[compiler-rt] Add ConsumeRandomLengthString() version without arguments.

Reviewers: hctim, metzman

Subscribers: dberris, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D76448

compiler-rt/include/fuzzer/FuzzedDataProvider.h

@@ -139,6 +139,11 @@ class FuzzedDataProvider {
     return result;
   }
 
+  // Returns a std::string of length from 0 to |remaining_bytes_|.
+  std::string ConsumeRandomLengthString() {
+    return ConsumeRandomLengthString(remaining_bytes_);
+  }
+
   // Returns a std::vector containing all remaining bytes of the input data.
   template <typename T> std::vector<T> ConsumeRemainingBytes() {
     return ConsumeBytes<T>(remaining_bytes_);

compiler-rt/lib/fuzzer/tests/FuzzedDataProviderUnittest.cpp

@@ -190,14 +190,26 @@ TEST(FuzzedDataProvider, ConsumeRandomLengthString) {
                 "\x1D\xBD\x4E\x17\x04\x1E\xBA\x26\xAC\x1F\xE3\x37\x1C\x15\x43"
                 "\x60\x41\x2A\x7C\xCA\x70\xCE\xAB\x20\x24\xF8\xD9\x1F\x14\x7C"),
             DataProv.ConsumeRandomLengthString(31337));
-  EXPECT_EQ(std::string(Data + 141, Data + 141 + 5),
+  size_t Offset = 141;
+  EXPECT_EQ(std::string(Data + Offset, Data + Offset + 5),
             DataProv.ConsumeRandomLengthString(5));
-  EXPECT_EQ(std::string(Data + 141 + 5, Data + 141 + 5 + 2),
+  Offset += 5;
+  EXPECT_EQ(std::string(Data + Offset, Data + Offset + 2),
             DataProv.ConsumeRandomLengthString(2));
+  Offset += 2;
+
+  // Call the overloaded method without arguments (uses max length available).
+  EXPECT_EQ(std::string(Data + Offset, Data + Offset + 664),
+            DataProv.ConsumeRandomLengthString());
+  Offset += 664 + 2; // +2 because of '\' character followed by any other byte.
+
+  EXPECT_EQ(std::string(Data + Offset, Data + Offset + 92),
+            DataProv.ConsumeRandomLengthString());
+  Offset += 92 + 2;
 
   // Exhaust the buffer.
   auto String = DataProv.ConsumeBytesAsString(31337);
-  EXPECT_EQ(size_t(876), String.length());
+  EXPECT_EQ(size_t(116), String.length());
   EXPECT_EQ(std::string(), DataProv.ConsumeRandomLengthString(1));
 }