@node _open, file system
@subheading Syntax

@example
#include <io.h>

int _open(const char *path, int attrib);
@end example

@subheading Description

This is a direct connection to the MS-DOS open function call, int 0x21,
%ah = 0x3d.  (When long file names are supported, @code{_open} calls
function 0x716c of Int 0x21.)  The file is set to binary mode.

This function can be hooked by the @dfn{File System Extensions}
(@pxref{File System Extensions}).  If you don't want this, you should
use @code{_dos_open} (@pxref{_dos_open}) (but note that the latter
doesn't support long file names).

@subheading Return Value

The new file descriptor, else -1 on error.

@subheading Portability

@portability !ansi, !posix