PXFFCNTL (L*X, M*X)

POSIX Subroutine: Manipulates an open file descriptor.

Module

USE IFPOSIX

CALL PXFFCNTL (ifildes,icmd,iargin,iargout,ierror)

ifildes	(Input) INTEGER(4). A file descriptor.
icmd	(Input) INTEGER(4). Defines an action for the file descriptor.
iargin	(Input; output) INTEGER(4). Interpretation of this argument depends on the value of icmd.
iargout	(Output) INTEGER(4). Interpretation of this argument depends on the value of icmd.
ierror	(Output) INTEGER(4). The error status.

If successful, ierror is set to zero; otherwise, an error code.

PXFFCNTL is a multi-purpose subroutine that causes an action to be performed on a file descriptor. The action, defined in icmd, can be obtained by using the values of predefined macros in C header fcntl.h, or by using PXFCONST or IPXFCONST with one of the following constant names:

Constant	Action
F_DUPFD	Returns into `iargout` the lowest available unopened file descriptor greater than or equal to `iargin`. The new file descriptor refers to the same open file as `ifildes` and shares any locks. The system flag FD_CLOEXEC for the new file descriptor is cleared so the new descriptor will not be closed on a call to PXFEXEC subroutine.
F_GETFD	Returns into `iargout` the value of system flag FD_CLOEXEC associated with `ifildes`. In this case, `iargin` is ignored.
F_SETFD	Sets or clears the system flag FD_CLOEXEC for file descriptor `ifildes`. The PXFEXEC family of functions will close all file descriptors with the FD_CLOEXEC flag set. The value for FD_CLOEXEC is obtained from argument `iargin`.
F_GETFL	Returns the file status flags for file descriptor `ifildes`. Unlike F_GETFD, these flags are associated with the file and shared by all descriptors. A combination of the following flags, which are symbolic names for PXFCONST or IPXFCONST, can be returned: O_APPEND - Specifies the file is opened in append mode. O_NONBLOCK - Specifies when the file is opened, it does not block waiting for data to become available. O_RDONLY - Specifies the file is opened for reading only. O_RDWR - Specifies the file is opened for both reading and writing. O_WRONLY - Specifies the file is opened for writing only.
F_SETFL	Sets the file status flags from `iargin` for file descriptor `ifildes`. Only O_APPEND or O_NONBLOCK flags can be modified. In this case, `iargout` is ignored.
F_GETLK	Gets information about a lock. Argument `iargin` must be a handle of structure `flock`. This structure is taken as the description of a lock for the file. If there is a lock already in place that would prevent this lock from being locked, it is returned to the structure associated with handle `iargin`. If there are no locks in place that would prevent the lock from being locked, field l_type in the structure is set to the value of the constant with symbolic name F_UNLCK.
F_SETLK	Sets or clears a lock. Argument `iargin` must be a handle of structure `flock`. The lock is set or cleared according to the value of structure field l_type. If the lock is busy, an error is returned.
F_SETLKW	Sets or clears a lock, but causes the process to wait if the lock is busy. Argument `iargin` must be a handle of structure `flock`. The lock is set or cleared according to the value of structure field l_type. If the lock is busy, PXFCNTL waits for an unlock.

Note

To get a handle for an instance of the flock structure, use PXFSTRUCTCREATE with the string 'flock' for the structure name.

PXFFCNTL (LX, MX)

Module

Note

See Also