Overview

This package implements the System V poll(2) system call for Unix-like systems that do not support poll. For instance, the following Unix-like operating systems do not support poll:

• NetBSD, prior to version 1.3
• FreeBSD, prior to version 3.0
• OpenBSD, prior to version 2.0
• BSD/OS. (See the BSD/OS man pages.)
• Apple's Mac OS X (prior to OS X 10.3) and Darwin
• QNX 6
• 4.4 BSD Lite 2 (not generally used by production systems)
• 386BSD (pretty much obsolete these days)

poll provides a method for multiplexing input and output on multiple open file descriptors; in traditional BSD systems, that capability is provided by select(2). While the semantics of select differ from those of poll, poll can be readily emulated in terms of select, which is exactly what this small piece of software does.

Brief documentation on this emulation can be found at the top of the poll.h header file. For a full description of poll, consult W. Richard Stevens' excellent book, Unix Network Programming (Prentice-Hall, 1990). The software should compile on most BSD UNIX systems without modification. I have successfully compiled it on:

• BSD/OS (BSDI) 1.1, 2.0, 2.1
• FreeBSD 2.1.0 through 4.11
• Mac OS X 10.4 (Tiger)

Acknowledgments

• Benjamin Reed, ranger @ befunk.com, has supplied the initial Makefile changes to build it on Mac OS X (Darwin).
• Sven Fischer, fischer @ deutaeit.de, informed me that it works, without change, on QNX 6.
• John Gilmore, gnu @ toad.com, reported some linkage errors on Mac OS X, suggested the addition of the nfds_t type, and suggested a revision of the license.

See the README and INSTALL files in the tarball for details.

License and Copyright

This software is released under the following license, adapted from http://opensource.org/licenses/bsd-license.php:

Copyright © 1995-2009, Brian M. Clapper
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• Neither the name of the clapper.org nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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