buflib: Add crc field protecting buflib cookie integrity

This should catch the case of buffer misuse which results
in corrupted cookie of next allocation. The check is performed
on move_block() so it may be a bit late.

There is buflib_check_valid() provided which checks the
integrity of all cookies for given context.
On DEBUG build with --sdl-thread this check is carried out
for core_ctx on every context switch to catch problems earlier.

Change-Id: I999d4576084592394e3dbd3bdf0f32935ff5f601
Reviewed-on: http://gerrit.rockbox.org/711
Reviewed-by: Thomas Martitz <kugel@rockbox.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/firmware/include/core_alloc.h b/firmware/include/core_alloc.h
index a100b7cc6c..095cb5da11 100644
--- a/firmware/include/core_alloc.h
+++ b/firmware/include/core_alloc.h
@@ -17,6 +17,9 @@ bool core_shrink(int handle, void* new_start, size_t new_size);
 int core_free(int handle);
 size_t core_available(void);
 size_t core_allocatable(void);
+#ifdef DEBUG
+void core_check_valid(void);
+#endif
 
 /* DO NOT ADD wrappers for buflib_buffer_out/in. They do not call
  * the move callbacks and are therefore unsafe in the core */