Recover when stored information is corrupted

[ Merge of http://go/wvgerrit/52040 ]

Information stored in files are serialized and protected by an MD5 hash.
When files cannot be read because the MD5 hash computed over it
fails verification, the file is deleted. This allows for recovery.

However if the protobuf deserialization fails we return an error
but do not delete the file. When errors of this sort occur
with usage information files, the CDM cannot recover.
removeAllSecureStops() will fail as well and new licenses
with PSTs cannot be processed. In order to recover the file will
be deleted when a protobuf deserialization error occurs.

Bug: 109765590
Test: WV unit, integration tests. GTS tests. Netflix and Play Movies playback
Change-Id: I408914924e644d5c22b2ba7865d3a7d598788ee6

libwvdrmengine/cdm/core/src/device_files.cpp

@@ -1203,6 +1203,9 @@ bool DeviceFiles::RetrieveHashedFile(
 
   if (bytes != static_cast<ssize_t>(serialized_hash_file.size())) {
     LOGW("DeviceFiles::RetrieveHashedFile: read failed");
+    // Remove the corrupted file so the caller will not get the same error
+    // when trying to access the file repeatedly, causing the system to stall.
+    file_system_->Remove(path);
     return false;
   }
 
@@ -1212,6 +1215,9 @@ bool DeviceFiles::RetrieveHashedFile(
   HashedFile hash_file;
   if (!hash_file.ParseFromString(serialized_hash_file)) {
     LOGW("DeviceFiles::RetrieveHashedFile: Unable to parse hash file");
+    // Remove the corrupted file so the caller will not get the same error
+    // when trying to access the file repeatedly, causing the system to stall.
+    file_system_->Remove(path);
     return false;
   }
 
@@ -1231,6 +1237,9 @@ bool DeviceFiles::RetrieveHashedFile(
 
   if (!deserialized_file->ParseFromString(hash_file.file())) {
     LOGW("DeviceFiles::RetrieveHashedFile: Unable to parse file");
+    // Remove the corrupted file so the caller will not get the same error
+    // when trying to access the file repeatedly, causing the system to stall.
+    file_system_->Remove(path);
     return false;
   }
   return true;