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Drives the unmodified httpd.c and uip.c through a handshake and a GET from a client that moves its receive window, and compares the bytes that reach the wire with the file they are meant to carry. The served file holds a position-dependent pattern, so a repeat or a gap is reported at its offset rather than as content that differs somewhere. The first scenario holds the window still and must pass: it is the check that the bench itself is sound, before the two moving-window scenarios are believed.
63 lines
3.8 KiB
Markdown
63 lines
3.8 KiB
Markdown
# Host unit-test harness
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Compile and test individual firmware translation units on the build host with
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**gcc + AddressSanitizer + UBSan** — no SDCC, no flashing, no hardware. This is
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the fast inner loop for the logic-level bugs in `../../NOTES/08-findings.md`
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(parser, line editor, HTTP header, DHCP): edit → `make` → see red/green in
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seconds instead of a minutes-long flash-and-reboot cycle.
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## Run
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```
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cd test
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make # build + run all tests (ASan/UBSan on)
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make clean
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```
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Exit status is non-zero if any check fails, a sanitizer trips, or the watchdog
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fires — so it drops straight into CI.
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## How it works
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- **`sdcc_shim.h`** (force-included) erases SDCC 8051 keywords (`__xdata`,
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`__code`, `__banked`, …) so firmware sources compile under host gcc. It changes
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no logic — the code under test is byte-for-byte the firmware source.
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- **`hw_mock.c` / `hw_mock.h`** simulate the ASIC edge: a flat register file
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behind `reg_read`/`reg_write` and the `SFR_DATA_*` registers, with a table
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engine that performs a VLAN or L2 operation the moment `TBL_CTRL` is written,
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fetches a MIB counter on `STAT_GET` and drops entries on `L2_TBL_FLUSH_CTRL`.
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Nothing ever reports busy, so a polling loop runs once. The header states the
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VLAN and L2 entry layouts independently of the firmware, so a test can hold
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what `rtl837x_port.c` writes against what `page_impl.c` reads.
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- **`env_tables.c`** carries the globals and leaf calls those two modules link
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against; **`stub/`** stands in for the two headers only a firmware build
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generates, so the harness needs no SDCC build first.
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- **`support.c` / `support.h`** mock the hardware edges: the 16-byte serial ring
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(`sbuf`), the command/history buffers, and the character-output sink
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(`write_char` etc.). Buffers are sized **exactly** as on target, so ASan
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redzones catch the same off-by-one overflows the 8051 hits.
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- Builds define **`RTLP_HOST_TEST`**, which hides the firmware's libc-named
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prototypes (`memset`/`strlen`/…) in `rtl837x_common.h` so they don't clash with
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glibc. Argument order matches libc, so on-host callers transparently use the C
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library. This guard is compiled out of normal firmware builds — zero on-target
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effect.
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- A **SIGALRM watchdog** (`watchdog_arm`) turns an infinite-loop bug into a fast
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test failure instead of a hung runner.
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## Current coverage
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| Test binary | TU under test | Findings exercised |
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|-------------|---------------|--------------------|
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| `test_cmd_editor` | `cmd_editor.c` | **C4** — full-line hang + `cmd_buffer` 1-byte overflow; basic entry & backspace regressions |
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| `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 |
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| `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` |
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| `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 |
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## Adding a test for another module
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1. Write `test_<module>.c` with `main()` driving the module's entry points and
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`CHECK(cond, msg)` assertions.
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2. Add any missing mocked symbols to `support.c` (only what the linker asks for).
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3. Add a target in the `Makefile` listing `test_<module>.c support.c ../<module>.c`.
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4. If the module calls a firmware libc-name (`memcpy`/`strcpy`/…), it will use the
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C library on host (compatible arg order); provide a `fw_*`-style mock only if
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the semantics differ in a way the test cares about.
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Good next targets (pure logic, high finding density): `cmd_parser.c` (C6/C8),
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the HTTP header parser in `httpd/httpd.c` (S1), `dhcp.c` (S5).
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