python/build/verify: add verify_file_digest()

python/build/download.py

-from build.verify import file_md5
+from build.verify import verify_file_digest
 import os
 import urllib.request
 
@@ -9,8 +9,7 @@ def download_and_verify(url, md5, parent_path):
     path = os.path.join(parent_path, os.path.basename(url))
 
     try:
-        calculated_md5 = file_md5(path)
-        if md5 == calculated_md5: return path
+        if verify_file_digest(path, md5): return path
         os.unlink(path)
     except FileNotFoundError:
         pass
@@ -19,8 +18,7 @@ def download_and_verify(url, md5, parent_path):
 
     print("download", url)
     urllib.request.urlretrieve(url, tmp_path)
-    calculated_md5 = file_md5(tmp_path)
-    if calculated_md5 != md5:
+    if not verify_file_digest(tmp_path, md5):
         os.unlink(tmp_path)
         raise RuntimeError("MD5 mismatch")
 

python/build/verify.py

@@ -27,3 +27,8 @@ def file_md5(path):
     """Calculate the MD5 checksum of a file and return it in hexadecimal notation."""
 
     return file_digest(hashlib.md5, path)
+
+def verify_file_digest(path, expected_digest):
+    """Verify the digest of a file, and return True if the digest matches with the given expected digest."""
+
+    return file_md5(path) == expected_digest