Add linter to check for binaries accidentally added to repository

This should catch mistakes like
a703fbce20969e6f02e74fee76c0a9e22b513426.

Adds an arcanist-external-json-linter submodule, which should eventually
be mirrored on haskell.org resources.

Test Plan: Validate

Reviewers: thomie, hvr, austin

Reviewed By: austin

Differential Revision: https://phabricator.haskell.org/D1515

2 files changed, 20 insertions, 0 deletions

diff --git a/.arc-linters/arcanist-external-json-linter b/.arc-linters/arcanist-external-json-linter
new file mode 160000
+Subproject 85ece0f8653e7b1e7de6024d372cfeaf36ab5fa
diff --git a/.arc-linters/check-binaries.py b/.arc-linters/check-binaries.py
new file mode 100755
index 0000000000..ae007567fa
--- /dev/null
+++ b/.arc-linters/check-binaries.py
@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+# A linter to warn when binary files are added to the repository
+
+import sys
+import os
+import json
+
+path = sys.argv[1]
+warnings = []
+if os.path.isfile(path):
+    with open(path) as f:
+        if '\0' in f.read(8000):
+            warning = {
+                'severity': 'warning',
+                'message': 'This file appears to be a binary file; does it really belong in the repository?'
+            }
+            warnings.append(warning)
+
+print json.dumps(warnings)