2.7.15rc1.rst

A regex in fpformat was vulnerable to catastrophic backtracking. This regex was a potential DOS vector (REDOS). Based on typical uses of fpformat the risk seems low. The regex has been refactored and is now safe. Patch by Jamie Davis.

Regexes in difflib and poplib were vulnerable to catastrophic backtracking. These regexes formed potential DOS vectors (REDOS). They have been refactored. This resolves CVE-2018-1060 and CVE-2018-1061. Patch by Jamie Davis.

Rewrite time.asctime() and time.ctime(). Backport and adapt the _asctime() function from the master branch to not depend on the implementation of asctime() and ctime() from the external C library. This change fixes a bug when Python is run using the musl C library.

Prevent environment variables injection in subprocess on Windows. Prevent passing other environment variables and command arguments.

Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of multiple security vulnerabilities including: CVE-2017-9233 (External entity infinite loop DoS), CVE-2016-9063 (Integer overflow, re-fix), CVE-2016-0718 (Fix regression bugs from 2.2.0's fix to CVE-2016-0718) and CVE-2012-0876 (Counter hash flooding with SipHash). Note: the CVE-2016-5300 (Use os-specific entropy sources like getrandom) doesn't impact Python, since Python already gets entropy from the OS to set the expat secret using XML_SetHashSalt().

Fix urllib.splithost() to correctly parse fragments. For example, splithost('//127.0.0.1#@evil.com/') now correctly returns the 127.0.0.1 host, instead of treating @evil.com as the host in an authentification (login@host).

Update expat copy from 2.1.1 to 2.2.0 to get fixes of CVE-2016-0718 and CVE-2016-4472. See https://sourceforge.net/p/expat/bugs/537/ for more information.

Fixed jumping out of "with" block by setting f_lineno.

Prevent jumps from 'return' and 'exception' trace events.

repr() on a dict containing its own viewvalues() or viewitems() no longer raises RuntimeError. Instead, use ..., as for other recursive structures. Patch by Ben North.

Yield expressions are now deprecated in comprehensions and generator expressions when checking Python 3 compatibility. They are still permitted in the definition of the outermost iterable, as that is evaluated directly in the enclosing scope.

The repr of deeply nested dict now raises a RecursionError instead of crashing due to a stack overflow.

Bytearray methods partition() and rpartition() now accept only bytes-like objects as separator, as documented. In particular they now raise TypeError rather of returning a bogus result when an integer is passed as a separator.

Add a new PYTHONSHOWREFCOUNT environment variable. In debug mode, Python now only print the total reference count if PYTHONSHOWREFCOUNT is set.

Add a new PYTHONSHOWALLOCCOUNT environment variable. When Python is compiled with COUNT_ALLOCS, PYTHONSHOWALLOCCOUNT now has to be set to dump allocation counts into stderr on shutdown. Moreover, allocations statistics are now dumped into stderr rather than stdout.

Prevent unwanted behavior in _random.Random.seed() in case the argument has a bad __abs__() method. Patch by Oren Milman.

Fixed crashes when iterating over a file on multiple threads.

Fix an assertion failure in ctypes class definition, in case the class has an attribute whose name is specified in _anonymous_ but not in _fields_. Patch by Oren Milman.

Raise a TypeError instead of SystemError in case warnings.onceregistry is not a dictionary. Patch by Oren Milman.

Include sys/sysmacros.h for major(), minor(), and makedev(). GNU C libray plans to remove the functions from sys/types.h.

Fix a crash in the __setstate__() method of ctypes._CData, in case of a bad __dict__. Patch by Oren Milman.

Fix a crash in some methods of io.TextIOWrapper, when the decoder's state is invalid. Patch by Oren Milman.

Fix potential crash during GC caused by tp_dealloc which doesn't call PyObject_GC_UnTrack().

Fixed possible integer overflow in PyString_DecodeEscape. Patch by Jay Bosamiya.

