1#!/bin/bash
2#
3# Script for running java with a timeout.
4#
5# The timeout in seconds must be the first argument.  The rest of the arguments
6# are passed to the java binary itself.
7#
8# For example:
9#     java-timeout 120 -cp classes.jar org.junit.runner.JUnitCore
10# runs:
11#     java -cp classes.jar org.junit.runner.JUnitCore
12# with a timeout of 2 minutes.
13
14set -euo pipefail
15
16# Prints a message and terminates the process.
17function fatal() {
18  echo "FATAL: $*"
19  exit 113
20}
21
22# Function that is invoked if java is terminated due to timeout.
23# It take the process ID of the java command as an argument if it has already
24# been started, or the empty string if not. It should very rarely receive the
25# empty string as the pid, but it is possible.
26function on_timeout() {
27  echo 'FATAL: command timed out'
28
29  local pid="${1-}"
30  shift || fatal '[on_timeout] missing argument: pid'
31  test $# = 0 || fatal '[on_timeout] too many arguments'
32
33  if [ "$pid" != '' ]; then
34    # It is possible that the process already terminated, but there is not much
35    # we can do about that.
36    kill -TERM -- "-$pid"  # Kill the entire process group.
37  fi
38}
39
40# Executes java with the given argument, waiting for a termination signal from
41# runalarm which this script is running under. The arguments are passed to the
42# java binary itself.
43function execute() {
44  # Trap SIGTERM, which is what we will receive if runalarm interrupts us.
45  local pid  # Set below after we run the process.
46  trap 'on_timeout $pid' SIGTERM
47  # Starts java within a new process group and saves it process ID before
48  # blocking waiting for it to complete. 'setsid' starts the process within a
49  # new process group, which means that it will not be killed when this shell
50  # command is killed. This is needed so that the signal handler in the trap
51  # command above to be invoked before the java command is terminated (and will
52  # in fact have to terminate it itself).
53  setsid java "$@" & pid="$!"; wait "$pid"
54}
55
56# Runs java with a timeout. The first argument is either the timeout in seconds
57# or the string 'execute', which is used internally to execute the command under
58# runalarm.
59function main() {
60  local timeout_secs="${1-}"
61  shift || fatal '[main]: missing argument: timeout_secs'
62  # The reset of the arguments are meant for the java binary itself.
63
64  if [[ $timeout_secs = '0' ]]; then
65    # Run without any timeout.
66    java "$@"
67  elif [[ $timeout_secs = 'execute' ]]; then
68    # This means we actually have to execute the command.
69    execute "$@"
70  elif (( timeout_secs < 30 )); then
71    # We want to have a timeout of at least 30 seconds, so that we are
72    # guaranteed to be able to start the java command in the subshell. This also
73    # catches non-numeric arguments.
74    fatal 'Must specify a timeout of at least 30 seconds.'
75  else
76    # Wrap the command with runalarm if available. If runalarm is not
77    # installed try timeout which is available on Mac if GNU coreutils
78    # is installed.
79    if type runalarm > /dev/null 2>&1 ; then
80      runalarm -t "$timeout_secs" "$0" 'execute' "$@"
81    elif type gtimeout > /dev/null 2>&1 ; then
82      gtimeout "${timeout_secs}s" "$0" 'execute' "$@"
83    else
84      # No way to set a timeout available, just execute directly.
85      echo "Warning: unable to enforce timeout." 1>&2
86      java "$@"
87    fi
88  fi
89}
90
91
92main "$@"
93