libptytty/doc/libptytty.3.pod

=head1 NAME

libptytty - OS independent and secure pty/tty and utmp/wtmp/lastlog handling

=head1 SYNOPSIS

   -lptytty

=head1 DESCRIPTION

TODO

=head1 SECURITY CONSIDERATIONS

I<< B<It is of paramount importance that you at least read the following
paragraph!> >>

If you are a typical terminal-like program that just wants one or more
ptys, you should call the C<ptytty::init ()> method as the very first
thing in your program:

   int main (int argc, char *argv[])
   {
      // do nothing here
      ptytty::init ();

      // initialise, parse arguments, etc.
   }

This checks wether the program runs setuid or setgid. If yes then it will
fork a helper process and drop privileges.

Some programs need finer control over if and when this helper process
is started, and if and how to drop privileges. For those programs, the
methods C<ptytty::use_helper> and C<ptytty::drop_privileges> are more
useful.

=head1 THE ptytty CLASS

=head2 STATIC METHODS

=over 4

=item ptytty::init ()

The default way to initialise libptytty. Must be called imemdiately as
the first thing in the C<main> function, or earlier e.g. during static
construction time. The earlier, the better.

This method checks wether the program runs with setuid/setgid permissions
and, if yes, spawns a helper process for pty/tty management. IT then
drops the privileges completely, so the actual program runs without
setuid/setgid privileges.

=item ptytty::use_helper ()

TODO

=item ptytty::drop_privileges ()

Drops privileges completely, i.e. sets real, effective and saved user id
to the real user id. Also aborts if this cnanot be achieved. Useful to
make sure that the process doesn't run with special privileges.

=item bool success = ptytty::send_fd (int socket, int fd)

Utility method to send a file descriptor over a unix domain
socket. Returns true if successful, false otherwise. This method is only
exposed for your convinience and is not required for normal operation.

=item int fd = ptytty::recv_fd (int socket)

Utility method to receive a file descriptor over a unix domain
socket. Returns the fd if sucecssful and C<-1> otherwise. This method
is only exposed for your convinience and is not required for normal
operation.

=item ptytty *pty = ptytty::create ()

Creates new ptytty object. Creation does not yet do anything besides
allocating the structure.

A static method is used because the actual ptytty implementation can
differ at runtime, so you need a dynamic object creation facility.

=back

=head2 DYNAMIC/SESSION-RELATED DATA MEMBERS AND METHODS

=over 4

=item int pty_fd = pty->pty

=item int tty_fd = pty->tty

These members contain the pty and tty file descriptors, respectively. They
initially contain C<-1> until a successful to C<ptytty::get>.

=item bool success = pty->get ()

Tries to find, allocate and initialise a new pty/tty pair. Returns C<true>
when successful.

=item pty->login (int cmd_pid, bool login_shell, const char *hostname)

Creates an entry in the systems session database(s) (utmp, wtmp, lastlog).
C<cmd_pid> must be the pid of the process representing the session
(such as the login shell), C<login_shell> defines wether the session is
associated with a login, which influences wether wtmp and lastlog entries
are created, and C<hostname> should identify the "hostname" the user logs
in from, which often is the value of the C<DISPLAY> variable or tty line
in case of local logins.

Calling this method is optional. A session starts at the time of the login
call and extends until the ptytty object is destroyed.

=item pty->close_tty ()

Closes the tty. Useful after forking in the parent/pty process.

=item bool success = pty->make_controlling_tty ()

Tries to make the pty/tty pair the controlling terminal of the current
process. Useful after forking in the child/tty process.

=item pty->set_utf8_mode (bool on)

On systems supporting special UTF-8 line disciplines (e.g. Linux), tries
to enable it for the given pty. Can be called at any time to change the
mode.

=back

=head1 BUGS

You kiddin'?

