svr4_patch   [plain text]

#!/bin/sh
#
# $XFree86: xc/programs/Xserver/hw/xfree86/etc/svr4_patch,v 3.2 1996/12/23 06:47:23 dawes Exp $
#
# Apply patch to kernel to prevent losing IOPL on signals.
#
# Version 1.0 - 11/18/92
#	initial version - dwex@goblin.org, dwex@aib.com
#
# $XConsortium: svr4_patch /main/4 1996/02/21 17:48:36 kaleb $
#

PATH=/sbin:/usr/sbin:/usr/bin

N=`basename $0`

#
# Make sure we're running on SVR4!
#
uname -r | grep '4' > /dev/null
if [ "$?" != "0" ]
then
	echo "$N: This only applies to SVR4!"
	exit 1
fi

#
# Next make sure we are running as root
#
id | grep 'uid=0' > /dev/null
if [ "$?" != "0" ]
then
	echo "$N: Must be run as root!"
	exit 1
fi

#
# Now make temp directory
#
TMPDIR=/tmp/xf86_pt.$$
mkdir ${TMPDIR}
if [ ! -d ${TMPDIR} ]
then
	echo "$N: Failed to make temp directory"
	exit 1
fi

#
# Go to temp directory
#
OWD=${PWD}
cd ${TMPDIR}

#
# Checksums for programs
#
CHECKER_SUM="34037 5 checker"
PATCHER_SUM="10505 10 patcher"

#
# Extract programs
#
cat > checker.uu <<\!EOF!
begin 777 checker
M?T5,1@$! 0            (  P !    X(,$"#0   #X!0       #0 (  %
M "@ $  /  8    T    -( $"     "@    H     4          P   -0 
M             !,         !          !    -    #2 ! @     I 0 
M *0$   %     !    $   #8!   V)0$"     "<    H     <     $   
M @    0%   $E00(     '          !P         O=7-R+VQI8B]L:6)C
M+G-O+C$  !$    1    #P    @    -          X    !     P    L 
M        #    !                D         !P                  
M                       $    !@         "                    
M      4    *                               !    <(,$"!P    2
M    "@   'B5! @     $0#Q_P\   # @P0(     !(    6    V)0$" 0 
M   1  L 'P   -B$! @     $0#Q_R8   " @P0(0    !(    M    T(,$
M"      2    ,@   '25! @     $0#Q_SD   "@@P0(     !(    ^    
M=)4$" 0    1  X 1    -2$! @$    $0 * %$   "0@P0(     !(   !;
M    W)0$"      1 /'_<0    25! @     $0#Q_WH   "P@P0(     !( 
M  "!    Q80$"      2  @  %]C;&5A;G5P %]E;F0 9V5T<&ED %]E;G9I
M<F]N %]E=&5X= !A=&5X:70 :VEL; !?961A=&$ 97AI= !E<G)N;P!?;&EB
M7W9E<G-I;VX 7U]F<'-T87)T %]'3$]"04Q?3T9&4T547U1!0DQ%7P!?1%E.
M04U)0P!S:6=S970 7V-E<G)O<@ O=7-R+VQI8B]L:6)C+G-O+C$ Z)0$" <!
M  #LE 0(!P8  /"4! @'#   ])0$" <)  #XE 0(!P\  /R4! @' P   )4$
M" <'  #"    _S7@E 0(_R7DE 0(     /\EZ)0$"&@     Z>#_____)>R4
M! AH"    .G0_____R7PE 0(:!    #IP/____\E])0$"&@8    Z;#_____
M)?B4! AH(    .F@_____R7\E 0(:"@   #ID/____\E )4$"&@P    Z8#_
M__]J &H B^Q2N'"#! B%P'0-:'"#! CHAO___X/$!+@$E00(A<!T!>AU____
M:-"$! CH:____XM%"(U4A1")%=B4! A2C54,4E#H+____^A>____Z"4   "#
MQ Q0Z&#___]J +@!    F@     ' /3#ZP3K ,G#58OLZ_>0ZTYH4(0$"&H0
MZ$;___^#Q AH #   &H$:D?H-P   (/$#"O 9KI@$NR)1?QJ$.@Q____4.@[
M____@\0(*\!FNF 2[(E%_&H Z/?^__]9R<-5B^Q0ZZRX,@   )H     !P /
M@@$   ##HW25! BX_____\/"               $E00(          !V@P0(
MAH,$"):#! BF@P0(MH,$",:#! C6@P0( 0   (D    ,    7(,$" T   #0
MA 0(!    .B ! @%    B(($" 8   !X@00("@   )P    +    $    !4 
M         P   -R4! @"    .    !0    1    %P   "2#! @         
M   N:6YT97)P "YH87-H "YD>6YS>6T +F1Y;G-T<@ N<F5L+G!L=  N:6YI
M=  N<&QT "YT97AT "YF:6YI "YR;V1A=&$ +F1A=&$ +F=O=  N9'EN86UI
M8P N8G-S "YS>6UT86( +G-T<G1A8@ N<VAS=')T86( +F-O;6UE;G0     
M                                                   !     0  
M  (   #4@ 0(U    !,               $         "0    4    "    
MZ( $".@   "0     P         $    !     \    +     @   'B!! AX
M 0  $ $   0    !    !    !     7     P    (   "(@@0(B (  )P 
M              $         'P    D    "    )(,$""0#   X     P  
M  <    $    "    "@    !    !@   %R#! A< P   P              
M!          N     0    8   !@@P0(8 ,  (                0    $
M    ,P    $    &    X(,$". #  #P               $         #D 
M   !    !@   -"$! C0!    P              !          _     0  
M  (   #4A 0(U 0   0               0         1P    $    #    
MV)0$"-@$   $               $         $T    !     P   -R4! C<
M!   *               !     0   !2    !@    ,    $E00(! 4  '  
M   $          0    (    6P    @    #    =)4$"'0%   $        
M       $         '     #              !T!0  @P              
( 0          
 
