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 	/* turn /tmp/launch/:0 into _tmp_launch_:0 (OS X 10.5) */
47 	for(p=disp; *p; p++)
48 		if(*p == '/')
49 			*p = '_';
50 
51 	p = smprint("/tmp/ns.%s.%s", getuser(), disp);
52 	free(disp);
53 	if(p == nil){
54 		werrstr("out of memory");
55 		return p;
56 	}
57 	if((fd=create(p, OREAD, DMDIR|0700)) >= 0){
58 		close(fd);
59 		return p;
60 	}
61 	if((d = dirstat(p)) == nil){
62 		free(d);
63 		werrstr("stat %s: %r", p);
64 		free(p);
65 		return nil;
66 	}
67 	if((d->mode&0777) != 0700 || !isme(d->uid)){
68 		werrstr("bad name space dir %s", p);
69 		free(p);
70 		free(d);
71 		return nil;
72 	}
73 	free(d);
74 	return p;
75 }
76 
77 char*
78 getns(void)
79 {
80 	char *ns;
81 
82 	ns = getenv("NAMESPACE");
83 	if(ns == nil)
84 		ns = nsfromdisplay();
85 	if(ns == nil){
86 		werrstr("$NAMESPACE not set, %r");
87 		return nil;
88 	}
89 	return ns;
90 }