src/rt/persist.c

/* Copyright (c) 1996 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 * Routines for persistent rtrace and rpict processes.
 */

#include "standard.h"

#ifdef F_SETLKW

#include "paths.h"
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifndef TIMELIM
#define TIMELIM         (8*3600)        /* time limit for holding pattern */
#endif

extern char     *strcpy(), *index();

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];


pfdetach()              /* 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;
}


pfclean()               /* 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);
}


pflock(lf)              /* 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");
}


persistfile(pfn)        /* 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 int sig_io() { got_io++; }

static int sig_alrm() { quit(0); }


pfhold()                /* holding pattern for idle rendering process */
{
        int     (*oldalrm)();
        char    buf[512];
        register int    n;
                                /* close input and output descriptors */
        close(fileno(stdin));
        close(fileno(stdout));
                                /* create named pipes for input and output */
        if (mknod(mktemp(strcpy(inpname,TEMPLATE)), S_IFIFO|0600, 0) < 0)
                goto createrr;
        if (mknod(mktemp(strcpy(outpname,TEMPLATE)), S_IFIFO|0600, 0) < 0)
                goto createrr;
        if (errfile == NULL &&
                mknod(mktemp(strcpy(errname,TEMPLATE)), S_IFIFO|0600, 0) < 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");
                                /* wait TIMELIM for someone to signal us */
        got_io = 0;
        signal(SIGIO, sig_io);
        oldalrm = (int (*)())signal(SIGALRM, sig_alrm);
        alarm(TIMELIM);
        pflock(0);                      /* unlock persist file for attach */
        while (!got_io)
                pause();                /* wait for attach */
        pflock(1);                      /* grab persist file right back! */
        alarm(0);                       /* turn off alarm */
        signal(SIGALRM, oldalrm);
        signal(SIGIO, SIG_DFL);
        if (lseek(persistfd, 0L, 0) < 0 || ftruncate(persistfd, 0L) < 0)
                error(SYSTEM, "seek/truncate error on persist file");
                                /* someone wants us; reopen stdin and stdout */
        if (freopen(inpname, "r", stdin) == NULL)
                goto openerr;
        if (freopen(outpname, "w", stdout) == NULL)
                goto openerr;
        if (errname[0]) {
                if (freopen(errname, "w", stderr) == NULL)
                        goto openerr;
                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");
openerr:
        error(SYSTEM, "cannot open named pipes in pfhold");
}


io_process()            /* just act as conduits to and from actual process */
{
        register char   *cp;
        register int    nr, n;
        char    buf[512], *pfin, *pfout, *pferr;
        int     pid, pid2 = -1;
                                        /* load persist file */
        while ((nr = read(persistfd, buf, sizeof(buf)-1)) == 0) {
                pflock(0);
                sleep(15);              /* wait until ready */
                pflock(1);
        }
        pfdetach();                     /* close persist file */
        if (nr < 0)
                error(SYSTEM, "error reading persist file");
        buf[nr] = '\0';
        if ((cp = index(buf, ' ')) == NULL)
                goto formerr;
        *cp++ = '\0';
        if ((pid = atoi(cp)) <= 0)
                goto formerr;
        if ((cp = index(cp, '\n')) == NULL)
                goto formerr;
        pfin = ++cp;
        if ((cp = index(cp, '\n')) == NULL)
                goto formerr;
        *cp++ = '\0';
        pfout = cp;
        if ((cp = index(cp, '\n')) == NULL)
                goto formerr;
        *cp++ = '\0';
        pferr = cp;
        if ((cp = index(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");
        pid = fork();           /* fork i/o process */
        if (pid < 0)
                goto forkerr;
                                /* connect to appropriate pipe */
        if (pid) {                      /* parent passes renderer output */
                close(0);
                if (pferr[0]) {
                        pid2 = fork();          /* fork another for stderr */
                        if (pid2 < 0)
                                goto forkerr;
                }
                if (pid2) {                     /* parent is still stdout */
                        if (open(pfout, O_RDONLY) != 0)
                                error(SYSTEM,
                                "cannot open output pipe in io_process");
                } else {                        /* second child is stderr */
                        if (open(pferr, O_RDONLY) != 0)
                                error(SYSTEM,
                                "cannot open error pipe in io_process");
                        dup2(2, 1);             /* attach stdout to stderr */
                }
        } else {                        /* child passes renderer input */
                close(1);
                if (open(pfin, O_WRONLY) != 1)
                        error(SYSTEM, "cannot open input pipe in io_process");
        }
                                /* pass input to output */
                                /* read as much as we can, write all of it */
        while ((nr = read(0, cp=buf, sizeof(buf))) > 0)
                do {
                        if ((n = write(1, cp, nr)) <= 0)
                                error(SYSTEM, "write error in io_process");
                        cp += n;
                } while ((nr -= n) > 0);
        if (nr < 0)
                error(SYSTEM, "read error in io_process");
        close(0);               /* close input */
        close(1);               /* close output */
        if (pid)                /* parent waits for stdin child */
                wait(0);
        if (pid2 > 0)           /* wait for stderr child also */
                wait(0);
        _exit(0);               /* all done, exit (not quit!) */
formerr:
        error(USER, "format error in persist file");
forkerr:
        error(SYSTEM, "fork failed in io_process");
}