end
!EOF!
uudecode checker.uu
rm -f checker.uu
if [ "`sum checker`" != "${CHECKER_SUM}" ]
then
	echo "$N: Program 'checker' extracted incorrectly!"
	cd ${OWD}
	rm -rf ${BKUP}
	exit 1
fi
chmod 700 checker

cat > patcher.uu <<\!EOF!
begin 777 patcher
M?T5,1@$! 0            (  P !    9(8$"#0   !<#P       #0 (  %
M "@ $0 0  8    T    -( $"     "@    H     4          P   -0 
M             !,         !          !    -    #2 ! @     ? T 
M 'P-   %     !    $   "P#0  L)T$"      @ 0  Y 0   <     $   
M @   & .  !@G@0(     '          !P         O=7-R+VQI8B]L:6)C
M+G-O+C$  !$    @    %     P    ;    &0   !X    :         !4 
M   <    &    !T    %          \    ?    "P   !              
M       !     @                                    D         
M           (          0    &         !,    #    $@   !8     
M    #@    <         #0   !$    *    %P                      
M   !    T)X$", #   1  \ !P   /2%! @     $@    P    4A@0(    
M !(    1    !(8$" P"   2    &    )2%! @     $@   !\   #0G@0(
MP ,  "$ #P D    5(4$"!P    2    +0   )2B! @     $0#Q_S(    ,
MG@0(!    !$ #  [    L(T$"      1 /'_0@   &2%! A     $@   $D 
M  #0G@0(     !$ \?]0    I(4$"      2    6    "2&! @     $@  
M %X   "$A00(     !(   !C    Q(4$"      2    :P   %2&! @     
M$@   '$     G@0(!    !$ # !X    D*($" 0    1  \ ?@    2>! @$
M    $0 , (4   #\BP0(!    !$ "@"2    M(4$"      2    F@   -2%
M! B0    $@   *(   !TA00(     !(   "L    _)T$" 0    1  P LP  
M  B>! @$    $0 , +H    0G@0(     !$ \?_0    -(8$"      2    
MUP   $2&! B,    $@   -X   !@G@0(     !$ \?_G    Y(4$"(0"   2
M     %]?:6]B &]P96X <F5A9 !M86QL;V, 7WAS=&%T %]I;V( 7V-L96%N
M=7  7V5N9 !?96YV:7)O;@!?971E>'0 871E>&ET %]E9&%T80!?;'AS=&%T
M &-L;W-E &5X:70 7WAM:VYO9 !W<FET90!O<'1I;F0 97)R;F\ ;W!T;W!T
M %]L:6)?=F5R<VEO;@!?9GAS=&%T &9P<FEN=&8 7U]F<'-T87)T &]P=&5R
M<@!O<'1A<F< 7T=,3T)!3%]/1D93151?5$%"3$5? &UE;6-P>0!P<FEN=&8 
M7T193D%-24, 9V5T;W!T "]U<W(O;&EB+VQI8F,N<V\N,0     <G@0(!P< 
M "">! @'"P  ))X$" <8   HG@0(!P\  "R>! @'!0  ,)X$" <-   TG@0(
M!Q8  #B>! @'$   /)X$" <7  ! G@0(!Q\  $2>! @' @  2)X$" <$  !,
MG@0(!P,  %">! @'#@  5)X$" <<  !8G@0(!QT  %R>! @'$0  P@   /\U
M%)X$"/\E&)X$"     #_)1R>! AH     .G@_____R4@G@0(: @   #IT/__
M__\E))X$"&@0    Z<#_____)2B>! AH&    .FP_____R4LG@0(:"    #I