Fixed various segfaults with dict when input collections are mutated during searching, inserting or comparing. Based on patches by Duane Griffin and Tim Mitchell.

Fixed type.__setattr__() and type.__delattr__() for non-interned or unicode attribute names. Based on patch by Eryk Sun.

Fixed error messages in the index() method of tuple and list when pass indices of wrong type.

Support __rmod__ for subclasses of str being called before str.__mod__. Patch by Martijn Pieters.

Fix incorrect handling of signed zeros in complex constructor for complex subclasses and for inputs having a __complex__ method. Patch by Serhiy Storchaka.

Fixed possibly dereferencing undefined pointers when creating weakref objects.

Allow sys.exit to accept longs as well as ints. Patch by Gareth Rees.

Fixed possible use-after-free bugs in the subscription of the buffer object with custom index object.

Fix overflow checks in string, bytearray and unicode. Patch by jan matejek and Xiang Zhang.

Do not include <sys/random.h> if it does not exist.

Allow ttk.Treeview.insert to insert iid that has a false boolean value. Note iid=0 and iid=False would be same. Patch by Garvit Khatri.

The ssl module now compiles with LibreSSL 2.7.1.

The ssl module now detects missing NPN support in LibreSSL.

Rewrite confusing message from setup.py upload from "No dist file created in earlier command" to the more helpful "Must create and upload files in one command".

Fixed guessing quote and delimiter in csv.Sniffer.sniff() when only the last field is quoted. Patch by Jake Davis.

The ctypes module used to depend on indirect linking for dlopen. The shared extension is now explicitly linked against libdl on platforms with dl.

distutils' upload command no longer corrupts tar files ending with a CR byte, and no longer tries to convert CR to CRLF in any of the upload text fields.

Fix the error handling in Aifc_read.initfp() when the SSND chunk is not found. Patch by Zackery Spytz.

The nis module is now compatible with new libnsl and headers location.

Fix OSError for os.listdir with deep paths (starting with \\?\) on windows. Patch by Anthony Sottile.

glibc has removed Sun RPC. Use replacement libtirpc headers and library in nis module.

telnetlib: select.error doesn't have an errno attribute. Patch by Segev Finer.

The SSL module no longer sends IP addresses in SNI TLS extension on platforms with OpenSSL 1.0.2+ or inet_pton.

Creating io.FileIO() and builtin file() objects now release the GIL when checking the file descriptor. io.FileIO.readall(), io.FileIO.read(), and file.read() now release the GIL when getting the file size. Fixed hang of all threads with inaccessible NFS server. Patch by Nir Soffer.

codecs.StreamReader.read(n) now returns not more than n characters/bytes for non-negative n. This makes it compatible with read() methods of other file-like objects.

Silence a 'NoneType' object is not callable in _removeHandlerRef error that could happen when a logging Handler is destroyed as part of cyclic garbage collection during process shutdown.

Prevent a crash in sqlite3.Cursor.close() in case the Cursor object is uninitialized. Patch by Oren Milman.

Fix CCompiler.set_executable() of distutils to handle properly Unicode strings.

Fixed determining the MAC address in the uuid module:

• Using ifconfig on NetBSD and OpenBSD.
• Using arp on Linux, FreeBSD, NetBSD and OpenBSD.

Based on patch by Takayuki Shimizukawa.

Fix potential missed signal in signal.signal().

Fixed reading arbitrary data when parse a AF_BLUETOOTH address on NetBSD and DragonFly BSD.

Fixed stack corruption in curses.box() and curses.ungetmouse() when the size of types chtype or mmask_t is less than the size of C long. curses.box() now accepts characters as arguments. Based on patch by Steve Fink.

Fix the method for checking pad state of curses WINDOW. Patch by Masayuki Yamamoto.

Fixed the layout of the kqueue_event structure on OpenBSD and NetBSD. Fixed the comparison of the kqueue_event objects.

