[Tizen] Account for 0-terminator in WriteConfigValueStr (#26510)

* [Tizen] Account for 0-terminator in WriteConfigValueStr

* Fix null-terminator implementation after review

* Update src/platform/Tizen/PosixConfig.cpp

---------

Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>

src/platform/Tizen/PosixConfig.cpp

@@ -101,7 +101,16 @@ CHIP_ERROR PosixConfig::ReadConfigValue(Key key, uint64_t & val)
 CHIP_ERROR PosixConfig::ReadConfigValueStr(Key key, char * buf, size_t bufSize, size_t & outLen)
 {
     VerifyOrReturnError(buf != nullptr, CHIP_ERROR_INVALID_ARGUMENT);
-    return PersistedStorage::KeyValueStoreMgr().Get(key.Name, buf, bufSize, &outLen);
+
+    auto err = PersistedStorage::KeyValueStoreMgr().Get(key.Name, buf, bufSize, &outLen);
+    VerifyOrReturnError(err == CHIP_NO_ERROR, err);
+
+    // We are storing string values in the config store without
+    // the null terminator, so we need to add it here.
+    VerifyOrReturnError(bufSize >= outLen + 1, CHIP_ERROR_BUFFER_TOO_SMALL);
+    buf[outLen] = '\0';
+
+    return CHIP_NO_ERROR;
 }
 
 CHIP_ERROR PosixConfig::ReadConfigValueBin(Key key, uint8_t * buf, size_t bufSize, size_t & outLen)

src/platform/tests/TestConfigurationMgr.cpp

@@ -449,7 +449,6 @@ static void TestConfigurationMgr_GetProductId(nlTestSuite * inSuite, void * inCo
  *   Test Suite. It lists all the test functions.
  */
 static const nlTest sTests[] = {
-
     NL_TEST_DEF("Test PlatformMgr::Init", TestPlatformMgr_Init),
 #if !defined(NDEBUG)
     NL_TEST_DEF("Test PlatformMgr::RunUnitTest", TestPlatformMgr_RunUnitTest),
@@ -466,8 +465,8 @@ static const nlTest sTests[] = {
     NL_TEST_DEF("Test ConfigurationMgr::GetVendorId", TestConfigurationMgr_GetVendorId),
     NL_TEST_DEF("Test ConfigurationMgr::GetProductName", TestConfigurationMgr_GetProductName),
     NL_TEST_DEF("Test ConfigurationMgr::GetProductId", TestConfigurationMgr_GetProductId),
-    NL_TEST_SENTINEL()
-}; // namespace
+    NL_TEST_SENTINEL(),
+};
 
 /**
  *  Set up the test suite.