343 lines
7.4 KiB
C
343 lines
7.4 KiB
C
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/*
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* Copyright (c) 1992, 1993, 1996
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* Berkeley Software Design, Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Berkeley Software
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* Design, Inc.
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*
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* THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* BSDI AsyncIO.c,v 2.2 1996/04/08 19:32:10 bostic Exp
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*/
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#include <stdio.h>
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#include <sys/param.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <sys/time.h>
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#include <signal.h>
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#include <errno.h>
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#include <limits.h>
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#include "doscmd.h"
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#define FD_ISZERO(p) ((p)->fds_bits[0] == 0)
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/*
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* Set or Clear the Async nature of an FD
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*/
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#define SETASYNC(fd) fcntl(fd, F_SETFL, handlers[fd].flag | FASYNC)
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#define CLRASYNC(fd) fcntl(fd, F_SETFL, handlers[fd].flag & ~FASYNC)
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/*
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* Request that ``func'' be called everytime data is available on ``fd''
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*/
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static fd_set fdset = { 0 }; /* File Descriptors to select on */
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typedef struct {
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void (*func)(void *, REGISTERS);
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/* Function to call when data arrives */
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void (*failure)(void *); /* Function to call on failure */
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void *arg; /* Argument to above functions */
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int lockcnt; /* Nested level of lock */
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fd_set members; /* Set of FD's to disable on SIGIO */
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int flag; /* The flag from F_GETFL (we own it) */
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} Async;
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static Async handlers[OPEN_MAX];
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static void HandleIO (struct sigframe *sf);
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static int in_handler = 0;
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void
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_RegisterIO(fd, func, arg, failure)
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int fd;
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void (*func)();
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void *arg;
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void (*failure)();
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{
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static int firsttime = 1;
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Async *as;
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if (fd < 0 || fd > OPEN_MAX) {
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printf("%d: Invalid FD\n", fd);
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return;
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}
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as = &handlers[fd];
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if ((as->flag = fcntl(fd, F_GETFL, 0)) == -1) {
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if (func) {
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/*@*/ perror("get fcntl");
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/*@*/ abort();
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return;
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}
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}
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if (firsttime) {
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struct sigaction sa;
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firsttime = 0;
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setsignal(SIGIO, HandleIO);
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}
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if (handlers[fd].func = func) {
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as->lockcnt = 0;
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as->arg = arg;
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as->failure = failure;
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FD_SET(fd, &fdset);
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FD_ZERO(&handlers[fd].members);
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FD_SET(fd, &handlers[fd].members);
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if (fcntl(fd, F_SETOWN, getpid()) < 0) {
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/*@*/ perror("SETOWN");
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}
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SETASYNC(fd);
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} else {
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as->arg = 0;
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as->failure = 0;
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as->lockcnt = 0;
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CLRASYNC(fd);
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FD_CLR(fd, &fdset);
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}
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}
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static void
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CleanIO()
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{
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int x;
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static struct timeval tv = { 0 };
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/*
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* For every file des in fd_set, we check to see if it
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* causes a fault on select(). If so, we unregister it
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* for the user.
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*/
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for (x = 0; x < OPEN_MAX; ++x) {
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fd_set set;
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if (!FD_ISSET(x, &fdset))
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continue;
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FD_ZERO(&set);
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FD_SET(x, &set);
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errno = 0;
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if (select(FD_SETSIZE, &set, 0, 0, &tv) < 0 &&
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errno == EBADF) {
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void (*f)();
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void *a;
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printf("Closed file descriptor %d\n", x);
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f = handlers[x].failure;
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a = handlers[x].arg;
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handlers[x].failure = 0;
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handlers[x].func = 0;
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handlers[x].arg = 0;
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handlers[x].lockcnt = 0;
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FD_CLR(x, &fdset);
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if (f)
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(*f)(a);
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}
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}
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}
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static void
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HandleIO(struct sigframe *sf)
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{
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++in_handler;
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for (;;) {
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static struct timeval tv = { 0 };
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fd_set readset;
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int x;
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int fd;
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readset = fdset;
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if ((x = select(FD_SETSIZE, &readset, 0, 0, &tv)) < 0) {
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/*
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* If we failed becuase of a BADFiledes, go find
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* which one(s), fail them out and then try a
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* new select to see if any of the good ones are
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* okay.
