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# User Rev Content
1 root 1.1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
2     <html xmlns="http://www.w3.org/1999/xhtml">
3     <head>
4     <title>libptytty - OS independent and secure pty/tty and utmp/wtmp/lastlog handling</title>
5     <link rev="made" href="mailto:perl-binary@plan9.de" />
6     </head>
7    
8     <body style="background-color: white">
9    
10     <p><a name="__index__"></a></p>
11     <!-- INDEX BEGIN -->
12    
13     <ul>
14    
15     <li><a href="#name">NAME</a></li>
16     <li><a href="#synopsis">SYNOPSIS</a></li>
17     <li><a href="#description">DESCRIPTION</a></li>
18 root 1.2 <li><a href="#security_considerations">SECURITY CONSIDERATIONS</a></li>
19     <li><a href="#c___interface__the_ptytty_class">C++ INTERFACE: THE ptytty CLASS</a></li>
20     <ul>
21    
22     <li><a href="#static_methods">STATIC METHODS</a></li>
23     <li><a href="#dynamic_sessionrelated_data_members_and_methods">DYNAMIC/SESSION-RELATED DATA MEMBERS AND METHODS</a></li>
24     </ul>
25    
26     <li><a href="#c_interface__the_ptytty_family_of_functions">C INTERFACE: THE ptytty FAMILY OF FUNCTIONS</a></li>
27 root 1.1 <li><a href="#bugs">BUGS</a></li>
28     <li><a href="#authors">AUTHORS</a></li>
29     </ul>
30     <!-- INDEX END -->
31    
32     <hr />
33     <p>
34     </p>
35     <h1><a name="name">NAME</a></h1>
36     <p>libptytty - OS independent and secure pty/tty and utmp/wtmp/lastlog handling</p>
37     <p>
38     </p>
39     <hr />
40     <h1><a name="synopsis">SYNOPSIS</a></h1>
41     <pre>
42     -lptytty</pre>
43     <p>
44     </p>
45     <hr />
46     <h1><a name="description">DESCRIPTION</a></h1>
47 root 1.2 <p>TODO</p>
48     <p>
49     </p>
50     <hr />
51     <h1><a name="security_considerations">SECURITY CONSIDERATIONS</a></h1>
52     <p><em><strong>It is of paramount importance that you at least read the following
53     paragraph!</strong> </em>&gt;</p>
54     <p>If you are a typical terminal-like program that just wants one or more
55     ptys, you should call the <a href="#item_init"><code>ptytty::init ()</code></a> method (C: <a href="#item_ptytty_init"><code>ptytty_init ()</code></a>
56     function) as the very first thing in your program:</p>
57     <pre>
58     int main (int argc, char *argv[])
59     {
60     // do nothing here
61     ptytty::init ();
62     // in C: ptytty_init ();</pre>
63     <pre>
64     // initialise, parse arguments, etc.
65     }</pre>
66     <p>This checks wether the program runs setuid or setgid. If yes then it will
67     fork a helper process and drop privileges.</p>
68     <p>Some programs need finer control over if and when this helper process
69     is started, and if and how to drop privileges. For those programs, the
70     methods <code>ptytty::use_helper</code> and <code>ptytty::drop_privileges</code> are more
71     useful.</p>
72 root 1.1 <p>
73     </p>
74     <hr />
75 root 1.2 <h1><a name="c___interface__the_ptytty_class">C++ INTERFACE: THE ptytty CLASS</a></h1>
76     <p>
77     </p>
78     <h2><a name="static_methods">STATIC METHODS</a></h2>
79 root 1.1 <dl>
80 root 1.2 <dt><strong><a name="item_init">ptytty::init ()</a></strong><br />
81     </dt>
82     <dd>
83     The default way to initialise libptytty. Must be called imemdiately as
84     the first thing in the <code>main</code> function, or earlier e.g. during static
85     construction time. The earlier, the better.
86     </dd>
87     <dd>
88     <p>This method checks wether the program runs with setuid/setgid permissions
89     and, if yes, spawns a helper process for pty/tty management. IT then
90     drops the privileges completely, so the actual program runs without
91     setuid/setgid privileges.</p>
92     </dd>
93     <p></p>
94     <dt><strong><a name="item_use_helper">ptytty::use_helper ()</a></strong><br />
95     </dt>
96     <dd>
97     Tries to start a helper process that retains privileges even when the
98     calling process does not. This is usually called from <code>ptytty::init</code> when
99     it detects that the program is running setuid or setgid, but can be called
100     manually if it is inconvinient to drop privileges at startup, or when
101     you are not running setuid/setgid but want to drop privileges (e.g. when
102     running as a root-started daemon).
