gh-116263: Do not rollover empty files in RotatingFileHandler (GH-122788)

1 files changed, 5 insertions, 2 deletions

diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index 0fa40f5..1cba64f 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -196,9 +196,12 @@ class RotatingFileHandler(BaseRotatingHandler):
         if self.stream is None:                 # delay was set...
             self.stream = self._open()
         if self.maxBytes > 0:                   # are we rolling over?
+            pos = self.stream.tell()
+            if not pos:
+                # gh-116263: Never rollover an empty file
+                return False
             msg = "%s\n" % self.format(record)
-            self.stream.seek(0, 2)  #due to non-posix-compliant Windows feature
-            if self.stream.tell() + len(msg) >= self.maxBytes:
+            if pos + len(msg) >= self.maxBytes:
                 # See bpo-45401: Never rollover anything other than regular files
                 if os.path.exists(self.baseFilename) and not os.path.isfile(self.baseFilename):
                     return False