aboutsummaryrefslogtreecommitdiffstats
path: root/trunk/main/poll.c
diff options
context:
space:
mode:
Diffstat (limited to 'trunk/main/poll.c')
-rw-r--r--trunk/main/poll.c306
1 files changed, 306 insertions, 0 deletions
diff --git a/trunk/main/poll.c b/trunk/main/poll.c
new file mode 100644
index 000000000..bd283866d
--- /dev/null
+++ b/trunk/main/poll.c
@@ -0,0 +1,306 @@
+/*---------------------------------------------------------------------------*\
+ $Id$
+
+ NAME
+
+ poll - select(2)-based poll() emulation function for BSD systems.
+
+ SYNOPSIS
+ #include "poll.h"
+
+ struct pollfd
+ {
+ int fd;
+ short events;
+ short revents;
+ }
+
+ int poll (struct pollfd *pArray, unsigned long n_fds, int timeout)
+
+ DESCRIPTION
+
+ This file, and the accompanying "poll.h", implement the System V
+ poll(2) system call for BSD systems (which typically do not provide
+ poll()). Poll() provides a method for multiplexing input and output
+ on multiple open file descriptors; in traditional BSD systems, that
+ capability is provided by select(). While the semantics of select()
+ differ from those of poll(), poll() can be readily emulated in terms
+ of select() -- which is how this function is implemented.
+
+ REFERENCES
+ Stevens, W. Richard. Unix Network Programming. Prentice-Hall, 1990.
+
+ NOTES
+ 1. This software requires an ANSI C compiler.
+
+ LICENSE
+
+ This software is released under the following license:
+
+ Copyright (c) 1995-2002 Brian M. Clapper
+ All rights reserved.
+
+ Redistribution and use in source and binary forms are
+ permitted provided that: (1) source distributions retain
+ this entire copyright notice and comment; (2) modifications
+ made to the software are prominently mentioned, and a copy
+ of the original software (or a pointer to its location) are
+ included; and (3) distributions including binaries display
+ the following acknowledgement: "This product includes
+ software developed by Brian M. Clapper <bmc@clapper.org>"
+ in the documentation or other materials provided with the
+ distribution. The name of the author may not be used to
+ endorse or promote products derived from this software
+ without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS
+ OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ PARTICULAR PURPOSE.
+
+ Effectively, this means you can do what you want with the software
+ except remove this notice or take advantage of the author's name.
+ If you modify the software and redistribute your modified version,
+ you must indicate that your version is a modification of the
+ original, and you must provide either a pointer to or a copy of the
+ original.
+\*---------------------------------------------------------------------------*/
+
+
+/*---------------------------------------------------------------------------*\
+ Includes
+\*---------------------------------------------------------------------------*/
+
+#include <unistd.h> /* standard Unix definitions */
+#include <sys/types.h> /* system types */
+#include <sys/time.h> /* time definitions */
+#include <assert.h> /* assertion macros */
+#include <string.h> /* string functions */
+
+#include "asterisk/poll-compat.h" /* this package */
+
+/*---------------------------------------------------------------------------*\
+ Macros
+\*---------------------------------------------------------------------------*/
+
+#ifndef MAX
+#define MAX(a,b) ((a) > (b) ? (a) : (b))
+#endif
+
+
+/*---------------------------------------------------------------------------*\
+ Private Functions
+\*---------------------------------------------------------------------------*/
+
+static int map_poll_spec
+#if __STDC__ > 0
+ (struct pollfd *pArray,
+ unsigned long n_fds,
+ fd_set *pReadSet,
+ fd_set *pWriteSet,
+ fd_set *pExceptSet)
+#else
+ (pArray, n_fds, pReadSet, pWriteSet, pExceptSet)
+ struct pollfd *pArray;
+ unsigned long n_fds;
+ fd_set *pReadSet;
+ fd_set *pWriteSet;
+ fd_set *pExceptSet;
+#endif
+{
+ register unsigned long i; /* loop control */
+ register struct pollfd *pCur; /* current array element */
+ register int max_fd = -1; /* return value */
+
+ /*
+ Map the poll() structures into the file descriptor sets required
+ by select().
+ */
+ for (i = 0, pCur = pArray; i < n_fds; i++, pCur++)
+ {
+ /* Skip any bad FDs in the array. */
+
+ if (pCur->fd < 0)
+ continue;
+
+ if (pCur->events & POLLIN)
+ {
+ /* "Input Ready" notification desired. */
+ FD_SET (pCur->fd, pReadSet);
+ }
+
+ if (pCur->events & POLLOUT)
+ {
+ /* "Output Possible" notification desired. */
+ FD_SET (pCur->fd, pWriteSet);
+ }
+
+ if (pCur->events & POLLPRI)
+ {
+ /*
+ "Exception Occurred" notification desired. (Exceptions
+ include out of band data.
