Add fuzzers for libutils classes

Adds fuzzers for BitSet, FileMap, String8, String16, and Vector.
Test: Ran fuzzers on Android Pixel 3a. Aggregate coverage was 1.2% (this is far lower than true coverage due to shared libraries being counted)

Change-Id: I739216fe88afa51dc2f73b857da91116853382f0

Removed unneeded cflags, moved libbase to defaults

Test: Built Android.bp successfully

Signed-off-by: Dylan Katz <dylan.katz@leviathansecurity.com>
Change-Id: I739216fe88afa51dc2f73b857da91116853382f0
diff --git a/libutils/String16_fuzz.cpp b/libutils/String16_fuzz.cpp
new file mode 100644
index 0000000..63c2800
--- /dev/null
+++ b/libutils/String16_fuzz.cpp
@@ -0,0 +1,122 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <iostream>
+
+#include "fuzzer/FuzzedDataProvider.h"
+#include "utils/String16.h"
+static constexpr int MAX_STRING_BYTES = 256;
+static constexpr uint8_t MAX_OPERATIONS = 50;
+
+std::vector<std::function<void(FuzzedDataProvider&, android::String16, android::String16)>>
+        operations = {
+
+                // Bytes and size
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16) -> void {
+                    str1.string();
+                }),
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16) -> void {
+                    str1.isStaticString();
+                }),
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16) -> void {
+                    str1.size();
+                }),
+
+                // Casing
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16) -> void {
+                    str1.makeLower();
+                }),
+
+                // Comparison
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16 str2) -> void {
+                    str1.startsWith(str2);
+                }),
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16 str2) -> void {
+                    str1.contains(str2.string());
+                }),
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16 str2) -> void {
+                    str1.compare(str2);
+                }),
+
+                // Append and format
+                ([](FuzzedDataProvider&, android::String16 str1, android::String16 str2) -> void {
+                    str1.append(str2);
+                }),
+                ([](FuzzedDataProvider& dataProvider, android::String16 str1,
+                    android::String16 str2) -> void {
+                    int pos = dataProvider.ConsumeIntegralInRange<int>(0, str1.size());
+                    str1.insert(pos, str2.string());
+                }),
+
+                // Find and replace operations
+                ([](FuzzedDataProvider& dataProvider, android::String16 str1,
+                    android::String16) -> void {
+                    char16_t findChar = dataProvider.ConsumeIntegral<char16_t>();
+                    str1.findFirst(findChar);
+                }),
+                ([](FuzzedDataProvider& dataProvider, android::String16 str1,
+                    android::String16) -> void {
+                    char16_t findChar = dataProvider.ConsumeIntegral<char16_t>();
+                    str1.findLast(findChar);
+                }),
+                ([](FuzzedDataProvider& dataProvider, android::String16 str1,
+                    android::String16) -> void {
+                    char16_t findChar = dataProvider.ConsumeIntegral<char16_t>();
+                    char16_t replaceChar = dataProvider.ConsumeIntegral<char16_t>();
+                    str1.replaceAll(findChar, replaceChar);
+                }),
+                ([](FuzzedDataProvider& dataProvider, android::String16 str1,
+                    android::String16) -> void {
+                    size_t len = dataProvider.ConsumeIntegral<size_t>();
+                    size_t begin = dataProvider.ConsumeIntegral<size_t>();
+                    str1.remove(len, begin);
+                }),
+};
+
+void callFunc(uint8_t index, FuzzedDataProvider& dataProvider, android::String16 str1,
+              android::String16 str2) {
+    operations[index](dataProvider, str1, str2);
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    FuzzedDataProvider dataProvider(data, size);
+    // We're generating two char vectors.
+    // First, generate lengths.
+    const size_t kVecOneLen = dataProvider.ConsumeIntegralInRange<size_t>(1, MAX_STRING_BYTES);
+    const size_t kVecTwoLen = dataProvider.ConsumeIntegralInRange<size_t>(1, MAX_STRING_BYTES);
+
+    // Next, populate the vectors
+    std::vector<char> vec = dataProvider.ConsumeBytesWithTerminator<char>(kVecOneLen);
+    std::vector<char> vec_two = dataProvider.ConsumeBytesWithTerminator<char>(kVecTwoLen);
+
+    // Get pointers to their data
+    char* char_one = vec.data();
+    char* char_two = vec_two.data();
+
+    // Create UTF16 representations
+    android::String16 str_one_utf16 = android::String16(char_one);
+    android::String16 str_two_utf16 = android::String16(char_two);
+
+    // Run operations against strings
+    int opsRun = 0;
+    while (dataProvider.remaining_bytes() > 0 && opsRun++ < MAX_OPERATIONS) {
+        uint8_t op = dataProvider.ConsumeIntegralInRange<uint8_t>(0, operations.size() - 1);
+        callFunc(op, dataProvider, str_one_utf16, str_two_utf16);
+    }
+
+    str_one_utf16.remove(0, str_one_utf16.size());
+    str_two_utf16.remove(0, str_two_utf16.size());
+    return 0;
+}