1 #include <u.h>
2 #include <signal.h>
3 #include "rc.h"
4 #include "getflags.h"
5 #include "exec.h"
6 #include "io.h"
7 #include "fns.h"
8 
9 int havefork = 1;
10 
11 void
12 Xasync(void)
13 {
14 	int null = open("/dev/null", 0);
15 	int pid;
16 	int tcpgrp, pgrp;
17 	char npid[10];
18 
19 	if(null<0){
20 		Xerror("Can't open /dev/null\n");
21 		return;
22 	}
23 	switch(pid = rfork(RFFDG|RFPROC|RFNOTEG)){
24 	case -1:
25 		close(null);
26 		Xerror("try again");
27 		break;
28 	case 0:
29 		/*
30 		 * Should make reads of tty fail, writes succeed.
31 		 */
32 		signal(SIGTTIN, SIG_IGN);
33 		signal(SIGTTOU, SIG_IGN);
34 
35 		pushredir(ROPEN, null, 0);
36 		start(runq->code, runq->pc+1, runq->local);
37 		runq->ret = 0;
38 		break;
39 	default:
40 		close(null);
41 		runq->pc = runq->code[runq->pc].i;
42 		inttoascii(npid, pid);
43 		setvar("apid", newword(npid, (word *)0));
44 		break;
45 	}
46 }
47 
48 void
49 Xpipe(void)
50 {
51 	struct thread *p = runq;
52 	int pc = p->pc, forkid;
53 	int lfd = p->code[pc++].i;
54 	int rfd = p->code[pc++].i;
55 	int pfd[2];
56 	if(pipe(pfd)<0){
57 		Xerror("can't get pipe");
58 		return;
59 	}
60 	switch(forkid = fork()){
61 	case -1:
62 		Xerror("try again");
63 		break;
64 	case 0:
65 		start(p->code, pc+2, runq->local);
66 		runq->ret = 0;
67 		close(pfd[PRD]);
68 		pushredir(ROPEN, pfd[PWR], lfd);
69 		break;
70 	default:
71 		start(p->code, p->code[pc].i, runq->local);
72 		close(pfd[PWR]);
73 		pushredir(ROPEN, pfd[PRD], rfd);
74 		p->pc = p->code[pc+1].i;
75 		p->pid = forkid;
76 		break;
77 	}
78 }
79 
80 /*
81  * Who should wait for the exit from the fork?
82  */
83 void
84 Xbackq(void)
85 {
86 	char wd[8193];
87 	int c;
88 	char *s, *ewd=&wd[8192], *stop;
89 	struct io *f;
90 	var *ifs = vlook("ifs");
91 	word *v, *nextv;
92 	int pfd[2];
93 	int pid;
94 	stop = ifs->val?ifs->val->word:"";
95 	if(pipe(pfd)<0){
96 		Xerror("can't make pipe");
97 		return;
98 	}
99 	switch(pid = fork()){
100 	case -1:
101 		Xerror("try again");
102 		close(pfd[PRD]);
103 		close(pfd[PWR]);
104 		return;
105 	case 0:
106 		close(pfd[PRD]);
107 		start(runq->code, runq->pc+1, runq->local);
108 		pushredir(ROPEN, pfd[PWR], 1);
109 		return;
110 	default:
111 		close(pfd[PWR]);
112 		f = openfd(pfd[PRD]);
113 		s = wd;
114 		v = 0;
115 		while((c = rchr(f))!=EOF){
116 			if(strchr(stop, c) || s==ewd){
117 				if(s!=wd){
118 					*s='\0';
119 					v = newword(wd, v);
120 					s = wd;
121 				}
122 			}
123 			else *s++=c;
124 		}
125 		if(s!=wd){
126 			*s='\0';
127 			v = newword(wd, v);
128 		}
129 		closeio(f);
130 		Waitfor(pid, 0);
131 		/* v points to reversed arglist -- reverse it onto argv */
132 		while(v){
133 			nextv = v->next;
134 			v->next = runq->argv->words;
135 			runq->argv->words = v;
136 			v = nextv;
137 		}
138 		runq->pc = runq->code[runq->pc].i;
139 		return;
140 	}
141 }
142 
143 void
144 Xpipefd(void)
145 {
146 	struct thread *p = runq;
147 	int pc = p->pc;
148 	char name[40];
149 	int pfd[2];
150 	int sidefd, mainfd;
151 	if(pipe(pfd)<0){
152 		Xerror("can't get pipe");
153 		return;
154 	}
155 	if(p->code[pc].i==READ){
156 		sidefd = pfd[PWR];
157 		mainfd = pfd[PRD];
158 	}
159 	else{
160 		sidefd = pfd[PRD];
161 		mainfd = pfd[PWR];
162 	}
163 	switch(fork()){
164 	case -1:
165 		Xerror("try again");
166 		break;
167 	case 0:
168 		start(p->code, pc+2, runq->local);
169 		close(mainfd);
170 		pushredir(ROPEN, sidefd, p->code[pc].i==READ?1:0);
171 		runq->ret = 0;
172 		break;
173 	default:
174 		close(sidefd);
175 		pushredir(ROPEN, mainfd, mainfd);	/* isn't this a noop? */
176 		strcpy(name, Fdprefix);
177 		inttoascii(name+strlen(name), mainfd);
178 		pushword(name);
179 		p->pc = p->code[pc+1].i;
180 		break;
181 	}
182 }
183 
184 void
185 Xsubshell(void)
186 {
187 	int pid;
188 	switch(pid = fork()){
189 	case -1:
190 		Xerror("try again");
191 		break;
192 	case 0:
193 		start(runq->code, runq->pc+1, runq->local);
194 		runq->ret = 0;
195 		break;
196 	default:
197 		Waitfor(pid, 1);
198 		runq->pc = runq->code[runq->pc].i;
199 		break;
200 	}
201 }
202 
203 int
204 execforkexec(void)
205 {
206 	int pid;
207 	int n;
208 	char buf[ERRMAX];
209 
210 	switch(pid = fork()){
211 	case -1:
212 		return -1;
213 	case 0:
214 		pushword("exec");
215 		execexec();
216 		strcpy(buf, "can't exec: ");
217 		n = strlen(buf);
218 		errstr(buf+n, ERRMAX-n);
219 		Exit(buf);
220 	}
221 	return pid;
222 }