import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

modules/libpref/nsPrefBranch.h

@@ -0,0 +1,269 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef nsPrefBranch_h
+#define nsPrefBranch_h
+
+#include "nsCOMPtr.h"
+#include "nsIObserver.h"
+#include "nsIPrefBranch.h"
+#include "nsIPrefBranchInternal.h"
+#include "nsIPrefLocalizedString.h"
+#include "nsXPCOM.h"
+#include "nsISupportsPrimitives.h"
+#include "nsIRelativeFilePref.h"
+#include "nsIFile.h"
+#include "nsString.h"
+#include "nsTArray.h"
+#include "nsWeakReference.h"
+#include "nsClassHashtable.h"
+#include "nsCRT.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/MemoryReporting.h"
+
+namespace mozilla {
+class PreferenceServiceReporter;
+} // namespace mozilla
+
+class nsPrefBranch;
+
+class PrefCallback : public PLDHashEntryHdr {
+  friend class mozilla::PreferenceServiceReporter;
+
+  public:
+    typedef PrefCallback* KeyType;
+    typedef const PrefCallback* KeyTypePointer;
+
+    static const PrefCallback* KeyToPointer(PrefCallback *aKey)
+    {
+      return aKey;
+    }
+
+    static PLDHashNumber HashKey(const PrefCallback *aKey)
+    {
+      uint32_t hash = mozilla::HashString(aKey->mDomain);
+      return mozilla::AddToHash(hash, aKey->mCanonical);
+    }
+
+
+  public:
+    // Create a PrefCallback with a strong reference to its observer.
+    PrefCallback(const char *aDomain, nsIObserver *aObserver,
+                 nsPrefBranch *aBranch)
+      : mDomain(aDomain),
+        mBranch(aBranch),
+        mWeakRef(nullptr),
+        mStrongRef(aObserver)
+    {
+      MOZ_COUNT_CTOR(PrefCallback);
+      nsCOMPtr<nsISupports> canonical = do_QueryInterface(aObserver);
+      mCanonical = canonical;
+    }
+
+    // Create a PrefCallback with a weak reference to its observer.
+    PrefCallback(const char *aDomain,
+                 nsISupportsWeakReference *aObserver,
+                 nsPrefBranch *aBranch)
+      : mDomain(aDomain),
+        mBranch(aBranch),
+        mWeakRef(do_GetWeakReference(aObserver)),
+        mStrongRef(nullptr)
+    {
+      MOZ_COUNT_CTOR(PrefCallback);
+      nsCOMPtr<nsISupports> canonical = do_QueryInterface(aObserver);
+      mCanonical = canonical;
+    }
+
+    // Copy constructor needs to be explicit or the linker complains.
+    explicit PrefCallback(const PrefCallback *&aCopy)
+      : mDomain(aCopy->mDomain),
+        mBranch(aCopy->mBranch),
+        mWeakRef(aCopy->mWeakRef),
+        mStrongRef(aCopy->mStrongRef),
+        mCanonical(aCopy->mCanonical)
+    {
+      MOZ_COUNT_CTOR(PrefCallback);
+    }
+
+    ~PrefCallback()
+    {
+      MOZ_COUNT_DTOR(PrefCallback);
+    }
+
+    bool KeyEquals(const PrefCallback *aKey) const
+    {
+      // We want to be able to look up a weakly-referencing PrefCallback after
+      // its observer has died so we can remove it from the table.  Once the
+      // callback's observer dies, its canonical pointer is stale -- in
+      // particular, we may have allocated a new observer in the same spot in
+      // memory!  So we can't just compare canonical pointers to determine
+      // whether aKey refers to the same observer as this.
+      //
+      // Our workaround is based on the way we use this hashtable: When we ask
+      // the hashtable to remove a PrefCallback whose weak reference has
+      // expired, we use as the key for removal the same object as was inserted
+      // into the hashtable.  Thus we can say that if one of the keys' weak
+      // references has expired, the two keys are equal iff they're the same
+      // object.
+
+      if (IsExpired() || aKey->IsExpired())
+        return this == aKey;
+
+      if (mCanonical != aKey->mCanonical)
+        return false;
+
+      return mDomain.Equals(aKey->mDomain);
+    }
+
+    PrefCallback *GetKey() const
+    {
+      return const_cast<PrefCallback*>(this);
+    }
+
+    // Get a reference to the callback's observer, or null if the observer was
+    // weakly referenced and has been destroyed.