MH/____\E,)X$"&@H    Z9#_____)32>! AH,    .F _____R4XG@0(:#@ 
M  #I</____\E/)X$"&A     Z6#_____)4">! AH2    .E0_____R5$G@0(
M:%    #I0/____\E2)X$"&A8    Z3#_____)4R>! AH8    .D@_____R50
MG@0(:&@   #I$/____\E5)X$"&AP    Z0#_____)5B>! AH>    .GP_O__
M_R5<G@0(:(    #IX/[__VH :@"+[%*X5(4$"(7 = UH5(4$".CF_O__@\0$
MN&">! B%P'0%Z-7^__]H^(L$".C+_O__BT4(C52%$(D5#)X$"%*-50Q24.B/
M_O__Z+[^___HK0   (/$#%#HP/[__VH N $   ":      < ],/K&O]U#/]U
M"&H"Z+'^__^#Q R)1?R+1?SK ,G#58OL4.O@B\#K&O]U#/]U"&H"Z)W^__^#
MQ R)1?R+1?SK ,G#58OL4.O@B\#K&O]U#/]U"&H"Z(G^__^#Q R)1?R+1?SK
M ,G#58OL4.O@B\#K'?]U$/]U#/]U"&H"Z'+^__^#Q!")1?R+1?SK ,G#58OL
M4.O=C4  Z7H$  #'A2#___\     QX4<____     .FG    Z8D   "#O1S_
M__\ =!^+10S_,&@ C 0(:/">! CH+/[__X/$#&H!Z-+]__]9QX4@____ 0  
M .MN@[T@____ '0?BT4,_S!H((P$"&CPG@0(Z/C]__^#Q QJ >B>_?__6<>%
M'/___P$   #K.HM%#/\P:$",! AH\)X$".C-_?__@\0,:@'H<_W__UGK&8N%
M)/___X/X/W34@_AC#X1C____@_AU=))H:(P$"/]U#/]U".BG_?__@\0,B84D
M____@_C_#X4W____@[T@____ '4.BT4(*P4 G@0(@_@"=1>#O2#___\ ="V+
M10@K!0">! B#^ %T'XM%#/\P:&R,! AH\)X$".A#_?__@\0,:@'HZ?S__UF+
M10R+%0">! C_!0">! B+!)")1?1J /]U].@Y_?__@\0(B47\A<!](_\UD*($
M"/]U]&B4C 0(:/">! CH]_S__X/$$&H!Z)W\__]9C85@____4/]U_.@E_O__
M@\0(A<!](_\UD*($"/]U]&BTC 0(:/">! CHOOS__X/$$&H!Z&3\__]9BUV0
M4^C:_/__68F%7/___U/_M5S_____=?SHU/S__X/$##O#="3_-9"B! C_=?13
M:-2,! AH\)X$".AT_/__@\04:@'H&OS__UG_=?SHL?S__UG'1>P     Z98!
M  "+1>R+!(7LG00(B47H_W7H:T7L'HV L)T$"%"-A2C___]0Z(W\__^#Q R#
MO2#___\ =0F#O1S___\ =!*+1>R+!(7TG00(QH0%*/____\S_S/VZR/K#8U&
M_ROX,_8[^W8"ZQ*+A5S___^*!#@ZA#4H____=>%'1CMUZ',$._MRU#MUZ ^%
M"@$  "M]Z(.](/___P!U#8.]'/___P /A($   "+QXM5[ ,$E?2=! B+E5S_
M__\/M@00/?\   !T'VC_    : "-! AH\)X$".B!^___@\0,:@'H)_O__UF#
MO2#___\ = AJ .@6^___68O'BU7L P25])T$"(N57/___\8$$,^+1>R+!(7T
MG00(C40' 5!H'(T$".BF^___@\0(ZWV+QXM5[ ,$E?2=! B+E5S___\/M@00
M/<\   !T'VC/    :""-! AH\)X$".@ ^___@\0,:@'HIOK__UF+QXM5[ ,$
ME?2=! B+E5S____&!!#_BT7LBP2%])T$"(U$!P%0:#R-! CH-OO__X/$".L-
M_T7L@WWL @^"8/[__X-][ )U(X.](/___P!U$FA C00(:/">! CHEOK__X/$
M"&H!Z#SZ__]9BT4,BQ4 G@0(BP20B47P:+8!  !H @$  /]U\.B*^O__@\0,
MB47XA<!](_\UD*($"/]U\&ADC00(:/">! CH2/K__X/$$&H!Z.[Y__]94_^U
M7/____]U^.BN^O__@\0,.\-T)/\UD*($"/]U\%-HA(T$"&CPG@0(Z [Z__^#
