Ensure that signal names can be parsed on Windows

To ensure the Windows and OS X remote clients can properly parse
container stop signal (when given as a name e.g. SIGTERM) and
set it in SpecGen, we need access to a list of Linux signal names
and the numbers they map to that is available on non-Linux OSes.
Fortunately, these are ABI constants that are extremely unlikely
to change, so we can just take the existing constant definitions
from the library and use them.

The signal numbers used here are sourced from AMD64, but should
be the same for every architecture that is not Alpha, SPARC,
MIPS, and PA-RISC. So `podman run --stop-signal SIGTTOU` from a
Windows client to a Podman service on a SPARC host will set an
incorrect stop signal, but I don't think this is a large problem.

Signed-off-by: Matthew Heon <mheon@redhat.com>

pkg/signal/signal_common.go

@@ -0,0 +1,41 @@
+package signal
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"syscall"
+)
+
+// 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
+	}
+	sig, ok := signalMap[strings.TrimPrefix(strings.ToUpper(rawSignal), "SIG")]
+	if !ok {
+		return -1, fmt.Errorf("invalid signal: %s", rawSignal)
+	}
+	return sig, nil
+}
+
+// ParseSignalNameOrNumber translates a string to a valid syscall signal.  Input
+// can be a name or number representation i.e. "KILL" "9"
+func ParseSignalNameOrNumber(rawSignal string) (syscall.Signal, error) {
+	basename := strings.TrimPrefix(rawSignal, "-")
+	s, err := ParseSignal(basename)
+	if err == nil {
+		return s, nil
+	}
+	for k, v := range signalMap {
+		if k == strings.ToUpper(basename) {
+			return v, nil
+		}
+	}
+	return -1, fmt.Errorf("invalid signal: %s", basename)
+}

pkg/signal/signal_linux.go

@@ -8,11 +8,8 @@ package signal
 // NOTE: this package has originally been copied from github.com/docker/docker.
 
 import (
-	"fmt"
 	"os"
 	"os/signal"
-	"strconv"
-	"strings"
 	"syscall"
 
 	"golang.org/x/sys/unix"
@@ -94,23 +91,6 @@ var signalMap = map[string]syscall.Signal{
 	"RTMAX":    sigrtmax,
 }
 
-// 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
-	}
-	sig, ok := signalMap[strings.TrimPrefix(strings.ToUpper(rawSignal), "SIG")]
-	if !ok {
-		return -1, fmt.Errorf("invalid signal: %s", rawSignal)
-	}
-	return sig, nil
-}
-
 // CatchAll catches all signals and relays them to the specified channel.
 func CatchAll(sigc chan os.Signal) {
 	var handledSigs []os.Signal
@@ -125,19 +105,3 @@ func StopCatch(sigc chan os.Signal) {
 	signal.Stop(sigc)
 	close(sigc)
 }
-
-// ParseSignalNameOrNumber translates a string to a valid syscall signal.  Input
-// can be a name or number representation i.e. "KILL" "9"
-func ParseSignalNameOrNumber(rawSignal string) (syscall.Signal, error) {
-	basename := strings.TrimPrefix(rawSignal, "-")
-	s, err := ParseSignal(basename)
-	if err == nil {
-		return s, nil
-	}
-	for k, v := range signalMap {
-		if k == strings.ToUpper(basename) {
-			return v, nil
-		}
-	}
-	return -1, fmt.Errorf("invalid signal: %s", basename)
-}

pkg/signal/signal_unsupported.go

@@ -4,17 +4,88 @@
 package signal
 
 import (
-	"fmt"
 	"os"
 	"syscall"
 )
 
