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getty: don't accept ancient '#' and '@' as backspace/kill line,

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it only confuses people.
(Alexander Griesser <alexander.griesser@lkh-vil.or.at> (LKH Villach))
various other cleanups.

function                                             old     new   delta
getty_main                                          2526    2546     +20
static.baud_index                                      4       -      -4
parse_speeds                                          91       -     -91
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 1/0 up/down: 20/-95)            Total: -75 bytes
   text    data     bss     dec     hex filename
 773152    1086    9008  783246   bf38e busybox_old
 773081    1086    9008  783175   bf347 busybox_unstripped
This commit is contained in:
Denis Vlasenko 2007-12-04 09:48:40 +00:00
parent 7221c8c22d
commit d0bbbdcd6e
2 changed files with 640 additions and 228 deletions
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docs/ctty.htm Normal file
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@ -0,0 +1,474 @@
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<html><head>
<!-- saved from http://www.win.tue.nl/~aeb/linux/lk/lk-10.html -->
<meta name="GENERATOR" content="SGML-Tools 1.0.9"><title>The Linux kernel: Processes</title>
</head>
<body>
<hr>
<h2><a name="s10">10. Processes</a></h2>
<p>Before looking at the Linux implementation, first a general Unix
description of threads, processes, process groups and sessions.
</p><p>A session contains a number of process groups, and a process group
contains a number of processes, and a process contains a number
of threads.
</p><p>A session can have a controlling tty.
At most one process group in a session can be a foreground process group.
An interrupt character typed on a tty ("Teletype", i.e., terminal)
causes a signal to be sent to all members of the foreground process group
in the session (if any) that has that tty as controlling tty.
</p><p>All these objects have numbers, and we have thread IDs, process IDs,
process group IDs and session IDs.
</p><p>
</p><h2><a name="ss10.1">10.1 Processes</a>
</h2>
<p>
</p><h3>Creation</h3>
<p>A new process is traditionally started using the <code>fork()</code>
system call:
</p><blockquote>
<pre>pid_t p;
p = fork();
if (p == (pid_t) -1)
/* ERROR */
else if (p == 0)
/* CHILD */
else
/* PARENT */
</pre>
</blockquote>
<p>This creates a child as a duplicate of its parent.
Parent and child are identical in almost all respects.
In the code they are distinguished by the fact that the parent
learns the process ID of its child, while <code>fork()</code>
returns 0 in the child. (It can find the process ID of its
parent using the <code>getppid()</code> system call.)
</p><p>
</p><h3>Termination</h3>
<p>Normal termination is when the process does
</p><blockquote>
<pre>exit(n);
</pre>
</blockquote>
or
<blockquote>
<pre>return n;
</pre>
</blockquote>
from its <code>main()</code> procedure. It returns the single byte <code>n</code>
to its parent.
<p>Abnormal termination is usually caused by a signal.
</p><p>
</p><h3>Collecting the exit code. Zombies</h3>
<p>The parent does
</p><blockquote>
<pre>pid_t p;
int status;
p = wait(&amp;status);
</pre>
</blockquote>
and collects two bytes:
<p>
<figure>
<eps file="absent">
<img src="ctty_files/exit_status.png">
</eps>
</figure></p><p>A process that has terminated but has not yet been waited for
is a <i>zombie</i>. It need only store these two bytes:
exit code and reason for termination.
</p><p>On the other hand, if the parent dies first, <code>init</code> (process 1)
inherits the child and becomes its parent.
</p><p>
</p><h3>Signals</h3>
<p>
</p><h3>Stopping</h3>
<p>Some signals cause a process to stop:
<code>SIGSTOP</code> (stop!),
<code>SIGTSTP</code> (stop from tty: probably ^Z was typed),
<code>SIGTTIN</code> (tty input asked by background process),
<code>SIGTTOU</code> (tty output sent by background process, and this was
disallowed by <code>stty tostop</code>).
</p><p>Apart from ^Z there also is ^Y. The former stops the process
when it is typed, the latter stops it when it is read.
</p><p>Signals generated by typing the corresponding character on some tty
are sent to all processes that are in the foreground process group
of the session that has that tty as controlling tty. (Details below.)
</p><p>If a process is being traced, every signal will stop it.
</p><p>
</p><h3>Continuing</h3>
<p><code>SIGCONT</code>: continue a stopped process.
</p><p>
</p><h3>Terminating</h3>
<p><code>SIGKILL</code> (die! now!),
<code>SIGTERM</code> (please, go away),
<code>SIGHUP</code> (modem hangup),
<code>SIGINT</code> (^C),
<code>SIGQUIT</code> (^\), etc.
Many signals have as default action to kill the target.
(Sometimes with an additional core dump, when such is
allowed by rlimit.)
The signals <code>SIGCHLD</code> and <code>SIGWINCH</code>
are ignored by default.
All except <code>SIGKILL</code> and <code>SIGSTOP</code> can be
caught or ignored or blocked.
For details, see <code>signal(7)</code>.
</p><p>
</p><h2><a name="ss10.2">10.2 Process groups</a>
</h2>
<p>Every process is member of a unique <i>process group</i>,
identified by its <i>process group ID</i>.
(When the process is created, it becomes a member of the process group
of its parent.)
By convention, the process group ID of a process group
equals the process ID of the first member of the process group,
called the <i>process group leader</i>.
A process finds the ID of its process group using the system call
<code>getpgrp()</code>, or, equivalently, <code>getpgid(0)</code>.
One finds the process group ID of process <code>p</code> using
<code>getpgid(p)</code>.
</p><p>One may use the command <code>ps j</code> to see PPID (parent process ID),
PID (process ID), PGID (process group ID) and SID (session ID)
of processes. With a shell that does not know about job control,
like <code>ash</code>, each of its children will be in the same session
and have the same process group as the shell. With a shell that knows
about job control, like <code>bash</code>, the processes of one pipeline. like
</p><blockquote>
<pre>% cat paper | ideal | pic | tbl | eqn | ditroff &gt; out
</pre>
</blockquote>
form a single process group.
<p>
</p><h3>Creation</h3>
<p>A process <code>pid</code> is put into the process group <code>pgid</code> by
</p><blockquote>
<pre>setpgid(pid, pgid);
</pre>
</blockquote>
If <code>pgid == pid</code> or <code>pgid == 0</code> then this creates
a new process group with process group leader <code>pid</code>.
