gh-138775: fix handle python -m base64 stdin correct with EOF signal (GH-138776)

yihong0618 · picnixz · ZeroIntensity · web-flow · commit f5c2a41f9a6b · 2025-11-11T23:47:57.000Z
* fix: handle  stdin correct with EOF single.
* fix: flollow the comments when pipe stdin use buffer
* Apply suggestions from code review
* fix: apply review comments in Lib/base64.py
* fix: address comments
* Reword comment and NEWS entry.

---------

Signed-off-by: yihong0618 &lt;zouzou0208@gmail.com&gt;
Co-authored-by: Bénédikt Tran &lt;10796600+picnixz@users.noreply.github.com&gt;
Co-authored-by: Peter Bierma &lt;zintensitydev@gmail.com&gt;
Co-authored-by: Gregory P. Smith &lt;greg@krypto.org&gt;
diff --git a/Lib/base64.py b/Lib/base64.py
@@ -604,7 +604,14 @@ def main():
         with open(args[0], 'rb') as f:
             func(f, sys.stdout.buffer)
     else:
-        func(sys.stdin.buffer, sys.stdout.buffer)
+        if sys.stdin.isatty():
+            # gh-138775: read terminal input data all at once to detect EOF
+            import io
+            data = sys.stdin.buffer.read()
+            buffer = io.BytesIO(data)
+        else:
+            buffer = sys.stdin.buffer
+        func(buffer, sys.stdout.buffer)
 
 
 if __name__ == '__main__':
diff --git a/Misc/NEWS.d/next/Library/2025-09-11-15-03-37.gh-issue-138775.w7rnSx.rst b/Misc/NEWS.d/next/Library/2025-09-11-15-03-37.gh-issue-138775.w7rnSx.rst
@@ -0,0 +1,2 @@
+Use of ``python -m`` with :mod:`base64` has been fixed to detect input from a
+terminal so that it properly notices EOF.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+Use of ``python -m`` with :mod:`base64` has been fixed to detect input from a
	`2`	`+terminal so that it properly notices EOF.`