format: don't format files in third_party

It's annoying, and it also makes appveyor slow because it will re-upload
the third_party cache every time something changes in there.

1 files changed, 17 insertions, 8 deletions

diff --git a/tools/util.py b/tools/util.py
index 2cb22ed6a..306f2109f 100644
--- a/tools/util.py
+++ b/tools/util.py
@@ -131,15 +131,24 @@ def touch(fname):
 
 
 # Recursive search for files of certain extensions.
-# (Recursive glob doesn't exist in python 2.7.)
-def find_exts(directory, *extensions):
+#   * Recursive glob doesn't exist in python 2.7.
+#   * On windows, `os.walk()` unconditionally follows symlinks.
+#     The `skip`  parameter should be used to avoid recursing through those.
+def find_exts(directories, extensions, skip=[]):
+    assert isinstance(directories, list)
+    assert isinstance(extensions, list)
+    skip = [os.path.normpath(i) for i in skip]
     matches = []
-    for root, dirnames, filenames in os.walk(directory):
-        for filename in filenames:
-            for ext in extensions:
-                if filename.endswith(ext):
-                    matches.append(os.path.join(root, filename))
-                    break
+    for directory in directories:
+        for root, dirnames, filenames in os.walk(directory):
+            if root in skip:
+                dirnames[:] = []  # Don't recurse further into this directory.
+                continue
+            for filename in filenames:
+                for ext in extensions:
+                    if filename.endswith(ext):
+                        matches.append(os.path.join(root, filename))
+                        break
     return matches