Add More Base Path Helpers to DeviceFiles

(This is a merge of http://go/wvgerrit/13910/ from the Widevine CDM
repository.)

DeviceFiles has a lot of repeated code whenever it needs to check for
file existence or remove a file. When reading and writing files, it
has wrappers that handle this repeated burden. This change adds
wrappers for the other functionality used by DeviceFiles as well, to
reduce duplication.

Change-Id: If959b504672c1b907346d28f31648d8028de8bdf

libwvdrmengine/cdm/core/include/device_files.h

@@ -3,6 +3,8 @@
 #ifndef WVCDM_CORE_DEVICE_FILES_H_
 #define WVCDM_CORE_DEVICE_FILES_H_
 
+#include <unistd.h>
+
 #include "scoped_ptr.h"
 #include "wv_cdm_types.h"
 
@@ -81,9 +83,14 @@ class DeviceFiles {
                                  CdmKeyResponse* license_response);
 
  private:
+  // Helpers that wrap the File interface and automatically handle hashing, as
+  // well as adding the device files base path to to the file name.
   bool StoreFileWithHash(const char* name, const std::string& serialized_file);
   bool StoreFileRaw(const char* name, const std::string& serialized_file);
   bool RetrieveHashedFile(const char* name, std::string* serialized_file);
+  bool FileExists(const char* name);
+  bool RemoveFile(const char* name);
+  ssize_t GetFileSize(const char* name);
 
   // Certificate and offline licenses are now stored in security
   // level specific directories. In an earlier version they were

libwvdrmengine/cdm/core/src/device_files.cpp

@@ -35,6 +35,7 @@ const char kCertificateFileName[] = "cert.bin";
 const char kUsageInfoFileNamePrefix[] = "usage";
 const char kUsageInfoFileNameExt[] = ".bin";
 const char kLicenseFileNameExt[] = ".lic";
+const char kEmptyFileName[] = "";
 const char kWildcard[] = "*";
 const char kDirectoryDelimiter = '/';
 const char* kSecurityLevelPathCompatibilityExclusionList[] = {"ay64.dat"};
@@ -268,15 +269,9 @@ bool DeviceFiles::DeleteLicense(const std::string& key_set_id) {
     return false;
   }
 
-  std::string path;
-  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
-    LOGW("DeviceFiles::DeleteLicense: Unable to get base path");
-    return false;
-  }
-  path.append(key_set_id);
-  path.append(kLicenseFileNameExt);
-
-  return file_->Remove(path);
+  std::string file_name(key_set_id);
+  file_name.append(kLicenseFileNameExt);
+  return RemoveFile(file_name.c_str());
 }
 
 bool DeviceFiles::DeleteAllLicenses() {
@@ -285,15 +280,9 @@ bool DeviceFiles::DeleteAllLicenses() {
     return false;
   }
 
-  std::string path;
-  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
-    LOGW("DeviceFiles::DeleteAllLicenses: Unable to get base path");
-    return false;
-  }
-  path.append(kWildcard);
-  path.append(kLicenseFileNameExt);
-
-  return file_->Remove(path);
+  std::string file_name(kWildcard);
+  file_name.append(kLicenseFileNameExt);
+  return RemoveFile(file_name.c_str());
 }
 
 bool DeviceFiles::DeleteAllFiles() {
@@ -302,13 +291,9 @@ bool DeviceFiles::DeleteAllFiles() {
     return false;
   }
 
-  std::string path;
-  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
-    LOGW("DeviceFiles::DeleteAllFiles: Unable to get base path");
-    return false;
-  }
-
-  return file_->Remove(path);
+  // We pass an empty string to RemoveFile to delete the device files base
+  // directory itself.
+  return RemoveFile(kEmptyFileName);
 }
 
 bool DeviceFiles::LicenseExists(const std::string& key_set_id) {
@@ -317,15 +302,9 @@ bool DeviceFiles::LicenseExists(const std::string& key_set_id) {
     return false;
   }
 
