1 files changed, 164 insertions, 0 deletions
diff --git a/xpcom/base/LogModulePrefWatcher.cpp b/xpcom/base/LogModulePrefWatcher.cpp
new file mode 100644
index 0000000000..bd06660533
--- /dev/null
+++ b/xpcom/base/LogModulePrefWatcher.cpp
@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "LogModulePrefWatcher.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+#include "nsIObserverService.h"
+#include "nsString.h"
+#include "nsXULAppAPI.h"
+#include "base/process_util.h"
+
+static const char kLoggingPrefPrefix[] = "logging.";
+static const char kLoggingConfigPrefPrefix[] = "logging.config";
+static const int kLoggingConfigPrefixLen = sizeof(kLoggingConfigPrefPrefix) - 1;
+static const char kLoggingPrefClearOnStartup[] =
+    "logging.config.clear_on_startup";
+static const char kLoggingPrefLogFile[] = "logging.config.LOG_FILE";
+static const char kLoggingPrefAddTimestamp[] = "logging.config.add_timestamp";
+static const char kLoggingPrefSync[] = "logging.config.sync";
+static const char kLoggingPrefStacks[] = "logging.config.profilerstacks";
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(LogModulePrefWatcher, nsIObserver)
+
+/**
+ * Resets all the preferences in the logging. branch
+ * This is needed because we may crash while logging, and this would cause us
+ * to log after restarting as well.
+ *
+ * If logging after restart is desired, set the logging.config.clear_on_startup
+ * pref to false, or use the MOZ_LOG_FILE and MOZ_LOG_MODULES env vars.
+ */
+static void ResetExistingPrefs() {
+  nsTArray<nsCString> names;
+  nsresult rv =
+      Preferences::GetRootBranch()->GetChildList(kLoggingPrefPrefix, names);
+  if (NS_SUCCEEDED(rv)) {
+    for (auto& name : names) {
+      // Clearing the pref will cause it to reload, thus resetting the log level
+      Preferences::ClearUser(name.get());
+    }
+  }
+}
+
+/**
+ * Loads the log level from the given pref and updates the corresponding
+ * LogModule.
+ */
+static void LoadPrefValue(const char* aName) {
+  LogLevel logLevel = LogLevel::Disabled;
+
+  nsresult rv;
+  int32_t prefLevel = 0;
+  nsAutoCString prefValue;
+
+  if (strncmp(aName, kLoggingConfigPrefPrefix, kLoggingConfigPrefixLen) == 0) {
+    nsAutoCString prefName(aName);
+
+    if (prefName.EqualsLiteral(kLoggingPrefLogFile)) {
+      rv = Preferences::GetCString(aName, prefValue);
+      // The pref was reset. Clear the user file.
+      if (NS_FAILED(rv) || prefValue.IsEmpty()) {
+        LogModule::SetLogFile(nullptr);
+        return;
+      }
+
+      // If the pref value doesn't have a PID placeholder, append it to the end.
+      if (!strstr(prefValue.get(), MOZ_LOG_PID_TOKEN)) {
+        prefValue.AppendLiteral(MOZ_LOG_PID_TOKEN);
+      }
+
+      LogModule::SetLogFile(prefValue.BeginReading());
+    } else if (prefName.EqualsLiteral(kLoggingPrefAddTimestamp)) {
+      bool addTimestamp = Preferences::GetBool(aName, false);
+      LogModule::SetAddTimestamp(addTimestamp);
+    } else if (prefName.EqualsLiteral(kLoggingPrefSync)) {
+      bool sync = Preferences::GetBool(aName, false);
+      LogModule::SetIsSync(sync);
+    } else if (prefName.EqualsLiteral(kLoggingPrefStacks)) {
+      bool captureStacks = Preferences::GetBool(aName, false);
+      LogModule::SetCaptureStacks(captureStacks);
+    }
+    return;
+  }
+
+  if (Preferences::GetInt(aName, &prefLevel) == NS_OK) {
+    logLevel = ToLogLevel(prefLevel);
+  } else if (Preferences::GetCString(aName, prefValue) == NS_OK) {
+    if (prefValue.LowerCaseEqualsLiteral("error")) {
+      logLevel = LogLevel::Error;
+    } else if (prefValue.LowerCaseEqualsLiteral("warning")) {
+      logLevel = LogLevel::Warning;
+    } else if (prefValue.LowerCaseEqualsLiteral("info")) {
+      logLevel = LogLevel::Info;
+    } else if (prefValue.LowerCaseEqualsLiteral("debug")) {
+      logLevel = LogLevel::Debug;
+    } else if (prefValue.LowerCaseEqualsLiteral("verbose")) {
+      logLevel = LogLevel::Verbose;
+    }
+  }
+
+  const char* moduleName = aName + strlen(kLoggingPrefPrefix);
+  LogModule::Get(moduleName)->SetLevel(logLevel);
+}
+
+static void LoadExistingPrefs() {
+  nsIPrefBranch* root = Preferences::GetRootBranch();
+  if (!root) {
+    return;
+  }
+
+  nsTArray<nsCString> names;
+  nsresult rv = root->GetChildList(kLoggingPrefPrefix, names);
+  if (NS_SUCCEEDED(rv)) {
+    for (auto& name : names) {
+      LoadPrefValue(name.get());
+    }
+  }
+}
+
+LogModulePrefWatcher::LogModulePrefWatcher() = default;
+
+void LogModulePrefWatcher::RegisterPrefWatcher() {
+  RefPtr<LogModulePrefWatcher> prefWatcher = new LogModulePrefWatcher();
+  Preferences::AddStrongObserver(prefWatcher, kLoggingPrefPrefix);
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService && XRE_IsParentProcess()) {
+    observerService->AddObserver(prefWatcher,
+                                 "browser-delayed-startup-finished", false);
+  }
+
+  LoadExistingPrefs();
+}
+
+NS_IMETHODIMP
+LogModulePrefWatcher::Observe(nsISupports* aSubject, const char* aTopic,
+                              const char16_t* aData) {
+  if (strcmp(NS_PREFBRANCH_PREFCHANGE_TOPIC_ID, aTopic) == 0) {
+    NS_LossyConvertUTF16toASCII prefName(aData);
+    LoadPrefValue(prefName.get());
+  } else if (strcmp("browser-delayed-startup-finished", aTopic) == 0) {
+    bool clear = Preferences::GetBool(kLoggingPrefClearOnStartup, true);
+    if (clear) {
+      ResetExistingPrefs();
+    }
+    nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+    if (observerService) {
+      observerService->RemoveObserver(this, "browser-delayed-startup-finished");
+    }
+  }
+
+  return NS_OK;
+}
+
+}  // namespace mozilla