1da2e3ebdSchin /***********************************************************************
2da2e3ebdSchin * *
3da2e3ebdSchin * This software is part of the ast package *
4*b30d1939SAndy Fiddaman * Copyright (c) 1985-2011 AT&T Intellectual Property *
5da2e3ebdSchin * and is licensed under the *
6*b30d1939SAndy Fiddaman * Eclipse Public License, Version 1.0 *
77c2fbfb3SApril Chin * by AT&T Intellectual Property *
8da2e3ebdSchin * *
9da2e3ebdSchin * 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) *
12da2e3ebdSchin * *
13da2e3ebdSchin * Information and Software Systems Research *
14da2e3ebdSchin * AT&T Research *
15da2e3ebdSchin * Florham Park NJ *
16da2e3ebdSchin * *
17da2e3ebdSchin * Glenn Fowler <gsf@research.att.com> *
18da2e3ebdSchin * David Korn <dgk@research.att.com> *
19da2e3ebdSchin * Phong Vo <kpv@research.att.com> *
20da2e3ebdSchin * *
21da2e3ebdSchin ***********************************************************************/
22da2e3ebdSchin #pragma prototyped
23da2e3ebdSchin /*
24da2e3ebdSchin * G. S. Fowler
25da2e3ebdSchin * D. G. Korn
26da2e3ebdSchin * AT&T Bell Laboratories
27da2e3ebdSchin *
28da2e3ebdSchin * shell library support
29da2e3ebdSchin */
30da2e3ebdSchin
31da2e3ebdSchin #include <ast.h>
32da2e3ebdSchin #include <sys/stat.h>
33da2e3ebdSchin
34da2e3ebdSchin /*
35da2e3ebdSchin * return pointer to the full path name of the shell
36da2e3ebdSchin *
37da2e3ebdSchin * SHELL is read from the environment and must start with /
38da2e3ebdSchin *
39da2e3ebdSchin * if set-uid or set-gid then the executable and its containing
40da2e3ebdSchin * directory must not be owned by the real user/group
41da2e3ebdSchin *
42da2e3ebdSchin * root/administrator has its own test
43da2e3ebdSchin *
44da2e3ebdSchin * astconf("SH",NiL,NiL) is returned by default
45da2e3ebdSchin *
46da2e3ebdSchin * NOTE: csh is rejected because the bsh/csh differentiation is
47da2e3ebdSchin * not done for `csh script arg ...'
48da2e3ebdSchin */
49da2e3ebdSchin
50da2e3ebdSchin char*
pathshell(void)51da2e3ebdSchin pathshell(void)
52da2e3ebdSchin {
53da2e3ebdSchin register char* sh;
54da2e3ebdSchin int ru;
55da2e3ebdSchin int eu;
56da2e3ebdSchin int rg;
57da2e3ebdSchin int eg;
58da2e3ebdSchin struct stat st;
59da2e3ebdSchin
60da2e3ebdSchin static char* val;
61da2e3ebdSchin
62da2e3ebdSchin if ((sh = getenv("SHELL")) && *sh == '/' && strmatch(sh, "*/(sh|*[!cC]sh)*([[:digit:]])?(-+([.[:alnum:]]))?(.exe)"))
63da2e3ebdSchin {
64da2e3ebdSchin if (!(ru = getuid()) || !eaccess("/bin", W_OK))
65da2e3ebdSchin {
66da2e3ebdSchin if (stat(sh, &st))
67da2e3ebdSchin goto defshell;
68da2e3ebdSchin if (ru != st.st_uid && !strmatch(sh, "?(/usr)?(/local)/?([ls])bin/?([[:lower:]])sh?(.exe)"))
69da2e3ebdSchin goto defshell;
70da2e3ebdSchin }
71da2e3ebdSchin else
72da2e3ebdSchin {
73da2e3ebdSchin eu = geteuid();
74da2e3ebdSchin rg = getgid();
75da2e3ebdSchin eg = getegid();
76da2e3ebdSchin if (ru != eu || rg != eg)
77da2e3ebdSchin {
78da2e3ebdSchin char* s;
79da2e3ebdSchin char dir[PATH_MAX];
80da2e3ebdSchin
81da2e3ebdSchin s = sh;
82da2e3ebdSchin for (;;)
83da2e3ebdSchin {
84da2e3ebdSchin if (stat(s, &st))
85da2e3ebdSchin goto defshell;
86da2e3ebdSchin if (ru != eu && st.st_uid == ru)
87da2e3ebdSchin goto defshell;
88da2e3ebdSchin if (rg != eg && st.st_gid == rg)
89da2e3ebdSchin goto defshell;
90da2e3ebdSchin if (s != sh)
91da2e3ebdSchin break;
92da2e3ebdSchin if (strlen(s) >= sizeof(dir))
93da2e3ebdSchin goto defshell;
94da2e3ebdSchin strcpy(dir, s);
95da2e3ebdSchin if (!(s = strrchr(dir, '/')))
96da2e3ebdSchin break;
97da2e3ebdSchin *s = 0;
98da2e3ebdSchin s = dir;
99da2e3ebdSchin }
100da2e3ebdSchin }
101da2e3ebdSchin }
102da2e3ebdSchin return sh;
103da2e3ebdSchin }
104da2e3ebdSchin defshell:
105da2e3ebdSchin if (!(sh = val))
106da2e3ebdSchin {
107da2e3ebdSchin if (!*(sh = astconf("SH", NiL, NiL)) || *sh != '/' || eaccess(sh, X_OK) || !(sh = strdup(sh)))
108da2e3ebdSchin sh = "/bin/sh";
109da2e3ebdSchin val = sh;
110da2e3ebdSchin }
111da2e3ebdSchin return sh;
112da2e3ebdSchin }
113