Added missing null checks in CdmSession.

[ Merge of http://go/wvgerrit/85743 ]

There were a few methods that did not check that the output parameter was not
set to null befor assigning to.  The new checks follow a similar pattern that
is used for DeviceFiles.

Bug: 135207278
Test: Linux unittest and Android tests
Change-Id: Idff25a71dd7a6db99f7f9c2dcf4949ac683208cc

libwvdrmengine/cdm/core/src/cdm_session.cpp

@@ -19,6 +19,22 @@
 #include "wv_cdm_constants.h"
 #include "wv_cdm_event_listener.h"
 
+// Stringify turns macro arguments into static C strings.
+//   Example: STRINGIFY(this_argument) -> "this_argument"
+#define STRINGIFY(PARAM...) #PARAM
+
+#define RETURN_STATUS_IF_NULL(PARAM)                              \
+  if ((PARAM) == nullptr) {                                       \
+    LOGE("Output parameter |" STRINGIFY(PARAM) "| not provided"); \
+    return PARAMETER_NULL;                                        \
+  }
+
+#define RETURN_FALSE_IF_NULL(PARAM)                               \
+  if ((PARAM) == nullptr) {                                       \
+    LOGE("Output parameter |" STRINGIFY(PARAM) "| not provided"); \
+    return false;                                                 \
+  }
+
 namespace {
 const size_t kKeySetIdLength = 14;
 
@@ -391,11 +407,7 @@ CdmResponseType CdmSession::GenerateKeyRequestInternal(
     LOGE("CDM session not initialized");
     return NOT_INITIALIZED_ERROR;
   }
-
+  RETURN_STATUS_IF_NULL(key_request);
-  if (!key_request) {
-    LOGE("No output destination provided");
-    return PARAMETER_NULL;
-  }
 
   switch (license_type) {
     case kLicenseTypeTemporary:
@@ -561,6 +573,7 @@ CdmResponseType CdmSession::QueryStatus(CdmQueryMap* query_response) {
     LOGE("CDM session not initialized");
     return NOT_INITIALIZED_ERROR;
   }
+  RETURN_STATUS_IF_NULL(query_response);
 
   switch (security_level_) {
     case kSecurityLevelL1:
@@ -603,9 +616,10 @@ CdmResponseType CdmSession::QueryKeyAllowedUsage(
 CdmResponseType CdmSession::QueryOemCryptoSessionId(
     CdmQueryMap* query_response) {
   if (!initialized_) {
-    LOGE("Not initialized");
+    LOGE("CDM session not initialized");
     return NOT_INITIALIZED_ERROR;
   }
+  RETURN_STATUS_IF_NULL(query_response);
 
   (*query_response)[QUERY_KEY_OEMCRYPTO_SESSION_ID] =
       std::to_string(crypto_session_->oec_session_id());
@@ -663,6 +677,8 @@ CdmResponseType CdmSession::GenerateRenewalRequest(CdmKeyRequest* key_request) {
     LOGE("CDM session not initialized");
     return NOT_INITIALIZED_ERROR;
   }
+  RETURN_STATUS_IF_NULL(key_request);
+
   CdmResponseType status = license_parser_->PrepareKeyUpdateRequest(
       true, app_parameters_, nullptr, &key_request->message, &key_request->url);
 
@@ -706,6 +722,7 @@ CdmResponseType CdmSession::GenerateReleaseRequest(CdmKeyRequest* key_request) {
     LOGE("CDM session not initialized");
     return NOT_INITIALIZED_ERROR;
   }
+  RETURN_STATUS_IF_NULL(key_request);
   is_release_ = true;
   license_request_latency_.Clear();
   CdmResponseType status = license_parser_->PrepareKeyUpdateRequest(
@@ -813,10 +830,7 @@ CdmSessionId CdmSession::GenerateSessionId() {
 }
 
 bool CdmSession::GenerateKeySetId(CdmKeySetId* key_set_id) {
-  if (!key_set_id) {
+  RETURN_FALSE_IF_NULL(key_set_id);
-    LOGW("Key set ID destination not provided");
-    return false;
-  }
 
   std::vector<uint8_t> random_data(
       (kKeySetIdLength - sizeof(KEY_SET_ID_PREFIX)) / 2, 0);
@@ -1062,10 +1076,7 @@ CdmResponseType CdmSession::GenericEncrypt(const std::string& in_buffer,
                                            const std::string& iv,
                                            CdmEncryptionAlgorithm algorithm,
                                            std::string* out_buffer) {
-  if (!out_buffer) {
+  RETURN_STATUS_IF_NULL(out_buffer);
-    LOGE("No output destination provided");
-    return PARAMETER_NULL;
-  }
   CdmResponseType sts;
   M_TIME(sts = crypto_session_->GenericEncrypt(in_buffer, key_id, iv, algorithm,
                                                out_buffer),
@@ -1079,10 +1090,7 @@ CdmResponseType CdmSession::GenericDecrypt(const std::string& in_buffer,
                                            const std::string& iv,
                                            CdmEncryptionAlgorithm algorithm,
                                            std::string* out_buffer) {
-  if (!out_buffer) {
+  RETURN_STATUS_IF_NULL(out_buffer);
-    LOGE("No output destination provided");
-    return PARAMETER_NULL;
-  }
   CdmResponseType sts;
   M_TIME(sts = crypto_session_->GenericDecrypt(in_buffer, key_id, iv, algorithm,
                                                out_buffer),
@@ -1095,10 +1103,7 @@ CdmResponseType CdmSession::GenericSign(const std::string& message,
                                         const std::string& key_id,
                                         CdmSigningAlgorithm algorithm,
                                         std::string* signature) {
-  if (!signature) {
+  RETURN_STATUS_IF_NULL(signature);
-    LOGE("No output destination provided");
-    return PARAMETER_NULL;
-  }
   CdmResponseType sts;
   M_TIME(
       sts = crypto_session_->GenericSign(message, key_id, algorithm, signature),