From: Adrien Conrath <adri@fb.com>
Date: Wed, 25 Nov 2015 16:34:09 +0000 (-0800)
Subject: Remove undefined behavior in goodMallocSize()
X-Git-Tag: deprecate-dynamic-initializer~231
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ffe26edc53bc90a14078c66e46764ea3e6a81df6;p=folly.git

Remove undefined behavior in goodMallocSize()

Reviewed By: ot

Differential Revision: D2695741

fb-gh-sync-id: d33263c1ffa5651d66f37992ce365dae157ed449
---

diff --git a/folly/Malloc.h b/folly/Malloc.h
index f8398911..828c1b65 100644
--- a/folly/Malloc.h
+++ b/folly/Malloc.h
@@ -177,6 +177,10 @@ inline bool usingJEMalloc() noexcept {
 }
 
 inline size_t goodMallocSize(size_t minSize) noexcept {
+  if (minSize == 0) {
+    return 0;
+  }
+
   if (!usingJEMalloc()) {
     // Not using jemalloc - no smarts
     return minSize;
diff --git a/folly/test/FBVectorTest.cpp b/folly/test/FBVectorTest.cpp
index 330dc4bb..ae845834 100644
--- a/folly/test/FBVectorTest.cpp
+++ b/folly/test/FBVectorTest.cpp
@@ -274,6 +274,16 @@ TEST(FBVector, vector_of_maps) {
   EXPECT_EQ(1, v[1].size());
 }
 
+TEST(FBVector, shrink_to_fit_after_clear) {
+  fbvector<int> fb1;
+  fb1.push_back(42);
+  fb1.push_back(1337);
+  fb1.clear();
+  fb1.shrink_to_fit();
+  EXPECT_EQ(fb1.size(), 0);
+  EXPECT_EQ(fb1.capacity(), 0);
+}
+
 int main(int argc, char** argv) {
   testing::InitGoogleTest(&argc, argv);
   gflags::ParseCommandLineFlags(&argc, &argv, true);