Otherwise, this puts <code>pid</code> into the already existing
process group <code>pgid</code>.
A zero <code>pid</code> refers to the current process.
The call <code>setpgrp()</code> is equivalent to <code>setpgid(0,0)</code>.
<p>
</p><h3>Restrictions on setpgid()</h3>
<p>The calling process must be <code>pid</code> itself, or its parent,
and the parent can only do this before <code>pid</code> has done
<code>exec()</code>, and only when both belong to the same session.
It is an error if process <code>pid</code> is a session leader
(and this call would change its <code>pgid</code>).
</p><p>
</p><h3>Typical sequence</h3>
<p>
</p><blockquote>
<pre>p = fork();
if (p == (pid_t) -1) {
/* ERROR */
} else if (p == 0) { /* CHILD */
setpgid(0, pgid);
...
} else { /* PARENT */
setpgid(p, pgid);
...
}
</pre>
</blockquote>
This ensures that regardless of whether parent or child is scheduled
first, the process group setting is as expected by both.
<p>
</p><h3>Signalling and waiting</h3>
<p>One can signal all members of a process group:
</p><blockquote>
<pre>killpg(pgrp, sig);
</pre>
</blockquote>
<p>One can wait for children in ones own process group:
</p><blockquote>
<pre>waitpid(0, &amp;status, ...);
</pre>
</blockquote>
or in a specified process group:
<blockquote>
<pre>waitpid(-pgrp, &amp;status, ...);
</pre>
</blockquote>
<p>
</p><h3>Foreground process group</h3>
<p>Among the process groups in a session at most one can be
the <i>foreground process group</i> of that session.
The tty input and tty signals (signals generated by ^C, ^Z, etc.)
go to processes in this foreground process group.
</p><p>A process can determine the foreground process group in its session
using <code>tcgetpgrp(fd)</code>, where <code>fd</code> refers to its
controlling tty. If there is none, this returns a random value
larger than 1 that is not a process group ID.
</p><p>A process can set the foreground process group in its session
using <code>tcsetpgrp(fd,pgrp)</code>, where <code>fd</code> refers to its
controlling tty, and <code>pgrp</code> is a process group in the
its session, and this session still is associated to the controlling
tty of the calling process.
</p><p>How does one get <code>fd</code>? By definition, <code>/dev/tty</code>
refers to the controlling tty, entirely independent of redirects
of standard input and output. (There is also the function
<code>ctermid()</code> to get the name of the controlling terminal.
On a POSIX standard system it will return <code>/dev/tty</code>.)
Opening the name of the
controlling tty gives a file descriptor <code>fd</code>.
</p><p>
</p><h3>Background process groups</h3>
<p>All process groups in a session that are not foreground
process group are <i>background process groups</i>.
Since the user at the keyboard is interacting with foreground
processes, background processes should stay away from it.
When a background process reads from the terminal it gets
a SIGTTIN signal. Normally, that will stop it, the job control shell
notices and tells the user, who can say <code>fg</code> to continue
this background process as a foreground process, and then this
process can read from the terminal. But if the background process
ignores or blocks the SIGTTIN signal, or if its process group
is orphaned (see below), then the read() returns an EIO error,
and no signal is sent. (Indeed, the idea is to tell the process
that reading from the terminal is not allowed right now.
If it wouldn't see the signal, then it will see the error return.)
</p><p>When a background process writes to the terminal, it may get
a SIGTTOU signal. May: namely, when the flag that this must happen
is set (it is off by default). One can set the flag by
</p><blockquote>
<pre>% stty tostop
</pre>
</blockquote>
and clear it again by
<blockquote>
<pre>% stty -tostop
</pre>
</blockquote>
and inspect it by
<blockquote>
<pre>% stty -a
</pre>
</blockquote>
Again, if TOSTOP is set but the background process ignores or blocks
the SIGTTOU signal, or if its process group is orphaned (see below),
then the write() returns an EIO error, and no signal is sent.
<p>
</p><h3>Orphaned process groups</h3>
<p>The process group leader is the first member of the process group.
It may terminate before the others, and then the process group is
without leader.
</p><p>A process group is called <i>orphaned</i> when <i>the
parent of every member is either in the process group
or outside the session</i>.
In particular, the process group of the session leader
is always orphaned.
</p><p>If termination of a process causes a process group to become
orphaned, and some member is stopped, then all are sent first SIGHUP
and then SIGCONT.
</p><p>The idea is that perhaps the parent of the process group leader
is a job control shell. (In the same session but a different
process group.) As long as this parent is alive, it can
handle the stopping and starting of members in the process group.
When it dies, there may be nobody to continue stopped processes.
Therefore, these stopped processes are sent SIGHUP, so that they
die unless they catch or ignore it, and then SIGCONT to continue them.
</p><p>Note that the process group of the session leader is already
orphaned, so no signals are sent when the session leader dies.
</p><p>Note also that a process group can become orphaned in two ways
by termination of a process: either it was a parent and not itself
in the process group, or it was the last element of the process group
with a parent outside but in the same session.
Furthermore, that a process group can become orphaned
other than by termination of a process, namely when some
member is moved to a different process group.
</p><p>
</p><h2><a name="ss10.3">10.3 Sessions</a>
</h2>
<p>Every process group is in a unique <i>session</i>.
(When the process is created, it becomes a member of the session
of its parent.)
By convention, the session ID of a session
equals the process ID of the first member of the session,
called the <i>session leader</i>.
A process finds the ID of its session using the system call
<code>getsid()</code>.
</p><p>Every session may have a <i>controlling tty</i>,
that then also is called the controlling tty of each of
its member processes.
A file descriptor for the controlling tty is obtained by
opening <code>/dev/tty</code>. (And when that fails, there was no
controlling tty.) Given a file descriptor for the controlling tty,
one may obtain the SID using <code>tcgetsid(fd)</code>.
</p><p>A session is often set up by a login process. The terminal
on which one is logged in then becomes the controlling tty
of the session. All processes that are descendants of the
login process will in general be members of the session.
</p><p>
</p><h3>Creation</h3>
<p>A new session is created by
</p><blockquote>
<pre>pid = setsid();
</pre>
</blockquote>
This is allowed only when the current process is not a process group leader.