103     </dd>
104     <dd>
105     <p>This method will try not to start more than one helper process. The same
106     helper process cna usually be used form the process starting it an all its
107     fork'ed (not exec'ed) children</p>
108     </dd>
109     <p></p>
110     <dt><strong><a name="item_drop_privileges">ptytty::drop_privileges ()</a></strong><br />
111     </dt>
112     <dd>
113     Drops privileges completely, i.e. sets real, effective and saved user id
114     to the real user id. Also aborts if this cnanot be achieved. Useful to
115     make sure that the process doesn't run with special privileges.
116     </dd>
117     <p></p>
118     <dt><strong><a name="item_send_fd">bool success = ptytty::send_fd (int socket, int fd)</a></strong><br />
119     </dt>
120     <dd>
121     Utility method to send a file descriptor over a unix domain
122     socket. Returns true if successful, false otherwise. This method is only
123     exposed for your convinience and is not required for normal operation.
124     </dd>
125     <p></p>
126     <dt><strong><a name="item_recv_fd">int fd = ptytty::recv_fd (int socket)</a></strong><br />
127     </dt>
128     <dd>
129     Utility method to receive a file descriptor over a unix domain
130     socket. Returns the fd if sucecssful and <code>-1</code> otherwise. This method
131     is only exposed for your convinience and is not required for normal
132     operation.
133     </dd>
134     <p></p>
135     <dt><strong><a name="item_create">ptytty *pty = ptytty::create ()</a></strong><br />
136 root 1.1 </dt>
137     <dd>
138 root 1.2 Creates new ptytty object. Creation does not yet do anything besides
139     allocating the structure.
140     </dd>
141     <dd>
142     <p>A static method is used because the actual ptytty implementation can
143     differ at runtime, so you need a dynamic object creation facility.</p>
144     </dd>
145     <p></p></dl>
146     <p>
147     </p>
148     <h2><a name="dynamic_sessionrelated_data_members_and_methods">DYNAMIC/SESSION-RELATED DATA MEMBERS AND METHODS</a></h2>
149     <dl>
150     <dt><strong><a name="item_pty">int pty_fd = pty-&gt;pty</a></strong><br />
151     </dt>
152     <dt><strong><a name="item_tty">int tty_fd = pty-&gt;tty</a></strong><br />
153     </dt>
154     <dd>
155     These members contain the pty and tty file descriptors, respectively. They
156     initially contain <code>-1</code> until a successful to <code>ptytty::get</code>.
157     </dd>
158     <p></p>
159     <dt><strong><a name="item_get">bool success = pty-&gt;get ()</a></strong><br />
160     </dt>
161     <dd>
162     Tries to find, allocate and initialise a new pty/tty pair. Returns <code>true</code>
163     when successful.
164     </dd>
165     <p></p>
166     <dt><strong><a name="item_login">pty-&gt;login (int cmd_pid, bool login_shell, const char *hostname)</a></strong><br />
167     </dt>
168     <dd>
169     Creates an entry in the systems session <code>database(s)</code> (utmp, wtmp, lastlog).
170     <code>cmd_pid</code> must be the pid of the process representing the session
171     (such as the login shell), <code>login_shell</code> defines wether the session is
172     associated with a login, which influences wether wtmp and lastlog entries
173     are created, and <code>hostname</code> should identify the ``hostname'' the user logs
174     in from, which often is the value of the <code>DISPLAY</code> variable or tty line
175     in case of local logins.
176     </dd>
177     <dd>
178     <p>Calling this method is optional. A session starts at the time of the login
179     call and extends until the ptytty object is destroyed.</p>
180     </dd>
181     <p></p>
182     <dt><strong><a name="item_close_tty">pty-&gt;close_tty ()</a></strong><br />
183     </dt>
184     <dd>
185     Closes the tty. Useful after forking in the parent/pty process.
186     </dd>
187     <p></p>
188     <dt><strong><a name="item_make_controlling_tty">bool success = pty-&gt;make_controlling_tty ()</a></strong><br />
189     </dt>
190     <dd>
191     Tries to make the pty/tty pair the controlling terminal of the current
192     process. Useful after forking in the child/tty process.
193     </dd>
194     <p></p>
195     <dt><strong><a name="item_set_utf8_mode">pty-&gt;set_utf8_mode (bool on)</a></strong><br />
196     </dt>
197     <dd>
198     On systems supporting special UTF-8 line disciplines (e.g. Linux), tries
199     to enable it for the given pty. Can be called at any time to change the
200     mode.
