feat(linux): own udev rules setup and diagnose unopenable ports (#1424) - #1425
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feat(linux): own udev rules setup and diagnose unopenable ports (#1424)#1425zackees wants to merge 3 commits into
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On Linux serial nodes are root:dialout 0660 and the invoking user is
usually not in `dialout`. `fbuild deploy` then flashes successfully and
cannot reopen the port it just flashed. Nothing in the toolchain set this
up: fbuild had no udev/setup/doctor path, and FastLED only *diagnoses*
(`ci/compiler/pio.py::check_usb_permissions`) on the legacy PlatformIO
path that the fbuild deploy path never calls. PlatformIO used to ship
`99-platformio-udev.rules` for manual install; fbuild replaced pio for
build and deploy but not that setup step.
The expensive part was the misdirection. fbuild found the port, called it
`health healthy`, printed `Permission denied`, and then advised cables,
BOOTSEL and RESET — a remedy unrelated to the cause. On an unattended
bench that reads as a hardware fault.
`port doctor` now reports it. A port can be attached, healthy, and still
impossible to open; that combination rendered as "attached and healthy"
with an empty remedy. The new verdict is checked before presence and
names the fix. It also says a one-shot chmod will not hold: deploy
re-enumerates the board (BOOTSEL -> application) and udev recreates the
node before fbuild reopens it, so only a vendor-keyed rule survives.
`fbuild port udev` prints rules for every vendor in the registry.
- Vendors come from the ingested FastLED/boards catalogue via the new
`usb::online_vendor_vids()`, never a local table — a hand-maintained
copy would drift the moment a vendor is ingested, which is what the
VID/PID source-of-truth rule exists to prevent. 36 vendors today.
- Prints, never installs. On NixOS `/etc` is generated from declarative
config, so a written file there is out-of-band and gets clobbered;
those users need the content for `services.udev.extraRules`. Elsewhere
it keeps the privileged write explicit.
- An empty registry is an error, not an empty file: one that looks
configured while granting nothing is worse than none.
- Defaults to `plugdev`, which unlike `dialout` does not also confer
modem/PPP access.
Rules render as lowercase zero-padded 4-digit hex because udev compares
ATTRS{idVendor} as a string against sysfs — "0x2E8A" or "2E8A" simply
never match, silently. Tests pin that, the padding, sort/dedup, the
group override, and the empty-registry refusal.
Verified: cargo check --all-targets clean; `cargo test -p fbuild-cli`
315 passed / 0 failed, including 6 new udev tests and 4 new port_doctor
tests (the existing 27 still pass, so the absent/failing-board verdicts
this command was written for are undisturbed). `fbuild port udev` emits
36 rules from the live registry, every VID exactly 4 lowercase hex
digits, including 2e8a and 303a.
Found while an RP2350 bench run kept failing post-deploy port reopen
(FastLED#3899).
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Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review. 📝 WalkthroughWalkthroughThe CLI now generates Linux udev rules from online USB vendor data. Linux port diagnosis uses nonblocking probes and clearer permission remediation output. ChangesLinux udev support
Estimated code review effort: 3 (Moderate) | ~25 minutes Merge Risk: ⚪ Minimal · up to The CLI adds read-only serial permission diagnosis and prints validated, vendor-keyed udev rules without installing them. No concrete current-head merge-blocking risk remains. Sequence Diagram(s)sequenceDiagram
participant User
participant run_udev
participant USBOverlay
participant render_udev_rules
User->>run_udev: invoke port udev
run_udev->>USBOverlay: refresh online overlay
run_udev->>USBOverlay: request online vendor VIDs
USBOverlay-->>run_udev: return vendor VIDs
run_udev->>render_udev_rules: validate group and render rules
render_udev_rules-->>run_udev: return rule text or no rules
run_udev-->>User: print rules and install hint
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Actionable comments posted: 4
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Inline comments:
In `@crates/fbuild-cli/src/cli/port_doctor.rs`:
- Line 118: Update the remediation string in render_report’s report construction
to remove literal whitespace runs between sentences, using Rust string
continuations or concatenated literals while preserving the complete guidance
and normal terminal spacing.
- Line 92: Update the port probe in the port-doctor flow around
OpenOptions::open to apply platform-specific custom flags for nonblocking access
and preventing acquisition of a controlling terminal, using the appropriate
OpenOptionsExt support. Preserve the existing read-only open and match behavior.
In `@crates/fbuild-cli/src/cli/udev.rs`:
- Around line 50-55: Format the changed Rust code in the udev rule-generation
function using the repository’s standard Rust formatting configuration. Preserve
the generated output and update the affected out.push_str calls involving
UDEV_RULES_FILENAME and group to match formatter output.
- Line 66: Validate the group value before formatting it in the udev rule
generated by the CLI: reject empty values and accept only a safe group-name
format that cannot contain quotes, newlines, or other rule syntax. Apply this
validation at the --group input boundary used by the udev rule generation flow,
while preserving normal valid group names.