MQ!1J >BT^?__6?]U^.A+^O__66H Z*/Y__]96UY?R<-5B^R![.P   !75E/I
M=?O__\(         )7,Z(&]N;'D@;VYE(&]F("UC+" M=2!A;&QO=V5D"@ E
M<SH@;VYL>2!O;F4@;V8@+6,L("UU(&%L;&]W960* '5S86=E.B E<R!;+6,@
M?" M=5T@:6XM9FEL92!;;W5T+69I;&5="@!C=0  =7-A9V4Z("5S(%LM8R!\
M("UU72!I;BUF:6QE(%MO=70M9FEL95T* &9A:6QE9"!T;R!O<&5N*"D@)7,L
M(&5R<FYO/25D"@  0V]U;&0@;F]T('-T870H*2 E<RP@97)R;F\])60*  !F
M86EL960@=&\@<F5A9"@I("5D(&)Y=&5S('1O("5S+"!E<G)N;STE9 H  #\_
M/R P>"4P,G@@;F]T(&9O=6YD(#\_/PH    E9 H /S\_(#!X)3 R>"!N;W0@
M9F]U;F0@/S\_"@   "5D"@!D:60@;F]T(&9I;F0@86YY(&UA=&-H('-T<FEN
M9W,A"@    !F86EL960@=&\@;W!E;B@I("5S+"!E<G)N;STE9 H  &9A:6QE
M9"!T;R!W<FET92@I("5D(&)Y=&5S('1O("5S+"!E<G)N;STE9 H BU0D!(%B
M0/_/__^!2D   @                  @6= _\___X%/0  "  "!3SP$    
M            $@   !4    (    !     $    !                    
M8)X$"           6H4$"&J%! AZA00(BH4$")J%! BJA00(NH4$",J%! C:
MA00(ZH4$"/J%! @*A@0(&H8$""J&! @ZA@0(2H8$"%J&! @!    [@    P 
M  ! A00(#0   /B+! @$    Z( $" 4   "T@P0(!@   +2!! @*     0$ 
M  L    0    %0         #    $)X$" (   "(    %    !$    7    
MN(0$"            "YI;G1E<G  +FAA<V@ +F1Y;G-Y;0 N9'EN<W1R "YR
M96PN<&QT "YI;FET "YP;'0 +G1E>'0 +F9I;FD +G)O9&%T80 N<F]D871A
M,0 N9&%T80 N9V]T "YD>6YA;6EC "YB<W, +G-Y;71A8@ N<W1R=&%B "YS
M:'-T<G1A8@ N8V]M;65N=                                       
M                 0    $    "    U( $"-0    3               !
M          D    %     @   .B ! CH    S     ,         !     0 
M   /    "P    (   "T@00(M $    "   $     0    0    0    %P  
M  ,    "    M(,$"+0#   ! 0             !         !\    )    
M @   +B$! BX!   B     ,    '    !     @    H     0    8   ! 
MA00(0 4   ,               0         +@    $    &    1(4$"$0%
M   @ 0             $    !    #,    !    !@   &2&! AD!@  E 4 
M            !          Y     0    8   #XBP0(^ L   ,         
M      0         /P    $    "    _(L$"/P+   $               $
M         $<    !     @    ",! @ #   L $             !       
M  !0     0    ,   "PG00(L T  &                0         5@  
M  $    #    $)X$"! .  !0               $    !    %L    &    
M P   &">! A@#@  <     0         !     @   !D    "     ,   #0
MG@0(T X  ,0#              0         >0    ,              - .
6  ",               !            
 
