[LINTER] Add a YAML linter

Summary:
This uses a relaxed rule set for now, which does not enforce a strict
number of indentation spaces but instead check the file is consistently
indented. The maximum line lenght rule is also disabled to accomodate
the scripts in the gitian descriptors.

Test Plan:
Should return no error:
  arc lint --everything
Revert the changes to the .travis.yml from this diff then run:
  arc lint
and check the indentation errors are catched by the linter.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D7358

.arclint

@@ -230,6 +230,10 @@
             "exclude": [
                 "(^src/(crypto/ctaes|secp256k1|univalue|leveldb)/)"
             ]
+        },
+        "yamllint": {
+            "type": "yamllint",
+            "include": "(\\.(yml|yaml)$)"
         }
     }
 }

.yamllint

@@ -0,0 +1,7 @@
+---
+extends: relaxed
+
+rules:
+  # Some YML files embed a script portion, for which the line length rule would
+  # decrease the readability.
+  line-length: disable

CONTRIBUTING.md

@@ -132,7 +132,7 @@ will have to install the following:
 
 On Ubuntu (>= 18.04+updates):
 ```
-sudo apt-get install clang-format-8 clang-tidy-8 clang-tools-8 cppcheck python-autopep8 flake8 php-codesniffer
+sudo apt-get install clang-format-8 clang-tidy-8 clang-tools-8 cppcheck python-autopep8 flake8 php-codesniffer yamllint
 ```
 
 On Debian (>= 10), the clang-8 family of tools is available from the `buster-backports` repository:

arcanist/__phutil_library_map__.php

@@ -41,6 +41,7 @@
     'StdintLinter' => 'linter/StdintLinter.php',
     'TestsLinter' => 'linter/TestsLinter.php',
     'WhitespaceLinter' => 'linter/WhitespaceLinter.php',
+    'YamllintLinter' => 'linter/YamllintLinter.php',
   ),
   'function' => array(),
   'xmap' => array(
@@ -78,5 +79,6 @@
     'StdintLinter' => 'ArcanistLinter',
     'TestsLinter' => 'ArcanistExternalLinter',
     'WhitespaceLinter' => 'ArcanistLinter',
+    'YamllintLinter' => 'ArcanistExternalLinter',
   ),
 ));

arcanist/linter/YamllintLinter.php

@@ -0,0 +1,82 @@
+<?php
+
+/**
+ * Uses the yamllint tool to lint the YAML files.
+ */
+final class YamllintLinter extends ArcanistExternalLinter {
+
+  const YAMLLINT_SEVERITY_MAP = array(
+      'warning' => ArcanistLintSeverity::SEVERITY_WARNING,
+      'error' => ArcanistLintSeverity::SEVERITY_ERROR,
+  );
+
+  public function getInfoName() {
+    return 'yamllint';
+  }
+
+  public function getInfoDescription() {
+    return pht('Use yamllint for linting YAML files.');
+  }
+
+  public function getLinterName() {
+    return 'YAMLLINT';
+  }
+
+  public function getLinterConfigurationName() {
+    return 'yamllint';
+  }
+
+  public function getDefaultBinary() {
+    return 'yamllint';
+  }
+
+  public function getInstallInstructions() {
+    return pht('Please install yamllint and make sure it is in your $PATH');
+  }
+
+  public function shouldExpectCommandErrors() {
+    return true;
+  }
+
+  public function getVersion() {
+    list($stdout) = execx('%C --version', $this->getExecutableCommand());
+
+    $regex = '/^yamllint (?P<version>\d+\.\d+\.\d+)/m';
+    if (preg_match($regex, $stdout, $matches)) {
+      return $matches['version'];
+    }
+
+    return false;
+  }
+
+  private function getSeverity($severity) {
+    if (array_key_exists($severity, self::YAMLLINT_SEVERITY_MAP)) {
+      return self::YAMLLINT_SEVERITY_MAP[$severity];
+    }
+
+    return ArcanistLintSeverity::SEVERITY_ERROR;
+  }
+
+  protected function parseLinterOutput($path, $err, $stdout, $stderr) {
+    $messages = array();
+
+    $pattern = '/(\d+):(\d+)\s+(\w+)\s+(.+) \((.+)\)/';
+    if (preg_match_all($pattern, $stdout, $errors, PREG_SET_ORDER)) {
+      foreach ($errors as $error) {
+        list(, $line, $char, $severity, $message, $category) = $error;
+
+        $messages[] = id(new ArcanistLintMessage())
+        ->setGranularity(ArcanistLinter::GRANULARITY_FILE)
+        ->setPath($path)
+        ->setLine(intval($line))
+        ->setChar(intval($char))
+        ->setCode($category)
+        ->setSeverity($this->getSeverity($severity))
+        ->setName('yamllint found an issue:')
+        ->setDescription($message);
+      }
+    }
+
+    return $messages;
+  }
+}

contrib/teamcity/setup-debian-buster.sh

@@ -66,6 +66,7 @@ PACKAGES=(
   software-properties-common
   tar
   wget
+  yamllint
   wine
 )
 

src/secp256k1/.travis.yml

@@ -88,15 +88,15 @@ jobs:
         - CMAKE_EXTRA_FLAGS=-DCMAKE_C_FLAGS=-DVALGRIND  CMAKE_TARGET="secp256k1-tests secp256k1-exhaustive_tests"
 
 script:
- - ./travis/build_autotools.sh
- - ./travis/build_cmake.sh
- - # travis_wait extends the 10 minutes without output allowed (https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received)
- - # the `--error-exitcode` is required to make the test fail if valgrind found errors, otherwise it'll return 0 (http://valgrind.org/docs/manual/manual-core.html)
- - if [ -n "$VALGRIND" ]; then
-   travis_wait 30 valgrind --error-exitcode=42 ./buildautotools/tests 16 &&
-   travis_wait 30 valgrind --error-exitcode=42 ./buildautotools/exhaustive_tests;
-   fi
- - if [ -n "$VALGRIND" ]; then
-   travis_wait 30 valgrind --error-exitcode=42 ./buildcmake/secp256k1-tests 16 &&
-   travis_wait 30 valgrind --error-exitcode=42 ./buildcmake/secp256k1-exhaustive_tests;
-   fi
+  - ./travis/build_autotools.sh
+  - ./travis/build_cmake.sh
+  - # travis_wait extends the 10 minutes without output allowed (https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received)
+  - # the `--error-exitcode` is required to make the test fail if valgrind found errors, otherwise it'll return 0 (http://valgrind.org/docs/manual/manual-core.html)
+  - if [ -n "$VALGRIND" ]; then
+    travis_wait 30 valgrind --error-exitcode=42 ./buildautotools/tests 16 &&
+    travis_wait 30 valgrind --error-exitcode=42 ./buildautotools/exhaustive_tests;
+    fi
+  - if [ -n "$VALGRIND" ]; then
+    travis_wait 30 valgrind --error-exitcode=42 ./buildcmake/secp256k1-tests 16 &&
+    travis_wait 30 valgrind --error-exitcode=42 ./buildcmake/secp256k1-exhaustive_tests;
+    fi