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crates/fbuild-cli/src/cli/mod.rscrates/fbuild-cli/src/cli/port_doctor.rscrates/fbuild-cli/src/cli/port_scan.rscrates/fbuild-cli/src/cli/udev.rscrates/fbuild-core/src/usb/data.rscrates/fbuild-core/src/usb/mod.rs
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#1424) Addresses CodeRabbit on #1425. Both findings were valid; the second was a bug I introduced. 1. `OpenOptions::new().read(true).open(port)` set neither O_NONBLOCK nor O_NOCTTY. On Linux a terminal with CLOCAL clear blocks until carrier detect, which would hang a command whose own docs promise a strictly read-only diagnostic; without O_NOCTTY the probe could also acquire a controlling terminal, so signals sent there would reach fbuild. Not theoretical: an open on a contended port measured 13.3 s on the bench that motivated this issue. Now uses `custom_flags(libc::O_NONBLOCK | libc::O_NOCTTY)`, with libc added to fbuild-cli under a `cfg(unix)` target since it was a workspace dependency but not a crate one. 2. The permission remedy carried literal runs of ~20 spaces: "...your user is not in that group..." The source was generated through a heredoc that consumed the `\` line-continuations as continuations of the *generating* language, joining the lines while keeping their indentation. Rebuilt from `concat!()` of separate literals, which cannot reproduce that. cargo check -p fbuild-cli --all-targets clean; `cargo test -p fbuild-cli port_doctor` 34 passed / 0 failed, including the four verdict tests that assert on the remedy text. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KkufoNxfnNRU9psT3R9F51
Two findings from the review that I had missed by reading only the first
comment rather than enumerating all of them.
1. Injection (CWE-74). `--group` reached the quoted udev value with no
validation. The rendered file is one an operator installs as root, so
--group 'plugdev\nSUBSYSTEM=="tty", MODE="0666"'
would close the quote and append a world-writable rule for every
serial device. There is no encoding that makes this safe: udev only
unescapes \" inside a standard quoted string, and "\n" stays literal,
so nothing neutralises an embedded newline. Reject instead.
`is_valid_group_name` mirrors useradd(8)'s NAME_REGEX -- an initial
alphanumeric or underscore, then alphanumerics, underscore, hyphen or
dot, up to 32 characters -- and `render_udev_rules` returns None for
anything else, alongside the existing empty-registry refusal.
2. rustfmt. I had never run `soldr cargo fmt`, so the formatting pipeline
was failing on this branch.
Tests cover quote injection, newline injection, empty, leading hyphen,
leading dot, embedded space, semicolon and slash, plus the ordinary names
that must keep working and the 32/33 character boundary.
soldr cargo test -p fbuild-cli: 318 passed / 0 failed.
soldr cargo fmt --all -- --check: clean.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KkufoNxfnNRU9psT3R9F51
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Closes #1424.
Problem
On Linux serial nodes are
root:dialout 0660and the invoking user is usually not indialout.fbuild deployflashes successfully and then cannot reopen the port it just flashed:fbuild finds the port, calls it
health healthy, printsPermission denied— and then advises cables, BOOTSEL and RESET. The remedy has nothing to do with the cause. On an unattended bench this reads as a hardware fault; it cost a long investigation before the permissions bit was noticed.Nothing set this up. fbuild had no udev/setup/doctor path, and FastLED only diagnoses (
ci/compiler/pio.py::check_usb_permissions) on the legacy PlatformIO path that the fbuild deploy path never calls. PlatformIO shipped99-platformio-udev.rulesfor manual install; fbuild replaced pio for build and deploy but not that setup step.port doctornow reports itA port can be attached, healthy, and impossible to open. That combination previously rendered as "attached and healthy" with an empty remedy. The new verdict is checked before presence and names the actual fix.
It also states that a one-shot
chmodwill not hold — deploy re-enumerates the board (BOOTSEL → application) and udev recreates the node before fbuild reopens it, so only a vendor-keyed rule survives. That detail is what makes the difference between a fix and an hour of confusion.The probe opens read-only, on Linux only: enough to surface
EACCESwithout asserting DTR/RTS, soport doctorkeeps its documented strictly-read-only contract.fbuild port udevPrints rules for every vendor in the registry.
usb::online_vendor_vids(), never a local table. A hand-maintained list would drift the moment a vendor is ingested — exactly what the VID/PID source-of-truth rule exists to prevent. 36 vendors today./etcis generated from declarative config, so a written file there is out-of-band and liable to be clobbered; those users need the content forservices.udev.extraRules. Elsewhere it keeps the privileged write explicit rather than doing it behind the user's back.plugdev, which unlikedialoutdoes not also confer modem/PPP access.--groupoverrides.Rules render as lowercase zero-padded 4-digit hex because udev compares
ATTRS{idVendor}as a string against sysfs —"0x2E8A"or"2E8A"simply never match, and the failure is silent. Tests pin that, the padding, sort/dedup, the group override, and the empty-registry refusal.Verification
cargo check -p fbuild-cli --all-targets— cleancargo test -p fbuild-cli— 315 passed, 0 failed, including 6 newudev::tests and 4 newport_doctor::tests. The existing 27port_doctortests still pass, so the absent/failing-board verdicts this command was written for are undisturbed.fbuild port udevagainst the live registry — 36 rules, every VID exactly four lowercase hex digits, including2e8a(Raspberry Pi) and303a(Espressif):Not included
fbuild port udev --install(write + reload). The issue ranked printing higher, and a privileged write deserves its own review — the generated content is the part users actually need. Happy to add it as a follow-up.Found while an RP2350 bench run kept failing post-deploy port reopen (FastLED#3899). Related: fbuild#1423.
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Summary by CodeRabbit
New Features
plugdevgroup by default and support custom group names.Bug Fixes