Fixed building the curses module on NetBSD.

Fixed buffer overflow in select.kqueue.control().

Prevent a crash when calling the __init__() method of a sqlite3.Cursor object more than once. Patch by Oren Milman.

Prevent crashes in _elementtree due to unsafe cleanup of Element.text and Element.tail. Patch by Oren Milman.

Fix possible crash in timedelta constructor called with custom integers.

Fix pkgutil.get_data to avoid leaking open files.

Fixed memory leaks in Tkinter's methods splitlist() and split() when pass a string larger than 2 GiB.

Fix the string representation of a netrc object.

Stop crashes when concurrently iterate over itertools.groupby() iterators.

functools.total_ordering() now implements the __ne__ method.

python -m ensurepip now exits with non-zero exit code if pip bootstrapping has failed.

The C accelerator module of ElementTree ignored exceptions raised when looking up TreeBuilder target methods in XMLParser().

The C accelerator module of ElementTree ignored exceptions raised when looking up TreeBuilder target methods in XMLParser().

SSLContext.load_dh_params() now supports non-ASCII path.

ssl.SSLContext() now uses OpenSSL error information when a context cannot be instantiated.

Work around a gc.disable() race condition in the subprocess module that could leave garbage collection disabled when multiple threads are spawning subprocesses at once. Users are strongly encouraged to use the subprocess32 module from PyPI on Python 2.7 instead, it is much more reliable.

expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying of partial characters for UTF-8 input (libexpat bug 115): libexpat/libexpat#115

Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

Fix poll.poll([timeout]) in the select module for arbitrary negative timeouts on all OSes where it can only be a non-negative integer or -1. Patch by Riccardo Coccioli.

Fix ctypes producing wrong PEP 3118 type codes for integer types.

The ssl and hashlib modules now call OPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The function detects CPU features and enables optimizations on some CPU architectures such as POWER8. Patch is based on research from Gustavo Serra Scalet.

Fix handling of long oids in ssl. Based on patch by Christian Heimes.

Change ttk.OptionMenu radiobuttons to be unique across instances of OptionMenu.

Update zlib to 1.2.11.

Prohibited the '=' character in environment variable names in os.putenv() and os.spawn*().

On Windows, subprocess.Popen.communicate() now also ignore EINVAL on stdin.write() if the child process is still running but closed the pipe.

Fix the problem that logging.handlers.SysLogHandler cannot handle IPv6 addresses.

Preserve generator state when _random.Random.setstate() raises an exception. Patch by Bryan Olson.

tkFont now supports unicode options (e.g. font family).

multiprocessing.Queue._feed background running thread do not break from main loop on exception.

Fix handling escape characters in HZ codec. Based on patch by Ma Lin.

Warnings emitted when compile a regular expression now always point to the line in the user code. Previously they could point into inners of the re module if emitted from inside of groups or conditionals.

Running Python with the -3 option now warns about regular expression syntax that is invalid or has different semantic in Python 3 or will change the behavior in future Python versions.

Running Python with the -3 option now emits deprecation warnings for getchildren() and getiterator() methods of the Element class in the xml.etree.cElementTree module and when pass the html argument to xml.etree.ElementTree.XMLParser().

Fixed a deprecation warning about the doctype() method of the xml.etree.ElementTree.XMLParser class. Now it is emitted only when define the doctype() method in the subclass of XMLParser.

imaplib now catchs the Windows socket WSAEINVAL error (code 10022) on shutdown(SHUT_RDWR): An invalid operation was attempted. This error occurs sometimes on SSL connections.

Fix sysconfig.is_python_build() if Python is built with Visual Studio 2008 (VS 9.0).

Fix range checking in GB18030 decoder. Original patch by Ma Lin.

Removed the __init__ methods of _json's scanner and encoder. Misusing them could cause memory leaks or crashes. Now scanner and encoder objects are completely initialized in the __new__ methods.

