Sweden-Number/files/async.c

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/*
* Generic async UNIX file IO handling
*
* Copyright 1996,1997 Alex Korobka
* Copyright 1998 Marcus Meissner
*/
/*
* This file handles asynchronous signaling for UNIX filedescriptors.
* The passed handler gets called when input arrived for the filedescriptor.
*
* This is done either by the kernel or (in the WINSOCK case) by the pipe
* handler, since pipes do not support asynchronous signaling.
* (Not all possible filedescriptors support async IO. Generic files do not
* for instance, sockets do, ptys don't.)
*
* To make this a bit better, we would need an additional thread doing select()
*/
#include <assert.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <fcntl.h>
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#ifdef HAVE_SYS_FILIO_H
# include <sys/filio.h>
#endif
#ifdef __svr4__
# include <sys/file.h>
#endif
#include "xmalloc.h"
#include "wintypes.h"
#include "miscemu.h"
#include "selectors.h"
#include "sig_context.h"
#include "async.h"
#include "debug.h"
typedef struct _async_fd {
int unixfd;
void (*handler)(int fd,void *private);
void *private;
} ASYNC_FD;
static ASYNC_FD *asyncfds = NULL;
static int nrofasyncfds = 0;
/***************************************************************************
* ASYNC_sigio [internal]
*
* Signal handler for asynchronous IO.
*
* Note: This handler and the function it calls may not block. Neither they
* are allowed to use blocking IO (write/read). No memory management.
* No possible blocking synchronization of any kind.
*/
HANDLER_DEF(ASYNC_sigio) {
struct timeval timeout;
fd_set rset,wset;
int i,maxfd=0;
HANDLER_INIT();
if (!nrofasyncfds)
return;
FD_ZERO(&rset);
FD_ZERO(&wset);
for (i=nrofasyncfds;i--;) {
if (asyncfds[i].unixfd == -1)
continue;
FD_SET(asyncfds[i].unixfd,&rset);
FD_SET(asyncfds[i].unixfd,&wset);
if (maxfd<asyncfds[i].unixfd)
maxfd=asyncfds[i].unixfd;
}
/* select() with timeout values set to 0 is nonblocking. */
memset(&timeout,0,sizeof(timeout));
if (select(maxfd+1,&rset,&wset,NULL,&timeout)<=0)
return; /* Can't be. hmm */
for (i=nrofasyncfds;i--;)
if ( (FD_ISSET(asyncfds[i].unixfd,&rset)) ||
(FD_ISSET(asyncfds[i].unixfd,&wset))
)
asyncfds[i].handler(asyncfds[i].unixfd,asyncfds[i].private);
}
/***************************************************************************
* ASYNC_MakeFDAsync [internal]
*
* Makes the passed filedescriptor async (or not) depending on flag.
*/
static BOOL32 ASYNC_MakeFDAsync(int unixfd,int async) {
int flags;
#if !defined(FASYNC) && defined(FIOASYNC)
#define FASYNC FIOASYNC
#endif
#ifdef F_SETOWN
if (-1==fcntl(unixfd,F_SETOWN,getpid()))
perror("fcntl F_SETOWN <pid>");
#endif
#ifdef FASYNC
if (-1==fcntl(unixfd,F_GETFL,&flags)) {
perror("fcntl F_GETFL");
return FALSE;
}
if (async)
flags|=FASYNC;
else
flags&=~FASYNC;
if (-1==fcntl(unixfd,F_SETFL,&flags)) {
perror("fcntl F_SETFL FASYNC");
return FALSE;
}
return TRUE;
#else
return FALSE;
#endif
}
/***************************************************************************
* ASYNC_RegisterFD [internal]
*
* Register a UNIX filedescriptor with handler and private data pointer.
* this function is _NOT_ safe to be called from a signal handler.
*
* Additional Constraint: The handler passed to this function _MUST_ adhere
* to the same signalsafeness as ASYNC_sigio itself. (nonblocking, no thread/
* signal unsafe operations, no blocking synchronization)
*/
void ASYNC_RegisterFD(int unixfd,void (*handler)(int fd,void *private),void *private) {
int i;
SIGNAL_MaskAsyncEvents( TRUE );
for (i=0;i<nrofasyncfds;i++) {
if (asyncfds[i].unixfd==unixfd) {
/* Might be a leftover entry. Make fd async anyway... */
if (asyncfds[i].handler==handler) {
ASYNC_MakeFDAsync(unixfd,1);
SIGNAL_MaskAsyncEvents( FALSE );
return;
}
}
}
for (i=0;i<nrofasyncfds;i++)
if (asyncfds[i].unixfd == -1)
break;
if (i==nrofasyncfds) {
if (nrofasyncfds)
asyncfds=(ASYNC_FD*)xrealloc(asyncfds,sizeof(ASYNC_FD)*(nrofasyncfds+1));
else
asyncfds=(ASYNC_FD*)xmalloc(sizeof(ASYNC_FD)*1);
nrofasyncfds++;
}
asyncfds[i].unixfd = unixfd;
asyncfds[i].handler = handler;
asyncfds[i].private = private;
ASYNC_MakeFDAsync(unixfd,1);
SIGNAL_MaskAsyncEvents( FALSE );
}
/***************************************************************************
* ASYNC_UnregisterFD [internal]
*
* Unregister a UNIX filedescriptor with handler. This function is basically
* signal safe, but try to not call it in the signal handler anyway.
*/
void ASYNC_UnregisterFD(int unixfd,void (*handler)(int fd,void *private)) {
int i;
for (i=nrofasyncfds;i--;)
if ((asyncfds[i].unixfd==unixfd)||(asyncfds[i].handler==handler))
break;
if (i==nrofasyncfds)
return;
asyncfds[i].unixfd = -1;
asyncfds[i].handler = NULL;
asyncfds[i].private = NULL;
return;
}