DSP_FD_CUR=3
DSP_FD_NEW=800

function usage() {
    echo usage: $0 pid ...
    echo "Note: This program assumes that the program's FD $DSP_FD_CUR is the sound"
    echo "      device FD, and that the program does not use memory-mapped writes."
    echo "      Also it is assumed that $DSP_FD_NEW is unused."
    exit 1
}
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=$$
    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 $PID
call dup2($DSP_FD_CUR, $DSP_FD_NEW)
call open("/dev/null", 2)
call dup2(\$2, $DSP_FD_CUR)
call close(\$2)
detach
EOF
    gdb -batch -x "$BATCHFILE" >/dev/null 2>&1 </dev/null
    rm "$BATCHFILE"
done