In order to be sure of that we fork first:
<blockquote>
<pre>p = fork();
if (p) exit(0);
pid = setsid();
</pre>
</blockquote>
The result is that the current process (with process ID <code>pid</code>)
becomes session leader of a new session with session ID <code>pid</code>.
Moreover, it becomes process group leader of a new process group.
Both session and process group contain only the single process <code>pid</code>.
Furthermore, this process has no controlling tty.
<p>The restriction that the current process must not be a process group leader
is needed: otherwise its PID serves as PGID of some existing process group
and cannot be used as the PGID of a new process group.
</p><p>
</p><h3>Getting a controlling tty</h3>
<p>How does one get a controlling terminal? Nobody knows,
this is a great mystery.
</p><p>The System V approach is that the first tty opened by the process
becomes its controlling tty.
</p><p>The BSD approach is that one has to explicitly call
</p><blockquote>
<pre>ioctl(fd, TIOCSCTTY, ...);
</pre>
</blockquote>
to get a controlling tty.
<p>Linux tries to be compatible with both, as always, and this
results in a very obscure complex of conditions. Roughly:
</p><p>The <code>TIOCSCTTY</code> ioctl will give us a controlling tty,
provided that (i) the current process is a session leader,
and (ii) it does not yet have a controlling tty, and
(iii) maybe the tty should not already control some other session;
if it does it is an error if we aren't root, or we steal the tty
if we are all-powerful.
</p><p>Opening some terminal will give us a controlling tty,
provided that (i) the current process is a session leader, and
(ii) it does not yet have a controlling tty, and
(iii) the tty does not already control some other session, and
(iv) the open did not have the <code>O_NOCTTY</code> flag, and
(v) the tty is not the foreground VT, and
(vi) the tty is not the console, and
(vii) maybe the tty should not be master or slave pty.
</p><p>
</p><h3>Getting rid of a controlling tty</h3>
<p>If a process wants to continue as a daemon, it must detach itself
from its controlling tty. Above we saw that <code>setsid()</code>
will remove the controlling tty. Also the ioctl TIOCNOTTY does this.
Moreover, in order not to get a controlling tty again as soon as it
opens a tty, the process has to fork once more, to assure that it
is not a session leader. Typical code fragment:
</p><p>
</p><pre> if ((fork()) != 0)
exit(0);
setsid();
if ((fork()) != 0)
exit(0);
</pre>
<p>See also <code>daemon(3)</code>.
</p><p>
</p><h3>Disconnect</h3>
<p>If the terminal goes away by modem hangup, and the line was not local,
then a SIGHUP is sent to the session leader.
Any further reads from the gone terminal return EOF.
(Or possibly -1 with <code>errno</code> set to EIO.)
</p><p>If the terminal is the slave side of a pseudotty, and the master side
is closed (for the last time), then a SIGHUP is sent to the foreground
process group of the slave side.
</p><p>When the session leader dies, a SIGHUP is sent to all processes
in the foreground process group. Moreover, the terminal stops being
the controlling terminal of this session (so that it can become
the controlling terminal of another session).
</p><p>Thus, if the terminal goes away and the session leader is
a job control shell, then it can handle things for its descendants,
e.g. by sending them again a SIGHUP.
If on the other hand the session leader is an innocent process
that does not catch SIGHUP, it will die, and all foreground processes
get a SIGHUP.
</p><p>
</p><h2><a name="ss10.4">10.4 Threads</a>
</h2>
<p>A process can have several threads. New threads (with the same PID
as the parent thread) are started using the <code>clone</code> system
call using the <code>CLONE_THREAD</code> flag. Threads are distinguished
by a <i>thread ID</i> (TID). An ordinary process has a single thread
with TID equal to PID. The system call <code>gettid()</code> returns the
TID. The system call <code>tkill()</code> sends a signal to a single thread.
</p><p>Example: a process with two threads. Both only print PID and TID and exit.
(Linux 2.4.19 or later.)
</p><pre>% cat &lt;&lt; EOF &gt; gettid-demo.c
#include &lt;unistd.h&gt;
#include &lt;sys/types.h&gt;
#define CLONE_SIGHAND 0x00000800
#define CLONE_THREAD 0x00010000
#include &lt;linux/unistd.h&gt;
#include &lt;errno.h&gt;
_syscall0(pid_t,gettid)
int thread(void *p) {
printf("thread: %d %d\n", gettid(), getpid());
}
main() {
unsigned char stack[4096];
int i;
i = clone(thread, stack+2048, CLONE_THREAD | CLONE_SIGHAND, NULL);
if (i == -1)
perror("clone");
else
printf("clone returns %d\n", i);
printf("parent: %d %d\n", gettid(), getpid());
}
EOF
% cc -o gettid-demo gettid-demo.c
% ./gettid-demo
clone returns 21826
parent: 21825 21825
thread: 21826 21825
%
</pre>
<p>
</p><p>
</p><hr>
</body></html>

394
loginutils/getty.c
View File

@ -33,7 +33,6 @@
#include <time.h> #include <time.h>
#if ENABLE_FEATURE_WTMP #if ENABLE_FEATURE_WTMP
extern void updwtmp(const char *filename, const struct utmp *ut); extern void updwtmp(const char *filename, const struct utmp *ut);
static void update_utmp(const char *line);
#endif #endif
#endif /* LOGIN_PROCESS */ #endif /* LOGIN_PROCESS */
@ -47,6 +46,7 @@ static void update_utmp(const char *line);
/* I doubt there are systems which still need this */ /* I doubt there are systems which still need this */
#undef HANDLE_ALLCAPS #undef HANDLE_ALLCAPS
#undef ANCIENT_BS_KILL_CHARS
#define _PATH_LOGIN "/bin/login" #define _PATH_LOGIN "/bin/login"
@ -76,36 +76,20 @@ static void update_utmp(const char *line);
* When multiple baud rates are specified on the command line, the first one * When multiple baud rates are specified on the command line, the first one
* we will try is the first one specified. * we will try is the first one specified.
