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/* sigsched.c, sigsched.h: signal-schedule thread library
Daniel J. Bernstein, brnstnd@nyu.edu.
Depends on ralloc.h, sod.h, config/fdsettrouble.h.
Requires BSDish environment: reliable signals, sig{vec,block,setmask}, select.
9/1/91: Added worst-case fdset, FD_ZERO, etc. definitions.
8/25/91: sigsched 1.1, public domain.
8/25/91: Fixed bug that sigs[sched->blah].r didn't force instant timeout.
8/25/91: Fixed bug that if select() returned -1 then fds were still checked.
7/21/91: Changed forever to a 1-hour wakeup.
7/19/91: Added isopen() to fix bug in case of bad descriptor.
7/18/91: Baseline. sigsched 1.0, public domain.
No known patent problems.
Documentation in sigsched.3.
XXX: how well do we clean up upon ss_exec() exit?
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include "config/fdsettrouble.h"
#include "sigsched.h"
#include "ralloc.h"
#include "sod.h"
/* XXX: should restore signal set exactly after ss_exec returns */
typedef int sigc_set; /*XXX */
#define sigc_ismember(x,i) (*(x) & (1 << ((i) - 1)))
#define sigc_addset(x,i) (*(x) |= (1 << ((i) - 1)))
#define sigc_emptyset(x) (*(x) = 0)
/* sigprocmask(SIG_UNBLOCK,xxxx,(sigc_set *) 0); */
#define sigc_unblock(x) (sigsetmask(sigblock(0) & ~*(x)))
/* sigprocmask(SIG_BLOCK,xxxx,(sigc_set *) 0); */
#define sigc_block(x) (sigblock(*(x)))
#ifndef NSIG
#define NSIG 64 /* it's not as if any sane system has more than 32 */
#endif
#define NUMSIGS NSIG
#ifndef FD_SETSIZE
#define FD_SETSIZE 256
#endif
#define NUMFDS FD_SETSIZE /* if select() can't handle it, we can't either */
#ifdef LACKING_FD_ZERO
#define NFDBITS (sizeof(fd_mask) * NBBY)
#define FD_SET(n,p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#define FD_ISSET(n,p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
#define FD_ZERO(p) bzero((caddr_t)(p),sizeof(*(p)))
#endif
#ifdef DESPERATION_FD_SET
#undef NFDBITS
#undef FD_SET
#undef FD_ISSET
#undef FD_ZERO
#undef fd_set
#define fd_set long
#define FD_SET(n,p) ((*p) |= (1 << (n)))
#define FD_ISSET(n,p) ((*p) & (1 << (n)))
#define FD_ZERO(p) (*p = 0L)
#endif
#define ASAP 1
#define SIGNAL 2
#define READ 3
#define WRITE 4
#define EXCEPT 5
#define JUNK 6
#define EXTERN 7
typedef struct { ss_sig s; int r; } ss_sigplus;
static ss_sigplus asap;
static ss_sigplus sigs[NUMSIGS];
static ss_sigplus reads[NUMFDS];
static ss_sigplus writes[NUMFDS];
static ss_sigplus excepts[NUMFDS];
static ss_sigplus junk; /* special case for internal use */
static void initsigs()
{
int i;
asap.s.type = ASAP; asap.s.u.n = 0; asap.r = 0;
for (i = 0;i < NUMSIGS;++i)
{ sigs[i].s.type = SIGNAL; sigs[i].s.u.n = i; sigs[i].r = 0; }
for (i = 0;i < NUMFDS;++i)
{ reads[i].s.type = READ; reads[i].s.u.n = i; reads[i].r = 0; }
for (i = 0;i < NUMFDS;++i)
{ writes[i].s.type = WRITE; writes[i].s.u.n = i; writes[i].r = 0; }
for (i = 0;i < NUMFDS;++i)
{ excepts[i].s.type = EXCEPT; excepts[i].s.u.n = i; excepts[i].r = 0; }
