Manual Reference Pages  - <poll.h> (P)

PROLOG

This manual page is part of the POSIX Programmer’s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

CONTENTS

Name
Synopsis
Description
Application Usage
Rationale
Future Directions
See Also
Copyright

NAME

poll.h - definitions for the poll() function

SYNOPSIS

#include <poll.h>

DESCRIPTION

The <poll.h> header shall define the pollfd structure that includes at least the following members:

int fd The following descriptor being polled. short events The input event flags (see below). short revents The output event flags (see below).

The <poll.h> header shall define the following type through typedef:
nfds_t An unsigned integer type used for the number of file descriptors.

The implementation shall support one or more programming environments in which the width of nfds_t is no greater than the width of type long. The names of these programming environments can be obtained using the confstr() function or the getconf utility.
The following symbolic constants shall be defined, zero or more of which may be OR’ed together to form the events or revents members in the pollfd structure:
POLLIN Data other than high-priority data may be read without blocking.
POLLRDNORM
  Normal data may be read without blocking.
POLLRDBAND
  Priority data may be read without blocking.
POLLPRI High priority data may be read without blocking.
POLLOUT Normal data may be written without blocking.
POLLWRNORM
  Equivalent to POLLOUT.
POLLWRBAND
  Priority data may be written.
POLLERR An error has occurred ( revents only).
POLLHUP Device has been disconnected ( revents only).
POLLNVAL
  Invalid fd member ( revents only).

The significance and semantics of normal, priority, and high-priority data are file and device-specific.

The following shall be declared as a function and may also be defined as a macro. A function prototype shall be provided.

int poll(struct pollfd[], nfds_t, int);

The following sections are informative.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

The System Interfaces volume of IEEE Std 1003.1-2001, confstr(), poll(), the Shell and Utilities volume of IEEE Std 1003.1-2001, getconf

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .


IEEE/The Open Group <poll.h> (P) 2003
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