diff --git a/poky/bitbake/lib/bb/utils.py b/poky/bitbake/lib/bb/utils.py
index d035949..8d40bcd 100644
--- a/poky/bitbake/lib/bb/utils.py
+++ b/poky/bitbake/lib/bb/utils.py
@@ -520,22 +520,26 @@
     fcntl.flock(lf.fileno(), fcntl.LOCK_UN)
     lf.close()
 
+def _hasher(method, filename):
+    import mmap
+
+    with open(filename, "rb") as f:
+        try:
+            with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mm:
+                for chunk in iter(lambda: mm.read(8192), b''):
+                    method.update(chunk)
+        except ValueError:
+            # You can't mmap() an empty file so silence this exception
+            pass
+    return method.hexdigest()
+
+
 def md5_file(filename):
     """
     Return the hex string representation of the MD5 checksum of filename.
     """
-    import hashlib, mmap
-
-    with open(filename, "rb") as f:
-        m = hashlib.md5()
-        try:
-            with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mm:
-                for chunk in iter(lambda: mm.read(8192), b''):
-                    m.update(chunk)
-        except ValueError:
-            # You can't mmap() an empty file so silence this exception
-            pass
-    return m.hexdigest()
+    import hashlib
+    return _hasher(hashlib.md5(), filename)
 
 def sha256_file(filename):
     """
@@ -543,24 +547,14 @@
     filename.
     """
     import hashlib
-
-    s = hashlib.sha256()
-    with open(filename, "rb") as f:
-        for line in f:
-            s.update(line)
-    return s.hexdigest()
+    return _hasher(hashlib.sha256(), filename)
 
 def sha1_file(filename):
     """
     Return the hex string representation of the SHA1 checksum of the filename
     """
     import hashlib
-
-    s = hashlib.sha1()
-    with open(filename, "rb") as f:
-        for line in f:
-            s.update(line)
-    return s.hexdigest()
+    return _hasher(hashlib.sha1(), filename)
 
 def preserved_envvars_exported():
     """Variables which are taken from the environment and placed in and exported