@node _dos_open, dos
@subheading Syntax

@example
#include <fcntl.h>
#include <share.h>
#include <dos.h>

unsigned int _dos_open(const char *filename, unsigned short mode, int *handle);
@end example

@subheading Description

This is a direct connection to the MS-DOS open function call (%ah = 0x3D).
This function opens the given file with the given mode and puts handle of
file into @var{handle} if openning is successful.
Meaning of @var{mode} parameter is the following:

Access mode bits (in FCNTL.H):
@table @code

@item O_RDONLY (_O_RDONLY) 0x00

Open for read only

@item O_WRONLY (_O_WRONLY) 0x01

Open for write only

@item O_RDWR (_O_RDWR) 0x02

Open for read and write

@end table

Sharing mode bits (in SHARE.H):
@table @code

@item SH_COMPAT (_SH_COMPAT) 0x00

Compatibility mode

@item SH_DENYRW (_SH_DENYRW) 0x10

Deny read/write mode

@item SH_DENYWR (_SH_DENYWR) 0x20

Deny write mode

@item SH_DENYRD (_SH_DENYRD) 0x30

Deny read mode

@item SH_DENYNO (_SH_DENYNO) 0x40

Deny none mode

@end table

Inheritance bits (in FCNTL.H):
@table @code

@item O_NOINHERIT (_O_NOINHERIT) 0x80

File is not inherited by child process

@end table

See also @ref{_dos_creat}, @ref{_dos_creatnew}, @ref{_dos_read},
@ref{_dos_write}, and @ref{_dos_close}.

This function does not support long filenames, even on systems where the
LFN API (@pxref{_use_lfn, LFN}) is available.  For LFN-aware functions
with similar functionality see @ref{_open}, @ref{_creat}, and
@ref{_creatnew}.  Also see @ref{open}, and @ref{creat}, which are
Posix-standard.

@subheading Return Value

Returns 0 if successful or DOS error code on error (and sets
@var{errno} to EACCES, EINVAL, EMFILE or ENOENT).

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
int handle;

if ( !_dos_open("FOO.DAT", O_RDWR, &handle) )
   puts("Wow, file opening was successful !");
@end example