*/ */
#define FIRST_SPEED 0
/* Storage for command-line options. */
#define MAX_SPEED 10 /* max. nr. of baud rates */ #define MAX_SPEED 10 /* max. nr. of baud rates */
/* Storage for command-line options. */
struct options { struct options {
int flags; /* toggle switches, see below */ int flags; /* toggle switches, see below */
unsigned timeout; /* time-out period */ unsigned timeout; /* time-out period */
const char *login; /* login program */ const char *login; /* login program */
const char *tty; /* name of tty */ const char *tty; /* name of tty */
const char *initstring; /* modem init string */ const char *initstring; /* modem init string */
const char *issue; /* alternative issue file */ const char *issue; /* alternative issue file */
int numspeed; /* number of baud rates to try */ int numspeed; /* number of baud rates to try */
int speeds[MAX_SPEED]; /* baud rates to be tried */ int speeds[MAX_SPEED]; /* baud rates to be tried */
}; };
static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:wn";
#define F_INITSTRING (1<<0) /* initstring is set */
#define F_LOCAL (1<<1) /* force local */
#define F_FAKEHOST (1<<2) /* force fakehost */
#define F_CUSTISSUE (1<<3) /* give alternative issue file */
#define F_RTSCTS (1<<4) /* enable RTS/CTS flow control */
#define F_ISSUE (1<<5) /* display /etc/issue */
#define F_LOGIN (1<<6) /* non-default login program */
#define F_PARSE (1<<7) /* process modem status messages */
#define F_TIMEOUT (1<<8) /* time out */
#define F_WAITCRLF (1<<9) /* wait for CR or LF */
#define F_NOPROMPT (1<<10) /* don't ask for login name! */
/* Storage for things detected while the login name was read. */ /* Storage for things detected while the login name was read. */
struct chardata { struct chardata {
unsigned char erase; /* erase character */ unsigned char erase; /* erase character */
@ -117,6 +101,7 @@ struct chardata {
#endif #endif
}; };
/* Initial values for the above. */ /* Initial values for the above. */
static const struct chardata init_chardata = { static const struct chardata init_chardata = {
DEF_ERASE, /* default erase character */ DEF_ERASE, /* default erase character */
@ -128,12 +113,25 @@ static const struct chardata init_chardata = {
#endif #endif
}; };
/* The following is used for understandable diagnostics. */ static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:wn";
#define F_INITSTRING (1 << 0) /* -I initstring is set */
#define F_LOCAL (1 << 1) /* -L force local */
#define F_FAKEHOST (1 << 2) /* -H force fakehost */
#define F_CUSTISSUE (1 << 3) /* -f give alternative issue file */
#define F_RTSCTS (1 << 4) /* -h enable RTS/CTS flow control */
#define F_ISSUE (1 << 5) /* -i display /etc/issue */
#define F_LOGIN (1 << 6) /* -l non-default login program */
#define F_PARSE (1 << 7) /* -m process modem status messages */
#define F_TIMEOUT (1 << 8) /* -t time out */
#define F_WAITCRLF (1 << 9) /* -w wait for CR or LF */
#define F_NOPROMPT (1 << 10) /* -n don't ask for login name! */
/* Fake hostname for ut_host specified on command line. */ /* Fake hostname for ut_host specified on command line. */
static char *fakehost = NULL; static char *fakehost = NULL;
#define line_buf bb_common_bufsiz1
/* ... */ /* The following is used for understandable diagnostics. */
#ifdef DEBUGGING #ifdef DEBUGGING
#define debug(s) fprintf(dbf,s); fflush(dbf) #define debug(s) fprintf(dbf,s); fflush(dbf)
#define DEBUGTERM "/dev/ttyp0" #define DEBUGTERM "/dev/ttyp0"
@ -158,14 +156,14 @@ static int bcode(const char *s)
return 0; return 0;
} }
/* parse_speeds - parse alternate baud rates */ /* parse_speeds - parse alternate baud rates */
static void parse_speeds(struct options *op, char *arg) static void parse_speeds(struct options *op, char *arg)
{ {
char *cp; char *cp;
/* NB: at least one iteration is always done */
debug("entered parse_speeds\n"); debug("entered parse_speeds\n");
for (cp = strtok(arg, ","); cp != 0; cp = strtok((char *) 0, ",")) { while ((cp = strsep(&arg, ",")) != NULL) {
op->speeds[op->numspeed] = bcode(cp); op->speeds[op->numspeed] = bcode(cp);
if (op->speeds[op->numspeed] <= 0) if (op->speeds[op->numspeed] <= 0)
bb_error_msg_and_die("bad speed: %s", cp); bb_error_msg_and_die("bad speed: %s", cp);
@ -173,18 +171,19 @@ static void parse_speeds(struct options *op, char *arg)
if (op->numspeed > MAX_SPEED) if (op->numspeed > MAX_SPEED)
bb_error_msg_and_die("too many alternate speeds"); bb_error_msg_and_die("too many alternate speeds");
} }
debug("exiting parsespeeds\n"); debug("exiting parse_speeds\n");
} }
/* parse_args - parse command-line arguments */ /* parse_args - parse command-line arguments */
static void parse_args(int argc, char **argv, struct options *op) static void parse_args(char **argv, struct options *op)
{ {
char *ts; char *ts;
opt_complementary = "-2"; /* at least 2 args */
op->flags = getopt32(argv, opt_string, op->flags = getopt32(argv, opt_string,
&(op->initstring), &fakehost, &(op->issue), &(op->initstring), &fakehost, &(op->issue),
&(op->login), &ts); &(op->login), &ts);
argv += optind;
if (op->flags & F_INITSTRING) { if (op->flags & F_INITSTRING) {
const char *p = op->initstring; const char *p = op->initstring;
char *q; char *q;
@ -202,45 +201,40 @@ static void parse_args(int argc, char **argv, struct options *op)
} }
*q = '\0'; *q = '\0';
} }
op->flags ^= F_ISSUE; /* revert flag show /etc/issue */ op->flags ^= F_ISSUE; /* invert flag show /etc/issue */
if (op->flags & F_TIMEOUT) { if (op->flags & F_TIMEOUT) {
op->timeout = xatoul_range(ts, 1, INT_MAX); op->timeout = xatoi_u(ts);
} }
argv += optind; debug("after getopt\n");
argc -= optind;