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*/
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if (errno == EBADF) {
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CleanIO();
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if (FD_ISZERO(&fdset))
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break;
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continue;
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}
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perror("select");
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break;
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}
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/*
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* If we run out of fds to look at, break out of the loop
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* and exit the handler.
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*/
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if (!x)
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break;
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/*
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* If there is at least 1 fd saying it has something for
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* us, then loop through the sets looking for those
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* bits, stopping when we have handleed the number it has
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* asked for.
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*/
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for (fd = 0; x && fd < OPEN_MAX; ++fd) {
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Async *as;
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if (!FD_ISSET(fd, &readset)) {
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continue;
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}
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--x;
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/*
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* Is suppose it is possible that one of the previous
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* io requests changed the fdset.
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* We do know that SIGIO is turned off right now,
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* so it is safe to checkit.
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*/
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if (!FD_ISSET(fd, &fdset)) {
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continue;
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}
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as = &handlers[fd];
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/*
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* as in above, maybe someone locked us...
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* we are in dangerous water now if we are
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* multi-tasked
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*/
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if (as->lockcnt) {
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/*@*/ fprintf(stderr, "Selected IO on locked %d\n",fd);
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continue;
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}
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/*
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* Okay, now if there exists a handler, we should
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* call it. We must turn back on SIGIO if there
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* are possibly other people waiting for it.
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*/
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if (as->func) {
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int afd;
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Async *aas;
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/*
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* STEP 1: Lock out all "members"
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*/
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aas = handlers;
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if (0)
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for (afd = 0; afd < OPEN_MAX; ++afd, ++aas) {
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if (FD_ISSET(afd, &as->members)) {
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if (aas->func) {
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if (as->lockcnt++ == 0) {
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FD_CLR(afd, &fdset);
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CLRASYNC(afd);
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}
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}
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}
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}
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/*
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* STEP 2: Renable SIGIO so other FDs can
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* use a hit.
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_UnblockIO();
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*/
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/*
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* STEP 3: Call the handler
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*/
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(*handlers[fd].func)(handlers[fd].arg, &sf->sf_sc);
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/*
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* STEP 4: Just turn SIGIO off. No check.
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_BlockIO();
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*/
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/*
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* STEP 5: Unlock all "members"
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*/
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aas = handlers;
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if (0)
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for (afd = 0; afd < OPEN_MAX; ++afd, ++aas) {
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if (FD_ISSET(afd, &as->members)) {
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if (aas->func) {
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if (--as->lockcnt == 0) {
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FD_SET(afd, &fdset);
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SETASYNC(afd);
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}
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}
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}
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}
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} else {
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/*
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* Otherwise deregister this guy.
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*/
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_RegisterIO(fd, 0, 0, 0);
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}
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}
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/*
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* If we did not process all the fd's, then we should
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* break out of the probable infinite loop.
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*/
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if (x) {
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break;
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}
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}
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--in_handler;
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}
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static int stackp = 0;
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void
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_BlockIO()
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{
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sigset_t set;
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if (stackp >= 64) {
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fprintf(stderr, "Signal stack count too deep\n");
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abort();
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}
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if (stackp++ == 0) {
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sigaddset(&set, SIGIO);
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sigprocmask(SIG_BLOCK, &set, 0);
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}
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}
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void
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_UnblockIO()
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{
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sigset_t set;
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if (stackp <= 0) {
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fprintf(stderr, "Negative signal stack count\n");
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abort();
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}
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if (--stackp == 0) {
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sigaddset(&set, SIGIO);
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sigprocmask(SIG_UNBLOCK, &set, 0);
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}
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}
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