@ +/** + * 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); +} + |