tdebase/tdm/backend/sessreg.c

/*

Copyright 1990, 1998  The Open Group
Copyright 2005 Oswald Buddenhagen <ossi@kde.org>

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation.

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of The Open Group shall
not be used in advertising or otherwise to promote the sale, use or
other dealings in this Software without prior written authorization
from The Open Group.

*/

/*

  Author: Keith Packard, MIT X Consortium
  Lastlog support and dynamic utmp entry allocation
    by Andreas Stolcke <stolcke@icsi.berkeley.edu>

*/

#define _FILE_OFFSET_BITS 64
#include "dm.h"
#include "dm_error.h"

#if defined(__svr4__) || defined(__Lynx__) || defined(__QNX__) || defined(__APPLE__) || defined(_SEQUENT_) /*|| defined(USE_PAM)*/
# define NO_LASTLOG
#endif

#ifndef NO_LASTLOG
# ifdef HAVE_LASTLOG_H
#  include <lastlog.h>
# endif
# ifndef LLOG_FILE
#  ifdef _PATH_LASTLOGX
#   define LLOG_FILE _PATH_LASTLOGX
#  elif defined(_PATH_LASTLOG)
#   define LLOG_FILE _PATH_LASTLOG
#  else
#   define LLOG_FILE "/usr/adm/lastlog"
#  endif
# endif
#endif

#if !defined(__svr4__) && !defined(__QNX__)
# define SESSREG_HOST
#endif

#ifdef BSD
# if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__)
/* *BSD doesn't like a ':0' type entry in utmp */
#  define NO_UTMP
# endif
#endif

#ifdef BSD_UTMP
# ifndef TTYS_FILE
#  define TTYS_FILE "/etc/ttys"
# endif
#endif

#ifdef _AIX
# define UTL_PFX "xdm/"
# define UTL_OFF strlen(UTL_PFX)
#else
# define UTL_OFF 0
#endif

#ifndef BSD_UTMP
static unsigned
crc32s( const unsigned char *str )
{
	int b;
	unsigned crc = 0xffffffff, by;

	for (; *str; str++) {
		by = (crc & 255) ^ *str;
		for (b = 0; b < 8; b++)
			by = (by >> 1) ^ (-(by & 1) & 0xedb88320);
		crc = (crc >> 8) ^ by;
	}
	return crc;
}
#endif

void
sessreg( struct display *d, int pid, const char *user, int uid )
{
	char *dot, *colon;
	int left, clen;
#ifdef BSD_UTMP
	FILE *ttys;
	int utmp, slot, freeslot;
	STRUCTUTMP entry;
#else
	unsigned crc, i;
#endif
	int wtmp, c;
#ifndef NO_LASTLOG
	int llog;
	struct LASTLOG ll;
#endif
	STRUCTUTMP ut_ent;

	if (!d->useSessReg)
		return;

	bzero( &ut_ent, sizeof(ut_ent) );

	if (pid) {
		strncpy( ut_ent.ut_user, user, sizeof(ut_ent.ut_user) );
#ifndef BSD_UTMP
		ut_ent.ut_pid = pid;
		ut_ent.ut_type = USER_PROCESS;
	} else {
		ut_ent.ut_type = DEAD_PROCESS;
#endif
	}
	ut_ent.ut_time = time( 0 );

	colon = strchr( d->name, ':' );
	clen = strlen( colon );
	if (clen > (int)(sizeof(ut_ent.ut_line) - UTL_OFF) - 2)
		return; /* uhm, well ... */
	if (colon == d->name) {
#ifndef BSD_UTMP
		strncpy( ut_ent.ut_id, d->name, sizeof(ut_ent.ut_id) );
#endif
		left = 0;
	} else {
#ifdef SESSREG_HOST
# ifndef BSD_UTMP
		if (pid)
# endif
		{
			if (colon - d->name > (int)sizeof(ut_ent.ut_host)) {
				ut_ent.ut_host[0] = '~';
				memcpy( ut_ent.ut_host + 1,
				        colon - (sizeof(ut_ent.ut_host) - 1),
				        sizeof(ut_ent.ut_host) - 1 );
			} else
				memcpy( ut_ent.ut_host, d->name, colon - d->name );
		}
#endif
#ifndef BSD_UTMP
		crc = crc32s( d->name );
		ut_ent.ut_id[0] = crc % 26 + 'A';
		crc /= 26;
		for (i = 1; i < sizeof(ut_ent.ut_id); i++) {
			c = crc % 62;
			crc /= 62;
			ut_ent.ut_id[i] = c < 26 ? c + 'A' :
							  c < 52 ? c - 26 + 'a' : c - 52 + '0';
		}
#endif
		left = sizeof(ut_ent.ut_line) - UTL_OFF - clen;
		if (colon - d->name <= left) {
			clen += colon - d->name;
			colon = d->name;
			left = 0;
		} else {
			dot = strchr( d->name, '.' );
			if (dot && dot - d->name < left) {
				memcpy( ut_ent.ut_line + UTL_OFF, d->name, left - 1 );
				ut_ent.ut_line[UTL_OFF + left - 1] = '~';
			} else {
				memcpy( ut_ent.ut_line + UTL_OFF, d->name, left/2 - 1 );
				ut_ent.ut_line[UTL_OFF + left/2 - 1] = '~';
				if (dot) {
					memcpy( ut_ent.ut_line + UTL_OFF + left/2,
					        dot - (left - left/2 - 1),
					        left - left/2 - 1 );
					ut_ent.ut_line[UTL_OFF + left - 1] = '~';
				} else
					memcpy( ut_ent.ut_line + UTL_OFF + left/2,
					        colon - (left - left/2), left - left/2 );
			}
		}
	}
#ifdef UTL_PFX
	memcpy( ut_ent.ut_line, UTL_PFX, UTL_OFF );
#endif
	memcpy( ut_ent.ut_line + UTL_OFF + left, colon, clen );

