ci: Add filesystem lint check

.cirrus.yml

@@ -84,6 +84,9 @@ task:
     memory: 1G
   # For faster CI feedback, immediately schedule the linters
   << : *CREDITS_TEMPLATE
+  test_runner_cache:
+    folder: "/lint_test_runner"
+    fingerprint_script: echo $CIRRUS_TASK_NAME $(git rev-parse HEAD:test/lint/test_runner)
   python_cache:
     folder: "/python_build"
     fingerprint_script: cat .python-version /etc/os-release

ci/lint/04_install.sh

@@ -33,6 +33,17 @@ export PATH="${PYTHON_PATH}/bin:${PATH}"
 command -v python3
 python3 --version
 
+export LINT_RUNNER_PATH="/lint_test_runner"
+if [ ! -d "${LINT_RUNNER_PATH}" ]; then
+  ${CI_RETRY_EXE} apt-get install -y cargo
+  (
+    cd ./test/lint/test_runner || exit 1
+    cargo build
+    mkdir -p "${LINT_RUNNER_PATH}"
+    mv target/debug/test_runner "${LINT_RUNNER_PATH}"
+  )
+fi
+
 ${CI_RETRY_EXE} pip3 install \
   codespell==2.2.5 \
   flake8==6.1.0 \

ci/lint/06_script.sh

@@ -30,6 +30,7 @@ test/lint/git-subtree-check.sh src/secp256k1
 test/lint/git-subtree-check.sh src/minisketch
 test/lint/git-subtree-check.sh src/leveldb
 test/lint/git-subtree-check.sh src/crc32c
+RUST_BACKTRACE=1 "${LINT_RUNNER_PATH}/test_runner"
 test/lint/check-doc.py
 test/lint/all-lint.py
 

ci/lint/container-entrypoint.sh

@@ -11,6 +11,7 @@ export LC_ALL=C
 git config --global --add safe.directory /bitcoin
 
 export PATH="/python_build/bin:${PATH}"
+export LINT_RUNNER_PATH="/lint_test_runner"
 
 if [ -z "$1" ]; then
   LOCAL_BRANCH=1 bash -ic "./ci/lint/06_script.sh"

test/lint/README.md

@@ -15,6 +15,14 @@ docker run --rm -v $(pwd):/bitcoin -it bitcoin-linter
 After building the container once, you can simply run the last command any time you
 want to lint.
 
+test runner
+===========
+
+To run the checks in the test runner outside the docker, use:
+
+```sh
+( cd ./test/lint/test_runner/ && cargo fmt && cargo clippy && cargo run )
+```
 
 check-doc.py
 ============

test/lint/test_runner/Cargo.toml

@@ -0,0 +1,12 @@
+# Copyright (c) The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://opensource.org/license/mit/.
+
+[package]
+name = "test_runner"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

test/lint/test_runner/src/main.rs

@@ -0,0 +1,77 @@
+// Copyright (c) The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://opensource.org/license/mit/.
+
+use std::env;
+use std::path::PathBuf;
+use std::process::Command;
+use std::process::ExitCode;
+
+use String as LintError;
+
+/// Return the git command
+fn git() -> Command {
+    Command::new("git")
+}
+
+/// Return stdout
+fn check_output(cmd: &mut std::process::Command) -> Result<String, LintError> {
+    let out = cmd.output().expect("command error");
+    if !out.status.success() {
+        return Err(String::from_utf8_lossy(&out.stderr).to_string());
+    }
+    Ok(String::from_utf8(out.stdout)
+        .map_err(|e| format!("{e}"))?
+        .trim()
+        .to_string())
+}
+
+/// Return the git root as utf8, or panic
+fn get_git_root() -> String {
+    check_output(git().args(["rev-parse", "--show-toplevel"])).unwrap()
+}
+
+fn lint_std_filesystem() -> Result<(), LintError> {
+    let found = git()
+        .args([
+            "grep",
+            "std::filesystem",
+            "--",
+            "./src/",
+            ":(exclude)src/util/fs.h",
+        ])
+        .status()
+        .expect("command error")
+        .success();
+    if found {
+        Err(r#"
+^^^
+Direct use of std::filesystem may be dangerous and buggy. Please include <util/fs.h> and use the
+fs:: namespace, which has unsafe filesystem functions marked as deleted.
+            "#
+        .to_string())
+    } else {
+        Ok(())
+    }
+}
+
+fn main() -> ExitCode {
+    let test_list = [("std::filesystem check", lint_std_filesystem)];
+
+    let git_root = PathBuf::from(get_git_root());
+
+    let mut test_failed = false;
+    for (lint_name, lint_fn) in test_list {
+        // chdir to root before each lint test
+        env::set_current_dir(&git_root).unwrap();
+        if let Err(err) = lint_fn() {
+            println!("{err}\n^---- Failure generated from {lint_name}!");
+            test_failed = true;
+        }
+    }
+    if test_failed {
+        ExitCode::FAILURE
+    } else {
+        ExitCode::SUCCESS
+    }
+}