end
!EOF!
uudecode patcher.uu
rm -f patcher.uu
if [ "`sum patcher`" != "${PATCHER_SUM}" ]
then
	echo "$N: Program 'patcher' extracted incorrectly!"
	cd ${OWD}
	rm -rf ${BKUP}
	exit 1
fi
chmod 700 patcher

echo "$N: The programs we need have been extracted successfully"

#
# OK.  Now we have the programs we need.  Run checker to see if the patch
# is needed.
#
rm -f core
(./checker; exit $? ) > /dev/null 2>&1
if [ "$?" != "0" ]
then
	if [ ! -f core ]
	then
		echo "$N: Check failed, but no core file???  Aborting."
		cd ${OWD}
		rm -rf ${TMPDIR}
		exit 1
	else
		rm -f core
		echo "$N: The bug exists.  Will proceed with the patch"
	fi
else
	echo "$N: Patch is not needed; bug not present."
	cd ${OWD}
	rm -rf ${TMPDIR}
	exit 0
fi

#
# OK.  We need to do the patch.  Make a directory in /etc/conf/pack.d/kernel
# to hold our stuff (we'll store a backup os.o there, and put the programs 
# there, and their source as well).
#
PACK=/etc/conf/pack.d/kernel
BKUP=${PACK}/.xfree86
if [ -d ${BKUP} ]
then
	echo "$N: Backup directory ${BKUP} exists"
	echo "    but bug not fixed. Aborting"
	cd ${OWD}
	rm -rf ${TMPDIR}
	exit 1
fi

mkdir ${BKUP}
if [ ! -d ${BKUP} ]
then
	echo "$N: Failed to make backup directory ${BKUP}"
	cd ${OWD}
	rm -rf ${TMPDIR}
	exit 1
fi
cp ${TMPDIR}/* ${BKUP}
cd ${BKUP}
rm -rf ${TMPDIR}
./patcher -c ../os.o
if [ "$?" = "0" ]
then
	echo "$N: Patch already applied, but bug not fixed. Aborting"
	cd ${OWD}
	rm -rf ${BKUP}
	exit 1
fi

