#!/usr/bin/env bash
# Take a backtrace of every thread of an emulator that is running under gdb.
#
# Pair with the wrapper at /sylph-home/re/bin/gdb-wrap/xenia_canary (see
# docs/re/mission-freeze-resume-spin.md): ptrace_scope=1 forbids attaching to a
# running emulator, so it has to be STARTED under gdb.
#
# SIGINT to gdb stops the inferior; commands then go in through the command file
# the wrapper is tailing, and the answer comes back in the gdb log. `continue` at
# the end so the run can carry on.
set -u
CMD="${GDB_CMD_FILE:-/tmp/gdb-cmd}"
OUT="${GDB_OUT_FILE:-/tmp/gdb-out.log}"
DEPTH="${1:-12}"
pid=$(pgrep -x gdb | head -1)
[ -n "$pid" ] || { echo "no gdb process — was the emulator started with XENIA_BIN=/sylph-home/re/bin/gdb-wrap/xenia_canary ?"; exit 1; }
mark="=== BT $(date +%s) ==="
before=$(wc -c < "$OUT")
kill -INT "$pid"
sleep 3
{ echo "echo $mark\\n"; echo "info threads"; echo "thread apply all bt $DEPTH"; echo "echo === END ===\\n"; echo "continue"; } >> "$CMD"
sleep 8
tail -c +$((before + 1)) "$OUT"