#!/bin/sh
#
# Trick process(es) to talk to current terminal
#
# Copyright (c) 2004, 2005 Timo Lindfors <timo.lindfors@iki.fi>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
#
# 3. The name of the author may not be used to endorse or promote
# products derived from this software without specific prior written
# permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
# GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
# OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
# IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

function usage() {
    echo usage: $0 pid ...
    exit 1
}
TCGETS=0x5401
TCSETS=0x5402
SIZEOF_STRUCT_TERMIOS=60
O_RDWR=2
((FLAGS=O_RDWR))

if [ x`which gdb` = x ]; then
    echo gdb not found in PATH. Please apt-get install gdb
    exit
fi
if [ x$1 = x ]; then
    usage;
fi

for PID in $@; do
    MYPID=$$
    MYFD0=`readlink /proc/$MYPID/fd/0`
    MYFD1=`readlink /proc/$MYPID/fd/1`
    MYFD2=`readlink /proc/$MYPID/fd/2`
    EXE=`readlink /proc/$PID/exe`
    if [ x$EXE = x ]; then
	echo $0: $PID: no such pid
	exit
    fi

    BATCHFILE=`mktemp /tmp/gdb.XXXXXXXXXXXX`
    cat >$BATCHFILE <<EOF
file $EXE
attach $PID
call malloc($SIZEOF_STRUCT_TERMIOS)
call malloc($SIZEOF_STRUCT_TERMIOS)
call malloc($SIZEOF_STRUCT_TERMIOS)
call ioctl(0, $TCGETS, \$1)
call ioctl(1, $TCGETS, \$2)
call ioctl(2, $TCGETS, \$3)
call close(0)
call close(1)
call close(2)
call open("$MYFD0", $FLAGS)
call open("$MYFD1", $FLAGS)
call open("$MYFD2", $FLAGS)
call ioctl(0, $TCSETS, \$1)
call ioctl(1, $TCSETS, \$2)
call ioctl(2, $TCSETS, \$3)
call free(\$1)
call free(\$2)
call free(\$3)
detach
EOF
    gdb -batch -x $BATCHFILE >/dev/null 2>&1 </dev/null
    rm $BATCHFILE
done
cat <<EOF
Process(es) $@ should now be talking to this pty. Refresh the screen
(e.g. CTRL+L) and have fun!
EOF

exec tail -f --pid=$PID /proc/$PID/stat