bpo-39259: ftplib.FTP/FTP_TLS now reject timeout = 0 (GH-17959)

2 files changed, 14 insertions, 0 deletions

diff --git a/Doc/library/ftplib.rst b/Doc/library/ftplib.rst
index 79a0286..a4bb695 100644
--- a/Doc/library/ftplib.rst
+++ b/Doc/library/ftplib.rst
@@ -72,6 +72,9 @@ The module defines the following items:
    .. versionchanged:: 3.3
       *source_address* parameter was added.
 
+   .. versionchanged:: 3.9
+      If the *timeout* parameter is set to be zero, it will raise a
+      :class:`ValueError` to prevent the creation of a non-blocking socket
 
 .. class:: FTP_TLS(host='', user='', passwd='', acct='', keyfile=None, certfile=None, context=None, timeout=None, source_address=None)
 
@@ -105,6 +108,10 @@ The module defines the following items:
        :func:`ssl.create_default_context` select the system's trusted CA
        certificates for you.
 
+   .. versionchanged:: 3.9
+      If the *timeout* parameter is set to be zero, it will raise a
+      :class:`ValueError` to prevent the creation of a non-blocking socket
+
    Here's a sample session using the :class:`FTP_TLS` class::
 
       >>> ftps = FTP_TLS('ftp.pureftpd.org')
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index b6ffa23..859bf44 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -159,6 +159,13 @@ Added constants :data:`~fcntl.F_OFD_GETLK`, :data:`~fcntl.F_OFD_SETLK`
 and :data:`~fcntl.F_OFD_SETLKW`.
 (Contributed by Dong-hee Na in :issue:`38602`.)
 
+ftplib
+-------
+
+:class:`~ftplib.FTP` and :class:`~ftplib.FTP_TLS` now raise a :class:`ValueError`
+if the given timeout for their constructor is zero to prevent the creation of
+a non-blocking socket. (Contributed by Dong-hee Na in :issue:`39259`.)
+
 gc
 --