refactor: move fs-related functions to submodule

fs/fs.go

@@ -0,0 +1,46 @@
+package fs
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// CaseInsensitive check
+func CaseInsensitive(dir string) (yes bool, err error) {
+	pathLowercase := filepath.Join(dir, "file")
+	fLowercase, err := os.Create(pathLowercase)
+	if err != nil {
+		return
+	}
+	defer fLowercase.Close()
+	defer os.Remove(pathLowercase)
+
+	pathUppercase := filepath.Join(dir, "FILE")
+	fUppercase, err := os.Create(pathUppercase)
+	if err != nil {
+		return
+	}
+	defer fUppercase.Close()
+	defer os.Remove(pathUppercase)
+
+	statLowercase, err := fLowercase.Stat()
+	if err != nil {
+		return
+	}
+
+	statUppercase, err := fUppercase.Stat()
+	if err != nil {
+		return
+	}
+
+	yes = os.SameFile(statLowercase, statUppercase)
+	return
+}
+
+// PathExists check
+func PathExists(path string) bool {
+	if _, err := os.Stat(path); err != nil {
+		return false
+	}
+	return true
+}