moby--moby/pkg/signal/signal.go

// Package signal provides helper functions for dealing with signals across
// various operating systems.
package signal // import "github.com/docker/docker/pkg/signal"

import (
	"fmt"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"syscall"
)

// CatchAll catches all signals and relays them to the specified channel.
// On Linux, SIGURG is not handled, as it's used by the Go runtime to support
// preemptable system calls.
func CatchAll(sigc chan os.Signal) {
	var handledSigs []os.Signal
	for _, s := range SignalMap {
		if isRuntimeSig(s) {
			// Do not handle SIGURG on Linux, as in go1.14+, the go runtime issues
			// SIGURG as an interrupt to support preemptable system calls on Linux.
			continue
		}
		handledSigs = append(handledSigs, s)
	}
	signal.Notify(sigc, handledSigs...)
}

// StopCatch stops catching the signals and closes the specified channel.
func StopCatch(sigc chan os.Signal) {
	signal.Stop(sigc)
	close(sigc)
}

// ParseSignal translates a string to a valid syscall signal.
// It returns an error if the signal map doesn't include the given signal.
func ParseSignal(rawSignal string) (syscall.Signal, error) {
	s, err := strconv.Atoi(rawSignal)
	if err == nil {
		if s == 0 {
			return -1, fmt.Errorf("Invalid signal: %s", rawSignal)
		}
		return syscall.Signal(s), nil
	}
	signal, ok := SignalMap[strings.TrimPrefix(strings.ToUpper(rawSignal), "SIG")]
	if !ok {
		return -1, fmt.Errorf("Invalid signal: %s", rawSignal)
	}
	return signal, nil
}

// ValidSignalForPlatform returns true if a signal is valid on the platform
func ValidSignalForPlatform(sig syscall.Signal) bool {
	for _, v := range SignalMap {
		if v == sig {
			return true
		}
	}
	return false
}