Implement sha256 hashing over file contents.

1 files changed, 23 insertions, 0 deletions

diff --git a/uploader/files.py b/uploader/files.py
index b163612..d37a53e 100644
--- a/uploader/files.py
+++ b/uploader/files.py
@@ -1,7 +1,9 @@
 """Utilities to deal with uploaded files."""
 import hashlib
 from pathlib import Path
+from typing import Iterator
 from datetime import datetime
+
 from flask import current_app
 
 from werkzeug.utils import secure_filename
@@ -21,6 +23,27 @@ def save_file(fileobj: FileStorage, upload_dir: Path) -> Path:
     fileobj.save(filepath)
     return filepath
 
+
 def fullpath(filename: str):
     """Get a file's full path. This makes use of `flask.current_app`."""
     return Path(current_app.config["UPLOAD_FOLDER"], filename).absolute()
+
+
+def chunked_binary_read(filepath: Path, chunksize: int = 2048) -> Iterator:
+    """Read a file in binary mode in chunks."""
+    with open(filepath, "rb") as inputfile:
+        while True:
+            data = inputfile.read(chunksize)
+            if data != b"":
+                yield data
+                continue
+            break
+
+
+def sha256_digest_over_file(filepath: Path) -> str:
+    """Compute the sha256 digest over a file's contents."""
+    filehash = hashlib.sha256()
+    for chunk in chunked_binary_read(filepath):
+        filehash.update(chunk)
+
+    return filehash.hexdigest()