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eina freeq - make it clear that content is invalid on submission 

and that the free function cannot access content of the pointer
(unless the pointer memory size is 0).
This commit is contained in:
Carsten Haitzler 2017-11-07 17:35:52 +09:00
parent eb67a08c8d
commit 3790c4d47a
1 changed files with 12 additions and 0 deletions
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12
src/lib/eina/eina_freeq.h
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@ -291,6 +291,18 @@ eina_freeq_ptr_pending(Eina_FreeQ *fq);
* tools like valgrind, eina detects this and will also immediately free
* the data so valgrind's own memory checkers can detect use after free
* as normal.
*
* Note: The free function must not access the CONTENT of the memory to be
* freed, or at least consider it invalid and full of garbage. It is already
* invalid at the moment it is added to the free queue. Just the actual
* free function may be delayed. The free function may also not access other
* memory already freed before being added to the free queue. They may do
* tricks like use memory headers that are outside the memory region to be
* freed (pass in pointer char *x, then char *header_address = x - 16 to get
* header information) as this header is not considered part of the free data.
* This note does not apply if you use a size of 0 for the pointer, but then
* you lose canary debugging ability when using 0 sized pointers on the free
* queue.
*
* @since 1.19
*/