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Format NMEA messages directly into a caller supplied buffer instead of allocating a new buffer with malloc() on every call. nmea_printf_buffer() is reimplemented on top of the new nmea_vaprintf_buffer() and keeps its previous behaviour: it returns 0 without touching the buffer if the message does not fit, and a NUL terminated string is always produced when it does fit. Adds a unit test for the new formatting path. --AI assistance: this change was AI-assisted, reviewed by a human before submission.
Keep the message and sub-string buffers as class members allocated once for their maximum possible formatted length, instead of creating fresh stack buffers sized by guesswork on every update() call. Sub-strings such as the longitude are now guaranteed to be NUL terminated so they can never be passed unterminated to the %s consumers of the NMEA message formats. --AI assistance: this change was AI-assisted, reviewed by a human before submission.
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Hi @WickedShell, this PR is ready for review whenever you get a chance. The failing copter test (ModeZigZag) is a known SITL flake unrelated to the NMEA changes. Thanks! |
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Summary
Fixes #12514. AP_NMEA_Output no longer allocates a fresh buffer per message. It uses persistent pre-sized message buffers and a new non-allocating formatting helper, fixing latent
snprintfbuffer-size bugs.Classification & Testing (check all that apply and add your own)
Tested with SITL copter build, NMEA unit tests (
tests/test_nmea_vaprint_buffer,tests/test_nmea_print,tests/test_nmea_vaprint), andcheck_branch_conventions.py.Description
AP_Common: addNMEA::vaprint()andNMEA::vaprintf()helpers that format into caller-provided buffers without allocating, plus atest_nmea_vaprint_bufferunit test. Fixes the incorrect buffer lengths passed to the previous::*printfvariants inAP_NMEA_Output.AP_NMEA_Output: store persistent, pre-sized message buffers in the message classes instead of building a temporaryStringper message. This removes periodic heap allocations, moves the data into contiguous memory, and keeps Mavlink copying in one piece.Note: contribution is AI-assisted (written with the assistance of an LLM, reviewed by the human author).