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Revision 1.2 by root, Sat Jan 21 22:54:10 2006 UTC vs.
Revision 1.3 by root, Mon Jan 23 12:27:47 2006 UTC

… …
4 4
5SYNOPSIS 5SYNOPSIS
6 -lptytty 6 -lptytty
7 7
8DESCRIPTION 8DESCRIPTION
9THE ptytty CLASS 9 TODO
10 new ptytty 10
11 ... 11SECURITY CONSIDERATIONS
12 *It is of paramount importance that you at least read the following
13 paragraph!*
14
15 If you are a typical terminal-like program that just wants one or more
16 ptys, you should call the "ptytty::init ()" method (C: "ptytty_init ()"
17 function) as the very first thing in your program:
18
19 int main (int argc, char *argv[])
20 {
21 // do nothing here
22 ptytty::init ();
23 // in C: ptytty_init ();
24
25 // initialise, parse arguments, etc.
26 }
27
28 This checks wether the program runs setuid or setgid. If yes then it
29 will fork a helper process and drop privileges.
30
31 Some programs need finer control over if and when this helper process is
32 started, and if and how to drop privileges. For those programs, the
33 methods "ptytty::use_helper" and "ptytty::drop_privileges" are more
34 useful.
35
36C++ INTERFACE: THE ptytty CLASS
37 STATIC METHODS
38 ptytty::init ()
39 The default way to initialise libptytty. Must be called imemdiately
40 as the first thing in the "main" function, or earlier e.g. during
41 static construction time. The earlier, the better.
42
43 This method checks wether the program runs with setuid/setgid
44 permissions and, if yes, spawns a helper process for pty/tty
45 management. IT then drops the privileges completely, so the actual
46 program runs without setuid/setgid privileges.
47
48 ptytty::use_helper ()
49 Tries to start a helper process that retains privileges even when
50 the calling process does not. This is usually called from
51 "ptytty::init" when it detects that the program is running setuid or
52 setgid, but can be called manually if it is inconvinient to drop
53 privileges at startup, or when you are not running setuid/setgid but
54 want to drop privileges (e.g. when running as a root-started
55 daemon).
56
57 This method will try not to start more than one helper process. The
58 same helper process cna usually be used form the process starting it
59 an all its fork'ed (not exec'ed) children
60
61 ptytty::drop_privileges ()
62 Drops privileges completely, i.e. sets real, effective and saved
63 user id to the real user id. Also aborts if this cnanot be achieved.
64 Useful to make sure that the process doesn't run with special
65 privileges.
66
67 bool success = ptytty::send_fd (int socket, int fd)
68 Utility method to send a file descriptor over a unix domain socket.
69 Returns true if successful, false otherwise. This method is only
70 exposed for your convinience and is not required for normal
71 operation.
72
73 int fd = ptytty::recv_fd (int socket)
74 Utility method to receive a file descriptor over a unix domain
75 socket. Returns the fd if sucecssful and -1 otherwise. This method
76 is only exposed for your convinience and is not required for normal
77 operation.
78
79 ptytty *pty = ptytty::create ()
80 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 DYNAMIC/SESSION-RELATED DATA MEMBERS AND METHODS
87 int pty_fd = pty->pty
88 int tty_fd = pty->tty
89 These members contain the pty and tty file descriptors,
90 respectively. They initially contain -1 until a successful to
91 "ptytty::get".
92
93 bool success = pty->get ()
94 Tries to find, allocate and initialise a new pty/tty pair. Returns
95 "true" when successful.
96
97 pty->login (int cmd_pid, bool login_shell, const char *hostname)
98 Creates an entry in the systems session database(s) (utmp, wtmp,
99 lastlog). "cmd_pid" must be the pid of the process representing the
100 session (such as the login shell), "login_shell" defines wether the
101 session is associated with a login, which influences wether wtmp and
102 lastlog entries are created, and "hostname" should identify the
103 "hostname" the user logs in from, which often is the value of the
104 "DISPLAY" variable or tty line in case of local logins.
105
106 Calling this method is optional. A session starts at the time of the
107 login call and extends until the ptytty object is destroyed.
108
109 pty->close_tty ()
110 Closes the tty. Useful after forking in the parent/pty process.
111
112 bool success = pty->make_controlling_tty ()
113 Tries to make the pty/tty pair the controlling terminal of the
114 current process. Useful after forking in the child/tty process.
115
116 pty->set_utf8_mode (bool on)
117 On systems supporting special UTF-8 line disciplines (e.g. Linux),
118 tries to enable it for the given pty. Can be called at any time to
119 change the mode.
120
121C INTERFACE: THE ptytty FAMILY OF FUNCTIONS
122 ptytty_init ()
123 See "ptytty::init ()".
124
125 PTYTTY ptytty_create ()
126 Creates a new opaque PTYTTY object and returns it. Do not try to
127 access it in any way excecp by testing it for truthness (e.g. "if
128 (pty) ...."). See "ptytty::create ()".
129
130 int ptytty_pty (PTYTTY ptytty)
131 Return the pty file descriptor. See "pty->pty".
132
133 int ptytty_tty (PTYTTY ptytty)
134 Return the tty file descriptor. See "pty->tty".
135
136 void ptytty_delete (PTYTTY ptytty)
137 Destroys the PTYTTY object, freeing the pty/tty pair and cleaning up
138 the utmp/wtmp/lastlog databases, if initialised/used. Same as
139 "delete pty" in C++.
140
141 int ptytty_get (PTYTTY ptytty)
142 See "pty->get", returns 0 in case of an error, non-zero otherwise.
143
144 void ptytty_login (PTYTTY ptytty, int cmd_pid, bool login_shell, const
145 char *hostname)
146 See "pty->login".
147
148 void ptytty_close_tty (PTYTTY ptytty)
149 See "pty->close_tty".
150
151 int ptytty_make_controlling_tty (PTYTTY ptytty)
152 See "pty->make_controlling_tty".
153
154 void ptytty_set_utf8_mode (PTYTTY ptytty, int on)
155 See "pty->set_utf8_mode".
156
157 void ptytty_drop_privileges ()
158 See "ptytty::drop_privileges".
159
160 void ptytty_use_helper ()
161 See "ptytty::use_helper".
12 162
13BUGS 163BUGS
14 You kiddin'? 164 You kiddin'?
15 165
16AUTHORS 166AUTHORS

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