HPUX ioctl[5]
ioctl in anderen Kapiteln des hpux Handbuch:
ioctl.2
ioctl(5) ioctl(5)
NAME
ioctl - generic device control commands
SYNOPSIS
#include <sys/ioctl.h>
ioctl(fildes, request, arg)
int fildes, request;
DESCRIPTION
The ioctl(2) system call provides for control over open devices. This
include file describes requests and arguments used in ioctl(2) which
are of a generic nature. For details about how individual requests
will affect any particular device, see the corresponding device manual
entry in Section (7). If a device does not support an ioctl request
it returns EINVAL.
FIONREAD
Returns in the long integer whose address is arg the number of
characters immediately readable from the device file.
FIOSSAIOSTAT
For those character device files which support this command,
if the integer whose address is arg is non-zero, system
asynchronous I/O is enabled; that is, enable SIGIO to be sent
to the process currently designated with FIOSSAIOOWN (see
below) whenever device-file-dependent events occur. If no
process has been designated with FIOSSAIOOWN, then enable
SIGIO to be sent to the first process to open the device file.
If the designated process has exited, the SIGIO signal is not
sent to any process.
If the integer whose address is arg is 0, system asynchronous
I/O is disabled.
FIOGSAIOSTAT
For those character device files which support this command,
the integer whose address is arg is set to 1, if system
asynchronous I/O is enabled. Otherwise, the integer whose
address is arg is set to 0.
FIOSSAIOOWN
For those character device files which support this command,
set process ID to receive the SIGIO signals with system
asynchronous I/O to the value of the integer whose address is
arg. Users with appropriate privileges can designate that any
process receive the SIGIO signals. If the request is not made
by the super-user, only the calling process is allowed to
designate that itself or another process whose real or saved
effective user ID matches its real or effective user ID, or a
process which is a descendant of the calling process, receive
Hewlett-Packard Company - 1 - HP-UX Release 9.0: August 1992
ioctl(5) ioctl(5)
the SIGIO signals. If no process can be found corresponding
to that specified by the integer whose address is arg, the
call will fail, with errno set to ESRCH. If the request is
not made by the super-user and the calling process attempts to
designate a process other than itself or (1) another process
whose real or saved effective user ID matches its real or
effective user ID, or (2) a process which is not a descendant
of the calling process, the call fails, with errno set to
EPERM.
If the designated process subsequently exits, the SIGIO signal
will not be sent to any process.
The default when opening a device file is that the process
performing the open is set to receive the SIGIO signals.
FIOGSAIOOWN
For those character device files which support this command,
the integer whose address is arg is set to the process ID
designated to receive SIGIO signals.
FIOSNBIO
For those character device files which support this command,
if the integer whose address is arg is non-zero, non-blocking
I/O is enabled; that is, subsequent reads and writes to the
device file are handled in a non-blocking manner (see below).
If the integer whose address is arg is 0, non-blocking I/O is
disabled.
For reads, non-blocking I/O prevents all read requests to that
device from blocking, whether the requests succeed or fail.
Such read requests complete in one of three ways:
o If there is enough data available to satisfy the entire
request, the read completes successfully, having read
all of the data, and returns the number of bytes read;
o If there is not enough data available to satisfy the
entire request, the read completes successfully, having
read as much data as possible, and returns the number of
bytes it was able to read;
o If there is no data available, the read fails and errno
is set to EWOULDBLOCK.
For writes, non-blocking I/O prevents all write requests to
that device file from blocking, whether the requests succeed
or fail. Such a write request completes in one of three ways:
o If there is enough space available in the system to
buffer all the data, the write completes successfully,
Hewlett-Packard Company - 2 - HP-UX Release 9.0: August 1992
ioctl(5) ioctl(5)
having written out all of the data, and returns the
number of bytes written;
o If there is not enough space in the buffer to write out
the entire request, the write completes successfully,
having written as much data as possible, and returns the
number of bytes it was able to write;
o If there is no space in the buffer, the write fails and
errno is set to EWOULDBLOCK.
To prohibit non-blocking I/O from interfering with the
O_NDELAY flag (see open(2) and fcntl(2)), the functionality of
O_NDELAY always supercedes the functionality of non-blocking
I/O. This means that if O_NDELAY is set, the driver performs
read requests in accordance with the definition of O_NDELAY.
When O_NDELAY is not set, the definition of non-blocking I/O
applies.
The default on open of a device file is that non-blocking I/O
is disabled.
FIOGNBIO
For those character device files which support this command,
the integer whose address is arg is set to 1, if non-blocking
I/O is enabled. Otherwise, the integer whose address is arg
is set to 0.
WARNINGS
FIOSSAIOSTAT is similar to 4.2 BSD FIOASYNC, with the addition of
provisions for security. FIOGSAIOSTAT is of HP origin, complements
FIOSSAIOSTAT, and allows saving and restoring system asynchronous I/O
TTY state for BSD style job control. FIOSSAIOOWN is similar to 4.2
BSD FIOSETOWN, with the addition of provisions for security.
FIOGSAIOOWN is similar to 4.2 BSD FIOGETOWN. Note also the difference
that the 4.2 BSD version of this functionality used process groups,
while the HP-UX version only uses processes. FIOSNBIO is the same as
4.2 BSD FIONBIO, except that it does not interfere with the AT&T
O_NDELAY open and fcntl flag. FIOGNBIO is of HP origin, complements
FIOSNBIO, and allows saving and restoring non-blocking I/O TTY state
for BSD-style job control.
SEE ALSO
ioctl(2).
Section 7 of this manual.
Hewlett-Packard Company - 3 - HP-UX Release 9.0: August 1992