Imported Upstream version 93u+upstream

1 files changed, 112 insertions, 0 deletions

diff --git a/src/lib/libast/path/pathshell.c b/src/lib/libast/path/pathshell.c
new file mode 100644
index 0000000..f4b2557
--- /dev/null
+++ b/src/lib/libast/path/pathshell.c
@@ -0,0 +1,112 @@
+/***********************************************************************
+*                                                                      *
+*               This software is part of the ast package               *
+*          Copyright (c) 1985-2011 AT&T Intellectual Property          *
+*                      and is licensed under the                       *
+*                 Eclipse Public License, Version 1.0                  *
+*                    by AT&T Intellectual Property                     *
+*                                                                      *
+*                A copy of the License is available at                 *
+*          http://www.eclipse.org/org/documents/epl-v10.html           *
+*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
+*                                                                      *
+*              Information and Software Systems Research               *
+*                            AT&T Research                             *
+*                           Florham Park NJ                            *
+*                                                                      *
+*                 Glenn Fowler <gsf@research.att.com>                  *
+*                  David Korn <dgk@research.att.com>                   *
+*                   Phong Vo <kpv@research.att.com>                    *
+*                                                                      *
+***********************************************************************/
+#pragma prototyped
+/*
+ * G. S. Fowler
+ * D. G. Korn
+ * AT&T Bell Laboratories
+ *
+ * shell library support
+ */
+
+#include <ast.h>
+#include <sys/stat.h>
+
+/*
+ * return pointer to the full path name of the shell
+ *
+ * SHELL is read from the environment and must start with /
+ *
+ * if set-uid or set-gid then the executable and its containing
+ * directory must not be owned by the real user/group
+ *
+ * root/administrator has its own test
+ *
+ * astconf("SH",NiL,NiL) is returned by default
+ *
+ * NOTE: csh is rejected because the bsh/csh differentiation is
+ *       not done for `csh script arg ...'
+ */
+
+char*
+pathshell(void)
+{
+	register char*	sh;
+	int		ru;
+	int		eu;
+	int		rg;
+	int		eg;
+	struct stat	st;
+
+	static char*	val;
+
+	if ((sh = getenv("SHELL")) && *sh == '/' && strmatch(sh, "*/(sh|*[!cC]sh)*([[:digit:]])?(-+([.[:alnum:]]))?(.exe)"))
+	{
+		if (!(ru = getuid()) || !eaccess("/bin", W_OK))
+		{
+			if (stat(sh, &st))
+				goto defshell;
+			if (ru != st.st_uid && !strmatch(sh, "?(/usr)?(/local)/?([ls])bin/?([[:lower:]])sh?(.exe)"))
+				goto defshell;
+		}
+		else
+		{
+			eu = geteuid();
+			rg = getgid();
+			eg = getegid();
+			if (ru != eu || rg != eg)
+			{
+				char*	s;
+				char	dir[PATH_MAX];
+
+				s = sh;
+				for (;;)
+				{
+					if (stat(s, &st))
+						goto defshell;
+					if (ru != eu && st.st_uid == ru)
+						goto defshell;
+					if (rg != eg && st.st_gid == rg)
+						goto defshell;
+					if (s != sh)
+						break;
+					if (strlen(s) >= sizeof(dir))
+						goto defshell;
+					strcpy(dir, s);
+					if (!(s = strrchr(dir, '/')))
+						break;
+					*s = 0;
+					s = dir;
+				}
+			}
+		}
+		return sh;
+	}
+ defshell:
+	if (!(sh = val))
+	{
+		if (!*(sh = astconf("SH", NiL, NiL)) || *sh != '/' || eaccess(sh, X_OK) || !(sh = strdup(sh)))
+			sh = "/bin/sh";
+		val = sh;
+	}
+	return sh;
+}