Improve/fix bugs for the cpp linter

Summary:
Previous our new `arc lint` has two annoying bugs:

* Keeping sending false alarm that we'd put c++ system files first -- even though we've already done that.
  - this problem is caused by our linter, which doesn't give the underlying cpplint.py right file path (it gives "-" as file name), making cpplint.py work incorrectly.
* Only works in rocksdb's root dir; Otherwise it'll throw exception saying "cannot find cpplint.py".

I copied open source ArcanistCpplintLinter and modifiy it for our use.

Test Plan: Ran arc lint and made sure the above-mentioned problem won't occur.

Reviewers: haobo, sdong, igor, ljin, yhchiang, dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16137

.arcconfig

@@ -6,6 +6,5 @@
     "linters"
   ],
   "lint.engine" : "FacebookFbcodeLintEngine",
-  "lint.engine.single.linter" : "FbcodeCppLinter",
-  "lint.cpplint.prefix" : "linters"
+  "lint.engine.single.linter" : "FbcodeCppLinter"
 }

linters/__phutil_library_map__.php

@@ -13,6 +13,7 @@ phutil_register_library_map(array(
     'FacebookFbcodeLintEngine' => 'lint_engine/FacebookFbcodeLintEngine.php',
     'FbcodeCppLinter' => 'cpp_linter/FbcodeCppLinter.php',
     'PfffCppLinter' => 'cpp_linter/PfffCppLinter.php',
+    'ArcanistCpplintLinter' => 'cpp_linter/ArcanistCpplintLinter.php',
   ),
   'function' =>
   array(

linters/cpp_linter/ArcanistCpplintLinter.php

@@ -0,0 +1,113 @@
+<?php
+
+/**
+ * Uses google's cpplint.py to check code. RocksDB team forked this file from
+ * phabricator's /src/lint/linter/ArcanistCpplintLinter.php, and customized it
+ * for its own use.
+ *
+ * You can get it here:
+ * http://google-styleguide.googlecode.com/svn/trunk/cpplint/cpplint.py
+ * @group linter
+ */
+final class ArcanistCpplintLinter extends ArcanistLinter {
+
+  public function willLintPaths(array $paths) {
+    return;
+  }
+
+  public function getLinterName() {
+    return 'cpplint.py';
+  }
+
+  public function getLintOptions() {
+    $config = $this->getEngine()->getConfigurationManager();
+    $options = $config->getConfigFromAnySource('lint.cpplint.options', '');
+
+    return $options;
+  }
+
+  public function getLintPath() {
+    $config = $this->getEngine()->getConfigurationManager();
+    $prefix = $config->getConfigFromAnySource('lint.cpplint.prefix');
+    $bin = $config->getConfigFromAnySource('lint.cpplint.bin', 'cpplint.py');
+
+    if ($prefix !== null) {
+      if (!Filesystem::pathExists($prefix.'/'.$bin)) {
+        throw new ArcanistUsageException(
+          "Unable to find cpplint.py binary in a specified directory. Make ".
+          "sure that 'lint.cpplint.prefix' and 'lint.cpplint.bin' keys are ".
+          "set correctly. If you'd rather use a copy of cpplint installed ".
+          "globally, you can just remove these keys from your .arcconfig.");
+      }
+
+      $bin = csprintf("%s/%s", $prefix, $bin);
+
+      return $bin;
+    }
+
+    // Search under current dir
+    list($err) = exec_manual('which %s/%s', $this->linterDir(), $bin);
+    if (!$err) {
+      return $this->linterDir().'/'.$bin;
+    }
+
+    // Look for globally installed cpplint.py
+    list($err) = exec_manual('which %s', $bin);
+    if ($err) {
+      throw new ArcanistUsageException(
+        "cpplint.py does not appear to be installed on this system. Install ".
+        "it (e.g., with 'wget \"http://google-styleguide.googlecode.com/".
+        "svn/trunk/cpplint/cpplint.py\"') or configure 'lint.cpplint.prefix' ".
+        "in your .arcconfig to point to the directory where it resides. ".
+        "Also don't forget to chmod a+x cpplint.py!");
+    }
+
+    return $bin;
+  }
+
+  public function lintPath($path) {
+    $bin = $this->getLintPath();
+    $options = $this->getLintOptions();
+    $path = $this->rocksdbDir().'/'.$path;
+
+    $f = new ExecFuture("%C %C $path", $bin, $options);
+
+    list($err, $stdout, $stderr) = $f->resolve();
+
+    if ($err === 2) {
+      throw new Exception("cpplint failed to run correctly:\n".$stderr);
+    }
+
+    $lines = explode("\n", $stderr);
+    $messages = array();
+    foreach ($lines as $line) {
+      $line = trim($line);
+      $matches = null;
+      $regex = '/^[^:]+:(\d+):\s*(.*)\s*\[(.*)\] \[(\d+)\]$/';
+      if (!preg_match($regex, $line, $matches)) {
+        continue;
+      }
+      foreach ($matches as $key => $match) {
+        $matches[$key] = trim($match);
+      }
+      $message = new ArcanistLintMessage();
+      $message->setPath($path);
+      $message->setLine($matches[1]);
+      $message->setCode($matches[3]);
+      $message->setName($matches[3]);
+      $message->setDescription($matches[2]);
+      $message->setSeverity(ArcanistLintSeverity::SEVERITY_WARNING);
+      $this->addLintMessage($message);
+    }
+  }
+
+  // The path of this linter
+  private function linterDir() {
+    return dirname(__FILE__);
+  }
+
+  // TODO(kaili) a quick and dirty way to figure out rocksdb's root dir.
+  private function rocksdbDir() {
+    return $this->linterDir()."/../..";
+  }
+}