1*b30d1939SAndy Fiddaman /***********************************************************************
2*b30d1939SAndy Fiddaman * *
3*b30d1939SAndy Fiddaman * This software is part of the ast package *
4*b30d1939SAndy Fiddaman * Copyright (c) 1985-2011 AT&T Intellectual Property *
5*b30d1939SAndy Fiddaman * and is licensed under the *
6*b30d1939SAndy Fiddaman * Eclipse Public License, Version 1.0 *
7*b30d1939SAndy Fiddaman * by AT&T Intellectual Property *
8*b30d1939SAndy Fiddaman * *
9*b30d1939SAndy Fiddaman * A copy of the License is available at *
10*b30d1939SAndy Fiddaman * http://www.eclipse.org/org/documents/epl-v10.html *
11*b30d1939SAndy Fiddaman * (with md5 checksum b35adb5213ca9657e911e9befb180842) *
12*b30d1939SAndy Fiddaman * *
13*b30d1939SAndy Fiddaman * Information and Software Systems Research *
14*b30d1939SAndy Fiddaman * AT&T Research *
15*b30d1939SAndy Fiddaman * Florham Park NJ *
16*b30d1939SAndy Fiddaman * *
17*b30d1939SAndy Fiddaman * Glenn Fowler <gsf@research.att.com> *
18*b30d1939SAndy Fiddaman * David Korn <dgk@research.att.com> *
19*b30d1939SAndy Fiddaman * Phong Vo <kpv@research.att.com> *
20*b30d1939SAndy Fiddaman * *
21*b30d1939SAndy Fiddaman ***********************************************************************/
22*b30d1939SAndy Fiddaman #pragma prototyped
23*b30d1939SAndy Fiddaman /*
24*b30d1939SAndy Fiddaman * G. S. Fowler
25*b30d1939SAndy Fiddaman * D. G. Korn
26*b30d1939SAndy Fiddaman * AT&T Bell Laboratories
27*b30d1939SAndy Fiddaman *
28*b30d1939SAndy Fiddaman * shell library support
29*b30d1939SAndy Fiddaman */
30*b30d1939SAndy Fiddaman
31*b30d1939SAndy Fiddaman #include <ast.h>
32*b30d1939SAndy Fiddaman #include <sys/stat.h>
33*b30d1939SAndy Fiddaman
34*b30d1939SAndy Fiddaman /*
35*b30d1939SAndy Fiddaman * return pointer to the full path name of the shell
36*b30d1939SAndy Fiddaman *
37*b30d1939SAndy Fiddaman * SHELL is read from the environment and must start with /
38*b30d1939SAndy Fiddaman *
39*b30d1939SAndy Fiddaman * if set-uid or set-gid then the executable and its containing
40*b30d1939SAndy Fiddaman * directory must not be owned by the real user/group
41*b30d1939SAndy Fiddaman *
42*b30d1939SAndy Fiddaman * root/administrator has its own test
43*b30d1939SAndy Fiddaman *
44*b30d1939SAndy Fiddaman * astconf("SH",NiL,NiL) is returned by default
45*b30d1939SAndy Fiddaman *
46*b30d1939SAndy Fiddaman * NOTE: csh is rejected because the bsh/csh differentiation is
47*b30d1939SAndy Fiddaman * not done for `csh script arg ...'
48*b30d1939SAndy Fiddaman */
49*b30d1939SAndy Fiddaman
50*b30d1939SAndy Fiddaman char*
pathshell(void)51*b30d1939SAndy Fiddaman pathshell(void)
52*b30d1939SAndy Fiddaman {
53*b30d1939SAndy Fiddaman register char* sh;
54*b30d1939SAndy Fiddaman int ru;
55*b30d1939SAndy Fiddaman int eu;
56*b30d1939SAndy Fiddaman int rg;
57*b30d1939SAndy Fiddaman int eg;
58*b30d1939SAndy Fiddaman struct stat st;
59*b30d1939SAndy Fiddaman
60*b30d1939SAndy Fiddaman static char* val;
61*b30d1939SAndy Fiddaman
62*b30d1939SAndy Fiddaman if ((sh = getenv("SHELL")) && *sh == '/' && strmatch(sh, "*/(sh|*[!cC]sh)*([[:digit:]])?(-+([.[:alnum:]]))?(.exe)"))
63*b30d1939SAndy Fiddaman {
64*b30d1939SAndy Fiddaman if (!(ru = getuid()) || !eaccess("/bin", W_OK))
65*b30d1939SAndy Fiddaman {
66*b30d1939SAndy Fiddaman if (stat(sh, &st))
67*b30d1939SAndy Fiddaman goto defshell;
68*b30d1939SAndy Fiddaman if (ru != st.st_uid && !strmatch(sh, "?(/usr)?(/local)/?([ls])bin/?([[:lower:]])sh?(.exe)"))
69*b30d1939SAndy Fiddaman goto defshell;
70*b30d1939SAndy Fiddaman }
71*b30d1939SAndy Fiddaman else
72*b30d1939SAndy Fiddaman {
73*b30d1939SAndy Fiddaman eu = geteuid();
74*b30d1939SAndy Fiddaman rg = getgid();
75*b30d1939SAndy Fiddaman eg = getegid();
76*b30d1939SAndy Fiddaman if (ru != eu || rg != eg)
77*b30d1939SAndy Fiddaman {
78*b30d1939SAndy Fiddaman char* s;
79*b30d1939SAndy Fiddaman char dir[PATH_MAX];
80*b30d1939SAndy Fiddaman
81*b30d1939SAndy Fiddaman s = sh;
82*b30d1939SAndy Fiddaman for (;;)
83*b30d1939SAndy Fiddaman {
84*b30d1939SAndy Fiddaman if (stat(s, &st))
85*b30d1939SAndy Fiddaman goto defshell;
86*b30d1939SAndy Fiddaman if (ru != eu && st.st_uid == ru)
87*b30d1939SAndy Fiddaman goto defshell;
88*b30d1939SAndy Fiddaman if (rg != eg && st.st_gid == rg)
89*b30d1939SAndy Fiddaman goto defshell;
90*b30d1939SAndy Fiddaman if (s != sh)
91*b30d1939SAndy Fiddaman break;
92*b30d1939SAndy Fiddaman if (strlen(s) >= sizeof(dir))
93*b30d1939SAndy Fiddaman goto defshell;
94*b30d1939SAndy Fiddaman strcpy(dir, s);
95*b30d1939SAndy Fiddaman if (!(s = strrchr(dir, '/')))
96*b30d1939SAndy Fiddaman break;
97*b30d1939SAndy Fiddaman *s = 0;
98*b30d1939SAndy Fiddaman s = dir;
99*b30d1939SAndy Fiddaman }
100*b30d1939SAndy Fiddaman }
101*b30d1939SAndy Fiddaman }
102*b30d1939SAndy Fiddaman return sh;
103*b30d1939SAndy Fiddaman }
104*b30d1939SAndy Fiddaman defshell:
105*b30d1939SAndy Fiddaman if (!(sh = val))
106*b30d1939SAndy Fiddaman {
107*b30d1939SAndy Fiddaman if (!*(sh = astconf("SH", NiL, NiL)) || *sh != '/' || eaccess(sh, X_OK) || !(sh = strdup(sh)))
108*b30d1939SAndy Fiddaman sh = "/bin/sh";
109*b30d1939SAndy Fiddaman val = sh;
110*b30d1939SAndy Fiddaman }
111*b30d1939SAndy Fiddaman return sh;
112*b30d1939SAndy Fiddaman }
113