CF writes to received SB buffer

[jphickey]

Checklist (Please check before submitting)

• [x] I reviewed the Contributing Guide.
• [x] I performed a cursory search to see if the bug report is relevant, not redundant, nor in conflict with other tickets.

Describe the bug The output from CFE_SB_ReceiveBuffer() is a pointer to a shared buffer, and thus should be interpreted as const data. The only reason it is not qualified const in the API was due to backward compatibility concerns.

However, CF is actually writing to the buffer in two places.

To Reproduce Send those commands

Expected behavior Should not write to a buffer that was received from SB

Code snips https://github.com/nasa/CF/blob/a0d35e1d7cc822952e18535b195a302a1d59a64c/fsw/src/cf_cmd.c#L147-L149 https://github.com/nasa/CF/blob/a0d35e1d7cc822952e18535b195a302a1d59a64c/fsw/src/cf_cmd.c#L190-L192

System observed on: Inspection

Additional context This is done to ensure null termination of the string. While a valid concern, a function like CFE_SB_MessageStringGet() should be used instead.

Reporter Info Joseph Hickey, Vantage Systems, Inc.