Implement Cdm::listStoredLicenses()

[ Merge of http://go/wvgerrit/23600 ]

This adds a new entry to IStorage:: -

  bool list(std::vector<std::string> file_names)

It returns the name of each file in the (origin-specific) file system.

b/34628115

Uses the current file system (origin-specific) bound to the CDM. Returns
the list of stored licenses (key_set_ids) in vector output parameter.

Test: verified by unittests on angler.

Change-Id: I988556b27c2a4b75f52b59bcd78cfeaddd649acd

libwvdrmengine/cdm/core/src/device_files.cpp

@@ -299,6 +299,39 @@ bool DeviceFiles::DeleteLicense(const std::string& key_set_id) {
   return RemoveFile(key_set_id + kLicenseFileNameExt);
 }
 
+bool DeviceFiles::ListLicenses(std::vector<std::string>* key_set_ids) {
+  if (!initialized_) {
+    LOGW("DeviceFiles::ListLicenses: not initialized");
+    return false;
+  }
+
+  if (key_set_ids == NULL) {
+    LOGW("DeviceFiles::ListLicenses: key_set_ids parameter not provided");
+    return false;
+  }
+
+  // Get list of filenames
+  std::vector<std::string> filenames;
+  if (!ListFiles(&filenames)) {
+    return false;
+  }
+
+  // Scan list of returned filenames, remove extension, and return
+  // as a list of key_set_ids.
+  key_set_ids->clear();
+  for (int i = 0; i < filenames.size(); i++) {
+    std::string* name = &filenames[i];
+    std::size_t pos = name->find(kLicenseFileNameExt);
+    if (pos == std::string::npos) {
+      // Skip this file - extension does not match
+      continue;
+    }
+    // Store filename (minus extension).  This should be a key set ID.
+    key_set_ids->push_back(name->substr(0, pos));
+  }
+  return true;
+}
+
 bool DeviceFiles::DeleteAllLicenses() {
   if (!initialized_) {
     LOGW("DeviceFiles::DeleteAllLicenses: not initialized");
@@ -821,7 +854,7 @@ bool DeviceFiles::RetrieveHashedFile(
 
   std::string path;
   if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
-    LOGW("DeviceFiles::StoreFileWithHash: Unable to get base path");
+    LOGW("DeviceFiles::RetrieveHashedFile: Unable to get base path");
     return false;
   }
 
@@ -898,6 +931,15 @@ bool DeviceFiles::FileExists(const std::string& name) {
   return file_system_->Exists(path);
 }
 
+bool DeviceFiles::ListFiles(std::vector<std::string>* names) {
+  std::string path;
+  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
+    LOGW("DeviceFiles::RemoveFile: Unable to get base path");
+    return false;
+  }
+  return file_system_->List(path, names);
+}
+
 bool DeviceFiles::RemoveFile(const std::string& name) {
   std::string path;
   if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {