Inserting

are there any open/write functions for C , which do not overwrite chars in a file , but insert them ?

or do i have to write a shitty loop that just reads , stores and writes a char ?

also discuss file and string handling libraries because most that i have seen suck .

>>8
i want to patch certain large files fast and with low heap usage .

BTW : there is no function in libc which can insert into buffers ? i assume i would have to implement a read store write loop for a buffer too ? after allocating memory ofcourse .