#
# Stash the backup
#
cp ../os.o ./os.o.SAV
echo "$N: A copy of os.o has been saved in ${BKUP}"
LOC=`./patcher ../os.o ./Nos.o`
if [ "$?" != "0" ]
then
	echo "$N: Patch failed!!!"
	cd ${OWD}
	rm -rf ${BKUP}
	exit 1
fi
LOC1=`cmp -l ../os.o ./Nos.o | awk '{print $1; exit}'`
if [ "$LOC" != "$LOC1" ]
then
	echo "$N: Patch sanity check failed!!!"
	cd ${OWD}
	rm -rf ${BKUP}
	exit 1
fi
echo "$N: Patch successfully applied.  Installing it."
mv ./Nos.o ../os.o

#
# OK.  Patch is installed.  Now do an idbuild
#
echo "$N: Building the new kernel."
/etc/conf/bin/idbuild 2>/tmp/idb.$$
if [ "$?" != "0" ]
then
	echo "$N: Kernel build failed!  Errors are in /tmp/idb.$$"
	cd ${OWD}
	exit 1
fi
rm -f /tmp/idb.$$

#
# Kernel is now rebuilt.  
#
echo "$N: Kernel successfully rebuilt."

#
# Stash the source files
#
echo "$N: Copies of the source for my programs"
echo "    will be in ${BKUP}"
cat >> checker.c <<\!EOF!
#include <sys/types.h>
#include <sys/proc.h>
#include <sys/sysi86.h>
#include <sys/tss.h>
#include <sys/v86.h>
#include <signal.h>
#include <stdio.h>

#ifdef __GNUC__
static __inline__ unsigned int
inb(port)
     short port;
{
  unsigned int ret;
  __asm__ __volatile__("in%B0 (%1)" :
                   "=a" (ret) :
                   "d" (port));
  return ret;
}
#else
#include <sys/inline.h>
#endif


#define PORT 0x1260

void sighand(signo)
int signo;

{
   return;
}

main()
{
        int i;

        sigset(SIGUSR1, sighand);
        sysi86(SI86V86, V86SC_IOPL, PS_IOPL);
        i = inb(PORT);
        kill(getpid(), SIGUSR1);
        i = inb(PORT);
        exit(0);
}
!EOF!
cat > patcher.c <<\!EOF!
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#ifdef __STDC__
# include <stdlib.h>
#else
# include <malloc.h>
#endif

#define NUM_PATTERNS	2
unsigned char match_buf[NUM_PATTERNS][30] = { 
	{
	/* SVR4 */
	0x8b,0x54,0x24,0x04,			/* movl 4(%esp),%edx */
	0x81,0x62,0x40,0xff,0xcf,0xff,0xff,	/* andl $0xffffcfff,64(%edx) */
	0x81,0x4a,0x40,0x00,0x02,0x00,0x00,	/* orl $0x200,64(%edx) */
	},
	{
	/* SVR3 */
	0x81,0x67,0x40,0xff,0xcf,0xff,0xff,	/* andl $0xffffcfff,64(%edi) */
	0x81,0x4f,0x40,0x00,0x02,0x00,0x00,	/* orl $0x200,64(%edi) */
	0x81,0x4f,0x3c,0x04,0x00,0x00,0x00,	/* orl $0x4,60(%edi) */
	},
};

int match_lengths[] = {18,21};
int match_offset[] = {8,4};
#define EXPECT	0xcf
#define CHANGE	0xff

main(argc, argv)
int argc;
char *argv[];
{
	int ifd, ofd;
	char *ifname, *ofname;
	unsigned int i, j, k;
	unsigned int file_len, match_len;
	struct stat stat_buf;
	unsigned char *file_buf, hold_buf[50]; 
	int c, check=0, undo=0;
	char *infname, *outfname;
	extern int optind;