#else

pfclean() {}

#endif
Revision:	2.15
Committed:	Sat Jul 6 23:19:57 1996 UTC (27 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.14:	+14 -15 lines
Log Message:	finally fixed synchronization problem caused by break in lock during fork
#	User	Rev	Content
1	greg	2.13	/* Copyright (c) 1996 Regents of the University of California */
2	greg	2.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Routines for persistent rtrace and rpict processes.
9			*/
10
11			#include "standard.h"
12	greg	2.6
13			#ifdef F_SETLKW
14
15	greg	2.1	#include "paths.h"
16			#include <signal.h>
17			#include <sys/types.h>
18			#include <sys/stat.h>
19
20	greg	2.2	#ifndef TIMELIM
21			#define TIMELIM (83600) / time limit for holding pattern */
22			#endif
23
24	greg	2.1	extern char strcpy(), index();
25
26			extern int headismine; /* boolean true if header belongs to me */
27
28	greg	2.12	extern char progname; / global program name */
29
30	greg	2.14	extern char errfile; / global error file name */
31
32	greg	2.1	static char persistfname = NULL; / persist file name */
33			static int persistfd = -1; /* persist file descriptor */
34
35	greg	2.14	static char inpname[TEMPLEN+1], outpname[TEMPLEN+1], errname[TEMPLEN+1];
36	greg	2.1
37
38			pfdetach() /* release persist (and header) resources */
39			{
40			if (persistfd >= 0)
41			close(persistfd);
42			persistfd = -1;
43			persistfname = NULL;
44			inpname[0] = '\0';
45			outpname[0] = '\0';
46	greg	2.14	errname[0] = '\0';
47	greg	2.1	headismine = 0;
48			}
49
50
51			pfclean() /* clean up persist files */
52			{
53			if (persistfd >= 0)
54			close(persistfd);
55			if (persistfname != NULL)
56			unlink(persistfname);
57			if (inpname[0])
58			unlink(inpname);
59			if (outpname[0])
60			unlink(outpname);
61	greg	2.14	if (errname[0])
62			unlink(errname);
63	greg	2.1	}
64
65
66			pflock(lf) /* place or release exclusive lock on file */
67			int lf;
68			{
69			struct flock fls;
70
71			fls.l_type = lf ? F_WRLCK : F_UNLCK;
72			fls.l_whence = 0;
73			fls.l_start = 0L;
74			fls.l_len = 0L;
75			if (fcntl(persistfd, F_SETLKW, &fls) < 0)
76			error(SYSTEM, "cannot (un)lock persist file");
77			}
78
79
80			persistfile(pfn) /* open persist file and lock it */
81			char *pfn;
82			{
83	greg	2.13	persistfd = open(pfn, O_WRONLY\|O_CREAT\|O_EXCL, 0644);
84	greg	2.1	if (persistfd >= 0) {
85			persistfname = pfn;
86			pflock(1);
87			return;
88			}
89			/* file exists -- switch to i/o process */
90			persistfd = open(pfn, O_RDWR);
91			if (persistfd < 0) {
92			sprintf(errmsg, "cannot open persist file \"%s\"", pfn);
93			error(SYSTEM, errmsg);
94			}
95			pflock(1);
96			io_process(); /* never returns */
97			}
98
99
100	greg	2.13	static int got_io;
101	greg	2.1
102	greg	2.13	static int sig_io() { got_io++; }
