prepping for walkers to be plugins

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

walker/func.go

@@ -1,8 +1,34 @@
 package walker
 
 import (
+	"fmt"
 	"os"
+	"plugin"
 	"time"
 )
 
+// LoadPlugin loads the file path and returns a Fuzzer
+func LoadPlugin(path string) (Fuzzer, error) {
+	p, err := plugin.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	sym, err := p.Lookup("MyFuzzerFunc")
+	if err != nil {
+		return nil, err
+	}
+	mff, ok := sym.(Fuzzer)
+	if !ok {
+		return nil, fmt.Errorf("plugin at %q did not provide a FuzzFunc named MyFuzzerFunc", path)
+	}
+	return mff, nil
+}
+
+// Fuzzer is a struct that produces a FuzzFunc
+type Fuzzer interface {
+	Name() string
+	Func() FuzzFunc
+}
+
+// FuzzFunc is like filepath.WalkerFunc, but for poking at `path`
 type FuzzFunc func(path string, info os.FileInfo, timeout time.Duration) error