The open Functions

void `f_affix'(file f, text path);
opens the f object file for the path file reading.
It is equivalent to `f_open'(f, path, `OPEN_READONLY', `0').
void `f_open'(file f, text path, mode bits, mode permissions);
opens the f object file for the path file reading and/or writing (actually reading and writing is not supported, only reading or writing).
The `f_open' semantics loosely follows the semantics of UNIX open function.
The bits argument specify the open mode and is the bitwise OR of some file open bits.
See File Open Definitions.
At least one of the `OPEN_READONLY' and `OPEN_WRITEONLY' better be specified. The two definitions may have funny values since they are (or may be) redefinitions of O_RDONLY and O_WRONLY. Due to their funny values failing to specify one of them will have undefined results.
If the file is to be created it will be created with the permissions permissions (in same way as the open(2) function, the permissions argument is passed unchanged as the third argument to the open(2) function).
If f is already opened `f_open' closes it before attempting open it for path operations.