#!/bin/sh
# 
# pstack -- print stack of a process
#
# v 1.0, 08/29/2014 10:27:27
#
# Copyright (c) 2014 Fortinet, Inc. All rights reserved.
# Written by Andrew Wang <wywang@fortinet.com>
#
WC="/bin/wc" 
if test $# -ne 1; then
    echo "Usage: $0 <process-id>" 1>&2
    exit 1
fi
 
if test ! -r /proc/$1; then
    echo "Process $1 not found." 1>&2
    exit 1
fi

if test ! -f $WC; then
	WC="/usr/bin/wc"
fi
 
# GDB doesn't allow "thread apply all bt" when the process isn't
# threaded; need to peek at the process to determine if that or the
# simpler "bt" should be used.
 
backtrace="bt"
if test -d /proc/$1/task ; then
    # Newer kernel; has a task/ directory.
    if test `/bin/ls /proc/$1/task | $WC -l` -gt 1 2>/dev/null ; then
        backtrace="thread apply all bt"
    fi
elif test -f /proc/$1/maps ; then
    # Older kernel; go by it loading libpthread.
    if /bin/grep -e libpthread /proc/$1/maps > /dev/null 2>&1 ; then
        backtrace="thread apply all bt"
    fi
fi
 
GDB=${GDB:-/bin/gdb}

if test ! -f $GDB; then
	GDB="gdb"
fi
 
if $GDB -nx --quiet --batch --readnever > /dev/null 2>&1; then
    readnever=--readnever
else
    readnever=
fi
 
# Run GDB, strip out unwanted noise.
$GDB --quiet $readnever -nx /proc/$1/exe $1 <<EOF 2>&1 |
$backtrace
EOF
/bin/sed -n \
    -e 's/^(gdb) //' \
    -e '/^#/p' \
    -e '/^Thread/p'


