1 #include "mk.h"
2 
3 static Shell *shells[] = {
4 	&shshell,
5 	&rcshell
6 };
7 
8 Shell *shellt;
9 Word *shellcmd;
10 
11 typedef struct Shellstack Shellstack;
12 struct Shellstack
13 {
14 	Shell *t;
15 	Word *w;
16 	Shellstack *next;
17 };
18 
19 Shellstack *shellstack;
20 
21 char*
22 setshell(Word *w)
23 {
24 	int i;
25 
26 	if(w->s == nil)
27 		return "shell name not found on line";
28 
29 	for(i=0; i<nelem(shells); i++)
30 		if(shells[i]->matchname(w->s))
31 			break;
32 	if(i == nelem(shells))
33 		return "cannot determine shell type";
34 	shellt = shells[i];
35 	shellcmd = w;
36 	return nil;
37 }
38 
39 void
40 initshell(void)
41 {
42 	shellcmd = stow(shells[0]->name);
43 	shellt = shells[0];
44 	setvar("MKSHELL", shellcmd);
45 }
46 
47 void
48 pushshell(void)
49 {
50 	Shellstack *s;
51 
52 	/* save */
53 	s = Malloc(sizeof *s);
54 	s->t = shellt;
55 	s->w = shellcmd;
56 	s->next = shellstack;
57 	shellstack = s;
58 
59 	initshell();	/* reset to defaults */
60 }
61 
62 void
63 popshell(void)
64 {
65 	Shellstack *s;
66 
67 	if(shellstack == nil){
68 		fprint(2, "internal shellstack error\n");
69 		Exit();
70 	}
71 
72 	s = shellstack;
73 	shellstack = s->next;
74 	shellt = s->t;
75 	shellcmd = s->w;
76 	setvar("MKSHELL", shellcmd);
77 	free(s);
78 }