diff options
| -rw-r--r-- | include/slibc-alloc.h | 62 | ||||
| -rw-r--r-- | src/slibc-alloc.c | 69 |
2 files changed, 130 insertions, 1 deletions
diff --git a/include/slibc-alloc.h b/include/slibc-alloc.h index 7bd2e81..70b1b4c 100644 --- a/include/slibc-alloc.h +++ b/include/slibc-alloc.h @@ -28,6 +28,26 @@ /** + * Configurations for `extalloc`. + * There are independent of each other, and + * multiple can be selected by using bitwise or + * between them. + */ +enum extalloc_mode + { + /** + * Clear disowned memory. + */ + EXTALLOC_CLEAR = 1, + + /** + * Create new allocation with `malloc` if necessary. + */ + EXTALLOC_MALLOC = 2, + }; + + +/** * This function is identical to `free`, except it is guaranteed not to * override the memory segment with zeroes before freeing the allocation. * @@ -134,6 +154,32 @@ void* custom_realloc(void*, size_t, int, int, int) __GCC_ONLY(__attribute__((warn_unused_result))); /** + * This function is similar to `realloc`, however it + * does not copy the data in the memory segment when + * a new pointer is created. Additionally, the + * behaviour is undefined if `ptr` is `NULL`, `size` + * is zero, or `size` equals the old allocation size. + * These additional quirks were added to improve + * performance; after all, this function was added + * to improve performance. + * + * The behaviour is undefined if `mode` does not + * contain a valid flag-combination. + * + * @param ptr The old allocation, see `realloc` for more details. + * @param size The new allocation size, see `realloc` for more details. + * @param mode `EXTALLOC_CLEAR` or `EXTALLOC_MALLOC`, or both or neither. + * @return The new allocation, see `realloc` for more details. + * If `EXTALLOC_MALLOC` is not used, `NULL` is returned + * and `errno` set to zero, if a new allocation is required. + * + * @throws 0 `errno` is set to zero success if `NULL` is returned. + * @throws ENOMEM The process cannot allocate more memory. + */ +void* extalloc(void*, size_t, enum extalloc_mode) + __GCC_ONLY(__attribute__((nonnull, warn_unused_result))); + +/** * This function behaves exactly like `fast_realloc`, except: * - Its behaviour is undefined if `ptr` is `NULL`. * - Its behaviour is undefined if `size` equals the old allocation size. @@ -149,6 +195,22 @@ void* custom_realloc(void*, size_t, int, int, int) void* naive_realloc(void*, size_t) /* sic! we limit ourself to ASCII */ __GCC_ONLY(__attribute__((nonnull, warn_unused_result))); +/** + * This function behaves exactly like `__attribute__`, except + * it will return `NULL` with `errno` set to zero, if it is + * not possible to perform the shrink or growth without creating + * new pointer. + * + * @param ptr The old allocation, see `realloc` for more details. + * @param size The new allocation size, see `realloc` for more details. + * @return `ptr` on success or `NULL` on error or if `malloc` is needed. + * + * @throws 0 `malloc` is require to perform the action. + * @throws ENOMEM The process cannot allocate more memory. + */ +void* naive_extalloc(void*, size_t) /* sic! we limit ourself to ASCII */ + __GCC_ONLY(__attribute__((nonnull, warn_unused_result))); + /** * This macro calls `fast_free` and then sets the pointer to `NULL`, diff --git a/src/slibc-alloc.c b/src/slibc-alloc.c index 1b85aad..9380d24 100644 --- a/src/slibc-alloc.c +++ b/src/slibc-alloc.c @@ -117,9 +117,11 @@ size_t allocsize(void* segment) new_ptr = naive_realloc(ptr); \ if (new_ptr != ptr) \ { \ + if (new_ptr == NULL) \ + return NULL; \ if (CLEAR_FREE) \ explicit_bzero(PURE_ALLOC(ptr), PURE_SIZE(ptr)); \ - fast_free(new_ptr); \ + fast_free(ptr); \ } \ \ if (CLEAR_NEW ? (old_size < size) : 0) \ @@ -207,6 +209,50 @@ void* custom_realloc(void* ptr, size_t size, int clear_old, int clear_new, int c /** + * This function is similar to `realloc`, however it + * does not copy the data in the memory segment when + * a new pointer is created. Additionally, the + * behaviour is undefined if `ptr` is `NULL`, `size` + * is zero, or `size` equals the old allocation size. + * These additional quirks were added to improve + * performance; after all, this function was added + * to improve performance. + * + * The behaviour is undefined if `mode` does not + * contain a valid flag-combination. + * + * @param ptr The old allocation, see `realloc` for more details. + * @param size The new allocation size, see `realloc` for more details. + * @param mode `EXTALLOC_CLEAR` or `EXTALLOC_MALLOC`, or both or neither. + * @return The new allocation, see `realloc` for more details. + * If `EXTALLOC_MALLOC` is not used, `NULL` is returned + * and `errno` set to zero, if a new allocation is required. + * + * @throws 0 `errno` is set to zero success if `NULL` is returned. + * @throws ENOMEM The process cannot allocate more memory. + */ +void* extalloc(void* ptr, size_t size, enum extalloc_mode mode) +{ + int clear = mode & EXTALLOC_CLEAR; + size_t old_size; + void* new_ptr; + + if (clear ? (old_size > size) : 0) + explicit_bzero(((char*)ptr) + size, old_size - size); + + new_ptr = ((mode & EXTALLOC_MALLOC) ? naive_realloc : naive_extalloc)(ptr); + if ((new_ptr != ptr) && (ptr_new != NULL)) + { + if (clear) + explicit_bzero(PURE_ALLOC(ptr), PURE_SIZE(ptr)); + fast_free(ptr); + } + + return new_ptr; +} + + +/** * This function behaves exactly like `fast_realloc`, except: * - Its behaviour is undefined if `ptr` is `NULL`. * - Its behaviour is undefined if `size` equals the old allocation size. @@ -226,3 +272,24 @@ void* naive_realloc(void* ptr, size_t size) (void) ptr; } + +/** + * This function behaves exactly like `__attribute__`, except + * it will return `NULL` with `errno` set to zero, if it is + * not possible to perform the shrink or growth without creating + * new pointer. + * + * @param ptr The old allocation, see `realloc` for more details. + * @param size The new allocation size, see `realloc` for more details. + * @return `ptr` on success or `NULL` on error or if `malloc` is needed. + * + * @throws 0 `malloc` is require to perform the action. + * @throws ENOMEM The process cannot allocate more memory. + */ +void* naive_extalloc(void* ptr, size_t size) +{ + /* TODO implement naive_extalloc */ + return NULL; + (void) ptr, (void) size; +} + |