#!/bin/sh

BASENAME=$(basename $0)

unset LD_PRELOAD

if [ -n "$VALGRIND" -o -n "$SMBD_VALGRIND" ]; then
	echo "${BASENAME}: Not running debugger under valgrind"
	exit 1
fi

if [ "x$PLEASE_NO_GDB_BACKTRACE" != "x" ]; then
	echo "${BASENAME}: Not running debugger because PLEASE_NO_GDB_BACKTRACE is set"
	exit 0
fi

# we want everything on stderr, so the program is not disturbed
exec 1>&2

UNAME=$(uname)

PID=$1
BINARY=$2

test x"${PID}" = x"" && {
	echo "Usage: ${BASENAME} <pid> [<binary>]"
	exit 1
}

DB_LIST="gdb"
case "${UNAME}" in
#
# on Tru64 we need to try ladebug first
# because gdb crashes itself...
#
OSF1)
	DB_LIST="ladebug ${DB_LIST}"
	;;
#
# On solaris dbx is working way more better than gdb
# let's try it first
#
SunOS)
	DB_LIST="dbx ${DB_LIST}"
	;;
#
# FreeBSD comes with a flavor that works gdb66 and one that don't gdb
# (gdb 6.1) let's try it first the one that works !
#
FreeBSD)
	DB_LIST="gdb66 ${DB_LIST}"
	;;
esac

for DB in ${DB_LIST}; do
	DB_BIN=$(which ${DB} 2>/dev/null | grep '^/')
	test x"${DB_BIN}" != x"" && {
		break
	}
done

test x"${DB_BIN}" = x"" && {
	echo "${BASENAME}: ERROR: No debugger found."
	exit 1
}

need_binary="no"
case "${DB}" in
# These debuggers need the process binary specified:
ladebug)
	need_binary="yes"
	;;
gdb66)
	need_binary="yes"
	;;
dbx)
	need_binary="yes"
	;;
esac

test x"${need_binary}" = x"yes" && {

	# we first try to use /proc/${PID}/exe or /proc/{$PID}/path for solaris
	# then fallback to the binary from the commandline
	# then we search for the commandline argument with
	# 'which'
	#
	test -f "/proc/${PID}/exe" && BINARY="/proc/${PID}/exe"
	test -f "/proc/${PID}/path/a.out" && BINARY=$(ls -l /proc/${PID}/path/a.out | sed 's/.*-> //')
	test x"${BINARY}" = x"" && BINARY="/proc/${PID}/exe"
	test -f "${BINARY}" || BINARY=$(which ${BINARY})

	test -f "${BINARY}" || {
		echo "${BASENAME}: ERROR: Cannot find binary '${BINARY}'."
		exit 1
	}
}

BATCHFILE_PRE=$(mktemp --tmpdir gdb_backtrace_pre.XXXXXXXXXX)
test -n "${BATCHFILE_PRE}" || {
	echo "mktemp doesn't work" 1>&2
	exit 1
}
BATCHFILE_MAIN=$(mktemp --tmpdir gdb_backtrace_main.XXXXXXXXXX)
test -n "${BATCHFILE_MAIN}" || {
	echo "mktemp doesn't work" 1>&2
	exit 1
}
case "${DB}" in
ladebug)
	cat <<EOF >${BATCHFILE_PRE}
set \$stoponattach
EOF

	cat <<EOF >${BATCHFILE_MAIN}
where
quit
EOF
	${DB_BIN} -c "${BATCHFILE_MAIN}" -i "${BATCHFILE_PRE}" -pid "${PID}" "${BINARY}"
	;;
gdb66)
	cat <<EOF >${BATCHFILE_MAIN}
set height 1000
bt full
info locals
kill
quit
EOF
	${DB_BIN} -x "${BATCHFILE_MAIN}" "${BINARY}" "${PID}"
	;;
gdb)
	cat <<EOF >${BATCHFILE_MAIN}
set height 0
echo \\n### detailed backtrace\\n\\n
bt full
init-if-undefined \$_inferior_thread_count = 0
if \$_inferior_thread_count != 1
  echo \\n### info threads\\n\\n
  info threads
  echo \\n### backtrace for all threads\\n\\n
  thread apply all bt full
end
echo \\n### info locals\\n\\n
info locals
if PyList_New
  echo \\n### Python traceback\\n\\n
  py-bt
  echo \\n### Python locals\\n\\n
  py-locals
  echo \\n### Python full traceback\\n\\n
  py-bt-full
end
quit
EOF
	${DB_BIN} -batch -x "${BATCHFILE_MAIN}" --pid "${PID}" </dev/null
	;;
dbx)
	${DB_BIN} "where;dump;kill;quit" "${BINARY}" "${PID}"
	;;
esac
/bin/rm -f ${BATCHFILE_PRE} ${BATCHFILE_MAIN}