=head1 AUTHORS

Emanuele Giaquinta L<< <e.giaquinta@glauco.it> >>, Marc Alexander Lehmann
L<< <rxvt-unicode@schmorp.de> >>.
Revision:	1.6
Committed:	Sun Jan 22 16:31:24 2006 UTC (20 years, 7 months ago) by root
Branch:	MAIN
Changes since 1.5:	+94 -6 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3	root	1.2	libptytty - OS independent and secure pty/tty and utmp/wtmp/lastlog handling
4	root	1.1
5			=head1 SYNOPSIS
6
7	root	1.2	-lptytty
8	root	1.1
9			=head1 DESCRIPTION
10
11	root	1.6	TODO
12
13	root	1.4	=head1 SECURITY CONSIDERATIONS
14	root	1.3
15	ayin	1.5	I<< B<It is of paramount importance that you at least read the following
16	root	1.4	paragraph!> >>
17
18			If you are a typical terminal-like program that just wants one or more
19			ptys, you should call the C<ptytty::init ()> method as the very first
20			thing in your program:
21
22			int main (int argc, char *argv[])
23			{
24			// do nothing here
25			ptytty::init ();
26
27			// initialise, parse arguments, etc.
28			}
29
30			This checks wether the program runs setuid or setgid. If yes then it will
31			fork a helper process and drop privileges.
32
33	root	1.6	Some programs need finer control over if and when this helper process
34			is started, and if and how to drop privileges. For those programs, the
35			methods C<ptytty::use_helper> and C<ptytty::drop_privileges> are more
36			useful.
37
38			=head1 THE ptytty CLASS
39
40			=head2 STATIC METHODS
41
42			=over 4
43
44			=item ptytty::init ()
45
46			The default way to initialise libptytty. Must be called imemdiately as
47			the first thing in the C<main> function, or earlier e.g. during static
48			construction time. The earlier, the better.
49
50			This method checks wether the program runs with setuid/setgid permissions
51			and, if yes, spawns a helper process for pty/tty management. IT then
52			drops the privileges completely, so the actual program runs without
53			setuid/setgid privileges.
54
55			=item ptytty::use_helper ()
56
57			TODO
58
59			=item ptytty::drop_privileges ()
60
61			Drops privileges completely, i.e. sets real, effective and saved user id
62			to the real user id. Also aborts if this cnanot be achieved. Useful to
63			make sure that the process doesn't run with special privileges.
64
65			=item bool success = ptytty::send_fd (int socket, int fd)
66
67			Utility method to send a file descriptor over a unix domain
68			socket. Returns true if successful, false otherwise. This method is only
69			exposed for your convinience and is not required for normal operation.
70
71			=item int fd = ptytty::recv_fd (int socket)
72
73			Utility method to receive a file descriptor over a unix domain
74			socket. Returns the fd if sucecssful and C<-1> otherwise. This method
75			is only exposed for your convinience and is not required for normal
76			operation.
77	root	1.4
78	root	1.6	=item ptytty *pty = ptytty::create ()
79	root	1.3
80	root	1.6	Creates new ptytty object. Creation does not yet do anything besides
81			allocating the structure.
82
83			A static method is used because the actual ptytty implementation can
84			differ at runtime, so you need a dynamic object creation facility.
85
86			=back
87
88			=head2 DYNAMIC/SESSION-RELATED DATA MEMBERS AND METHODS
89	root	1.1
90			=over 4
91
92	root	1.6	=item int pty_fd = pty->pty
93
94			=item int tty_fd = pty->tty
95
96			These members contain the pty and tty file descriptors, respectively. They
97			initially contain C<-1> until a successful to C<ptytty::get>.
98
99			=item bool success = pty->get ()
100
101			Tries to find, allocate and initialise a new pty/tty pair. Returns C<true>
102			when successful.
103
104			=item pty->login (int cmd_pid, bool login_shell, const char *hostname)
105
106			Creates an entry in the systems session database(s) (utmp, wtmp, lastlog).
107			C<cmd_pid> must be the pid of the process representing the session
108			(such as the login shell), C<login_shell> defines wether the session is
109			associated with a login, which influences wether wtmp and lastlog entries
110			are created, and C<hostname> should identify the "hostname" the user logs
111			in from, which often is the value of the C<DISPLAY> variable or tty line
112			in case of local logins.
113
114			Calling this method is optional. A session starts at the time of the login
115			call and extends until the ptytty object is destroyed.
116
117			=item pty->close_tty ()
118
119			Closes the tty. Useful after forking in the parent/pty process.
120
121			=item bool success = pty->make_controlling_tty ()
122
123			Tries to make the pty/tty pair the controlling terminal of the current
124			process. Useful after forking in the child/tty process.
125
126			=item pty->set_utf8_mode (bool on)
127	root	1.1
128	root	1.6	On systems supporting special UTF-8 line disciplines (e.g. Linux), tries
129			to enable it for the given pty. Can be called at any time to change the
130			mode.
131	root	1.1
132			=back
133
134			=head1 BUGS
135
136			You kiddin'?
137
138			=head1 AUTHORS
139
140			Emanuele Giaquinta L<< <e.giaquinta@glauco.it> >>, Marc Alexander Lehmann
141			L<< <rxvt-unicode@schmorp.de> >>.