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// Copyright 2016 CoreOS, Inc.
// Copyright 2016 Luke Shumaker
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sd_daemon
import (
"os"
"strconv"
"time"
)
// WatchdogEnabled returns how often the process is expected to send a
// keep-alive notification to the service manager.
//
// Notify(0, false, "WATCHDOG=1", nil) // send keep-alive notification
//
// If unsetEnv is true, then (regardless of whether the function call
// itself succeeds or not) it will unset the environmental variables
// WATCHDOG_USEC and WATCHDOG_PID, which will cause further calls to
// this function to fail.
//
// If an error is returned, then the duration is 0. If the service
// manager is not expecting a keep-alive notification from this
// process (or if this has already been called with unsetEnv=true),
// then ErrDisabled is returned. If there is an error parsing the
// service manager's watchdog request, then an appropriate other error
// is returned.
func WatchdogEnabled(unsetEnv bool) (time.Duration, error) {
if unsetEnv {
defer func() {
_ = os.Unsetenv("WATCHDOG_USEC")
_ = os.Unsetenv("WATCHDOG_PID")
}()
}
usecStr, haveUsec := os.LookupEnv("WATCHDOG_USEC")
if !haveUsec {
return 0, ErrDisabled
}
usec, err := strconv.ParseInt(usecStr, 10, 64)
if err != nil || usec < 0 {
return 0, err
}
if pidStr, havePid := os.LookupEnv("WATCHDOG_PID"); havePid {
pid, err := strconv.Atoi(pidStr)
if err != nil {
return 0, err
}
if pid != os.Getpid() {
return 0, ErrDisabled
}
}
return time.Duration(usec) * time.Microsecond, nil
}
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