From 348fff3dd435538c9e71d32497ffcc2ead86e684 Mon Sep 17 00:00:00 2001
From: Chris Bracken <chris@bracken.jp>
Date: Tue, 21 Nov 2017 15:42:17 -0800
Subject: [PATCH] Catch divide-by-zero errors early in license tool
 (flutter/engine#4382)

If Progress is instantiated with a max of 0, throw immediately to avoid
a divide-by-zero later in toString(). This typically happens if the tool
recurses over an empty top-level component, which can happen when a
component is moved around in the repo and the developer hasn't cleaned
up old empty directories from their git client.
---
 engine/src/flutter/tools/licenses/lib/main.dart | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/engine/src/flutter/tools/licenses/lib/main.dart b/engine/src/flutter/tools/licenses/lib/main.dart
index d855b3a9153..7f4566a87fa 100644
--- a/engine/src/flutter/tools/licenses/lib/main.dart
+++ b/engine/src/flutter/tools/licenses/lib/main.dart
@@ -2313,7 +2313,13 @@ class RepositoryRoot extends RepositoryDirectory {
 
 
 class Progress {
-  Progress(this.max);
+  Progress(this.max) {
+    // This may happen when a git client contains left-over empty component
+    // directories after DEPS file changes.
+    if (max <= 0)
+      throw new ArgumentError('Progress.max must be > 0 but was: $max');
+  }
+
   final int max;
   int get withLicense => _withLicense;
   int _withLicense = 0;