junk.s.type = JUNK; junk.s.u.n = 0; junk.r = 0;
}
ss_sig *ss_asap()
{ return &(asap.s); }
#define OKsig(i) ((i >= 0) && (i < NUMSIGS))
ss_sig *ss_signal(i) int i;
{ if (!OKsig(i)) return 0; return &(sigs[i].s); }
#define OKfd(fd) ((fd >= 0) && (fd < NUMFDS))
ss_sig *ss_sigread(fd) int fd;
{ if (!OKfd(fd)) return 0; return &(reads[fd].s); }
ss_sig *ss_sigwrite(fd) int fd;
{ if (!OKfd(fd)) return 0; return &(writes[fd].s); }
ss_sig *ss_sigexcept(fd) int fd;
{ if (!OKfd(fd)) return 0; return &(excepts[fd].s); }
void ss_externsetsig(sig,x)
ss_sig *sig;
ss_extern *x;
{
sig->type = EXTERN;
sig->u.c = (char *) x;
}
struct sched
{
ss_sig *sig;
ss_thread *t;
union { ss_id i; ss_idptr p; } id;
int flagi;
int wait;
}
;
SODdecl(schedlist,struct sched);
static schedlist schedhead = 0;
static int schednum = 0;
static int schedjunked = 0;
static int numwait = 0;
void ss_forcewait()
{
++numwait;
}
void ss_unforcewait()
{
--numwait;
}
int ss_schedvwait(sig,t,flagi,i,p,wait)
ss_sig *sig;
ss_thread *t;
int flagi;
ss_id i;
ss_idptr p;
int wait;
{
schedlist s;
if (sig->type == EXTERN)
{
ss_extern *x;
x = (ss_extern *) sig->u.c;
return x->sched(x,t,flagi,i,p,wait);
}
s = SODalloc(schedlist,s,ralloc);
if (!s)
return -1;
SODdata(s).sig = sig;
SODdata(s).t = t;
if (SODdata(s).flagi = flagi)
SODdata(s).id.i = i;
else
SODdata(s).id.p = p;
SODdata(s).wait = wait;
SODpush(schedhead,s);
++schednum;
if (wait)
++numwait;
return 0;
}
int ss_schedwait(sig,t,i,wait)
ss_sig *sig;
ss_thread *t;
ss_id i;
int wait;
{
return ss_schedvwait(sig,t,1,i,(ss_idptr) 0,wait);
}
int ss_sched(sig,t,i)
ss_sig *sig;
ss_thread *t;
ss_id i;
{
return ss_schedvwait(sig,t,1,i,(ss_idptr) 0,0);
}
struct oncestuff { ss_sig *sig; ss_thread *t; ss_id i; } ;
/* XXX: this is the same as some other struct */
static void once(p)
ss_idptr p;
{
struct oncestuff *os;
os = (struct oncestuff *) p;
if (ss_unschedv(os->sig,once,0,0,p) == -1)
; /* impossible */
os->t(os->i);
RFREE(os);
}
int ss_schedonce(sig,t,i)
ss_sig *sig;
ss_thread *t;
ss_id i;
{
struct oncestuff *os;
os = (struct oncestuff *) ralloc(sizeof(struct oncestuff));
if (!os)
return -1;
os->sig = sig; os->t = t; os->i = i;
return ss_schedvwait(sig,once,0,0,(ss_idptr) os,1);
}
/* XXX: could rallocinstall() this, if it has the recvhead() test */
static int schedcleanup()
{
schedlist s;
schedlist t;
schedlist sprev;
/* if (recvhead) return 0; XXX: needs recvhead in scope */
if (!schedjunked)
return 0;
sprev = 0;
s = schedhead;
while (s)
{
if (SODdata(s).sig == &(junk.s))
{
if (sprev)
{
SODpop(SODnext(sprev),t); /* XXX: not part of official sod interface */
s = SODnext(sprev);
}
else
{
SODpop(s,t);
schedhead = s;
}
SODfree(t,rfree);
--schednum;
--schedjunked;
}
else
{
sprev = s;
s = SODnext(s);
}
}
/* schednum -= schedjunked; now done dynamically inside loop */
/* schedjunked = 0; */
return 1;
}
static void nothing(id)
ss_id id;
{
;
}
int ss_unschedv(sig,t,flagi,i,p)
ss_sig *sig;
ss_thread *t;
