/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <bio.h>#include <thread.h> enum {	Stacksize	= 8*1024,	Bufsize		= 8*1024,}; Channel *out;Channel *quit;Channel *forkc;int nread = 0; typedef struct Str Str;struct Str {	char	*buf;	int	len;}; voiddie(char *s){	fprint(2, "%s\n", s);	exits(s);} voidcwrite(int fd, char *path, char *cmd, int len){	werrstr("");	if (write(fd, cmd, len) < len) {		fprint(2, "cwrite: %s: failed writing %d bytes: %r\n",			path, len);		sendp(quit, nil);		threadexits(nil);	}} Str *newstr(void){	Str *s; 	s = mallocz(sizeof(Str) + Bufsize, 1);	if (s == nil)		sysfatal("malloc");	s->buf = (char *)&s[1];	return s;} voidreader(void *v){	int cfd, tfd, forking = 0, exiting, pid, newpid;	char *ctl, *truss;	Str *s;	static char start[] = "start";	static char waitstop[] = "waitstop"; 	pid = (int)(uintptr)v;	ctl = smprint("/proc/%d/ctl", pid);	if ((cfd = open(ctl, OWRITE)) < 0)		die(smprint("%s: %r", ctl));	truss = smprint("/proc/%d/syscall", pid);	if ((tfd = open(truss, OREAD)) < 0)		die(smprint("%s: %r", truss)); 	/* child was stopped by hang msg earlier */	cwrite(cfd, ctl, waitstop, sizeof waitstop - 1); 	cwrite(cfd, ctl, "startsyscall", 12);	s = newstr();	exiting = 0;	while((s->len = pread(tfd, s->buf, Bufsize - 1, 0)) >= 0){		if (forking && s->buf[1] == '=' && s->buf[3] != '-') {			forking = 0;			newpid = strtol(&s->buf[3], 0, 0);			sendp(forkc, (void*)newpid);			procrfork(reader, (void*)newpid, Stacksize, 0);		} 		/*		 * There are three tests here and they (I hope) guarantee		 * no false positives.		 */		if (strstr(s->buf, " Rfork") != nil) {			char *a[8];			char *rf; 			rf = strdup(s->buf);         		if (tokenize(rf, a, 8) == 5 &&			    strtoul(a[4], 0, 16) & RFPROC)				forking = 1;			free(rf);		} else if (strstr(s->buf, " Exits") != nil)			exiting = 1; 		sendp(out, s);	/* print line from /proc/$child/syscall */		if (exiting) {			s = newstr();			strcpy(s->buf, "\n");			sendp(out, s);			break;		} 		/* flush syscall trace buffer */		cwrite(cfd, ctl, "startsyscall", 12);		s = newstr();	} 	sendp(quit, nil);	threadexitsall(nil);} voidwriter(void *){	int newpid;	Alt a[4];	Str *s; 	a[0].op = CHANRCV;	a[0].c = quit;	a[0].v = nil;	a[1].op = CHANRCV;	a[1].c = out;	a[1].v = &s;	a[2].op = CHANRCV;	a[2].c = forkc;	a[2].v = &newpid;	a[3].op = CHANEND; 	for(;;)		switch(alt(a)){		case 0:			/* quit */			nread--;			if(nread <= 0)				goto done;			break;		case 1:			/* out */			/* it's a nice null terminated thing */			fprint(2, "%s", s->buf);			free(s);			break;		case 2:			/* forkc */			// procrfork(reader, (void*)newpid, Stacksize, 0);			nread++;			break;		}done:	exits(nil);} voidusage(void){	fprint(2, "Usage: ratrace [-c cmd [arg...]] | [pid]\n");	exits("usage");} voidhang(void){	int me;	char *myctl;	static char hang[] = "hang"; 	myctl = smprint("/proc/%d/ctl", getpid());	me = open(myctl, OWRITE);	if (me < 0)		sysfatal("can't open %s: %r", myctl);	cwrite(me, myctl, hang, sizeof hang - 1);	close(me);	free(myctl);} voidthreadmain(int argc, char **argv){	int pid;	char *cmd = nil;	char **args = nil; 	/*	 * don't bother with fancy arg processing, because it picks up options	 * for the command you are starting.  Just check for -c as argv[1]	 * and then take it from there.	 */	if (argc < 2)		usage();	while (argv[1][0] == '-') {		switch(argv[1][1]) {		case 'c':			if (argc < 3)				usage();			cmd = strdup(argv[2]);			args = &argv[2];			break;		default:			usage();		}		++argv;		--argc;	} 	/* run a command? */	if(cmd) {		pid = fork();		if (pid < 0)			sysfatal("fork failed: %r");		if(pid == 0) {			hang();			exec(cmd, args);			if(cmd[0] != '/')				exec(smprint("/bin/%s", cmd), args);			sysfatal("exec %s failed: %r", cmd);		}	} else {		if(argc != 2)			usage();		pid = atoi(argv[1]);	} 	out   = chancreate(sizeof(char*), 0);	quit  = chancreate(sizeof(char*), 0);	forkc = chancreate(sizeof(ulong *), 0);	nread++;	procrfork(writer, nil, Stacksize, 0);	reader((void*)pid);}