diff mbox series

knotty: fix TIOCGWINSZ call for Python 3.14 and later

Message ID 20251112114847.53576-1-enrico.scholz@sigma-chemnitz.de
State New
Headers show
Series knotty: fix TIOCGWINSZ call for Python 3.14 and later | expand

Commit Message

Enrico Scholz Nov. 12, 2025, 11:48 a.m. UTC 
From: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>

Python 3.14 enforces stricter type and size checking for fcntl.ioctl()
buffer arguments. The previous code passed a short 4-byte string ('1234')
to TIOCGWINSZ, which worked by accident in older Python versions but causes
a SystemError ("buffer overflow") in 3.14.

TIOCGWINSZ expects an 8-byte (4x 16-bit) buffer corresponding to
(rows, cols, xpix, ypix). Use an 8-byte bytes literal instead and unpack
the first two values.

Tested with Python 3.11, 3.13, and 3.14.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
---
 lib/bb/ui/knotty.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/lib/bb/ui/knotty.py b/lib/bb/ui/knotty.py
index 00258c80f..66b2146c5 100644
--- a/lib/bb/ui/knotty.py
+++ b/lib/bb/ui/knotty.py
@@ -143,7 +143,7 @@  class TerminalFilter(object):
     def getTerminalColumns(self):
         def ioctl_GWINSZ(fd):
             try:
-                cr = struct.unpack('hh', fcntl.ioctl(fd, self.termios.TIOCGWINSZ, '1234'))
+                cr = struct.unpack('hhhh', fcntl.ioctl(fd, self.termios.TIOCGWINSZ, b'12345678'))[0:2]
             except:
                 return None
             return cr