--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/courier-authlib/changeuidgid.c	Wed Jan 16 22:39:43 2008 +0100
@@ -0,0 +1,110 @@
+/*
+** Copyright 1998 - 1999 Double Precision, Inc.  See COPYING for
+** distribution information.
+*/
+
+#if	HAVE_CONFIG_H
+#include	"config.h"
+#endif
+#include	<sys/types.h>
+#if	HAVE_UNISTD_H
+#include	<unistd.h>
+#endif
+#include	<stdio.h>
+#include	<stdlib.h>
+#include	<grp.h>
+#include	<pwd.h>
+#include	<errno.h>
+
+#include	"auth.h"
+
+static const char rcsid[]="$Id: changeuidgid.c,v 1.1 2000/04/13 17:55:05 bruce Exp $";
+
+void authchangegroup(gid_t gid)
+{
+	if ( setgid(gid))
+	{
+		perror("setgid");
+		authexit(1);
+	}
+
+#if HAVE_SETGROUPS
+	if ( getuid() == 0 && setgroups(1, &gid) )
+	{
+		perror("setgroups");
+		authexit(1);
+	}
+#endif
+}
+
+void authchangeuidgid(uid_t uid, gid_t gid)
+{
+	authchangegroup(gid);
+	if ( setuid(uid))
+	{
+		perror("setuid");
+		authexit(1);
+	}
+}
+
+void authchangeusername(const char *uname, const gid_t *forcegrp)
+{
+struct passwd *pw;
+uid_t	changeuid;
+gid_t	changegid;
+
+/* uname might be a pointer returned from a previous called to getpw(),
+** and libc has a problem getting it back.
+*/
+char	*p=malloc(strlen(uname)+1);
+
+	if (!p)
+	{
+		perror("malloc");
+		authexit(1);
+	}
+	strcpy(p, uname);
+
+	errno=ENOENT;
+	if ((pw=getpwnam(p)) == 0)
+	{
+		free(p);
+		perror("getpwnam");
+		authexit(1);
+	}
+	free(p);
+
+	changeuid=pw->pw_uid;
+
+	if ( !forcegrp )	forcegrp= &pw->pw_gid;
+
+	changegid= *forcegrp;
+
+	if ( setgid( changegid ))
+	{
+		perror("setgid");
+		authexit(1);
+	}
+
+#if HAVE_INITGROUPS
+	if ( getuid() == 0 && initgroups(pw->pw_name, changegid) )
+	{
+		perror("initgroups");
+		authexit(1);
+	}
+#else
+#if HAVE_SETGROUPS
+	if ( getuid() == 0 && setgroups(1, &changegid) )
+	{
+		perror("setgroups");
+		authexit(1);
+	}
+#endif
+#endif
+
+	if (setuid(changeuid))
+	{
+		perror("setuid");
+		authexit(1);
+	}
+}