debug("after getopt loop\n");
if (argc < 2) /* check parameter count */
bb_show_usage();
/* we loosen up a bit and accept both "baudrate tty" and "tty baudrate" */ /* we loosen up a bit and accept both "baudrate tty" and "tty baudrate" */
op->tty = argv[0]; /* tty name */
ts = argv[1]; /* baud rate(s) */
if (isdigit(argv[0][0])) { if (isdigit(argv[0][0])) {
/* a number first, assume it's a speed (BSD style) */ /* a number first, assume it's a speed (BSD style) */
parse_speeds(op, argv[0]); /* baud rate(s) */ op->tty = ts; /* tty name is in argv[1] */
op->tty = argv[1]; /* tty name */ ts = argv[0]; /* baud rate(s) */
} else {
op->tty = argv[0]; /* tty name */
parse_speeds(op, argv[1]); /* baud rate(s) */
} }
parse_speeds(op, ts);
if (argv[2]) if (argv[2])
setenv("TERM", argv[2], 1); setenv("TERM", argv[2], 1);
debug("exiting parseargs\n"); debug("exiting parse_args\n");
} }
/* open_tty - set up tty as standard { input, output, error } */ /* open_tty - set up tty as standard { input, output, error } */
static void open_tty(const char *tty, struct termios *tp, int local) static void open_tty(const char *tty)
{ {
int chdir_to_root = 0;
/* Set up new standard input, unless we are given an already opened port. */ /* Set up new standard input, unless we are given an already opened port. */
if (NOT_LONE_DASH(tty)) { if (NOT_LONE_DASH(tty)) {
struct stat st; struct stat st;
int cur_dir_fd;
int fd; int fd;
/* Sanity checks... */ /* Sanity checks... */
cur_dir_fd = xopen(".", O_DIRECTORY | O_NONBLOCK);
xchdir("/dev"); xchdir("/dev");
chdir_to_root = 1;
xstat(tty, &st); xstat(tty, &st);
if ((st.st_mode & S_IFMT) != S_IFCHR) if ((st.st_mode & S_IFMT) != S_IFCHR)
bb_error_msg_and_die("%s: not a character device", tty); bb_error_msg_and_die("%s: not a character device", tty);
@ -248,9 +242,23 @@ static void open_tty(const char *tty, struct termios *tp, int local)
/* Open the tty as standard input. */ /* Open the tty as standard input. */
debug("open(2)\n"); debug("open(2)\n");
fd = xopen(tty, O_RDWR | O_NONBLOCK); fd = xopen(tty, O_RDWR | O_NONBLOCK);
/* Restore current directory */
fchdir(cur_dir_fd);
/* Open the tty as standard input, continued */
xdup2(fd, 0); xdup2(fd, 0);
/* fd is >= cur_dir_fd, and cur_dir_fd gets closed too here: */
while (fd > 2) while (fd > 2)
close(fd--); close(fd--);
/* Set proper protections and ownership. Mode 0622
* is suitable for SYSV < 4 because /bin/login does not change
* protections. SunOS 4 login will change the protections to 0620
* (write access for group tty) after the login has succeeded.
*/
fchown(0, 0, 0); /* 0:0 */
fchmod(0, 0622); /* crw--w--w- */
} else { } else {
/* /*
* Standard input should already be connected to an open port. Make * Standard input should already be connected to an open port. Make
@ -259,71 +267,6 @@ static void open_tty(const char *tty, struct termios *tp, int local)
if ((fcntl(0, F_GETFL) & O_RDWR) != O_RDWR) if ((fcntl(0, F_GETFL) & O_RDWR) != O_RDWR)
bb_error_msg_and_die("stdin is not open for read/write"); bb_error_msg_and_die("stdin is not open for read/write");
} }
/* Replace current standard output/error fd's with new ones */
debug("duping\n");
xdup2(0, 1);
xdup2(0, 2);
/*
* The following ioctl will fail if stdin is not a tty, but also when
* there is noise on the modem control lines. In the latter case, the
* common course of action is (1) fix your cables (2) give the modem more
* time to properly reset after hanging up. SunOS users can achieve (2)
* by patching the SunOS kernel variable "zsadtrlow" to a larger value;
* 5 seconds seems to be a good value.
*/
ioctl_or_perror_and_die(0, TCGETS, tp, "%s: TCGETS", tty);
/*
* It seems to be a terminal. Set proper protections and ownership. Mode
* 0622 is suitable for SYSV <4 because /bin/login does not change
* protections. SunOS 4 login will change the protections to 0620 (write
* access for group tty) after the login has succeeded.
*/
#ifdef DEBIAN
#warning Debian /dev/vcs[a]NN hack is deprecated and will be removed
{
/* tty to root.dialout 660 */
struct group *gr;
int id;
gr = getgrnam("dialout");
id = gr ? gr->gr_gid : 0;
chown(tty, 0, id);
chmod(tty, 0660);
/* vcs,vcsa to root.sys 600 */
if (!strncmp(tty, "tty", 3) && isdigit(tty[3])) {
char *vcs, *vcsa;
vcs = xstrdup(tty);
vcsa = xmalloc(strlen(tty) + 2);
strcpy(vcs, "vcs");
strcpy(vcs + 3, tty + 3);
strcpy(vcsa, "vcsa");
strcpy(vcsa + 4, tty + 3);
gr = getgrnam("sys");
id = gr ? gr->gr_gid : 0;
chown(vcs, 0, id);
chmod(vcs, 0600);
chown(vcsa, 0, id);
chmod(vcs, 0600);
free(vcs);
free(vcsa);
}
}
#else
if (NOT_LONE_DASH(tty)) {
chown(tty, 0, 0); /* 0:0 */
chmod(tty, 0622); /* crw--w--w- */
}
#endif
if (chdir_to_root)
xchdir("/");
} }
/* termios_init - initialize termios settings */ /* termios_init - initialize termios settings */
@ -351,17 +294,13 @@ static void termios_init(struct termios *tp, int speed, struct options *op)
tp->c_cc[VTIME] = 0; tp->c_cc[VTIME] = 0;
/* Optionally enable hardware flow control */ /* Optionally enable hardware flow control */
#ifdef CRTSCTS
#ifdef CRTSCTS
if (op->flags & F_RTSCTS) if (op->flags & F_RTSCTS)
tp->c_cflag |= CRTSCTS; tp->c_cflag |= CRTSCTS;
#endif #endif
ioctl(0, TCSETS, tp); ioctl(0, TCSETS, tp);
/* go to blocking input even in local mode */
ndelay_off(0);
debug("term_io 2\n"); debug("term_io 2\n");
} }
@ -393,26 +332,24 @@ static void auto_baud(char *buf, unsigned size_buf, struct termios *tp)
* Use 7-bit characters, don't block if input queue is empty. Errors will * Use 7-bit characters, don't block if input queue is empty. Errors will
* be dealt with later on. * be dealt with later on.
