reallocf man page
reallocf — general purpose memory allocation functions
reallocf(void *ptr, size_t size);
The reallocf() function changes the size of the previously allocated memory referenced by ptr to size bytes. The contents of the memory are unchanged up to the lesser of the new and old sizes. If the new size is larger, the contents of the newly allocated portion of the memory are undefined. Upon success, the memory referenced by ptr is freed and a pointer to the newly allocated memory is returned. Note that reallocf() may move the memory allocation, resulting in a different return value than ptr. If ptr is NULL, the reallocf() function behaves identically to malloc() for the specified size. Upon failure, when the requested memory cannot be allocated, the passed pointer is freed to ease the problems with traditional coding styles for reallocf() causing memory leaks in libraries.
The reallocf() function returns a pointer, possibly identical to ptr, to the allocated memory if successful; otherwise a NULL pointer is returned, and errno is set to ENOMEM if the error was the result of an allocation failure. The buffer is deallocated in this case.
brk(2), mmap(2), alloca(3), calloc(3), free(3), malloc(3), posix_memalign(3), realloc(3),
The reallocf() function first appeared in FreeBSD 3.0.