NAME

io_timeout_ctl − establish a time limit for I/O operations

SYNOPSIS

int io_timeout_ctl (eid, time);
int eid;
long time;

HP-UX COMPATIBILITY

Level: Device I/O Library − HP-UX/EXTENDED

Origin: HP

DESCRIPTION

Io_timeout_ctl  enables you to assign a timeout  value to the specified entity id.  Eid is an entity identifier of an open HP-IB raw bus device file obtained from an open(2), dup(2), fcntl(2), or creat(2) call.  open(2), dup(2), fcntl(2), or creat(2) call.  Time is a 32-bit integer value specifying the length of the timeout in microseconds. 

This  timeout  applies to future read and write requests on this entity id. If a read or write request does not complete  within the  specified  time limit, the  request  is aborted  and returns an error indication.  The errno value for a timed-out request is EIO, specifying that a timeout has occurred. 

Although the timeout value is specified in microseconds, the resolution of the timeout is system-dependent.  For example, a particular  system might have a resolution  of 10  milliseconds,  in which case the specified  timeout value is  rounded  up to the next 10 msec  boundary.  A timeout value of zero means that the system  never causes a timeout.  When a file is opened, a zero timeout value is assigned by default. 

Entity ids for the  same  device file  obtained  by  separate open(2)   requests  have  their   own  timeout  values associated  with  them. Entity ids for the  same  device file obtained by  dup(2) or  inherited by a  fork(2)  request share the  same  timeout  value.  In the  latter case, if one process  changes the  timeout,  the  new  timeout  is in effect for all such entity ids. 

HARDWARE DEPENDENCIES

Series 500:
The timeout resolution is 10 msec.  If an I/O operation is aborted due to a timeout, an errinfo(2) value of 56 is returned. 

Series 200 and 300:
The default timeout for Series 200/300 is 15 seconds.  Timeout resolution is 20 msec.

RETURN VALUE

Io_timeout_ctl  returns 0 (zero) if  successful,  or −1 if an error was encountered. 

DIAGNOSTICS

Io_timeout_ctl fails under the following circumstances, and sets errno (see errno(2)) to the value in square brackets:

eid does not refer to an open file [EBADF];

eid does not refer to a channel device file [ENOTTY]. 

Hewlett-Packard  —  last mod. May 11, 2021