+ */
+ FD_SET (pCur->fd, pExceptSet);
+ }
+
+ max_fd = MAX (max_fd, pCur->fd);
+ }
+
+ return max_fd;
+}
+
+static struct timeval *map_timeout
+#if __STDC__ > 0
+ (int poll_timeout, struct timeval *pSelTimeout)
+#else
+ (poll_timeout, pSelTimeout)
+ int poll_timeout;
+ struct timeval *pSelTimeout;
+#endif
+{
+ struct timeval *pResult;
+
+ /*
+ Map the poll() timeout value into a select() timeout. The possible
+ values of the poll() timeout value, and their meanings, are:
+
+ VALUE MEANING
+
+ -1 wait indefinitely (until signal occurs)
+ 0 return immediately, don't block
+ >0 wait specified number of milliseconds
+
+ select() uses a "struct timeval", which specifies the timeout in
+ seconds and microseconds, so the milliseconds value has to be mapped
+ accordingly.
+ */
+
+ assert (pSelTimeout != (struct timeval *) NULL);
+
+ switch (poll_timeout)
+ {
+ case -1:
+ /*
+ A NULL timeout structure tells select() to wait indefinitely.
+ */
+ pResult = (struct timeval *) NULL;
+ break;
+
+ case 0:
+ /*
+ "Return immediately" (test) is specified by all zeros in
+ a timeval structure.
+ */
+ pSelTimeout->tv_sec = 0;
+ pSelTimeout->tv_usec = 0;
+ pResult = pSelTimeout;
+ break;
+
+ default:
+ /* Wait the specified number of milliseconds. */
+ pSelTimeout->tv_sec = poll_timeout / 1000; /* get seconds */
+ poll_timeout %= 1000; /* remove seconds */
+ pSelTimeout->tv_usec = poll_timeout * 1000; /* get microseconds */
+ pResult = pSelTimeout;
+ break;
+ }
+
+
+ return pResult;
+}
+
+static void map_select_results
+#if __STDC__ > 0
+ (struct pollfd *pArray,
+ unsigned long n_fds,
+ fd_set *pReadSet,
+ fd_set *pWriteSet,
+ fd_set *pExceptSet)
+#else
+ (pArray, n_fds, pReadSet, pWriteSet, pExceptSet)
+ struct pollfd *pArray;
+ unsigned long n_fds;
+ fd_set *pReadSet;
+ fd_set *pWriteSet;
+ fd_set *pExceptSet;
+#endif
+{
+ register unsigned long i; /* loop control */
+ register struct pollfd *pCur; /* current array element */
+
+ for (i = 0, pCur = pArray; i < n_fds; i++, pCur++)
+ {
+ /* Skip any bad FDs in the array. */
+
+ if (pCur->fd < 0)
+ continue;
+
+ /* Exception events take priority over input events. */
+
+ pCur->revents = 0;
+ if (FD_ISSET (pCur->fd, pExceptSet))
+ pCur->revents |= POLLPRI;
+
+ else if (FD_ISSET (pCur->fd, pReadSet))
+ pCur->revents |= POLLIN;
+
+ if (FD_ISSET (pCur->fd, pWriteSet))
+ pCur->revents |= POLLOUT;
+ }
+
+ return;
+}
+
+/*---------------------------------------------------------------------------*\
+ Public Functions
+\*---------------------------------------------------------------------------*/
+
+int poll
+
+#if __STDC__ > 0
+ (struct pollfd *pArray, unsigned long n_fds, int timeout)
+#else
+ (pArray, n_fds, timeout)
+ struct pollfd *pArray;
+ unsigned long n_fds;
+ int timeout;
+#endif
+
+{
+ fd_set read_descs; /* input file descs */
+ fd_set write_descs; /* output file descs */
+ fd_set except_descs; /* exception descs */
+ struct timeval stime; /* select() timeout value */
+ int ready_descriptors; /* function result */
+ int max_fd; /* maximum fd value */
+ struct timeval *pTimeout; /* actually passed */
+
+ FD_ZERO (&read_descs);
+ FD_ZERO (&write_descs);
+ FD_ZERO (&except_descs);
+
+ assert (pArray != (struct pollfd *) NULL);
+
+ /* Map the poll() file descriptor list in the select() data structures. */
+
+ max_fd = map_poll_spec (pArray, n_fds,
+ &read_descs, &write_descs, &except_descs);
+
+ /* Map the poll() timeout value in the select() timeout structure. */
+
+ pTimeout = map_timeout (timeout, &stime);
+
+ /* Make the select() call. */
+
+ ready_descriptors = select (max_fd + 1, &read_descs, &write_descs,
+ &except_descs, pTimeout);
+
+ if (ready_descriptors >= 0)
+ {
+ map_select_results (pArray, n_fds,
+ &read_descs, &write_descs, &except_descs);
+ }
+
+ return ready_descriptors;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-18 03:33:01 +0000