Various small fixes to the builtin module to ensure no buffer
overflows.
- chunk #1:
Proper casting to ensure no truncation, and hence no surprises, in the
comparison.
- chunk #2:
The id() function guarantees a unique return value for different
objects. It does this by returning the pointer to the object. By
returning a PyInt, on Win64 (sizeof(long) < sizeof(void*)) the pointer
is truncated and the guarantee may be proven false. The appropriate
return function is PyLong_FromVoidPtr, this returns a PyLong if that
is necessary to return the pointer without truncation.
[GvR: note that this means that id() can now return a long on Win32
platforms. This *might* break some code...]
- chunk #3:
Ensure no overflow in raw_input(). Granted the user would have to pass
in >2GB of data but it *is* a possible buffer overflow condition.
As I really do not have anything better to do at the moment, I have written
a patch to Python/marshal.c that prevents Python dumping core when trying
to marshal stack bustingly deep (or recursive) data structure.
It just throws an exception; even slightly clever handling of recursive
data is what pickle is for...
[Fred Drake:] Moved magic constant 5000 to a #define.
This closes SourceForge patch #100645.
the number of children of a node exceeds the max possible value for
the short that is used to count them. The Python runtime converts
this parser error into the SyntaxError "expression too long."
module and into _exceptions.c. This includes all the PyExc_* globals,
the bltin_exc table, init_class_exc(), fini_instances(),
finierrors().
Renamed _PyBuiltin_Init_1() to _PyBuiltin_Init() since the two phase
initializations are necessary any more.
Removed as obsolete _PyBuiltin_Init_2(), _PyBuiltin_Fini_1() and
_PyBuiltin_Fini_2().
need two phase init or fini of the builtin module. Change the call of
_PyBuiltin_Init_1() to _PyBuiltin_Init(). Add a call to
init_exceptions().
Py_Finalize(): Don't call _PyBuiltin_Fini_1(). Instead call
fini_exceptions() but move this to before the thread state is
cleared.
Limit the 'b' formatter of PyArg_ParseTuple to valid values of an unsigned
char, i.e. [0,UCHAR_MAX]. It is expected that this is the common usage of 'b'.
An OverflowError is raised if the parsed value is outside this range.
Changes the 'b', 'h', and 'i' formatters in PyArg_ParseTuple to raise an
Overflow exception if they overflow (previously they just silently
overflowed).
Changes by Guido: always accept values [0..255] (in addition to
[CHAR_MIN..CHAR_MAX]) for 'b' format; changed some spaces into tabs in
other code.
who wrote:
Here's the new version of thread_nt.h. More particular, there is a
new version of thread lock that uses kernel object (e.g. semaphore)
only in case of contention; in other case it simply uses interlocked
functions, which are faster by the order of magnitude. It doesn't
make much difference without threads present, but as soon as thread
machinery initialised and (mostly) the interpreter global lock is on,
difference becomes tremendous. I've included a small script, which
initialises threads and launches pystone. With original thread_nt.h,
Pystone results with initialised threads are twofold worse then w/o
threads. With the new version, only 10% worse. I have used this
patch for about 6 months (with threaded and non-threaded
applications). It works remarkably well (though I'd desperately
prefer Python was free-threaded; I hope, it will soon).
For more comments, read the patches@python.org archives.
For documentation read the comments in mymalloc.h and objimpl.h.
(This is not exactly what Vladimir posted to the patches list; I've
made a few changes, and Vladimir sent me a fix in private email for a
problem that only occurs in debug mode. I'm also holding back on his
change to main.c, which seems unnecessary to me.)
- When 'import exceptions' fails, don't suggest to use -v to print the traceback;
this doesn't actually work.
- Remove comment about fallback to string exceptions.
- Remove a PyErr_Occurred() check after all is said and done that can
never trigger.
- Remove static function newstdexception() which is no longer called.
Added 'u' and 'u#' tags for PyArg_ParseTuple - these turn a
PyUnicodeObject argument into a Py_UNICODE * buffer, or a Py_UNICODE *
buffer plus a length with the '#'. Also added an analog to 'U'
for Py_BuildValue.
return 0 (exceptions don't match). This means that if an ImportError
is raised because exceptions.py can't be imported, the interpreter
will exit "cleanly" with an error message instead of just core
dumping.
PyErr_SetFromErrnoWithFilename(), PyErr_SetFromWindowsErrWithFilename():
Don't test on Py_UseClassExceptionsFlag.
are no longer supported (i.e. -X option is removed).
_PyBuiltin_Init_1(): Don't call initerrors(). This does mean that it
is possible to raise an ImportError before that exception has been
initialized, say because exceptions.py can't be found, or contains
bogosity. See changes to errors.c for how this is handled.
_PyBuiltin_Init_2(): Don't test Py_UseClassExceptionsFlag, just go
ahead and initialize the class-based standard exceptions. If this
fails, we throw a Py_FatalError.
Changed all references to the MAGIC constant to use a global
pyc_magic instead. This global is initially set to MAGIC, but can be
changed by the _PyImport_Init() function to provide for
special features implemented in the compiler which are settable
using command line switches and affect the way PYC files are
generated.
Currently this change is only done for the -U flag.
Support for the new -U command line option option:
with the option enabled the Python compiler
interprets all "..." strings as u"..." (same with r"..." and
ur"...").
Follow a suggestion in an /*XXX*/ comment [in com_add()] to speed up
compilation by using supplemental dictionaries to keep track of names
and constants, eliminating quadratic behavior. With this patch in
place, the time to import a 5000-line file with lots of constants [at
the global level] is reduced from 20 seconds to under 3 on my system.
Here's a patch which changes modsupport to add 'u' and 'u#',
to support building Unicode objects from a null-terminated
Py_UNICODE *, and a Py_UNICODE * with length, respectively.
[Conversion from 'U' to 'u' by Fred, based on python-dev comments.]
Note that the use of None for NULL values of the Py_UNICODE* value is
still in; I'm not sure of the conclusion on that issue.
remaining object references if the environment variable PYTHONDUMPREFS
exists. The default behaviour caused problems for background or
otherwise invisible processes that use the debug build of Python.
Fixed a memory leak found by Fredrik Lundh. Instead of
PyUnicode_AsUTF8String() we now use _PyUnicode_AsUTF8String() which
returns the string object without incremented refcount (and assures
that the so obtained object remains alive until the Unicode object is
garbage collected).
"""
Running "test_extcall" repeatedly results in memory leaks.
One of these can't be fixed (at least not easily!), it happens since
this code:
def saboteur(**kw):
kw['x'] = locals()
d = {}
saboteur(a=1, **d)
creates a circular reference - d['x']['d']==d
The others are due to some missing decrefs in ceval.c, fixed by the
patch attached below.
Note: I originally wrote this without the "goto", just adding the
missing decref's where needed. But I think the goto is justified in
keeping the executable code size of ceval as small as possible.
"""
[I think the circular reference is more like kw['x']['kw'] == kw. --GvR]
