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DrDoof
214cc6b737
stp_timers() ran every fourth pass of the main loop and stp_clock counted passes, which only measures time while a pass is one tick long. It never quite was: a pass is as long as the packets it handles, and #482 now takes up to four of them, so under an IPv4 stream a pass is about 16 ms and STP time runs at a third of its rate, with hellos 6 s apart and a root aged out after a minute. Since #483 the loop also stops sleeping while packets wait, so under a flood of cheap frames passes come faster than ticks and STP time runs fast instead, shortening the forward delay in exactly the situation a loop produces. uip_periodic() had the same problem from the other side: it ran once per pass, so the retransmit timer sped up with the loop. Both now go by the tick counter the timer interrupt keeps. The STP block catches up on ticks a long pass missed, at most eight steps at a time, and handle_tx() runs its periodics once per tick at most. One byte of xdata more, 48 bytes of code. A host test drives the gate with one pass every 5 ms, every 16 ms and every 0.6 ms for ten seconds each; the STP clock lands on 500 steps in all three, where counting passes gave 156 and 4166. A pass of 1.3 s loses time rather than firing 65 steps at once, and the arithmetic survives the tick counter wrapping.
Host unit-test harness
Compile and test individual firmware translation units on the build host with
gcc + AddressSanitizer + UBSan — no SDCC, no flashing, no hardware. This is
the fast inner loop for the logic-level bugs in ../../NOTES/08-findings.md
(parser, line editor, HTTP header, DHCP): edit → make → see red/green in
seconds instead of a minutes-long flash-and-reboot cycle.
Run
cd test
make # build + run all tests (ASan/UBSan on)
make clean
Exit status is non-zero if any check fails, a sanitizer trips, or the watchdog fires — so it drops straight into CI.
How it works
sdcc_shim.h(force-included) erases SDCC 8051 keywords (__xdata,__code,__banked, …) so firmware sources compile under host gcc. It changes no logic — the code under test is byte-for-byte the firmware source.hw_mock.c/hw_mock.hsimulate the ASIC edge: a flat register file behindreg_read/reg_writeand theSFR_DATA_*registers, with a table engine that performs a VLAN or L2 operation the momentTBL_CTRLis written, fetches a MIB counter onSTAT_GETand drops entries onL2_TBL_FLUSH_CTRL. Nothing ever reports busy, so a polling loop runs once. The header states the VLAN and L2 entry layouts independently of the firmware, so a test can hold whatrtl837x_port.cwrites against whatpage_impl.creads.env_tables.ccarries the globals and leaf calls those two modules link against;stub/stands in for the two headers only a firmware build generates, so the harness needs no SDCC build first.support.c/support.hmock the hardware edges: the 16-byte serial ring (sbuf), the command/history buffers, and the character-output sink (write_charetc.). Buffers are sized exactly as on target, so ASan redzones catch the same off-by-one overflows the 8051 hits.- Builds define
RTLP_HOST_TEST, which hides the firmware's libc-named prototypes (memset/strlen/…) inrtl837x_common.hso they don't clash with glibc. Argument order matches libc, so on-host callers transparently use the C library. This guard is compiled out of normal firmware builds — zero on-target effect. - A SIGALRM watchdog (
watchdog_arm) turns an infinite-loop bug into a fast test failure instead of a hung runner.
Current coverage
| Test binary | TU under test | Findings exercised |
|---|---|---|
test_cmd_editor |
cmd_editor.c |
C4 — full-line hang + cmd_buffer 1-byte overflow; basic entry & backspace regressions |
test_port_tables |
rtl837x_port.c |
VLAN entry layout and round trip, PVID register sharing, static multicast and management entries, per-port flush, trunk membership and hash seed |
test_page_json |
httpd/page_impl.c + rtl837x_port.c |
/vlan.json, /vlanlist, /l2.json (walk, wrap marker, paging inside outbuf), 64-bit counters in /status.json and /counters.json |
test_httpd_tx |
httpd/httpd.c + uip/uip.c |
a GET of a static file against a client that moves its receive window: ACK accounting, continuation chunks out of flash, retransmission |
Adding a test for another module
- Write
test_<module>.cwithmain()driving the module's entry points andCHECK(cond, msg)assertions. - Add any missing mocked symbols to
support.c(only what the linker asks for). - Add a target in the
Makefilelistingtest_<module>.c support.c ../<module>.c. - If the module calls a firmware libc-name (
memcpy/strcpy/…), it will use the C library on host (compatible arg order); provide afw_*-style mock only if the semantics differ in a way the test cares about.
Good next targets (pure logic, high finding density): cmd_parser.c (C6/C8),
the HTTP header parser in httpd/httpd.c (S1), dhcp.c (S5).