-  std::string path;
-  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
-    LOGW("DeviceFiles::LicenseExists: Unable to get base path");
-    return false;
-  }
-  path.append(key_set_id);
-  path.append(kLicenseFileNameExt);
-
-  return file_->Exists(path);
+  std::string file_name(key_set_id);
+  file_name.append(kLicenseFileNameExt);
+  return FileExists(file_name.c_str());
 }
 
 bool DeviceFiles::ReserveLicenseId(const std::string& key_set_id) {
@@ -429,14 +408,9 @@ bool DeviceFiles::DeleteAllUsageInfoForApp(
     return false;
   }
   provider_session_tokens->clear();
-  std::string path;
-  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
-    LOGW("DeviceFiles::DeleteAllUsageInfoForApp: Unable to get base path");
-    return false;
-  }
+
   std::string file_name = GetUsageInfoFileName(app_id);
-  path.append(file_name);
-  if (!file_->Exists(path)) return true;
+  if (!FileExists(file_name.c_str())) return true;
   std::string serialized_file;
   if (RetrieveHashedFile(file_name.c_str(), &serialized_file)) {
     video_widevine_client::sdk::File file_proto;
@@ -451,7 +425,7 @@ bool DeviceFiles::DeleteAllUsageInfoForApp(
   } else {
     LOGW("DeviceFiles::DeleteAllUsageInfoForApp: Unable to retrieve file");
   }
-  return file_->Remove(path);
+  return RemoveFile(file_name.c_str());
 }
 
 bool DeviceFiles::RetrieveUsageInfo(
@@ -472,14 +446,7 @@ bool DeviceFiles::RetrieveUsageInfo(
   std::string serialized_file;
   std::string file_name = GetUsageInfoFileName(app_id);
   if (!RetrieveHashedFile(file_name.c_str(), &serialized_file)) {
-    std::string path;
-    if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
-      return false;
-    }
-
-    path += file_name;
-
-    if (!file_->Exists(path) || 0 == file_->FileSize(path)) {
+    if (!FileExists(file_name.c_str()) || GetFileSize(file_name.c_str()) == 0) {
       usage_info->resize(0);
       return true;
     }
@@ -696,6 +663,69 @@ bool DeviceFiles::RetrieveHashedFile(const char* name,
   return true;
 }
 
+bool DeviceFiles::FileExists(const char* name) {
+  if (!file_.get()) {
+    LOGW("DeviceFiles::FileExists: Invalid file handle");
+    return false;
+  }
+
+  if (!name) {
+    LOGW("DeviceFiles::FileExists: Unspecified file name parameter");
+    return false;
+  }
+
+  std::string path;
+  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
+    LOGW("DeviceFiles::FileExists: Unable to get base path");
+    return false;
+  }
+  path += name;
+
+  return file_->Exists(path);
+}
+
+bool DeviceFiles::RemoveFile(const char* name) {
+  if (!file_.get()) {
+    LOGW("DeviceFiles::RemoveFile: Invalid file handle");
+    return false;
+  }
+
+  if (!name) {
+    LOGW("DeviceFiles::RemoveFile: Unspecified file name parameter");
+    return false;
+  }
+
+  std::string path;
+  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
+    LOGW("DeviceFiles::RemoveFile: Unable to get base path");
+    return false;
+  }
+  path += name;
+
+  return file_->Remove(path);
+}
+
+ssize_t DeviceFiles::GetFileSize(const char* name) {
+  if (!file_.get()) {
+    LOGW("DeviceFiles::GetFileSize: Invalid file handle");
+    return -1;
+  }
+
+  if (!name) {
+    LOGW("DeviceFiles::GetFileSize: Unspecified file name parameter");
+    return -1;
+  }
+
+  std::string path;
+  if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {
+    LOGW("DeviceFiles::GetFileSize: Unable to get base path");
+    return -1;
+  }
+  path += name;
+
+  return file_->FileSize(path);
+}
+
 void DeviceFiles::SecurityLevelPathBackwardCompatibility() {
   std::string path;
   if (!Properties::GetDeviceFilesBasePath(security_level_, &path)) {