io_readfile - open a file for reading and writing

       io_readwritefile sets d to the number of a new descriptor reading from and writing to the disk file named
       s, and returns 1.  The file needs to exist.

       If  something  goes  wrong, io_readwritefile sets errno to indicate the error, and returns 0; it does not
       create a new descriptor, and it does not touch d.

       io_readfile - open a file for reading and writing

io_readfile(3), io_createfile(3), io_appendfile(3)

                                                                                             io_readwritefile(3)

#include<libowfat/io.h>

       int io_readwritefile(int64* d,const char* s);