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process.subr
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process.subr
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# Copyright 2012 Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# * Neither the name of Google Inc. nor the names of its contributors
# may be used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
shtk_import cleanup
shtk_import cli
shtk_process_run() {
local timeout=
local OPTIND
while getopts ':t:' arg "${@}"; do
case "${arg}" in
t) # Timeout.
timeout="${OPTARG}"
;;
:)
shtk_cli_error "Missing argument to option -${OPTARG} in" \
"shtk_process_run"
;;
\?)
shtk_cli_error "Unknown option -${OPTARG} in shtk_process_run"
;;
esac
done
shift $((${OPTIND} - 1))
OPTIND=1 # Should not be necessary due to the 'local' above.
shtk_cli_info "Running '${@}' in $(pwd)"
local ret=
if [ -z "${timeout}" ]; then
ret=0
"${@}" || ret="${?}"
else
# Spawning a process with a timeout is tricky because we have to spawn
# two subprocesses: one to run the actual process and one to act as a
# watchdog. Because both of these processes are blocking, we cannot
# perform their duties on the current process. These two processes kill
# themselves mutually on completion regardless of the order in which
# they finish and, because their interdependency, we need to pass
# details between them with a file. Once they are both dead, we have to
# guess what actually happened.
#
# The cookie file below works like this: first, the PID of the
# subprocess running the desired command is written to it. The watchdog
# process uses the content of this file to kill the subprocess if
# needed. Once the subprocess has finished, its exit status is written
# to the cookie. If the subprocess has been killed, then the magic word
# TIMEOUT is written to the cookie.
local pattern="${TMPDIR:-/tmp}/shtk.XXXXXX"
local cookie="$(mktemp "${pattern}" 2>/dev/null)"
[ -f "${cookie}" ] || shtk_cli_error "Failed to create temporary file" \
"using pattern ${pattern}"
eval "shtk_process_run_remove_cookie() { rm -f '${cookie}'; }"
shtk_cleanup_register shtk_process_run_remove_cookie
(
sleep "${timeout}"
while [ -z "$(cat "${cookie}")" ]; do
# Race protection: the process has not yet started.
sleep 1
done
local pid="$(cat "${cookie}")"
shtk_cli_warning "Timer expired; killing ${pid}"
kill -9 "${pid}"
echo "TIMEOUT" >"${cookie}"
) &
local watchdog="${!}"
(
local ret=0
"${@}" || ret="${?}"
kill -9 "${watchdog}"
while [ -z "$(cat "${cookie}")" ]; do
# Race protection: the parent has not yet written the cookie.
sleep 1
done
echo "${ret}" >"${cookie}"
) &
local subprocess="${!}"
echo "${subprocess}" >"${cookie}"
wait >/dev/null 2>&1 # Silence 'Killed' notifications.
ret="$(cat "${cookie}")"
rm -f "${cookie}"
fi
[ -n "${ret}" ] || shtk_cli_error "ret not initialized; something failed"
if [ "${ret}" = "TIMEOUT" ]; then
shtk_cli_warning "Command timed out after ${timeout} seconds"
ret=127
elif [ "${ret}" -eq 0 ]; then
shtk_cli_info "Command finished successfully"
else
shtk_cli_warning "Command failed with code ${ret}"
fi
return "${ret}"
}