Re-create OCI runtimes by path when it is missing

When an OCI runtime is given by full path, we need to ensure we
use the same runtime on subsequent use. Unfortunately, users are
often not considerate enough to use the same `--runtime` flag
every time they invoke runtime - and if the runtime was not in
containers.conf, that means we don't have it stored inn the
libpod Runtime.

Fortunately, since we have the full path, we can initialize the
OCI runtime for use at the point where we pull the container from
the database.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

libpod/boltdb_state_internal.go

@@ -2,7 +2,7 @@ package libpod
 
 import (
 	"bytes"
-	"path/filepath"
+	"os"
 	"runtime"
 	"strings"
 
@@ -400,14 +400,30 @@ func (s *BoltState) getContainerFromDB(id []byte, ctr *Container, ctrsBkt *bolt.
 		// Handle legacy containers which might use a literal path for
 		// their OCI runtime name.
 		runtimeName := ctr.config.OCIRuntime
-		if strings.HasPrefix(runtimeName, "/") {
-			runtimeName = filepath.Base(runtimeName)
-		}
-
 		ociRuntime, ok := s.runtime.ociRuntimes[runtimeName]
 		if !ok {
-			// Use a MissingRuntime implementation
-			ociRuntime = getMissingRuntime(runtimeName, s.runtime)
+			runtimeSet := false
+
+			// If the path starts with a / and exists, make a new
+			// OCI runtime for it using the full path.
+			if strings.HasPrefix(runtimeName, "/") {
+				if stat, err := os.Stat(runtimeName); err == nil && !stat.IsDir() {
+					newOCIRuntime, err := newConmonOCIRuntime(runtimeName, []string{runtimeName}, s.runtime.conmonPath, s.runtime.runtimeFlags, s.runtime.config)
+					if err == nil {
+						// The runtime lock should
+						// protect against concurrent
+						// modification of the map.
+						ociRuntime = newOCIRuntime
+						s.runtime.ociRuntimes[runtimeName] = ociRuntime
+						runtimeSet = true
+					}
+				}
+			}
+
+			if !runtimeSet {
+				// Use a MissingRuntime implementation
+				ociRuntime = getMissingRuntime(runtimeName, s.runtime)
+			}
 		}
 		ctr.ociRuntime = ociRuntime
 	}