Change resulted because of zipfile breakage. (See also: bpo-29094)

Fixed leaks and crashes in errors handling in the parser module.

Fixed crashes in IOBase methods next() and readlines() when readline() or next() respectively return non-sizeable object. Fixed possible other errors caused by not checking results of PyObject_Size(), PySequence_Size(), or PyMapping_Size().

Fixed race condition in HTMLParser.unescape().

_io._IOBase.readlines will check if it's closed first when hint is present.

Fixed multiple crashes in ElementTree caused by race conditions and wrong types.

Fix a crash in itertools.chain.from_iterable when encountering long runs of empty iterables.

Release references to tasks, their arguments and their results as soon as they are finished in multiprocessing.Pool.

Fixed integer overflow in cPickle when pickle large strings or too many objects.

Fix file object leak in aifc.open() when file is given as a filesystem path and is not in valid AIFF format. Original patch by Anthony Zhang.

Fixed inspect.getargs() for parameters which are cell variables.

Fix subprocess.Popen.wait() when the child process has exited to a stopped instead of terminated state (ex: when under ptrace).

Fixed infinite recursion in the repr of uninitialized ctypes.CDLL instances.

Fixed loading libraries in ctypes by unicode names on Windows. Original patch by Chi Hsuan Yen.

Support glibc 2.24 on Linux: don't use getentropy() function but read from /dev/urandom to get random bytes, for example in os.urandom(). On Linux, getentropy() is implemented which getrandom() is blocking mode, whereas os.urandom() should not block.

In urllib, suffixes in no_proxy environment variable with leading dots could match related hostnames again (e.g. .b.c matches a.b.c). Patch by Milan Oberkirch.

Fixed recursion errors in large or resized curses.textpad.Textbox. Based on patch by Tycho Andersen.

curses.ascii predicates now work correctly with negative integers.

old keys should not remove new values from WeakValueDictionary when collecting from another thread.

More APIs now support longs as well as ints.

Remove editor artifacts from Tix.py, including encoding not recognized by codecs.lookup.

Fix dict.fromkeys(x) overallocates when x is sparce dict. Original patch by Rasmus Villemoes.

Fix bugs in WeakValueDictionary.setdefault() and WeakValueDictionary.pop() when a GC collection happens in another thread.

cPickle now correctly propagates errors when unpickle instances of old-style classes.

Modify documentation for the :func:`islice` recipe to consume initial values up to the start index.

Update link to w3c doc for xml default namespaces.

Explain real behaviour of sys.settrace and sys.setprofile and their C-API counterparts regarding which type of events are received in each function. Patch by Pablo Galindo Salgado.

Add a note about curses.addch and curses.addstr exception behavior when writing outside a window, or pad.

Add RFC 7525 and Mozilla server side TLS links to SSL documentation.

Add missing attribute related constants in curses documentation.

Link the documentation to its source file on GitHub.

Add canonical header link on each page to corresponding major version of the documentation. Patch by Matthias Bussonnier.

Rewrite Comparisons section in the Expressions chapter of the language reference. Some of the details of comparing mixed types were incorrect or ambiguous. Added default behaviour and consistency suggestions for user-defined classes. Based on patch from Andy Maier.

Fix test_regrtest.test_crashed() on s390x. Add a new _testcapi._read_null() function to crash Python in a reliable way on s390x. On s390x, ctypes.string_at(0) returns an empty string rather than crashing.

Debian Unstable has disabled TLS 1.0 and 1.1 for SSLv23_METHOD(). Change TLS/SSL protocol of some tests to PROTOCOL_TLS or PROTOCOL_TLSv1_2 to make them pass on Debian.

Remove sha256.tbs-internet.com ssl test

Fix sporadic failures in test_multiprocessing.WithProcessesTestCondition.

Backported test.regrtest options -m/--match and -G/--failfast from Python 3.