	
	while ((c=getopt(argc, argv, "cu")) != EOF) {
		switch (c) {
		case 'c':
			if (undo) {
				fprintf(stderr, 
					"%s: only one of -c, -u allowed\n", 
					argv[0]);
				exit(1);
			}
			check = 1;
			break;
		case 'u':
			if (check) {
				fprintf(stderr, 
					"%s: only one of -c, -u allowed\n", 
					argv[0]);
				exit(1);
			}
			undo = 1;
			break;
		case '?':
			fprintf(stderr, 
				"usage: %s [-c | -u] in-file [out-file]\n", 
				argv[0]);
			exit(1);
		}
	}
				
	if ((!check && (argc-optind != 2)) || (check && (argc-optind != 1))) {
		fprintf(stderr, "usage: %s [-c | -u] in-file [out-file]\n", 
			argv[0]);
		exit(1);
	}

	ifname = argv[optind++];
	if ((ifd = open(ifname, O_RDONLY)) < 0) {
		fprintf(stderr, "failed to open() %s, errno=%d\n",
			ifname, errno);
		exit(1);
	}
	if (fstat(ifd, &stat_buf) < 0) {
		fprintf(stderr, "Could not stat() %s, errno=%d\n",
			ifname, errno);
		exit(1);
	}
	file_len = stat_buf.st_size;
	file_buf = malloc(file_len);
	if (read(ifd, file_buf, file_len) != file_len) {
		fprintf(stderr, "failed to read() %d bytes to %s, errno=%d\n",
			file_len, ifname, errno);
		exit(1);
	}
	close(ifd);

	for (k=0; k < NUM_PATTERNS; k++) {
		match_len = match_lengths[k];
		memcpy(hold_buf, match_buf[k], match_len);
		if (check || undo)
			hold_buf[match_offset[k]] = CHANGE;
		for (i=0, j=0; j < match_len && i < file_len; i++, j++) {
			while (file_buf[i] != hold_buf[j]) {
				i -= j-1;
				j = 0;
				if (i > file_len)
					break;
			}
		}
		if (j == match_len) {
			/* 
	 		 * Here, i is pointing to the end of the match 
			 * string.  Move it back to the beginning.
	 		 */
			i -= match_len;
			if (check || undo) {
				/*
			 	 * Sanity check.
			 	 */
				if (file_buf[i+match_offset[k]] != CHANGE) {
					fprintf(stderr, 
						"??? 0x%02x not found ???\n",
						CHANGE);
					exit(1);
				}
				if (check)
					exit(0);

				file_buf[i+match_offset[k]] = EXPECT;
				/*
			 	 * Print out the byte offset of the change.  We
			  	 * can double-check this with 'cmp -l'.
			 	 */
				printf("%d\n", i + match_offset[k] + 1);
				break;
			}
			else {
				/*
			 	 * Sanity check.
			 	 */
				if (file_buf[i+match_offset[k]] != EXPECT) {
					fprintf(stderr, 
						"??? 0x%02x not found ???\n",
						EXPECT);
					exit(1);
				}
				file_buf[i+match_offset[k]] = CHANGE;
				/*
			 	 * Print out the byte offset of the change.  We
			  	 * can double-check this with 'cmp -l'.
			 	 */
				printf("%d\n", i + match_offset[k] + 1);
				break;
			}
		}
	}

	if (k == NUM_PATTERNS) {
		if (!check)
			fprintf(stderr, "did not find any match strings!\n");
		exit(1);
	}

	ofname = argv[optind];
	if ((ofd = open(ofname, O_RDWR|O_CREAT, 0666)) < 0) {
		fprintf(stderr, "failed to open() %s, errno=%d\n",
			ofname, errno);
		exit(1);
	}
	if (write(ofd, file_buf, file_len) != file_len) {
		fprintf(stderr, "failed to write() %d bytes to %s, errno=%d\n",
			file_len, ofname, errno);
		exit(1);
	}
	close(ofd);
	exit(0);
}
!EOF!

