Initialize scalar members in TLVReader (project-chip#32129)

* Initialize scalar members in TLVReader

The documented return values for multiple TLVReader functions do match
the actual return value for the uninitialize case. Explicitly initialize
members with null/0 values to match the documentation.

* Restyled by clang-format

* Don't inline constructor

* Restyled by clang-format

---------

Co-authored-by: Restyled.io <commits@restyled.io>

Author: mwswartwout

src/lib/core/TLVReader.cpp

@@ -49,6 +49,12 @@ using namespace chip::Encoding;
 
 static const uint8_t sTagSizes[] = { 0, 1, 2, 4, 2, 4, 6, 8 };
 
+TLVReader::TLVReader() :
+    ImplicitProfileId(kProfileIdNotSpecified), AppData(nullptr), mElemLenOrVal(0), mBackingStore(nullptr), mReadPoint(nullptr),
+    mBufEnd(nullptr), mLenRead(0), mMaxLen(0), mContainerType(kTLVType_NotSpecified), mControlByte(kTLVControlByte_NotSpecified),
+    mContainerOpen(false)
+{}
+
 void TLVReader::Init(const uint8_t * data, size_t dataLen)
 {
     // TODO: Maybe we can just make mMaxLen and mLenRead size_t instead?

src/lib/core/TLVReader.h

@@ -86,6 +86,8 @@ class DLL_EXPORT TLVReader
     friend class TLVUpdater;
 
 public:
+    TLVReader();
+
     /**
      * Initializes a TLVReader object from another TLVReader object.
      *

src/lib/core/tests/TestTLV.cpp

@@ -3832,6 +3832,27 @@ void TestTLVReader_SkipOverContainer(nlTestSuite * inSuite)
     ForEachElement(inSuite, reader, nullptr, TestTLVReader_SkipOverContainer_ProcessElement);
 }
 
+/**
+ * Tests using an uninitialized TLVReader.
+ */
+void TestTLVReaderUninitialized(nlTestSuite * inSuite)
+{
+    TLVReader reader;
+
+    NL_TEST_ASSERT(inSuite, reader.GetType() == kTLVType_NotSpecified);
+    NL_TEST_ASSERT(inSuite, reader.GetLength() == 0);
+    NL_TEST_ASSERT(inSuite, reader.GetControlByte() == kTLVControlByte_NotSpecified);
+    NL_TEST_ASSERT(inSuite, reader.GetContainerType() == kTLVType_NotSpecified);
+    NL_TEST_ASSERT(inSuite, reader.GetLengthRead() == 0);
+    NL_TEST_ASSERT(inSuite, reader.GetRemainingLength() == 0);
+    NL_TEST_ASSERT(inSuite, reader.GetTotalLength() == 0);
+    NL_TEST_ASSERT(inSuite, reader.GetBackingStore() == nullptr);
+    NL_TEST_ASSERT(inSuite, reader.IsElementDouble() == false);
+    NL_TEST_ASSERT(inSuite, reader.GetReadPoint() == nullptr);
+    NL_TEST_ASSERT(inSuite, reader.ImplicitProfileId == kProfileIdNotSpecified);
+    NL_TEST_ASSERT(inSuite, reader.AppData == nullptr);
+}
+
 /**
  *  Test CHIP TLV Reader
  */
@@ -3852,6 +3873,8 @@ void CheckTLVReader(nlTestSuite * inSuite, void * inContext)
     TestTLVReader_NextOverContainer(inSuite);
 
     TestTLVReader_SkipOverContainer(inSuite);
+
+    TestTLVReaderUninitialized(inSuite);
 }
 
 /**