Platform-specific prune state storage.

chrome/browser/safe_browsing/incident_reporting/platform_state_store_win.cc

Index: chrome/browser/safe_browsing/incident_reporting/platform_state_store_win.cc
diff --git a/chrome/browser/safe_browsing/incident_reporting/platform_state_store_win.cc b/chrome/browser/safe_browsing/incident_reporting/platform_state_store_win.cc
new file mode 100644
index 0000000000000000000000000000000000000000..da2e2f50a5cb63d79462e4ea9d2f8865805fc4b1
--- /dev/null
+++ b/chrome/browser/safe_browsing/incident_reporting/platform_state_store_win.cc
@@ -0,0 +1,103 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// State is stored in the Windows registry in a value of the key
+// HKEY_CURRENT_USER\Software\<browser>\IncidentsSent for each profile. The
+// value names are profile directory BaseNames.
+
+#include "chrome/browser/safe_browsing/incident_reporting/platform_state_store.h"
+
+#include <windows.h>
+
+#include "base/numerics/safe_conversions.h"
+#include "base/win/registry.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/installer/util/browser_distribution.h"
+
+namespace safe_browsing {
+namespace platform_state_store {
+
+namespace {
+
+// Returns the path to the registry key holding profile-specific state values.
+base::string16 GetStateStoreKeyName() {
+  base::string16 key_name(L"Software\\");
+  return key_name.append(
+                     BrowserDistribution::GetDistribution()->GetInstallSubDir())

[robertshield, 2015/09/01 14:20:12]

FYI, I've seen two ways of building such reg key paths in the code base, this
one:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/met...
and the one you have here. This is a fair bit nicer (and probably more correct),
so go with this, but thought I'd mention the difference. 

[grt (UTC plus 2), 2015/09/03 18:12:05]

Thanks for pointing that out. The other way doesn't separate SxS from Google
Chrome. I wonder if all consumers of PRODUCT_STRING_PATH are aware of this?

[robertshield, 2015/09/05 03:23:24]

I reckon not, though for cases that don't store profile- or install- specific
state it might not matter and in some cases sharing stuff between chrome and
canary might be desirable. 

+      .append(L"\\IncidentsSent");
+}
+
+// Returns the name of the registry value for |profile|'s state.
+base::string16 GetValueNameForProfile(Profile* profile) {
+  return profile->GetPath().BaseName().value();
+}
+
+// Clears |profile|'s state.
+PlatformStateStoreLoadResult ClearStoreData(Profile* profile) {
+  base::win::RegKey key;
+
+  if (key.Open(HKEY_CURRENT_USER, GetStateStoreKeyName().c_str(),
+               KEY_QUERY_VALUE | KEY_SET_VALUE | KEY_WOW64_32KEY) ==
+      ERROR_SUCCESS) {
+    base::string16 value_name(GetValueNameForProfile(profile));
+    if (key.HasValue(value_name.c_str())) {
+      if (key.DeleteValue(value_name.c_str()) == ERROR_SUCCESS)
+        return PlatformStateStoreLoadResult::CLEARED_DATA;
+      return PlatformStateStoreLoadResult::DATA_CLEAR_FAILED;
+    }
+  }
+  return PlatformStateStoreLoadResult::CLEARED_NO_DATA;
+}
+
+}  // namespace
+
+PlatformStateStoreLoadResult ReadStoreData(Profile* profile,
+                                           std::string* data) {
+  // Clear any old state if this is a new profile.
+  if (profile->IsNewProfile()) {
+    data->clear();
+    return ClearStoreData(profile);
+  }
+
+  base::string16 value_name(GetValueNameForProfile(profile));
+  base::win::RegKey key;
+  if (key.Open(HKEY_CURRENT_USER, GetStateStoreKeyName().c_str(),
+               KEY_QUERY_VALUE | KEY_WOW64_32KEY) == ERROR_SUCCESS) {
+    while (true) {
+      void* buffer = data->empty() ? nullptr : &(*data)[0];
+      DWORD buffer_size = base::saturated_cast<DWORD, size_t>(data->size());
+      LONG result =
+          key.ReadValue(value_name.c_str(), buffer, &buffer_size, nullptr);
+      // Trim the output string and return if all data was read.
+      if (result == ERROR_SUCCESS && buffer_size <= data->size()) {
+        data->resize(buffer_size);
+        return PlatformStateStoreLoadResult::SUCCESS;
+      }
+      // Increase the buffer and retry if more space was needed. Otherwise bail.
+      if (buffer_size > data->size())
+        data->resize(buffer_size);
+      else
+        return PlatformStateStoreLoadResult::READ_FAILED;
+    }
+  }
+
+  return PlatformStateStoreLoadResult::OPEN_FAILED;
+}
+
+void WriteStoreData(Profile* profile, const std::string& data) {
+  base::win::RegKey key;
+  if (key.Create(HKEY_CURRENT_USER, GetStateStoreKeyName().c_str(),
+                 KEY_SET_VALUE | KEY_WOW64_32KEY) == ERROR_SUCCESS) {
+    if (data.empty()) {
+      key.DeleteValue(GetValueNameForProfile(profile).c_str());
+    } else {
+      key.WriteValue(GetValueNameForProfile(profile).c_str(), &data[0],
+                     base::saturated_cast<DWORD, size_t>(data.size()),
+                     REG_BINARY);
+    }
+  }
+}
+
+}  // namespace platform_state_store
+}  // namespace safe_browsing