#include "rc.h"#include "getflags.h"#include "exec.h"#include "io.h"#include "fns.h" int havefork = 1; voidXasync(void){	int null = open("/dev/null", 0);	int pid;	char npid[10];	if(null<0){		Xerror("Can't open /dev/null\n");		return;	}	switch(pid = rfork(RFFDG|RFPROC|RFNOTEG)){	case -1:		close(null);		Xerror("try again");		break;	case 0:		clearwaitpids();		pushredir(ROPEN, null, 0);		start(runq->code, runq->pc+1, runq->local);		runq->ret = 0;		break;	default:		addwaitpid(pid);		close(null);		runq->pc = runq->code[runq->pc].i;		inttoascii(npid, pid);		setvar("apid", newword(npid, (word *)0));		break;	}} voidXpipe(void){	struct thread *p = runq;	int pc = p->pc, forkid;	int lfd = p->code[pc++].i;	int rfd = p->code[pc++].i;	int pfd[2];	if(pipe(pfd)<0){		Xerror("can't get pipe");		return;	}	switch(forkid = fork()){	case -1:		Xerror("try again");		break;	case 0:		clearwaitpids();		start(p->code, pc+2, runq->local);		runq->ret = 0;		close(pfd[PRD]);		pushredir(ROPEN, pfd[PWR], lfd);		break;	default:		addwaitpid(forkid);		start(p->code, p->code[pc].i, runq->local);		close(pfd[PWR]);		pushredir(ROPEN, pfd[PRD], rfd);		p->pc = p->code[pc+1].i;		p->pid = forkid;		break;	}} /* * Who should wait for the exit from the fork? */enum { Stralloc = 100, }; voidXbackq(void){	int l, n, pw, inc, pid;	int pfd[2];	char *s, *wd, *ewd, *stop;	struct io *f;	word *v, *nextv;	Rune r; 	stop = "";	pw = 0;	if(runq->argv && runq->argv->words){		stop = runq->argv->words->word;		pw = 1;	}	if(pipe(pfd)<0){		Xerror("can't make pipe");		return;	}	switch(pid = fork()){	case -1:		Xerror("try again");		close(pfd[PRD]);		close(pfd[PWR]);		return;	case 0:		clearwaitpids();		close(pfd[PRD]);		start(runq->code, runq->pc+1, runq->local);		pushredir(ROPEN, pfd[PWR], 1);		return;	default:		addwaitpid(pid);		close(pfd[PWR]);		f = openfd(pfd[PRD]);		s = wd = ewd = 0;		v = 0;		inc = Stralloc;		for(;;){			/* always eat 4 byte runes */			if(s+2*UTFmax>=ewd){				l = s-wd;				wd = erealloc(wd, l+inc);				ewd = wd+l+inc-1;				s = wd+l;				inc *= 2;			}			if((n = rutf(s, &r, f))==EOF)				break;			s[n] = 0;			if(strstr(stop, s)){				if(s!=wd){					*s='\0';					v = newword(wd, v);					s = wd;				}			}else				s += n;		}		if(s!=wd){			*s='\0';			v = newword(wd, v);		}		if(wd)			efree(wd);		closeio(f);		Waitfor(pid, 0);		if(pw)			popword();	/* ditch split in "stop" */		/* v points to reversed arglist -- reverse it onto argv */		while(v){			nextv = v->next;			v->next = runq->argv->words;			runq->argv->words = v;			v = nextv;		}		runq->pc = runq->code[runq->pc].i;		return;	}} voidXpipefd(void){	struct thread *p = runq;	int pc = p->pc, pid;	char name[40];	int pfd[2];	int sidefd, mainfd;	if(pipe(pfd)<0){		Xerror("can't get pipe");		return;	}	if(p->code[pc].i==READ){		sidefd = pfd[PWR];		mainfd = pfd[PRD];	}	else{		sidefd = pfd[PRD];		mainfd = pfd[PWR];	}	switch(pid = fork()){	case -1:		Xerror("try again");		break;	case 0:		clearwaitpids();		start(p->code, pc+2, runq->local);		close(mainfd);		pushredir(ROPEN, sidefd, p->code[pc].i==READ?1:0);		runq->ret = 0;		break;	default:		addwaitpid(pid);		close(sidefd);		pushredir(ROPEN, mainfd, mainfd);	/* isn't this a noop? */		strcpy(name, Fdprefix);		inttoascii(name+strlen(name), mainfd);		pushword(name);		p->pc = p->code[pc+1].i;		break;	}} voidXsubshell(void){	int pid;	switch(pid = fork()){	case -1:		Xerror("try again");		break;	case 0:		clearwaitpids();		start(runq->code, runq->pc+1, runq->local);		runq->ret = 0;		break;	default:		addwaitpid(pid);		Waitfor(pid, 1);		runq->pc = runq->code[runq->pc].i;		break;	}} intexecforkexec(void){	int pid;	int n;	char buf[ERRMAX]; 	switch(pid = fork()){	case -1:		return -1;	case 0:		clearwaitpids();		pushword("exec");		execexec();		strcpy(buf, "can't exec: ");		n = strlen(buf);		errstr(buf+n, ERRMAX-n);		Exit(buf);	}	addwaitpid(pid);	return pid;}