103	greg	2.1
104	greg	2.13	static int sig_alrm() { quit(0); }
105
106
107	greg	2.1	pfhold() /* holding pattern for idle rendering process */
108			{
109	greg	2.13	int (*oldalrm)();
110	greg	2.12	char buf[512];
111	greg	2.1	register int n;
112			/* close input and output descriptors */
113			close(fileno(stdin));
114			close(fileno(stdout));
115			/* create named pipes for input and output */
116	greg	2.11	if (mknod(mktemp(strcpy(inpname,TEMPLATE)), S_IFIFO\|0600, 0) < 0)
117	greg	2.1	goto createrr;
118	greg	2.11	if (mknod(mktemp(strcpy(outpname,TEMPLATE)), S_IFIFO\|0600, 0) < 0)
119	greg	2.1	goto createrr;
120	greg	2.14	if (errfile == NULL &&
121			mknod(mktemp(strcpy(errname,TEMPLATE)), S_IFIFO\|0600, 0) < 0)
122			goto createrr;
123			sprintf(buf, "%s %d\n%s\n%s\n%s\n", progname, getpid(),
124			inpname, outpname, errname);
125	greg	2.1	n = strlen(buf);
126			if (write(persistfd, buf, n) < n)
127	greg	2.10	error(SYSTEM, "error writing persist file");
128	greg	2.2	/* wait TIMELIM for someone to signal us */
129	greg	2.13	got_io = 0;
130			signal(SIGIO, sig_io);
131			oldalrm = (int (*)())signal(SIGALRM, sig_alrm);
132	greg	2.2	alarm(TIMELIM);
133	greg	2.15	pflock(0); /* unlock persist file for attach */
134	greg	2.13	while (!got_io)
135	greg	2.15	pause(); /* wait for attach */
136			pflock(1); /* grab persist file right back! */
137			alarm(0); /* turn off alarm */
138	greg	2.13	signal(SIGALRM, oldalrm);
139	greg	2.2	signal(SIGIO, SIG_DFL);
140	greg	2.15	if (lseek(persistfd, 0L, 0) < 0 \|\| ftruncate(persistfd, 0L) < 0)
141			error(SYSTEM, "seek/truncate error on persist file");
142	greg	2.1	/* someone wants us; reopen stdin and stdout */
143			if (freopen(inpname, "r", stdin) == NULL)
144			goto openerr;
145			if (freopen(outpname, "w", stdout) == NULL)
146			goto openerr;
147	greg	2.14	if (errname[0]) {
148			if (freopen(errname, "w", stderr) == NULL)
149			goto openerr;
150			unlink(errname);
151			errname[0] = '\0';
152			}
153	greg	2.1	unlink(inpname);
154			inpname[0] = '\0';
155			unlink(outpname);
156			outpname[0] = '\0';
157			return;
158			createrr:
159			error(SYSTEM, "cannot create named pipes in pfhold");
160			openerr:
161			error(SYSTEM, "cannot open named pipes in pfhold");
162			}
163
164
165			io_process() /* just act as conduits to and from actual process */
166			{
167			register char *cp;
168			register int nr, n;
169	greg	2.14	char buf[512], pfin, pfout, *pferr;
170			int pid, pid2 = -1;
171	greg	2.15	/* load persist file */
172			while ((nr = read(persistfd, buf, sizeof(buf)-1)) == 0) {
173			pflock(0);
174			sleep(15); /* wait until ready */
175			pflock(1);
176			}
177			pfdetach(); /* close persist file */
178			if (nr < 0)
179	greg	2.14	error(SYSTEM, "error reading persist file");