#
# Now store the removal script.
#
cat > ${N}_rem <<\!EOF!
#!/bin/sh
######################################################################
#
# Back out the patch to kernel that prevents losing IOPL on signals.
#
# Version 1.0 - 11/18/92
#	initial version - dwex@goblin.org, dwex@aib.com
#

N=`basename $0`

#
# Make sure we're running on SVR4!
#
uname -r | grep '4' > /dev/null
if [ "$?" != "0" ]
then
	echo "$N: This only applies to SVR4!"
	exit 1
fi

#
# Next make sure we are running as root
#
id | grep 'uid=0' > /dev/null
if [ "$?" != "0" ]
then
	echo "$N: Must be run as root!"
	exit 1
fi

#
# OK.  Now undo the patch.
#
PACK=/etc/conf/pack.d/kernel
BKUP=${PACK}/.xfree86
if [ ! -d ${BKUP} ]
then
	echo "$N: Backup directory ${BKUP} does not exist!"
	exit 1
fi
OWD=${PWD}
cd ${BKUP}

./patcher -c ../os.o
if [ "$?" != "0" ]
then
	echo "$N: Patch not applied. Aborting"
	cd ${OWD}
	exit 1
fi

LOC=`./patcher -u ../os.o ./Nos.o`
if [ "$?" != "0" ]
then
	echo "$N: Patch removal failed!!!"
	cd ${OWD}
	exit 1
fi
LOC1=`cmp -l ../os.o ./Nos.o | awk '{print $1; exit}'`
if [ "$LOC" != "$LOC1" ]
then
	echo "$N: Patch sanity check failed!!!"
	cd ${OWD}
	exit 1
fi
echo "$N: Patch successfully removed.  Installing unpatched module."
mv ./Nos.o ../os.o

#
# OK.  Patch is removed.  Now do an idbuild
#
echo "$N: Building the new kernel."
/etc/conf/bin/idbuild 2>/tmp/idb.$$
if [ "$?" != "0" ]
then
	echo "$N: Kernel build failed!  Errors are in /tmp/idb.$$"
	cd ${OWD}
	exit 1
fi
rm -f /tmp/idb.$$

#
# Kernel is now rebuilt.  
#
echo "$N: Kernel successfully rebuilt."
cd ${OWD}
rm -rf ${BKUP}

#
# Kernel is now rebuilt.  Check if we should reboot now.
#
REBOOT=0
echo "$N: You must reboot before patch takes effect.  Reboot now? \c"
read RESP
case ${RESP} in
	[yY]*)
		REBOOT=1
		;;
	*)
		echo "$N: OK.  But remember to reboot later"
		;;
esac

cd ${OWD}
rm -rf ${BKUP}
#
# All done.  Reboot if necessary
#
if [ ${REBOOT} = "1" ]
then
	cd /
	sync
	/usr/sbin/shutdown -i6 -g15 -y &
fi
exit 0
######################################################################
!EOF!
chmod 700 ${N}_rem

#
# Give the user some info that he will surely forget
#
echo ""
echo "$N: To back out this patch, execute the script ${N}_rem,"
echo "    a copy of which can be found in the save directory"
echo "    ${BKUP}.  To verify that the patch"
echo "    was successful, after rebooting with the new kernel,"
echo "    you can execute the program 'checker' (as root), which"
echo "    is also located in the save directory.  This program"
echo '    should exit with an exit code of 0 (i.e. $? == 0).'
echo ""

#
# Check if we should reboot now.
#
REBOOT=0
echo "$N: You must reboot before patch takes effect.  Reboot now? \c"
read RESP
case ${RESP} in
	[yY]*)
		REBOOT=1
		;;
	*)
		echo "$N: OK.  But remember to reboot later"
		;;
esac

#
# All done.  Reboot if necessary
#
if [ ${REBOOT} = "1" ]
then
	cd /
	sync
	/usr/sbin/shutdown -i6 -g15 -y &
fi
exit 0