1 #include "mk.h"
2 
3 static Shell *shells[] = {
4 	&rcshell,
5 	&shshell
6 };
7 
8 Shell *shelldefault = &shshell;
9 
10 Shell *shellt;
11 Word *shellcmd;
12 
13 typedef struct Shellstack Shellstack;
14 struct Shellstack
15 {
16 	Shell *t;
17 	Word *w;
18 	Shellstack *next;
19 };
20 
21 Shellstack *shellstack;
22 
23 char*
24 setshell(Word *w)
25 {
26 	int i;
27 
28 	if(w->s == nil)
29 		return "shell name not found on line";
30 
31 	for(i=0; i<nelem(shells); i++)
32 		if(shells[i]->matchname(w->s))
33 			break;
34 	if(i == nelem(shells))
35 		return "cannot determine shell type";
36 	shellt = shells[i];
37 	shellcmd = w;
38 	return nil;
39 }
40 
41 void
42 initshell(void)
43 {
44 	shellcmd = stow(shelldefault->name);
45 	shellt = shelldefault;
46 	setvar("MKSHELL", shellcmd);
47 }
48 
49 void
50 pushshell(void)
51 {
52 	Shellstack *s;
53 
54 	/* save */
55 	s = Malloc(sizeof *s);
56 	s->t = shellt;
57 	s->w = shellcmd;
58 	s->next = shellstack;
59 	shellstack = s;
60 
61 	initshell();	/* reset to defaults */
62 }
63 
64 void
65 popshell(void)
66 {
67 	Shellstack *s;
68 
69 	if(shellstack == nil){
70 		fprint(2, "internal shellstack error\n");
71 		Exit();
72 	}
73 
74 	s = shellstack;
75 	shellstack = s->next;
76 	shellt = s->t;
77 	shellcmd = s->w;
78 	setvar("MKSHELL", shellcmd);
79 	free(s);
80 }