Fix handler and systemd activation errors

On panic from handler: log warning and stack trace, report
InternalServerError to client

When using `podman system service` make determining the listening endpoint deterministic.

  // When determining _*THE*_ listening endpoint --
  // 1) User input wins always
  // 2) systemd socket activation
  // 3) rootless honors XDG_RUNTIME_DIR
  // 4) if varlink -- adapter.DefaultVarlinkAddress
  // 5) lastly adapter.DefaultAPIAddress

Fixes #5150
Fixes #5151

Signed-off-by: Jhon Honce <jhonce@redhat.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/pkg/systemd/activation.go b/pkg/systemd/activation.go
new file mode 100644
index 000000000..c8b2389dc
--- /dev/null
+++ b/pkg/systemd/activation.go
@@ -0,0 +1,40 @@
+package systemd
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+// SocketActivated determine if podman is running under the socket activation protocol
+func SocketActivated() bool {
+	pid, pid_found := os.LookupEnv("LISTEN_PID")
+	fds, fds_found := os.LookupEnv("LISTEN_FDS")
+	fdnames, fdnames_found := os.LookupEnv("LISTEN_FDNAMES")
+
+	if !(pid_found && fds_found && fdnames_found) {
+		return false
+	}
+
+	p, err := strconv.Atoi(pid)
+	if err != nil || p != os.Getpid() {
+		return false
+	}
+
+	nfds, err := strconv.Atoi(fds)
+	if err != nil || nfds < 1 {
+		return false
+	}
+
+	// First available file descriptor is always 3.
+	if nfds > 1 {
+		names := strings.Split(fdnames, ":")
+		for _, n := range names {
+			if strings.Contains(n, "podman") {
+				return true
+			}
+		}
+	}
+
+	return true
+}