1 #include <u.h>
2 #include <libc.h>
3 #include <ctype.h>
4 
5 static int
6 isme(char *uid)
7 {
8 	int n;
9 	char *p;
10 
11 	n = strtol(uid, &p, 10);
12 	if(*p == 0 && p > uid)
13 		return n == getuid();
14 	return strcmp(getuser(), uid) == 0;
15 }
16 /*
17  * Absent other hints, it works reasonably well to use
18  * the X11 display name as the name space identifier.
19  * This is how sam's B has worked since the early days.
20  * Since most programs using name spaces are also using X,
21  * this still seems reasonable.  Terminal-only sessions
22  * can set $NAMESPACE.
23  */
24 static char*
25 nsfromdisplay(void)
26 {
27 	int fd;
28 	Dir *d;
29 	char *disp, *p;
30 
31 	if((disp = getenv("DISPLAY")) == nil){
32 		werrstr("$DISPLAY not set");
33 		return nil;
34 	}
35 
36 	/* canonicalize: xxx:0.0 => xxx:0 */
37 	p = strrchr(disp, ':');
38 	if(p){
39 		p++;
40 		while(isdigit((uchar)*p))
41 			p++;
42 		if(strcmp(p, ".0") == 0)
43 			*p = 0;
44 	}
45 
46 	p = smprint("/tmp/ns.%s.%s", getuser(), disp);
47 	free(disp);
48 	if(p == nil){
49 		werrstr("out of memory");
50 		return p;
51 	}
52 	if((fd=create(p, OREAD, DMDIR|0700)) >= 0){
53 		close(fd);
54 		return p;
55 	}
56 	if((d = dirstat(p)) == nil){
57 		free(d);
58 		werrstr("stat %s: %r", p);
59 		free(p);
60 		return nil;
61 	}
62 	if((d->mode&0777) != 0700 || !isme(d->uid)){
63 		werrstr("bad name space dir %s", p);
64 		free(p);
65 		free(d);
66 		return nil;
67 	}
68 	free(d);
69 	return p;
70 }
71 
72 char*
73 getns(void)
74 {
75 	char *ns;
76 
77 	ns = getenv("NAMESPACE");
78 	if(ns == nil)
79 		ns = nsfromdisplay();
80 	if(ns == nil){
81 		werrstr("$NAMESPACE not set, %r");
82 		return nil;
83 	}
84 	return ns;
85 }