python.man UNIX man page for the python interpreter
python-mode.el Emacs mode for editing Python programs
README The file you're reading now
+README.valgrind Information for Valgrind users, see valgrind-python.supp
RFD Request For Discussion about a Python newsgroup
RPM (Old) tools to build RPMs
SpecialBuilds.txt Describes extra symbols you can set for debug builds
setuid-prog.c C helper program for set-uid Python scripts
vgrindefs Python configuration for vgrind (a generic pretty printer)
+valgrind-python.supp Valgrind suppression file, see README.valgrind
--- /dev/null
+This document describes some caveats about the use of Valgrind with
+Python. Valgrind is used periodically by Python developers to try
+to ensure there are no memory leaks or invalid memory reads/writes.
+
+If you don't want to read about the details of using Valgrind, there
+are still two things you must do to suppress the warnings. First,
+you must use a suppressions file. One is supplied in
+Misc/valgrind-python.supp. Second, you must do one of the following:
+
+ * Uncomment Py_USING_MEMORY_DEBUGGER in Objects/obmalloc.c,
+ then rebuild Python
+ * Uncomment the lines in Misc/valgrind-python.supp that
+ suppress the warnings for PyObject_Free and PyObject_Realloc
+
+Details:
+--------
+Python uses its own allocation scheme on top of malloc called PyMalloc.
+Valgrind my show some unexpected results when PyMalloc is used.
+Starting with Python 2.3, PyMalloc is used by default. You can disable
+PyMalloc when configuring python by adding the --without-pymalloc option.
+If you disable PyMalloc, most of the information in this document and
+the supplied suppressions file will not be useful.
+
+If you use valgrind on a default build of Python, you will see
+many errors like:
+
+ ==6399== Use of uninitialised value of size 4
+ ==6399== at 0x4A9BDE7E: PyObject_Free (obmalloc.c:711)
+ ==6399== by 0x4A9B8198: dictresize (dictobject.c:477)
+
+These are expected and not a problem. Tim Peters explains
+the situation:
+
+ PyMalloc needs to know whether an arbitrary address is one
+ that's managed by it, or is managed by the system malloc.
+ The current scheme allows this to be determined in constant
+ time, regardless of how many memory areas are under pymalloc's
+ control.
+
+ The memory pymalloc manages itself is in one or more "arenas",
+ each a large contiguous memory area obtained from malloc.
+ The base address of each arena is saved by pymalloc
+ in a vector, and a field at the start of each arena contains
+ the index of that arena's base address in that vector.
+
+ Given an arbitrary address, pymalloc computes the arena base
+ address corresponding to it, then looks at "the index" stored
+ near there. If the index read up is out of bounds for the
+ vector of arena base addresses pymalloc maintains, then
+ pymalloc knows for certain that this address is not under
+ pymalloc's control. Otherwise the index is in bounds, and
+ pymalloc compares
+
+ the arena base address stored at that index in the vector
+
+ to
+
+ the computed arena address
+
+ pymalloc controls this arena if and only if they're equal.
+
+ It doesn't matter whether the memory pymalloc reads up ("the
+ index") is initialized. If it's not initialized, then
+ whatever trash gets read up will lead pymalloc to conclude
+ (correctly) that the address isn't controlled by it.
+
+ This determination has to be made on every call to one of
+ pymalloc's free/realloc entry points, so its speed is critical
+ (Python allocates and frees dynamic memory at a ferocious rate
+ -- everything in Python, from integers to "stack frames",
+ lives in the heap).
--- /dev/null
+#
+# This is a valgrind suppression file that should be used when using valgrind.
+#
+# Here's an example of running valgrind:
+#
+# cd python/dist/src
+# valgrind --tool=memcheck --suppressions=Misc/valgrind-python.supp \
+# ./python -E -tt ./Lib/test/regrtest.py -u bsddb,network
+#
+# You must edit Objects/obmalloc.c and uncomment Py_USING_MEMORY_DEBUGGER
+# to use the preferred suppressions with Py_ADDRESS_IN_RANGE.
+#
+# If you do not want to recompile Python, you can uncomment
+# suppressions for PyObject_Free and PyObject_Realloc.
+#
+# See Misc/README.valgrind for more information.
+
+# all tool names: Addrcheck,Memcheck,cachegrind,helgrind,massif
+{
+ ADDRESS_IN_RANGE/Invalid read of size 4
+ Memcheck:Addr4
+ fun:Py_ADDRESS_IN_RANGE
+}
+
+{
+ ADDRESS_IN_RANGE/Invalid read of size 4
+ Memcheck:Value4
+ fun:Py_ADDRESS_IN_RANGE
+}
+
+{
+ ADDRESS_IN_RANGE/Conditional jump or move depends on uninitialised value
+ Memcheck:Cond
+ fun:Py_ADDRESS_IN_RANGE
+}
+
+###{
+### ADDRESS_IN_RANGE/Invalid read of size 4
+### Memcheck:Addr4
+### fun:PyObject_Free
+###}
+###
+###{
+### ADDRESS_IN_RANGE/Invalid read of size 4
+### Memcheck:Value4
+### fun:PyObject_Free
+###}
+###
+###{
+### ADDRESS_IN_RANGE/Conditional jump or move depends on uninitialised value
+### Memcheck:Cond
+### fun:PyObject_Free
+###}
+
+###{
+### ADDRESS_IN_RANGE/Invalid read of size 4
+### Memcheck:Addr4
+### fun:PyObject_Realloc
+###}
+###
+###{
+### ADDRESS_IN_RANGE/Invalid read of size 4
+### Memcheck:Value4
+### fun:PyObject_Realloc
+###}
+###
+###{
+### ADDRESS_IN_RANGE/Conditional jump or move depends on uninitialised value
+### Memcheck:Cond
+### fun:PyObject_Realloc
+###}
+
+###
+### All the suppressions below are for errors that occur within libraries
+### that Python uses. The problems to not appear to be related to Python's
+### use of the libraries.
+###
+{
+ GDBM problems, see test_gdbm
+ Memcheck:Param
+ write(buf)
+ fun:write
+ fun:gdbm_open
+
+}
+
+###
+### These occur from somewhere within the SSL, when running
+### test_socket_sll. They are too general to leave on by default.
+###
+###{
+### somewhere in SSL stuff
+### Memcheck:Cond
+### fun:memset
+###}
+###{
+### somewhere in SSL stuff
+### Memcheck:Value4
+### fun:memset
+###}
+###
+###{
+### somewhere in SSL stuff
+### Memcheck:Cond
+### fun:MD5_Update
+###}
+###
+###{
+### somewhere in SSL stuff
+### Memcheck:Value4
+### fun:MD5_Update
+###}
+
+#
+# All of these problems come from using test_socket_ssl
+#
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:BN_bin2bn
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:BN_num_bits_word
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Value4
+ fun:BN_num_bits_word
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:BN_mod_exp_mont_word
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:BN_mod_exp_mont
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Param
+ write(buf)
+ fun:write
+ obj:/usr/lib/libcrypto.so.0.9.7
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:RSA_verify
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Value4
+ fun:RSA_verify
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Value4
+ fun:DES_set_key_unchecked
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Value4
+ fun:DES_encrypt2
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ obj:/usr/lib/libssl.so.0.9.7
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Value4
+ obj:/usr/lib/libssl.so.0.9.7
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:BUF_MEM_grow_clean
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:memcpy
+ fun:ssl3_read_bytes
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Cond
+ fun:SHA1_Update
+}
+
+{
+ from test_socket_ssl
+ Memcheck:Value4
+ fun:SHA1_Update
+}
+
+
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