int flagi;
ss_id i;
ss_idptr p;
{
schedlist s;
if (sig->type == EXTERN)
{
ss_extern *x;
x = (ss_extern *) sig->u.c;
return x->unsched(x,t,flagi,i,p);
}
for (s = schedhead;s;s = SODnext(s))
if (SODdata(s).sig == sig && SODdata(s).t == t)
if (SODdata(s).flagi == flagi)
if (flagi ? (SODdata(s).id.i == i) : (SODdata(s).id.p == p))
{
SODdata(s).sig = &(junk.s);
SODdata(s).t = nothing; /* just in case */
if (SODdata(s).wait)
--numwait;
SODdata(s).wait = 0;
++schedjunked;
return 0;
}
return 1;
}
int ss_unsched(sig,t,i)
ss_sig *sig;
ss_thread *t;
ss_id i;
{
return ss_unschedv(sig,t,1,i,(ss_idptr) 0);
}
static struct timeval timeout;
static struct timeval instant = { 0, 0 };
static struct timeval forever = { 3600, 0 };
/* XXX: talk to me */
static void handle(i)
int i;
{
timeout = instant; /* XXX: structure copying */
sigs[i].r = 1;
}
static sigc_set sigstorage;
static sigc_set *xxxx = 0;
int ss_addsig(i)
int i;
{
if (!OKsig(i))
return -1;
if (!xxxx)
{
xxxx = &sigstorage;
sigc_emptyset(xxxx);
}
sigc_addset(xxxx,i);
return 0;
}
static int isopen(fd)
int fd;
{
/* XXX: should call this only if select() fails */
return fcntl(fd,F_GETFL,0) != -1;
}
SODdecl(recvlist,schedlist);
int ss_exec()
{
int i;
struct sigvec sv;
recvlist recvhead;
recvlist temp;
schedlist sch;
initsigs();
if (xxxx)
{
sigc_block(xxxx);
sv.sv_handler = handle;
sv.sv_mask = *xxxx; /* so handle won't interrupt itself */
sv.sv_flags = 0;
/* XXX: Does anyone but me find it absolutely idiotic that POSIX
doesn't provide a way to get each member of a signal set in turn? */
for (i = 0;i < NUMSIGS;i++)
{
if (sigc_ismember(xxxx,i))
if (sigvec(i,&sv,(struct sigvec *) 0) == -1) /*XXX: really trash orig? */
; /* not our problem */
}
}
recvhead = 0;
while (numwait)
{
if (recvhead)
{
int w;
SODpop(recvhead,temp);
sch = SODdata(temp);
/* This is the only section where we call user code. */
#define DOIT \
if (SODdata(sch).flagi) \
SODdata(sch).t(SODdata(sch).id.i); \
else \
SODdata(sch).t(SODdata(sch).id.p);
switch(SODdata(sch).sig->type)
{
case JUNK:
break; /* has been unscheduled while waiting on the receive list */
case ASAP:
DOIT
break;
case READ:
if (reads[w = SODdata(sch).sig->u.n].r)
DOIT
reads[w].r = 0;
break;
case WRITE:
if (writes[w = SODdata(sch).sig->u.n].r)
DOIT
writes[w].r = 0;
break;
case EXCEPT:
if (excepts[w = SODdata(sch).sig->u.n].r)
DOIT
excepts[w].r = 0;
break;
case SIGNAL:
if (sigs[w = SODdata(sch).sig->u.n].r)
DOIT
sigs[w].r = 0;
/* ``after the end of the last...'' */
break;
case EXTERN:
/* by definition, an external library handles this */
break;
default: /* XXX: huh? */
;
}
SODfree(temp,rfree);
}
else
{
schedlist sp;
static fd_set rfds;
static fd_set wfds;
static fd_set efds;
static int maxfd;
int r;
if (schedjunked > 100)
if (schednum / schedjunked < 3)
(void) schedcleanup(); /* now's as good a time as any */
timeout = forever;
FD_ZERO(&rfds);
FD_ZERO(&wfds);
FD_ZERO(&efds);
maxfd = -1;
for (sp = schedhead;sp;sp = SODnext(sp))
{
