/*  * 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 "rc.h"#include "getflags.h"#include "exec.h"#include "io.h"#include "fns.h"#include <String.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? */ voidXbackq(void){	int n, pid;	int pfd[2];	char *stop;	char utf[UTFmax+1];	struct io *f;	var *ifs = vlook("ifs");	word *v, *nextv;	Rune r;	String *word; 	stop = ifs->val? ifs->val->word: "";	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]);		word = s_new();		v = nil;		/* rutf requires at least UTFmax+1 bytes in utf */		while((n = rutf(f, utf, &r)) != EOF){			utf[n] = '\0';			if(utfutf(stop, utf) == nil)				s_nappend(word, utf, n);			else				/*				 * utf/r is an ifs rune (e.g., \t, \n), thus				 * ends the current word, if any.				 */				if(s_len(word) > 0){					v = newword(s_to_c(word), v);					s_reset(word);				}		}		if(s_len(word) > 0)			v = newword(s_to_c(word), v);		s_free(word);		closeio(f);		Waitfor(pid, 0);		/* 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;}