*/ */
iflag = tp->c_iflag; iflag = tp->c_iflag;
tp->c_iflag |= ISTRIP; /* enable 8th-bit stripping */ tp->c_iflag |= ISTRIP; /* enable 8th-bit stripping */
vmin = tp->c_cc[VMIN]; vmin = tp->c_cc[VMIN];
tp->c_cc[VMIN] = 0; /* don't block if queue empty */ tp->c_cc[VMIN] = 0; /* don't block if queue empty */
ioctl(0, TCSETS, tp); ioctl(0, TCSETS, tp);
/* /*
* Wait for a while, then read everything the modem has said so far and * Wait for a while, then read everything the modem has said so far and
* try to extract the speed of the dial-in call. * try to extract the speed of the dial-in call.
*/ */
sleep(1); sleep(1);
nread = read(0, buf, size_buf - 1); nread = safe_read(0, buf, size_buf - 1);
if (nread > 0) { if (nread > 0) {
buf[nread] = '\0'; buf[nread] = '\0';
for (bp = buf; bp < buf + nread; bp++) { for (bp = buf; bp < buf + nread; bp++) {
if (isascii(*bp) && isdigit(*bp)) { if (isdigit(*bp)) {
speed = bcode(bp); speed = bcode(bp);
if (speed) { if (speed > 0) {
tp->c_cflag &= ~CBAUD; tp->c_cflag &= ~CBAUD;
tp->c_cflag |= speed; tp->c_cflag |= speed;
} }
@ -420,25 +357,13 @@ static void auto_baud(char *buf, unsigned size_buf, struct termios *tp)
} }
} }
} }
/* Restore terminal settings. Errors will be dealt with later on. */
/* Restore terminal settings. Errors will be dealt with later on. */
tp->c_iflag = iflag; tp->c_iflag = iflag;
tp->c_cc[VMIN] = vmin; tp->c_cc[VMIN] = vmin;
ioctl(0, TCSETS, tp); ioctl(0, TCSETS, tp);
} }
/* next_speed - select next baud rate */
static void next_speed(struct termios *tp, struct options *op)
{
static int baud_index = FIRST_SPEED; /* current speed index */
baud_index = (baud_index + 1) % op->numspeed;
tp->c_cflag &= ~CBAUD;
tp->c_cflag |= op->speeds[baud_index];
ioctl(0, TCSETS, tp);
}
/* do_prompt - show login prompt, optionally preceded by /etc/issue contents */ /* do_prompt - show login prompt, optionally preceded by /etc/issue contents */
static void do_prompt(struct options *op, struct termios *tp) static void do_prompt(struct options *op, struct termios *tp)
{ {
@ -449,9 +374,9 @@ static void do_prompt(struct options *op, struct termios *tp)
} }
#ifdef HANDLE_ALLCAPS #ifdef HANDLE_ALLCAPS
/* caps_lock - string contains upper case without lower case */ /* all_is_upcase - string contains upper case without lower case */
/* returns 1 if true, 0 if false */ /* returns 1 if true, 0 if false */
static int caps_lock(const char *s) static int all_is_upcase(const char *s)
{ {
while (*s) while (*s)
if (islower(*s++)) if (islower(*s++))
@ -460,8 +385,8 @@ static int caps_lock(const char *s)
} }
#endif #endif
/* get_logname - get user name, establish parity, speed, erase, kill, eol */ /* get_logname - get user name, establish parity, speed, erase, kill, eol;
/* return NULL on failure, logname on success */ * return NULL on BREAK, logname on success */
static char *get_logname(char *logname, unsigned size_logname, static char *get_logname(char *logname, unsigned size_logname,
struct options *op, struct chardata *cp, struct termios *tp) struct options *op, struct chardata *cp, struct termios *tp)
{ {
@ -477,26 +402,19 @@ static char *get_logname(char *logname, unsigned size_logname,
"\210\240\210", /* no parity */ "\210\240\210", /* no parity */
}; };
/* Initialize kill, erase, parity etc. (also after switching speeds). */ /* NB: *cp is pre-initialized with init_chardata */
*cp = init_chardata;
/* Flush pending input (esp. after parsing or switching the baud rate). */ /* Flush pending input (esp. after parsing or switching the baud rate). */
sleep(1); sleep(1);
ioctl(0, TCFLSH, TCIFLUSH); ioctl(0, TCFLSH, TCIFLUSH);
/* Prompt for and read a login name. */ /* Prompt for and read a login name. */
logname[0] = '\0'; logname[0] = '\0';
while (!logname[0]) { while (!logname[0]) {
/* Write issue file and prompt, with "parity" bit == 0. */ /* Write issue file and prompt, with "parity" bit == 0. */
do_prompt(op, tp); do_prompt(op, tp);
/* Read name, watch for break, parity, erase, kill, end-of-line. */ /* Read name, watch for break, parity, erase, kill, end-of-line. */
bp = logname; bp = logname;
cp->eol = '\0'; cp->eol = '\0';
while (cp->eol == '\0') { while (cp->eol == '\0') {
@ -508,7 +426,8 @@ static char *get_logname(char *logname, unsigned size_logname,
bb_perror_msg_and_die("%s: read", op->tty); bb_perror_msg_and_die("%s: read", op->tty);
} }
/* Do BREAK handling elsewhere. */ /* BREAK. If we have speeds to try,
* return NULL (will switch speeds and return here) */
if (c == '\0' && op->numspeed > 1) if (c == '\0' && op->numspeed > 1)
return NULL; return NULL;
@ -535,18 +454,22 @@ static char *get_logname(char *logname, unsigned size_logname,
break; break;
case BS: case BS:
case DEL: case DEL:
#ifdef ANCIENT_BS_KILL_CHARS
case '#': case '#':
#endif
cp->erase = ascval; /* set erase character */ cp->erase = ascval; /* set erase character */
if (bp > logname) { if (bp > logname) {
write(1, erase[cp->parity], 3); full_write(1, erase[cp->parity], 3);
bp--; bp--;
} }
break; break;
case CTL('U'): case CTL('U'):
#ifdef ANCIENT_BS_KILL_CHARS
case '@': case '@':
#endif
cp->kill = ascval; /* set kill character */ cp->kill = ascval; /* set kill character */
while (bp > logname) { while (bp > logname) {
write(1, erase[cp->parity], 3); full_write(1, erase[cp->parity], 3);
bp--; bp--;
} }
break; break;
@ -558,7 +481,7 @@ static char *get_logname(char *logname, unsigned size_logname,
} else if (bp - logname >= size_logname - 1) { } else if (bp - logname >= size_logname - 1) {