To unify running tests in Python 2.7 and Python 3, the test package can be run as a script. This is equivalent to running the test.regrtest module as a script.

To simplify backports from Python 3, the test.test_support module was converted into a package and renamed to test.support. The test.script_helper module was moved into the test.support package. Names test.test_support and test.script_helper are left as aliases to test.support and test.support.script_helper.

Enhanced function swap_attr() in the test.test_support module. It now works when delete replaced attribute inside the with statement. The old value of the attribute (or None if it doesn't exist) now will be assigned to the target of the "as" clause, if there is one. Also backported function swap_item().

Skip test_asyncore and test_eintr poll failures on macOS. Skip some tests of select.poll when running on macOS due to unresolved issues with the underlying system poll function on some macOS versions.

Convert ElementTree doctests to unittests.

Upgrade pip to 9.0.3 and setuptools to v39.0.1.

Disable computed gotos by default for clang < 5.0. It caused significant performance regression.

Fix segfault of the crypt module when libxcrypt is provided instead of libcrypt at the system.

Abort the build when building out of a not clean source tree.

Fix -Wint-in-bool-context warnings in PyMem_MALLOC and PyMem_REALLOC macros

Prevent unnecessary rebuilding of Python during make test, make install and some other make targets when configured with --enable-optimizations.

Don't regenerate generated files based on file modification time anymore: the action is now explicit. Replace make touch with make regen-all.

sys.version and the platform module python_build(), python_branch(), and python_revision() functions now use git information rather than hg when building from a repo.

Fix --enable-optimization configure option didn't work.

Update Windows build and OS X installers to use OpenSSL 1.0.2k.

Fix implicit declaration of function _setmode. Patch by Masayuki Yamamoto

Update Windows build to use OpenSSL 1.0.2o.

Fix a memory leak in os.chdir() on Windows if the current directory is set to a UNC path.

Bump Tcl/Tk to 8.5.19.

Pull build dependencies from GitHub rather than svn.python.org.

Provide an additional, more modern macOS installer variant that supports macOS 10.9+ systems in 64-bit mode only. Upgrade the supplied third-party libraries to OpenSSL 1.0.2n and SQLite 3.22.0. The 10.9+ installer now supplies its own private copy of Tcl/Tk 8.6.8.

Default macOS deployment target is now set by configure to the build system's OS version (as is done by Python 3), not 10.4; override with, for example, ./configure MACOSX_DEPLOYMENT_TARGET=10.4.

All 2.7 macOS installer variants now supply their own version of OpenSSL 1.0.2; the Apple-supplied SSL libraries and root certificates are not longer used. The Installer Certificate command in /Applications/Python 2.7 may be used to download and install a default set of root certificates from the third-party certifi package.

python.org macOS Pythons no longer supply a default SDK value (e.g. -isysroot /) or specific compiler version default (e.g. gcc-4.2) when building extension modules. Use CC, SDKROOT, and DEVELOPER_DIR environment variables to override compilers or to use an SDK. See Apple's xcrun man page for more info.

Update macOS installer build to use OpenSSL 1.0.2o.

Fixed handling directories as arguments in the pygettext script. Based on patch by Oleg Krasnikov.

Fixed Tools/scripts/reindent.py for non-ASCII files. It now processes files as binary streams. This also fixes "make reindent".

2to3 and lib2to3 can now read pickled grammar files using pkgutil.get_data() rather than probing the filesystem. This lets 2to3 and lib2to3 work when run from a zipfile.

Fix PyGILState_Ensure(). When PyGILState_Ensure() is called in a non-Python thread before PyEval_InitThreads(), only call PyEval_InitThreads() after calling PyThreadState_New() to fix a crash.

When Python is built in debug mode, the memory debug hooks now fail with a fatal error if realloc() fails to shrink a memory block, because the debug hook just erased freed bytes without keeping a copy of them.