[compiler-rt] df87aeb - [Scudo] Improve ScopedString constructor

[Vitaly Buka via llvm-commits]

Author: Vitaly Buka
Date: 2021-06-04T18:28:29-07:00
New Revision: df87aeb8268240a1f9042aff1450d84900c52ae5

URL: https://github.com/llvm/llvm-project/commit/df87aeb8268240a1f9042aff1450d84900c52ae5
DIFF: https://github.com/llvm/llvm-project/commit/df87aeb8268240a1f9042aff1450d84900c52ae5.diff

LOG: [Scudo] Improve ScopedString constructor

Avoid referencing elements beyond internal vector size.

Reviewed By: cryptoad

Differential Revision: https://reviews.llvm.org/D103718

Added: 
    

Modified: 
    compiler-rt/lib/scudo/standalone/string_utils.h
    compiler-rt/lib/scudo/standalone/tests/strings_test.cpp

Removed: 
    


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diff  --git a/compiler-rt/lib/scudo/standalone/string_utils.h b/compiler-rt/lib/scudo/standalone/string_utils.h
index 7c1cd5753068..7d9c539c2711 100644
--- a/compiler-rt/lib/scudo/standalone/string_utils.h
+++ b/compiler-rt/lib/scudo/standalone/string_utils.h
@@ -18,12 +18,12 @@ namespace scudo {
 
 class ScopedString {
 public:
-  explicit ScopedString() : String() {}
+  explicit ScopedString() { String.push_back('\0'); }
   uptr length() { return Length; }
   const char *data() { return String.data(); }
   void clear() {
-    if (!String.empty())
-      String[0] = '\0';
+    String.clear();
+    String.push_back('\0');
     Length = 0;
   }
   void append(const char *Format, va_list Args);

diff  --git a/compiler-rt/lib/scudo/standalone/tests/strings_test.cpp b/compiler-rt/lib/scudo/standalone/tests/strings_test.cpp
index 332bac2f796e..298977a14c80 100644
--- a/compiler-rt/lib/scudo/standalone/tests/strings_test.cpp
+++ b/compiler-rt/lib/scudo/standalone/tests/strings_test.cpp
@@ -12,6 +12,12 @@
 
 #include <limits.h>
 
+TEST(ScudoStringsTest, Constructor) {
+  scudo::ScopedString Str;
+  EXPECT_EQ(0, Str.length());
+  EXPECT_EQ('\0', *Str.data());
+}
+
 TEST(ScudoStringsTest, Basic) {
   scudo::ScopedString Str;
   Str.append("a%db%zdc%ue%zuf%xh%zxq%pe%sr", static_cast<int>(-1),
@@ -28,6 +34,23 @@ TEST(ScudoStringsTest, Basic) {
   EXPECT_STREQ(expectedString.c_str(), Str.data());
 }
 
+TEST(ScudoStringsTest, Clear) {
+  scudo::ScopedString Str;
+  Str.append("123");
+  Str.clear();
+  EXPECT_EQ(0, Str.length());
+  EXPECT_EQ('\0', *Str.data());
+}
+
+TEST(ScudoStringsTest, ClearLarge) {
+  scudo::ScopedString Str;
+  for (int i = 0; i < 10000; ++i)
+    Str.append("123");
+  Str.clear();
+  EXPECT_EQ(0, Str.length());
+  EXPECT_EQ('\0', *Str.data());
+}
+
 TEST(ScudoStringsTest, Precision) {
   scudo::ScopedString Str;
   Str.append("%.*s", 3, "12345");