Add original unix v6

source/s1/if.c

@@ -0,0 +1,146 @@
+/* if command */
+
+int	ap;
+int	ac;
+char	**av;
+
+main(argc, argv)
+char *argv[];
+{
+
+	argv[argc] = 0;
+	ac = argc; av = argv; ap = 1;
+	if (argc<2) return;
+	if (exp()) 
+		if(doex(0)) {
+			write(1, "no command\n", 11);
+			seek(0, 0, 2);
+		}
+}
+
+char *nxtarg() {
+
+	if (ap>ac) return(0*ap++);
+	return(av[ap++]);
+}
+
+exp(s) {
+	int p1;
+
+	p1 = e1();
+	if (eq(nxtarg(), "-o")) return(p1 | exp());
+	ap--;
+	return(p1);
+}
+
+e1() {
+	int p1;
+
+	p1 = e2();
+	if (eq(nxtarg(), "-a")) return (p1 & e1());
+	ap--;
+	return(p1);
+}
+
+e2() {
+	if (eq(nxtarg(), "!"))
+		return(!e3());
+	ap--;
+	return(e3());
+}
+
+e3() {
+	int p1, ccode;
+	register char *a;
+
+	ccode = 0;
+	if ((a=nxtarg())==0) goto err;
+	if(eq(a, "(")) {
+		p1 = exp();
+		if(!eq(nxtarg(), ")")) goto err;
+		return(p1);
+	}
+
+	if(eq(a, "-r"))
+		return(tio(nxtarg(), 0));
+
+	if(eq(a, "-w"))
+		return(tio(nxtarg(), 1));
+
+	if(eq(a, "-c"))
+		return(tcreat(nxtarg()));
+
+	if(eq(a, "{")) { /* execute a command for exit code */
+		if(fork()) /*parent*/ wait(&ccode);
+		else { /*child*/
+			doex(1);
+			goto err;
+		}
+		while((a=nxtarg()) && (!eq(a,"}")));
+		return(ccode? 0 : 1);
+	}
+
+	p1 = nxtarg();
+	if (p1==0) goto err;
+	if(eq(p1, "="))
+		return(eq(a, nxtarg()));
+
+	if(eq(p1, "!="))
+		return(!eq(a, nxtarg()));
+err:
+	write(1, "if error\n", 9);
+	exit(9);
+}
+
+tio(a, f) {
+
+	a = open(a, f);
+	if (a>=0) {
+		close(a);
+		return(1);
+	}
+	return(0);
+}
+
+tcreat(a) {
+	return(1);
+}
+
+eq(a, b)
+char *a, *b;
+{
+	register int i;
+
+	i = 0;
+l:
+	if(a[i] != b[i])
+		return(0);
+	if(a[i++] == '\0')
+		return(1);
+	goto l;
+}
+
+doex(earg) {
+
+	register int np, i, c;
+	char *nargv[50], *ncom, *na;
+
+	np = 0;
+	while (na=nxtarg()) {
+		if(earg && eq(na,"}")) break;
+		nargv[np++] = na;
+	}
+	if(earg && (!eq(na, "}"))) return(9);
+	nargv[np] = 0;
+	if (np==0) return(earg);
+	execv(nargv[0], nargv, np);
+	i = 0;
+	ncom = "/usr/bin/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
+	while(c=nargv[0][i])  {
+		ncom[9+i++] = c;
+	}
+	ncom[9+i] = '\0';
+	execv(ncom+4, nargv, np);
+	execv(ncom, nargv, np);
+	return(1);
+}