python - fix buffer overflows in unicode processing and elsewhere

Doc/c-api/memory.rst

 .. highlightlang:: c
 
 
 .. _memory:
 
 *****************
 Memory Management
 *****************
 
 .. sectionauthor:: Vladimir Marangozov <Vladimir.Marangozov@inrialpes.fr>
@@ skipping 118 matching lines @@
 
    Same as :cfunc:`PyMem_Malloc`, but allocates ``(n * sizeof(TYPE))`` bytes of
    memory.  Returns a pointer cast to :ctype:`TYPE\*`.  The memory will not have
    been initialized in any way.
 
 
 .. cfunction:: TYPE* PyMem_Resize(void *p, TYPE, size_t n)
 
    Same as :cfunc:`PyMem_Realloc`, but the memory block is resized to ``(n *
    sizeof(TYPE))`` bytes.  Returns a pointer cast to :ctype:`TYPE\*`. On return,
-   *p* will be a pointer to the new memory area, or *NULL* in the event of failure.
+   *p* will be a pointer to the new memory area, or *NULL* in the event of
+   failure.  This is a C preprocessor macro; p is always reassigned.  Save
+   the original value of p to avoid losing memory when handling errors.
 
 
 .. cfunction:: void PyMem_Del(void *p)
 
    Same as :cfunc:`PyMem_Free`.
 
 In addition, the following macro sets are provided for calling the Python memory
 allocator directly, without involving the C API functions listed above. However,
 note that their use does not preserve binary compatibility across Python
 versions and is therefore deprecated in extension modules.
@@ skipping 48 matching lines @@
    free(buf2);       /* Right -- allocated via malloc() */
    free(buf1);       /* Fatal -- should be PyMem_Del()  */
 
 In addition to the functions aimed at handling raw memory blocks from the Python
 heap, objects in Python are allocated and released with :cfunc:`PyObject_New`,
 :cfunc:`PyObject_NewVar` and :cfunc:`PyObject_Del`.
 
 These will be explained in the next chapter on defining and implementing new
 object types in C.