bb_error_msg_and_die("%s: input overrun", op->tty); bb_error_msg_and_die("%s: input overrun", op->tty);
} else { } else {
write(1, &c, 1); /* echo the character */ full_write(1, &c, 1); /* echo the character */
*bp++ = ascval; /* and store it */ *bp++ = ascval; /* and store it */
} }
break; break;
@ -568,7 +491,7 @@ static char *get_logname(char *logname, unsigned size_logname,
/* Handle names with upper case and no lower case. */ /* Handle names with upper case and no lower case. */
#ifdef HANDLE_ALLCAPS #ifdef HANDLE_ALLCAPS
cp->capslock = caps_lock(logname); cp->capslock = all_is_upcase(logname);
if (cp->capslock) { if (cp->capslock) {
for (bp = logname; *bp; bp++) for (bp = logname; *bp; bp++)
if (isupper(*bp)) if (isupper(*bp))
@ -641,7 +564,6 @@ static void termios_final(struct options *op, struct termios *tp, struct chardat
ioctl_or_perror_and_die(0, TCSETS, tp, "%s: TCSETS", op->tty); ioctl_or_perror_and_die(0, TCSETS, tp, "%s: TCSETS", op->tty);
} }
#ifdef SYSV_STYLE #ifdef SYSV_STYLE
#if ENABLE_FEATURE_UTMP #if ENABLE_FEATURE_UTMP
/* update_utmp - update our utmp entry */ /* update_utmp - update our utmp entry */
@ -666,17 +588,16 @@ static void update_utmp(const char *line)
utmpname(_PATH_UTMP); utmpname(_PATH_UTMP);
setutent(); setutent();
while ((utp = getutent()) while ((utp = getutent())
&& !(utp->ut_type == INIT_PROCESS && utp->ut_pid == mypid)) && !(utp->ut_type == INIT_PROCESS && utp->ut_pid == mypid)
/* nothing */; ) {
continue;
if (utp) {
memcpy(&ut, utp, sizeof(ut));
} else {
/* some inits don't initialize utmp... */
memset(&ut, 0, sizeof(ut));
safe_strncpy(ut.ut_id, line + 3, sizeof(ut.ut_id));
} }
/* endutent(); */
/* some inits don't initialize utmp... */
memset(&ut, 0, sizeof(ut));
safe_strncpy(ut.ut_id, line + 3, sizeof(ut.ut_id));
if (utp)
memcpy(&ut, utp, sizeof(ut));
strcpy(ut.ut_user, "LOGIN"); strcpy(ut.ut_user, "LOGIN");
safe_strncpy(ut.ut_line, line, sizeof(ut.ut_line)); safe_strncpy(ut.ut_line, line, sizeof(ut.ut_line));
@ -700,42 +621,43 @@ static void update_utmp(const char *line)
#endif /* CONFIG_FEATURE_UTMP */ #endif /* CONFIG_FEATURE_UTMP */
#endif /* SYSV_STYLE */ #endif /* SYSV_STYLE */
int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int getty_main(int argc, char **argv) int getty_main(int argc, char **argv)
{ {
int nullfd; int n;
char *logname = NULL; /* login name, given to /bin/login */ char *logname; /* login name, given to /bin/login */
/* Merging these into "struct local" may _seem_ to reduce /* Merging these into "struct local" may _seem_ to reduce
* parameter passing, but today's gcc will inline * parameter passing, but today's gcc will inline
* statics which are called once anyway, so don't do that */ * statics which are called once anyway, so don't do that */
struct chardata chardata; /* set by get_logname() */ struct chardata chardata; /* set by get_logname() */
struct termios termios; /* terminal mode bits */ struct termios termios; /* terminal mode bits */
struct options options = { struct options options;
0, /* show /etc/issue (SYSV_STYLE) */
0, /* no timeout */ memset(&options, 0, sizeof(options));
_PATH_LOGIN, /* default login program */ options.login = _PATH_LOGIN; /* default login program */
"tty1", /* default tty line */ options.tty = "tty1"; /* default tty line */
"", /* modem init string */ options.initstring = ""; /* modem init string */
#ifdef ISSUE #ifdef ISSUE
ISSUE, /* default issue file */ options.issue = ISSUE; /* default issue file */
#else
NULL,
#endif #endif
0, /* no baud rates known yet */
};
/* Already too late because of theoretical /* Already too late because of theoretical
* possibility of getty --help somehow triggered * possibility of getty --help somehow triggered
* inadvertently before we reach this. Oh well. */ * inadvertently before we reach this. Oh well. */
logmode = LOGMODE_NONE; logmode = LOGMODE_NONE;
/* Create new session, lose controlling tty, if any */
/* docs/ctty.htm says:
* "This is allowed only when the current process
* is not a process group leader" - is this a problem? */
setsid(); setsid();
nullfd = xopen(bb_dev_null, O_RDWR);
/* dup2(nullfd, 0); - no, because of possible "getty - 9600" */ n = xopen(bb_dev_null, O_RDWR);
/* open_tty() will take care of fd# 0 anyway */ /* dup2(n, 0); - no, because of possible "getty - 9600" */
dup2(nullfd, 1); dup2(n, 1);
dup2(nullfd, 2); dup2(n, 2);
while (nullfd > 2) close(nullfd--); while (n > 2)
close(n--);
/* We want special flavor of error_msg_and_die */ /* We want special flavor of error_msg_and_die */
die_sleep = 10; die_sleep = 10;
msg_eol = "\r\n"; msg_eol = "\r\n";
@ -744,69 +666,74 @@ int getty_main(int argc, char **argv)
#ifdef DEBUGGING #ifdef DEBUGGING
dbf = xfopen(DEBUGTERM, "w"); dbf = xfopen(DEBUGTERM, "w");
for (n = 1; n < argc; n++) {
{ debug(argv[n]);
int i; debug("\n");
for (i = 1; i < argc; i++) {
debug(argv[i]);
debug("\n");
}
} }
#endif #endif
/* Parse command-line arguments. */ /* Parse command-line arguments. */
parse_args(argc, argv, &options); parse_args(argv, &options);
debug("calling open_tty\n");
/* Open the tty as standard input, if it is not "-" */
open_tty(options.tty);
debug("duping\n");
ndelay_off(0);
xdup2(0, 1);
xdup2(0, 2);
/*
* The following ioctl will fail if stdin is not a tty, but also when
* there is noise on the modem control lines. In the latter case, the
* common course of action is (1) fix your cables (2) give the modem more
* time to properly reset after hanging up. SunOS users can achieve (2)
* by patching the SunOS kernel variable "zsadtrlow" to a larger value;
* 5 seconds seems to be a good value.
