binman: Avoid setting sys.path globally

At present we set the Python path at the start of binman so we can read
modules in the 'etype' directory. This is a bit messy since it affects
'import' statements through binman.

Adjust the code to set the path locally, just where it is needed. Move
the 'entry' module in with the other base modules to help with this. It
makes more sense here anyway since it does not implement an entry type.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/binman.py

@@ -23,9 +23,6 @@ for dirname in ['../patman', '../dtoc', '..']:
 # Bring in the libfdt module
 sys.path.insert(0, 'scripts/dtc/pylibfdt')
 
-# Also allow entry-type modules to be brought in from the etype directory.
-sys.path.insert(0, os.path.join(our_path, 'etype'))
-
 import cmdline
 import command
 import control

tools/binman/entry.py

@@ -14,10 +14,14 @@ except:
     have_importlib = False
 
 import fdt_util
+import os
+import sys
 import tools
 
 modules = {}
 
+our_path = os.path.dirname(os.path.realpath(__file__))
+
 class Entry(object):
     """An Entry in the section
 
@@ -80,8 +84,12 @@ class Entry(object):
             module_name = module_name.split('@')[0]
         module = modules.get(module_name)
 
+        # Also allow entry-type modules to be brought in from the etype directory.
+
         # Import the module if we have not already done so.
         if not module:
+            old_path = sys.path
+            sys.path.insert(0, os.path.join(our_path, 'etype'))
             try:
                 if have_importlib:
                     module = importlib.import_module(module_name)
@@ -90,6 +98,8 @@ class Entry(object):
             except ImportError:
                 raise ValueError("Unknown entry type '%s' in node '%s'" %
                         (etype, node.path))
+            finally:
+                sys.path = old_path
             modules[module_name] = module
 
         # Call its constructor to get the object we want.