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persist.c
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Thu, Jun 6, 11:24

persist.c
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#ifndef lint
static const char RCSid[] = "$Id: persist.c,v 2.44 2016/03/06 01:13:18 schorsch Exp $";
#endif
/*
* Routines for persistent rtrace and rpict processes.
*
* External symbols declared in ray.h
*/
#include "copyright.h"
#include <string.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "platform.h"
#ifndef NON_POSIX /* XXX need abstraction for process management */
#include <sys/wait.h>
#endif
#include "rtprocess.h" /* getpid() */
#include "standard.h"
#include "random.h"
#include "ray.h"
#ifdef F_SETLKW
#include "paths.h"
#include "selcall.h"
#ifndef TIMELIM
#define TIMELIM (8*3600) /* time limit for holding pattern */
#endif
extern int headismine; /* boolean true if header belongs to me */
extern char *progname; /* global program name */
extern char *errfile; /* global error file name */
static char *persistfname = NULL; /* persist file name */
static int persistfd = -1; /* persist file descriptor */
static char inpname[TEMPLEN+1], outpname[TEMPLEN+1], errname[TEMPLEN+1];
typedef void (rsighandler_t)(int);
static rsighandler_t sig_io;
static rsighandler_t sig_alrm;
void
pfdetach(void) /* release persist (and header) resources */
{
if (persistfd >= 0)
close(persistfd);
persistfd = -1;
persistfname = NULL;
inpname[0] = '\0';
outpname[0] = '\0';
errname[0] = '\0';
headismine = 0;
}
void
pfclean(void) /* clean up persist files */
{
if (persistfd >= 0)
close(persistfd);
if (persistfname != NULL)
unlink(persistfname);
if (inpname[0])
unlink(inpname);
if (outpname[0])
unlink(outpname);
if (errname[0])
unlink(errname);
}
void
pflock( /* place or release exclusive lock on file */
int lf
)
{
struct flock fls;
fls.l_type = lf ? F_WRLCK : F_UNLCK;
fls.l_whence = 0;
fls.l_start = 0L;
fls.l_len = 0L;
if (fcntl(persistfd, F_SETLKW, &fls) < 0)
error(SYSTEM, "cannot (un)lock persist file");
}
void
persistfile( /* open persist file and lock it */
char *pfn
)
{
persistfd = open(pfn, O_WRONLY|O_CREAT|O_EXCL, 0644);
if (persistfd >= 0) {
persistfname = pfn;
pflock(1);
return;
}
/* file exists -- switch to i/o process */
persistfd = open(pfn, O_RDWR);
if (persistfd < 0) {
sprintf(errmsg, "cannot open persist file \"%s\"", pfn);
error(SYSTEM, errmsg);
}
pflock(1);
io_process(); /* never returns */
}
static int got_io;
static void sig_io(int i) { got_io++; }
static void sig_alrm(int i) { quit(0); }
void
pfhold(void) /* holding pattern for idle rendering process */
{
rsighandler_t *oldalrm;
char buf[512];
int n;
/* close input and output descriptors */
close(0);
close(1);
if (errfile == NULL)
close(2);
/* create named pipes for input and output */
if (mkfifo(mktemp(strcpy(inpname,TEMPLATE)), 0600) < 0)
goto createrr;
if (mkfifo(mktemp(strcpy(outpname,TEMPLATE)), 0600) < 0)
goto createrr;
if (errfile == NULL &&
mkfifo(mktemp(strcpy(errname,TEMPLATE)), 0600) < 0)
goto createrr;
sprintf(buf, "%s %d\n%s\n%s\n%s\n", progname, getpid(),
inpname, outpname, errname);
n = strlen(buf);
if (write(persistfd, buf, n) < n)
error(SYSTEM, "error writing persist file");
lseek(persistfd, (off_t)0, SEEK_SET);
/* wait TIMELIM for someone to signal us */
got_io = 0;
signal(SIGIO, sig_io);
oldalrm = signal(SIGALRM, sig_alrm);
alarm(TIMELIM);
pflock(0); /* unlock persist file for attach */
while (!got_io)
pause(); /* wait for attach */
alarm(0); /* turn off alarm */
signal(SIGALRM, oldalrm);
signal(SIGIO, SIG_DFL);
pflock(1); /* grab persist file back */
/* someone wants us; reopen stdin and stdout */
close(0);
if (open(inpname, O_RDONLY) != 0)
error(INTERNAL, "unexpected stdin file number");
clearerr(stdin);
close(1);
if (open(outpname, O_WRONLY) != 1)
error(INTERNAL, "unexpected stdout file number");
sleep(3); /* give them a chance to open their pipes */
if (errname[0]) {
close(2);
if (open(errname, O_WRONLY) != 2)
error(INTERNAL, "unexpected stderr file number");