-const SIGWINCH = syscall.Signal(0xff)
+const (
+	sigrtmin = 34
+	sigrtmax = 64
 
-// 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) {
-	return 0, fmt.Errorf("unsupported on non-linux platforms")
+	SIGWINCH = syscall.Signal(0xff)
+)
+
+// signalMap is a map of Linux signals.
+// These constants are sourced from the Linux version of golang.org/x/sys/unix
+// (I don't see much risk of this changing).
+// This should work as long as Podman only runs containers on Linux, which seems
+// a safe assumption for now.
+var signalMap = map[string]syscall.Signal{
+	"ABRT":     syscall.Signal(0x6),
+	"ALRM":     syscall.Signal(0xe),
+	"BUS":      syscall.Signal(0x7),
+	"CHLD":     syscall.Signal(0x11),
+	"CLD":      syscall.Signal(0x11),
+	"CONT":     syscall.Signal(0x12),
+	"FPE":      syscall.Signal(0x8),
+	"HUP":      syscall.Signal(0x1),
+	"ILL":      syscall.Signal(0x4),
+	"INT":      syscall.Signal(0x2),
+	"IO":       syscall.Signal(0x1d),
+	"IOT":      syscall.Signal(0x6),
+	"KILL":     syscall.Signal(0x9),
+	"PIPE":     syscall.Signal(0xd),
+	"POLL":     syscall.Signal(0x1d),
+	"PROF":     syscall.Signal(0x1b),
+	"PWR":      syscall.Signal(0x1e),
+	"QUIT":     syscall.Signal(0x3),
+	"SEGV":     syscall.Signal(0xb),
+	"STKFLT":   syscall.Signal(0x10),
+	"STOP":     syscall.Signal(0x13),
+	"SYS":      syscall.Signal(0x1f),
+	"TERM":     syscall.Signal(0xf),
+	"TRAP":     syscall.Signal(0x5),
+	"TSTP":     syscall.Signal(0x14),
+	"TTIN":     syscall.Signal(0x15),
+	"TTOU":     syscall.Signal(0x16),
+	"URG":      syscall.Signal(0x17),
+	"USR1":     syscall.Signal(0xa),
+	"USR2":     syscall.Signal(0xc),
+	"VTALRM":   syscall.Signal(0x1a),
+	"WINCH":    syscall.Signal(0x1c),
+	"XCPU":     syscall.Signal(0x18),
+	"XFSZ":     syscall.Signal(0x19),
+	"RTMIN":    sigrtmin,
+	"RTMIN+1":  sigrtmin + 1,
+	"RTMIN+2":  sigrtmin + 2,
+	"RTMIN+3":  sigrtmin + 3,
+	"RTMIN+4":  sigrtmin + 4,
+	"RTMIN+5":  sigrtmin + 5,
+	"RTMIN+6":  sigrtmin + 6,
+	"RTMIN+7":  sigrtmin + 7,
+	"RTMIN+8":  sigrtmin + 8,
+	"RTMIN+9":  sigrtmin + 9,
+	"RTMIN+10": sigrtmin + 10,
+	"RTMIN+11": sigrtmin + 11,
+	"RTMIN+12": sigrtmin + 12,
+	"RTMIN+13": sigrtmin + 13,
+	"RTMIN+14": sigrtmin + 14,
+	"RTMIN+15": sigrtmin + 15,
+	"RTMAX-14": sigrtmax - 14,
+	"RTMAX-13": sigrtmax - 13,
+	"RTMAX-12": sigrtmax - 12,
+	"RTMAX-11": sigrtmax - 11,
+	"RTMAX-10": sigrtmax - 10,
+	"RTMAX-9":  sigrtmax - 9,
+	"RTMAX-8":  sigrtmax - 8,
+	"RTMAX-7":  sigrtmax - 7,
+	"RTMAX-6":  sigrtmax - 6,
+	"RTMAX-5":  sigrtmax - 5,
+	"RTMAX-4":  sigrtmax - 4,
+	"RTMAX-3":  sigrtmax - 3,
+	"RTMAX-2":  sigrtmax - 2,
+	"RTMAX-1":  sigrtmax - 1,
+	"RTMAX":    sigrtmax,
 }
 
 // CatchAll catches all signals and relays them to the specified channel.
@@ -26,9 +97,3 @@ func CatchAll(sigc chan os.Signal) {
 func StopCatch(sigc chan os.Signal) {
 	panic("Unsupported on non-linux platforms")
 }
-
-// ParseSignalNameOrNumber translates a string to a valid syscall signal.  Input
-// can be a name or number representation i.e. "KILL" "9"
-func ParseSignalNameOrNumber(rawSignal string) (syscall.Signal, error) {
-	return 0, fmt.Errorf("unsupported on non-linux platforms")
-}