201     </dd>
202     <p></p></dl>
203     <p>
204     </p>
205     <hr />
206     <h1><a name="c_interface__the_ptytty_family_of_functions">C INTERFACE: THE ptytty FAMILY OF FUNCTIONS</a></h1>
207     <dl>
208     <dt><strong><a name="item_ptytty_init">ptytty_init ()</a></strong><br />
209     </dt>
210     <dd>
211     See <a href="#item_init"><code>ptytty::init ()</code></a>.
212    
213     </dd>
214     <dd>
215     <pre>
216    
217     =item PTYTTY ptytty_create ()</pre>
218     </dd>
219     <dd>
220     <p>Creates a new opaque PTYTTY object and returns it. Do not try to access it
221     in any way excecp by testing it for truthness (e.g. <code>if (pty) ....</code>). See
222     <a href="#item_create"><code>ptytty::create ()</code></a>.</p>
223     </dd>
224     <p></p>
225     <dt><strong><a name="item_ptytty_pty">int ptytty_pty (PTYTTY ptytty)</a></strong><br />
226     </dt>
227     <dd>
228     Return the pty file descriptor. See <a href="#item_pty"><code>pty-&gt;pty</code></a>.
229    
230     </dd>
231     <dd>
232     <pre>
233    
234     =item int ptytty_tty (PTYTTY ptytty)</pre>
235     </dd>
236     <dd>
237     <p>Return the tty file descriptor. See <a href="#item_tty"><code>pty-&gt;tty</code></a>.
238     </p>
239     </dd>
240     <dd>
241     <pre>
242    
243     =item void ptytty_delete (PTYTTY ptytty)</pre>
244     </dd>
245     <dd>
246     <p>Destroys the PTYTTY object, freeing the pty/tty pair and cleaning up the
247     utmp/wtmp/lastlog databases, if initialised/used. Same as <code>delete pty</code> in
248     C++.</p>
249     </dd>
250     <p></p>
251     <dt><strong><a name="item_ptytty_get">int ptytty_get (PTYTTY ptytty)</a></strong><br />
252     </dt>
253     <dd>
254     See <a href="#item_get"><code>pty-&gt;get</code></a>, returns 0 in case of an error, non-zero otherwise.
255     </dd>
256     <p></p>
257     <dt><strong><a name="item_ptytty_login">void ptytty_login (PTYTTY ptytty, int cmd_pid, bool login_shell, const char *hostname)</a></strong><br />
258     </dt>
259     <dd>
260     See <a href="#item_login"><code>pty-&gt;login</code></a>.
261     </dd>
262     <p></p>
263     <dt><strong><a name="item_ptytty_close_tty">void ptytty_close_tty (PTYTTY ptytty)</a></strong><br />
264     </dt>
265     <dd>
266     See <a href="#item_close_tty"><code>pty-&gt;close_tty</code></a>.
267    
268     </dd>
269     <dd>
270     <pre>
271    
272     =item int ptytty_make_controlling_tty (PTYTTY ptytty)</pre>
273     </dd>
274     <dd>
275     <p>See <a href="#item_make_controlling_tty"><code>pty-&gt;make_controlling_tty</code></a>.
276     </p>
277     </dd>
278     <dd>
279     <pre>
280    
281     =item void ptytty_set_utf8_mode (PTYTTY ptytty, int on)</pre>
282     </dd>
283     <dd>
284     <p>See <a href="#item_set_utf8_mode"><code>pty-&gt;set_utf8_mode</code></a>.</p>
285     </dd>
286     <p></p>
287     <dt><strong><a name="item_ptytty_drop_privileges">void ptytty_drop_privileges ()</a></strong><br />
288     </dt>
289     <dd>
290     See <code>ptytty::drop_privileges</code>.
291    
292     </dd>
293     <dd>
294     <pre>
295    
296     =item void ptytty_use_helper ()</pre>
297     </dd>
298     <dd>
299     <p>See <code>ptytty::use_helper</code>.
300    
301     </p>
302 root 1.1 </dd>
303     <p></p></dl>
304     <p>
305     </p>
306     <hr />
307     <h1><a name="bugs">BUGS</a></h1>
308 root 1.2 <p>You kiddin'?
309    
310     </p>
311 root 1.1 <p>
312     </p>
313     <hr />
314     <h1><a name="authors">AUTHORS</a></h1>
315     <p>Emanuele Giaquinta <em><a href="mailto:<e.giaquinta@glauco.it"><e.giaquinta@glauco.it</a></em>&gt;, Marc Alexander Lehmann
316 root 1.2 <em><a href="mailto:<rxvt-unicode@schmorp.de"><rxvt-unicode@schmorp.de</a></em>&gt;.
317     </p>
318 root 1.1
319     </body>
320    
321     </html>