180	greg	2.1	buf[nr] = '\0';
181	greg	2.12	if ((cp = index(buf, ' ')) == NULL)
182	greg	2.1	goto formerr;
183			*cp++ = '\0';
184	greg	2.12	if ((pid = atoi(cp)) <= 0)
185	greg	2.1	goto formerr;
186			if ((cp = index(cp, '\n')) == NULL)
187			goto formerr;
188	greg	2.12	pfin = ++cp;
189			if ((cp = index(cp, '\n')) == NULL)
190			goto formerr;
191	greg	2.1	*cp++ = '\0';
192			pfout = cp;
193			if ((cp = index(cp, '\n')) == NULL)
194			goto formerr;
195			*cp++ = '\0';
196	greg	2.14	pferr = cp;
197			if ((cp = index(cp, '\n')) == NULL)
198			goto formerr;
199			*cp++ = '\0';
200	greg	2.1	if (cp-buf != nr)
201			goto formerr;
202	greg	2.12	if (strcmp(buf, progname)) {
203			sprintf(errmsg, "persist file for %s, not %s", buf, progname);
204			error(USER, errmsg);
205			}
206	greg	2.1	/* wake up rendering process */
207	greg	2.2	if (kill(pid, SIGIO) < 0)
208	greg	2.1	error(SYSTEM, "cannot signal rendering process in io_process");
209			pid = fork(); /* fork i/o process */
210			if (pid < 0)
211	greg	2.14	goto forkerr;
212	greg	2.1	/* connect to appropriate pipe */
213			if (pid) { /* parent passes renderer output */
214	greg	2.7	close(0);
215	greg	2.14	if (pferr[0]) {
216			pid2 = fork(); /* fork another for stderr */
217			if (pid2 < 0)
218			goto forkerr;
219			}
220			if (pid2) { /* parent is still stdout */
221			if (open(pfout, O_RDONLY) != 0)
222			error(SYSTEM,
223			"cannot open output pipe in io_process");
224			} else { /* second child is stderr */
225			if (open(pferr, O_RDONLY) != 0)
226			error(SYSTEM,
227			"cannot open error pipe in io_process");
228			dup2(2, 1); /* attach stdout to stderr */
229			}
230	greg	2.1	} else { /* child passes renderer input */
231	greg	2.7	close(1);
232			if (open(pfin, O_WRONLY) != 1)
233	greg	2.14	error(SYSTEM, "cannot open input pipe in io_process");
234	greg	2.1	}
235			/* pass input to output */
236	greg	2.9	/* read as much as we can, write all of it */
237			while ((nr = read(0, cp=buf, sizeof(buf))) > 0)
238			do {
239			if ((n = write(1, cp, nr)) <= 0)
240	greg	2.14	error(SYSTEM, "write error in io_process");
241	greg	2.9	cp += n;
242			} while ((nr -= n) > 0);
243	greg	2.7	if (nr < 0)
244			error(SYSTEM, "read error in io_process");
245			close(0); /* close input */
246			close(1); /* close output */
247	greg	2.14	if (pid) /* parent waits for stdin child */
248	greg	2.1	wait(0);
249	greg	2.14	if (pid2 > 0) /* wait for stderr child also */
250			wait(0);
251			_exit(0); /* all done, exit (not quit!) */
252	greg	2.1	formerr:
253			error(USER, "format error in persist file");
254	greg	2.14	forkerr:
255			error(SYSTEM, "fork failed in io_process");
256	greg	2.1	}
257	greg	2.6
258	greg	2.8	#else
259
260			pfclean() {}
261
262	greg	2.6	#endif