bitbake: utils.py: Add sha1_file call

This is useful as npm-lockdown uses sha1 because npm releases the sha1 of
packages and whilst this is undocumented it seems no other algorithm is
supported

(Bitbake rev: fd5d9011f6dd7029895b64d8a02d33185b9aa8ae)

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/utils.py

@@ -534,6 +534,21 @@ def sha256_file(filename):
             s.update(line)
     return s.hexdigest()
 
+def sha1_file(filename):
+    """
+    Return the hex string representation of the SHA1 checksum of the filename
+    """
+    try:
+        import hashlib
+    except ImportError:
+        return None
+
+    s = hashlib.sha1()
+    with open(filename, "rb") as f:
+        for line in f:
+            s.update(line)
+    return s.hexdigest()
+
 def preserved_envvars_exported():
     """Variables which are taken from the environment and placed in and exported
     from the metadata"""