unlink(errname);
errname[0] = '\0';
}
unlink(inpname);
inpname[0] = '\0';
unlink(outpname);
outpname[0] = '\0';
return;
createrr:
error(SYSTEM, "cannot create named pipes in pfhold");
}
void
io_process(void) /* just act as go-between for actual process */
{
char *cp;
int nr, n;
char buf[BUFSIZ], *pfin, *pfout, *pferr;
int pid, nfds;
int fdout, fderr = -1;
int status = 0;
fd_set readfds, excepfds;
/* load persist file */
n = 40;
while ((nr = read(persistfd, buf, sizeof(buf)-1)) == 0) {
if (!n--)
error(USER, "unattended persist file?");
pflock(0);
sleep(3+(3*getpid()+random())%13); /* wait until ready */
pflock(1);
}
if (nr < 0)
error(SYSTEM, "error reading persist file");
ftruncate(persistfd, (off_t)0L); /* truncate persist file */
pfdetach(); /* close & release persist file */
buf[nr] = '\0'; /* parse what we got */
if ((cp = strchr(buf, ' ')) == NULL)
goto formerr;
*cp++ = '\0';
if ((pid = atoi(cp)) <= 0)
goto formerr;
if ((cp = strchr(cp, '\n')) == NULL)
goto formerr;
pfin = ++cp;
if ((cp = strchr(cp, '\n')) == NULL)
goto formerr;
*cp++ = '\0';
pfout = cp;
if ((cp = strchr(cp, '\n')) == NULL)
goto formerr;
*cp++ = '\0';
pferr = cp;
if ((cp = strchr(cp, '\n')) == NULL)
goto formerr;
*cp++ = '\0';
if (cp-buf != nr)
goto formerr;
if (strcmp(buf, progname)) {
sprintf(errmsg, "persist file for %s, not %s", buf, progname);
error(USER, errmsg);
}
/* wake up rendering process */
if (kill(pid, SIGIO) < 0)
error(SYSTEM, "cannot signal rendering process in io_process");
/* fork child feeder process */
pid = fork();
if (pid < 0)
error(SYSTEM, "fork failed in io_process");
if (pid == 0) { /* feeder loop */
int fdin;
close(1); /* open input pipe */
if ((fdin = open(pfin, O_WRONLY)) < 0)
error(SYSTEM, "cannot open feed pipe in io_process");
/* renderer stdin */
while ((nr = read(0, cp=buf, sizeof(buf))) > 0) {
do {
if ((n = write(fdin, cp, nr)) <= 0)
goto writerr;
cp += n;
} while ((nr -= n) > 0);
}
if (nr < 0)
goto readerr;
_exit(0);
}
close(0);
/* open output pipes, in order */
if ((fdout = open(pfout, O_RDONLY)) < 0)
error(SYSTEM, "cannot open output pipe in io_process");
if (pferr[0] && (fderr = open(pferr, O_RDONLY)) < 0)
error(SYSTEM, "cannot open error pipe in io_process");
for ( ; ; ) { /* eater loop */
FD_ZERO(&readfds);
FD_ZERO(&excepfds);
nfds = 0;
if (fdout >= 0) {
FD_SET(fdout, &readfds);
FD_SET(fdout, &excepfds);
nfds = fdout+1;
}
if (fderr >= 0) {
FD_SET(fderr, &readfds);
FD_SET(fderr, &excepfds);
nfds = fderr+1;
}
if (nfds == 0)
break; /* all done, exit */
if (select(nfds, &readfds, NULL, &excepfds, NULL) < 0)
error(SYSTEM, "error in select call in io_process");
/* renderer stderr */
if (fderr >= 0 && (FD_ISSET(fderr, &readfds) ||
FD_ISSET(fderr, &excepfds))) {
nr = read(fderr, cp=buf, sizeof(buf));
if (nr < 0)
goto readerr;
if (nr == 0) {
close(fderr);
/* close(2); don't close stderr! */
fderr = -1;
} else {
cp[nr] = '\0'; /* deduce status if we can */
n = strlen(progname);
if (!strncmp(cp, progname, n) &&
cp[n++] == ':' &&
cp[n++] == ' ') {
struct erract *ep;
for (ep = erract; ep < erract+NERRS;
ep++)
if (ep->pre[0] &&
!strncmp(cp+n, ep->pre,
strlen(ep->pre))) {
status = ep->ec;
break;
}
}
do { /* write message */
if ((n = write(2, cp, nr)) <= 0)
goto writerr;
cp += n;
} while ((nr -= n) > 0);
}
}
/* renderer stdout */
if (fdout >= 0 && (FD_ISSET(fdout, &readfds) ||
FD_ISSET(fdout, &excepfds))) {
nr = read(fdout, cp=buf, sizeof(buf));
if (nr < 0)
goto readerr;
if (nr == 0) { /* EOF */
close(fdout);
close(1);
fdout = -1;
} else
do { /* write it all */
if ((n = write(1, cp, nr)) <= 0)
goto writerr;
cp += n;
} while ((nr -= n) > 0);
}
}
kill(pid, SIGTERM); /* no more process to feed, so... */
waitpid(pid, 0, 0); /* wait for feeder process */
_exit(status);
formerr:
error(USER, "format error in persist file");
readerr:
error(SYSTEM, "read error in io_process");
writerr:
error(SYSTEM, "write error in io_process");
}
#else
void pfclean(void) {}
#endif

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