Initialize buffer structure
#include <buffer.h>
void buffer_init_free(buffer &b,
ssize_t (*op)(int,char*,size_t), int fd, char* y, size_t ylen);
buffer_init_free is like buffer_init except that the memory (y is marked to be freed by buffer_close().
buffer_init(3), buffer_mmap_read(3), buffer(3)