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@@ -0,0 +1,72 @@
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+// Copyright 2016 CoreOS, Inc.
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+//
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+// Licensed under the Apache License, Version 2.0 (the "License");
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+// you may not use this file except in compliance with the License.
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+// You may obtain a copy of the License at
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+//
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+// http://www.apache.org/licenses/LICENSE-2.0
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+//
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+// Unless required by applicable law or agreed to in writing, software
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+// distributed under the License is distributed on an "AS IS" BASIS,
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+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+// See the License for the specific language governing permissions and
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+// limitations under the License.
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+
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+package daemon
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+
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+import (
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+ "fmt"
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+ "os"
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+ "strconv"
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+ "time"
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+)
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+
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+// SdWatchdogEnabled return watchdog information for a service.
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+// Process should send daemon.SdNotify("WATCHDOG=1") every time / 2.
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+// If `unsetEnvironment` is true, the environment variables `WATCHDOG_USEC`
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+// and `WATCHDOG_PID` will be unconditionally unset.
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+//
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+// It returns one of the following:
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+// (0, nil) - watchdog isn't enabled or we aren't the watched PID.
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+// (0, err) - an error happened (e.g. error converting time).
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+// (time, nil) - watchdog is enabled and we can send ping.
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+// time is delay before inactive service will be killed.
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+func SdWatchdogEnabled(unsetEnvironment bool) (time.Duration, error) {
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+ wusec := os.Getenv("WATCHDOG_USEC")
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+ wpid := os.Getenv("WATCHDOG_PID")
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+ if unsetEnvironment {
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+ wusecErr := os.Unsetenv("WATCHDOG_USEC")
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+ wpidErr := os.Unsetenv("WATCHDOG_PID")
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+ if wusecErr != nil {
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+ return 0, wusecErr
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+ }
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+ if wpidErr != nil {
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+ return 0, wpidErr
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+ }
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+ }
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+
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+ if wusec == "" {
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+ return 0, nil
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+ }
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+ s, err := strconv.Atoi(wusec)
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+ if err != nil {
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+ return 0, fmt.Errorf("error converting WATCHDOG_USEC: %s", err)
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+ }
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+ if s <= 0 {
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+ return 0, fmt.Errorf("error WATCHDOG_USEC must be a positive number")
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+ }
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+ interval := time.Duration(s) * time.Microsecond
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+
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+ if wpid == "" {
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+ return interval, nil
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+ }
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+ p, err := strconv.Atoi(wpid)
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+ if err != nil {
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+ return 0, fmt.Errorf("error converting WATCHDOG_PID: %s", err)
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+ }
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+ if os.Getpid() != p {
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+ return 0, nil
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+ }
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+
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+ return interval, nil
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+}
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