55 lines
1.6 KiB
Go
55 lines
1.6 KiB
Go
// Copyright 2026 Alibaba Group
|
|
// 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.
|
|
|
|
//go:build !windows
|
|
|
|
package process
|
|
|
|
import (
|
|
"errors"
|
|
"syscall"
|
|
)
|
|
|
|
var killProcess = syscall.Kill
|
|
|
|
// Alive reports whether a process with the given PID is currently running.
|
|
// Returns false for non-positive PIDs without performing any syscall.
|
|
//
|
|
// On Unix this uses signal 0 (syscall.Kill(pid, 0)), which performs the
|
|
// normal permission/existence check without delivering a signal:
|
|
// - nil error → process exists and we have permission
|
|
// - syscall.EPERM → process exists but owned by another user
|
|
// (still counts as alive for our purpose)
|
|
// - syscall.ESRCH → no such process
|
|
//
|
|
// Any other error is treated as "alive" defensively, so we never steal a
|
|
// lock based on an ambiguous syscall failure.
|
|
func Alive(pid int) bool {
|
|
if pid <= 0 {
|
|
return false
|
|
}
|
|
err := killProcess(pid, 0)
|
|
if err == nil {
|
|
return true
|
|
}
|
|
if errors.Is(err, syscall.EPERM) {
|
|
// Process exists, we just can't signal it.
|
|
return true
|
|
}
|
|
if errors.Is(err, syscall.ESRCH) {
|
|
return false
|
|
}
|
|
// Unknown error: be conservative, treat as alive.
|
|
return true
|
|
}
|