+    already_AddRefed<nsIObserver> GetObserver() const
+    {
+      if (!IsWeak()) {
+        nsCOMPtr<nsIObserver> copy = mStrongRef;
+        return copy.forget();
+      }
+
+      nsCOMPtr<nsIObserver> observer = do_QueryReferent(mWeakRef);
+      return observer.forget();
+    }
+
+    const nsCString& GetDomain() const
+    {
+      return mDomain;
+    }
+
+    nsPrefBranch* GetPrefBranch() const
+    {
+      return mBranch;
+    }
+
+    // Has this callback's weak reference died?
+    bool IsExpired() const
+    {
+      if (!IsWeak())
+        return false;
+
+      nsCOMPtr<nsIObserver> observer(do_QueryReferent(mWeakRef));
+      return !observer;
+    }
+
+    enum { ALLOW_MEMMOVE = true };
+
+  private:
+    nsCString             mDomain;
+    nsPrefBranch         *mBranch;
+
+    // Exactly one of mWeakRef and mStrongRef should be non-null.
+    nsWeakPtr             mWeakRef;
+    nsCOMPtr<nsIObserver> mStrongRef;
+
+    // We need a canonical nsISupports pointer, per bug 578392.
+    nsISupports          *mCanonical;
+
+    bool IsWeak() const
+    {
+      return !!mWeakRef;
+    }
+};
+
+class nsPrefBranch final : public nsIPrefBranchInternal,
+                           public nsIObserver,
+                           public nsSupportsWeakReference
+{
+  friend class mozilla::PreferenceServiceReporter;
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPREFBRANCH
+  NS_DECL_NSIPREFBRANCH2
+  NS_DECL_NSIOBSERVER
+
+  nsPrefBranch(const char *aPrefRoot, bool aDefaultBranch);
+
+  int32_t GetRootLength() { return mPrefRootLength; }
+
+  nsresult RemoveObserverFromMap(const char *aDomain, nsISupports *aObserver);
+
+  static void NotifyObserver(const char *newpref, void *data);
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf);
+
+  static void ReportToConsole(const nsAString& aMessage);
+
+protected:
+  virtual ~nsPrefBranch();
+
+  nsPrefBranch()    /* disallow use of this constructer */
+    : mPrefRootLength(0)
+    , mIsDefault(false)
+    , mFreeingObserverList(false)
+  {}
+
+  nsresult   GetDefaultFromPropertiesFile(const char *aPrefName, char16_t **return_buf);
+  // As SetCharPref, but without any check on the length of |aValue|
+  nsresult   SetCharPrefInternal(const char *aPrefName, const char *aValue);
+  // Reject strings that are more than 1Mb, warn if strings are more than 16kb
+  nsresult   CheckSanityOfStringLength(const char* aPrefName, const nsAString& aValue);
+  nsresult   CheckSanityOfStringLength(const char* aPrefName, const char* aValue);
+  nsresult   CheckSanityOfStringLength(const char* aPrefName, const uint32_t aLength);
+  void RemoveExpiredCallback(PrefCallback *aCallback);
+  const char *getPrefName(const char *aPrefName);
+  void       freeObserverList(void);
+
+private:
+  int32_t               mPrefRootLength;
+  nsCString             mPrefRoot;
+  bool                  mIsDefault;
+
+  bool                  mFreeingObserverList;
+  nsClassHashtable<PrefCallback, PrefCallback> mObservers;
+};
+
+
+class nsPrefLocalizedString final : public nsIPrefLocalizedString,
+                                    public nsISupportsString
+{
+public:
+  nsPrefLocalizedString();
+
+  NS_DECL_ISUPPORTS
+  NS_FORWARD_NSISUPPORTSSTRING(mUnicodeString->)
+  NS_FORWARD_NSISUPPORTSPRIMITIVE(mUnicodeString->)
+
+  nsresult Init();
+
+private:
+  virtual ~nsPrefLocalizedString();
+
+  NS_IMETHOD GetData(char16_t**) override;
+  NS_IMETHOD SetData(const char16_t* aData) override;
+  NS_IMETHOD SetDataWithLength(uint32_t aLength, const char16_t *aData) override;
+
+  nsCOMPtr<nsISupportsString> mUnicodeString;
+};
+
+
+class nsRelativeFilePref : public nsIRelativeFilePref
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIRELATIVEFILEPREF
+
+  nsRelativeFilePref();
+
+private:
+  virtual ~nsRelativeFilePref();
+
+  nsCOMPtr<nsIFile> mFile;
+  nsCString mRelativeToKey;
+};
+
+#endif