*/
ioctl_or_perror_and_die(0, TCGETS, &termios, "%s: TCGETS", options.tty);
#ifdef SYSV_STYLE #ifdef SYSV_STYLE
#if ENABLE_FEATURE_UTMP #if ENABLE_FEATURE_UTMP
/* Update the utmp file. */ /* Update the utmp file */
update_utmp(options.tty); update_utmp(options.tty);
#endif #endif
#endif #endif
debug("calling open_tty\n");
/* Open the tty as standard { input, output, error }. */
open_tty(options.tty, &termios, options.flags & F_LOCAL);
#ifdef __linux__ #ifdef __linux__
{ /* Make ourself a foreground process group within our session */
int iv; tcsetpgrp(0, getpid());
// /* Forcibly make fd 0 our controlling tty, even if another session
iv = getpid(); // * has it as a ctty. (Another session loses ctty). */
ioctl(0, TIOCSPGRP, &iv); // ioctl(0, TIOCSCTTY, (void*)1);
}
#endif #endif
/* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */ /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
debug("calling termios_init\n"); debug("calling termios_init\n");
termios_init(&termios, options.speeds[FIRST_SPEED], &options); termios_init(&termios, options.speeds[0], &options);
/* write the modem init string and DON'T flush the buffers */ /* Write the modem init string and DON'T flush the buffers */
if (options.flags & F_INITSTRING) { if (options.flags & F_INITSTRING) {
debug("writing init string\n"); debug("writing init string\n");
write(1, options.initstring, strlen(options.initstring)); full_write(1, options.initstring, strlen(options.initstring));
} }
if (!(options.flags & F_LOCAL)) { /* Optionally detect the baud rate from the modem status message */
/* go to blocking write mode unless -L is specified */
ndelay_off(1);
}
/* Optionally detect the baud rate from the modem status message. */
debug("before autobaud\n"); debug("before autobaud\n");
if (options.flags & F_PARSE) if (options.flags & F_PARSE)
auto_baud(bb_common_bufsiz1, sizeof(bb_common_bufsiz1), &termios); auto_baud(line_buf, sizeof(line_buf), &termios);
/* Set the optional timer. */ /* Set the optional timer */
if (options.timeout) if (options.timeout)
alarm(options.timeout); alarm(options.timeout);
/* optionally wait for CR or LF before writing /etc/issue */ /* Optionally wait for CR or LF before writing /etc/issue */
if (options.flags & F_WAITCRLF) { if (options.flags & F_WAITCRLF) {
char ch; char ch;
debug("waiting for cr-lf\n"); debug("waiting for cr-lf\n");
while (read(0, &ch, 1) == 1) { while (safe_read(0, &ch, 1) == 1) {
ch &= 0x7f; /* strip "parity bit" */ ch &= 0x7f; /* strip "parity bit" */
#ifdef DEBUGGING #ifdef DEBUGGING
fprintf(dbf, "read %c\n", ch); fprintf(dbf, "read %c\n", ch);
@ -816,31 +743,42 @@ int getty_main(int argc, char **argv)
} }
} }
logname = NULL;
chardata = init_chardata; chardata = init_chardata;
if (!(options.flags & F_NOPROMPT)) { if (!(options.flags & F_NOPROMPT)) {
/* Read the login name. */ /* NB:termios_init already set line speed
debug("reading login name\n"); * to options.speeds[0] */
logname = get_logname(bb_common_bufsiz1, sizeof(bb_common_bufsiz1), int baud_index = 0;
while (1) {
/* Read the login name. */
debug("reading login name\n");
logname = get_logname(line_buf, sizeof(line_buf),
&options, &chardata, &termios); &options, &chardata, &termios);
while (logname == NULL) if (logname)
next_speed(&termios, &options); break;
/* we are here only if options.numspeed > 1 */
baud_index = (baud_index + 1) % options.numspeed;
termios.c_cflag &= ~CBAUD;
termios.c_cflag |= options.speeds[baud_index];
ioctl(0, TCSETS, &termios);
}
} }
/* Disable timer. */ /* Disable timer. */
if (options.timeout) if (options.timeout)
alarm(0); alarm(0);
/* Finalize the termios settings. */ /* Finalize the termios settings. */
termios_final(&options, &termios, &chardata); termios_final(&options, &termios, &chardata);
/* Now the newline character should be properly written. */ /* Now the newline character should be properly written. */
full_write(1, "\n", 1);
write(1, "\n", 1);
/* Let the login program take care of password validation. */ /* Let the login program take care of password validation. */
/* We use PATH because we trust that root doesn't set "bad" PATH,
execl(options.login, options.login, "--", logname, (char *) 0); * and getty is not suid-root applet. */
/* Hmm... with -n, logname == NULL! Is it ok? */
BB_EXECLP(options.login, options.login, "--", logname, NULL);
bb_error_msg_and_die("%s: can't exec %s", options.tty, options.login); bb_error_msg_and_die("%s: can't exec %s", options.tty, options.login);
} }