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>

1 files changed, 41 insertions, 0 deletions

diff --git a/pkg/signal/signal_common.go b/pkg/signal/signal_common.go
new file mode 100644
index 000000000..8ff4b4dbf
--- /dev/null
+++ b/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)
+}