switch(SODdata(sp).sig->type)
{
case JUNK:
break;
case ASAP:
timeout = instant;
break;
case SIGNAL:
if (sigs[SODdata(sp).sig->u.n].r)
timeout = instant;
break;
case READ:
if (isopen(SODdata(sp).sig->u.n))
FD_SET(SODdata(sp).sig->u.n,&rfds);
if (SODdata(sp).sig->u.n > maxfd)
maxfd = SODdata(sp).sig->u.n;
break;
case WRITE:
if (isopen(SODdata(sp).sig->u.n))
FD_SET(SODdata(sp).sig->u.n,&wfds);
if (SODdata(sp).sig->u.n > maxfd)
maxfd = SODdata(sp).sig->u.n;
break;
case EXCEPT:
if (isopen(SODdata(sp).sig->u.n))
FD_SET(SODdata(sp).sig->u.n,&efds);
if (SODdata(sp).sig->u.n > maxfd)
maxfd = SODdata(sp).sig->u.n;
break;
case EXTERN:
break;
default: /*XXX: huh? */
break;
}
}
if (xxxx)
sigc_unblock(xxxx);
/* This is the only section where handle() can be called. */
/* XXX: If maxfd == -1, this select functions as a pause. */
/* XXX: If maxfd == -1 and timeout is instant, should skip select. */
/* XXX: Random bug of note: Real BSD systems will say that the
fd is writable as soon as a network connect() fails. The first
I/O will show the error (though it's rather stupid that you
can't find out the error without doing I/O). What does Ultrix
4.1 do? It pauses for 75 seconds. Dolts. */
r = select(maxfd + 1,&rfds,&wfds,&efds,&timeout);
/* XXX: does this necessarily prevent timeout race conditions? */
if (xxxx)
sigc_block(xxxx);
if (r == -1)
{
FD_ZERO(&rfds);
FD_ZERO(&wfds);
FD_ZERO(&efds);
switch(errno)
{
case EINTR: /* fine, this will happen on any signal */ break;
case EBADF: /* who knows? */ break;
case EINVAL: /* simply impossible */ break;
default: /*XXX*/ ;
/* well, that was real useful */
}
}
for (sp = schedhead;sp;sp = SODnext(sp))
{
switch(SODdata(sp).sig->type)
{
case JUNK:
break;
case ASAP:
temp = SODalloc(recvlist,temp,ralloc);
if (!temp)
return -1; /*XXX*/
SODdata(temp) = sp;
SODpush(recvhead,temp);
break;
case SIGNAL:
if (sigs[SODdata(sp).sig->u.n].r)
{
temp = SODalloc(recvlist,temp,ralloc);
if (!temp)
return -1; /*XXX*/
SODdata(temp) = sp;
SODpush(recvhead,temp);
}
break;
case READ:
if (FD_ISSET(SODdata(sp).sig->u.n,&rfds))
{
FD_CLR(SODdata(sp).sig->u.n,&rfds);
reads[SODdata(sp).sig->u.n].r = 1;
temp = SODalloc(recvlist,temp,ralloc);
if (!temp)
return -1; /*XXX*/
SODdata(temp) = sp;
SODpush(recvhead,temp);
}
break;
case WRITE:
if (FD_ISSET(SODdata(sp).sig->u.n,&wfds))
{
FD_CLR(SODdata(sp).sig->u.n,&wfds);
writes[SODdata(sp).sig->u.n].r = 1;
temp = SODalloc(recvlist,temp,ralloc);
if (!temp)
return -1; /*XXX*/
SODdata(temp) = sp;
SODpush(recvhead,temp);
}
break;
case EXCEPT:
if (FD_ISSET(SODdata(sp).sig->u.n,&efds))
{
FD_CLR(SODdata(sp).sig->u.n,&efds);
excepts[SODdata(sp).sig->u.n].r = 1;
temp = SODalloc(recvlist,temp,ralloc);
if (!temp)
return -1; /*XXX*/
SODdata(temp) = sp;
SODpush(recvhead,temp);
}
break;
case EXTERN:
break;
default:
break;
}
}
}
}
if (xxxx)
sigc_unblock(xxxx);
/* XXX: should put this at other returns as well */
return 0;
}
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