[PROTON-2455] Workaround for bad use of pn_buffer_append in messenger library

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: proton-c-0.36.0
• Fix Version/s: proton-c-0.37.0
• Component/s: proton-c
• Assignee: Andrew Stitcher
• Reporter: Andrew Stitcher
• Created: 04/Nov/21 15:43
• Updated: 07/Apr/22 17:01
• Resolved: 04/Nov/21 15:55

Description

The messenger library uses the pn_buffer API as a way to get expandable memory space. However it just writes directly into the space it gets and then append that space (which is internal to a buffer) to the buffer to adjust the buffers internal bookkeeping.

This is not supposed to be allowed in the API, but didn't matter before as pn_buffer_append used memmove(). It is now technically undefined as we started using memcpy() in pn_buffer_append.

The operation has the same source and destination address so can be elided as aworkaround to avoid the undefined behaviour.

Issue Links

• is caused by: PROTON-2425 Tweak pn_buffer code to use memcpy instead of memmove