[bitWarrior]

Summary

Resolves an off-nominal condition in file packet ingest. A packet consisting of only the 2-byte FW_PACKET_FILE descriptor with no body passed the minimum-size guards in FileUplink and CfdpManager, which then built a zero-length Fw::Buffer over a valid pointer. Since the LinearBufferBase refactor, its constructor required a null pointer whenever capacity is zero, so this input tripped an assertion rather than being reported as a decode error.

Changes

• Fw/Types/Serializable.cpp: LinearBufferBase now accepts a valid pointer with zero capacity. This matches the existing contract of ExternalSerializeBuffer::setExtBuffer and restores the behavior from before the refactor. A null pointer with nonzero capacity still asserts.
• Svc/FileUplink/FileUplink.cpp: the size guard rejects packets that carry no bytes after the descriptor, logging InvalidPacketReceived as it does for shorter packets.
• Svc/Ccsds/CfdpManager/CfdpManager.cpp: the same boundary check on dataIn, returning the buffer silently as the existing too-small path does.

The constructor change is the root fix. The two guard changes are defense in depth so neither component depends on the buffer contract for this case.

Tests

• Fw_Types_ut_exe: zero-capacity ExternalSerializeBuffer and SerialBuffer over a valid pointer construct cleanly and report the expected statuses. Null with zero capacity still works. Null with nonzero capacity still asserts (death test).
• Svc_FileUplink_ut_exe: 1-byte, 2-byte descriptor-only, and 3-byte truncated-body packets each return the buffer and emit exactly one warning event.
• Svc_Ccsds_CfdpManager_ut_exe: 2-byte descriptor-only packet returns the buffer with no events. 3-byte control reaches the engine and reports a header deserialization failure.

All three suites pass (68, 15 and 195 tests). With the source changes reverted, the new 2-byte tests in both components abort at the assertion, confirming they exercise the reported path.

🤖 Generated with Claude Code

[bitWarrior]

Retargeting this to nasa/fprime.