freebsd-dev/usr.bin/doscmd/AsyncIO.c

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