#ifndef NO_UTMP
# ifdef BSD_UTMP
	if ((utmp = open( UTMP_FILE, O_RDWR )) < 0)
		Debug( "cannot open utmp file " UTMP_FILE ": %m\n" );
	else {

		slot = 1;
		if (pid) {
			if (!(ttys = fopen( TTYS_FILE, "r" )))
				LogWarn( "Cannot open tty file " TTYS_FILE ": %m\n" );
			else {
				int column0 = 1;
				while ((c = getc( ttys )) != EOF)
					if (c == '\n') {
						slot++;
						column0 = 1;
					} else
						column0 = 0;
				if (!column0)
					slot++;
				fclose( ttys );
			}
		}
		freeslot = -1;
		lseek( utmp, slot * sizeof(entry), SEEK_SET );
		while (read( utmp, (char *)&entry, sizeof(entry) ) == sizeof(entry)) {
			if (!strncmp( entry.ut_line, ut_ent.ut_line,
			              sizeof(entry.ut_line) ))
#  ifdef SESSREG_HOST
				if (!strncmp( entry.ut_host, ut_ent.ut_host,
				              sizeof(entry.ut_host) ))
#  endif
					goto found;
			if (freeslot < 0 && *entry.ut_user == '\0')
				freeslot = slot;
			slot++;
		}
		if (!pid) {
			Debug( "utmp entry for display %s vanished\n", d->name );
			goto skip;
		}
		if (freeslot >= 0)
			slot = freeslot;
	  found:

#  ifdef SESSREG_HOST
		if (!pid)
			bzero( ut_ent.ut_host, sizeof(ut_ent.ut_host) );
#  endif
		lseek( utmp, slot * sizeof(ut_ent), SEEK_SET );
		if (write( utmp, (char *)&ut_ent, sizeof(ut_ent) ) != sizeof(ut_ent))
			LogError( "Cannot write utmp file " UTMP_FILE ": %m\n" );
	  skip:
		close( utmp );
	}
# else
	UTMPNAME( UTMP_FILE );
	SETUTENT();
	PUTUTLINE( &ut_ent );
	ENDUTENT();
# endif
#endif

	if ((wtmp = open( WTMP_FILE, O_WRONLY|O_APPEND )) < 0)
		Debug( "cannot open wtmp file " WTMP_FILE ": %m\n" );
	else {
		if (write( wtmp, (char *)&ut_ent, sizeof(ut_ent) ) != sizeof(ut_ent))
			LogError( "Cannot write wtmp file " WTMP_FILE ": %m\n" );
		close( wtmp );
	}

#ifndef NO_LASTLOG
	if (pid) {
		bzero( (char *)&ll, sizeof(ll) );
		ll.ll_time = ut_ent.ut_time;
		memcpy( ll.ll_line, ut_ent.ut_line, sizeof(ll.ll_line) );
		memcpy( ll.ll_host, ut_ent.ut_host, sizeof(ll.ll_host) );
# ifdef HAVE_UTMPX
		updlastlogx( LLOG_FILE, uid, &ll );
# else
		if ((llog = open( LLOG_FILE, O_RDWR )) < 0)
			Debug( "cannot open lastlog file " LLOG_FILE ": %m\n" );
		else {
			lseek( llog, (off_t)uid * sizeof(ll), SEEK_SET );
			if (write( llog, (char *)&ll, sizeof(ll) ) != sizeof(ll))
				LogError( "Cannot write llog file " WTMP_FILE ": %m\n" );
			close( llog );
		}
# endif
	}
#else
	(void)uid;
#endif

#ifdef UTL_PFX
	{
		char tmp[sizeof("/dev/") + sizeof(ut_ent.ut_line)];
		mkdir( "/dev/" UTL_PFX, 0755 );
		chmod( "/dev/" UTL_PFX, 0755 );
		sprintf( tmp, "/dev/%.*s", sizeof(ut_ent.ut_line), ut_ent.ut_line );
		if (pid)
			close( creat( tmp, 0644 ) );
		else
			unlink( tmp );
	}
#endif
}