Refactor file_store to use smart pointers

Bug: b/119276649
Merge from: http://go/wvgerrit/66367
Test: Android, CE CDM, Linux unit tests

The FileSystem interface as it exists expects an Open for a file and
then a Close when finished. However, the Close doesn't delete the file
itself and depending on the platform, the underlying impl_ as well,
leading to a memory leak. To fix this leak as well as harden against
future memory issues, this change refactors the interface to shift away
from raw pointers and towards smart pointers.

Change-Id: I7a7132ea95cd3775796a540f510b698f4f27dd24

libwvdrmengine/oemcrypto/ref/src/oemcrypto_engine_ref.cpp

@@ -118,7 +118,7 @@ time_t CryptoEngine::RollbackCorrectedOfflineTime() {
   // Use the device key for encrypt/decrypt.
   const std::vector<uint8_t>& key = DeviceRootKey();
 
-  wvcdm::File* file;
+  std::unique_ptr<wvcdm::File> file;
   std::string path;
   // Note: this path is OK for a real implementation, but using security level 1
   // would be better.
@@ -140,7 +140,6 @@ time_t CryptoEngine::RollbackCorrectedOfflineTime() {
       return time(NULL);
     }
     file->Read(reinterpret_cast<char*>(&encrypted_buffer[0]), sizeof(TimeInfo));
-    file->Close();
     // Decrypt the encrypted TimeInfo buffer.
     AES_KEY aes_key;
     AES_set_decrypt_key(&key[0], 128, &aes_key);
@@ -180,7 +179,6 @@ time_t CryptoEngine::RollbackCorrectedOfflineTime() {
     return time(NULL);
   }
   file->Write(reinterpret_cast<char*>(&encrypted_buffer[0]), sizeof(TimeInfo));
-  file->Close();
 
   // Return time with offset.
   return current_time;

libwvdrmengine/oemcrypto/ref/src/oemcrypto_old_usage_table_ref.cpp

@@ -64,7 +64,7 @@ OldUsageTable::OldUsageTable(CryptoEngine *ce) {
 
   // Load saved table.
   wvcdm::FileSystem *file_system = ce->file_system();
-  wvcdm::File *file;
+  std::unique_ptr<wvcdm::File> file;
   std::string path;
   // Note: this path is OK for a real implementation, but using security level 1
   // would be better.
@@ -93,7 +93,6 @@ OldUsageTable::OldUsageTable(CryptoEngine *ce) {
     return;
   }
   file->Read(reinterpret_cast<char *>(&encrypted_buffer[0]), file_size);
-  file->Close();
 
   // Verify the signature of the usage table file.
 
@@ -148,7 +147,6 @@ OldUsageTable::OldUsageTable(CryptoEngine *ce) {
     return;
   }
   file->Read(reinterpret_cast<char *>(&generation_), sizeof(int64_t));
-  file->Close();
   if ((stored_table->generation > generation_ + 1) ||
       (stored_table->generation < generation_ - 1)) {
     LOGE("OldUsageTable: Rollback detected. Clearing Usage Table. %lx -> %lx",

libwvdrmengine/oemcrypto/ref/src/oemcrypto_usage_table_ref.cpp

@@ -669,7 +669,7 @@ bool UsageTable::SaveGenerationNumber() {
   // On a real implementation, you should NOT put the generation number in
   // a file in user space.  It should be stored in secure memory.
   std::string filename = path + "GenerationNumber.dat";
-  wvcdm::File* file = file_system->Open(
+  auto file = file_system->Open(
       filename, wvcdm::FileSystem::kCreate | wvcdm::FileSystem::kTruncate);
   if (!file) {
     LOGE("UsageTable: File open failed: %s", path.c_str());
@@ -677,7 +677,6 @@ bool UsageTable::SaveGenerationNumber() {
   }
   file->Write(reinterpret_cast<char*>(&master_generation_number_),
               sizeof(int64_t));
-  file->Close();
   return true;
 }
 
@@ -696,7 +695,7 @@ bool UsageTable::LoadGenerationNumber(bool or_make_new_one) {
   // On a real implementation, you should NOT put the generation number in
   // a file in user space.  It should be stored in secure memory.
   std::string filename = path + "GenerationNumber.dat";
-  wvcdm::File* file = file_system->Open(filename, wvcdm::FileSystem::kReadOnly);
+  auto file = file_system->Open(filename, wvcdm::FileSystem::kReadOnly);
   if (!file) {
     if (or_make_new_one) {
       RAND_bytes(reinterpret_cast<uint8_t*>(&master_generation_number_),
@@ -709,7 +708,6 @@ bool UsageTable::LoadGenerationNumber(bool or_make_new_one) {
   }
   file->Read(reinterpret_cast<char*>(&master_generation_number_),
              sizeof(int64_t));
-  file->Close();
   return true;
 }