diff -r 000000000000 -r 6474c204b198 modules/libpref/src/prefapi.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/modules/libpref/src/prefapi.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,191 @@
+/* -*- Mode: C; tab-width: 4; 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/. */
+
+/*
+// <pre>
+*/
+#ifndef PREFAPI_H
+#define PREFAPI_H
+
+#include "nscore.h"
+#include "pldhash.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// 1 MB should be enough for everyone.
+static const uint32_t MAX_PREF_LENGTH = 1 * 1024 * 1024;
+// Actually, 4kb should be enough for everyone.
+static const uint32_t MAX_ADVISABLE_PREF_LENGTH = 4 * 1024;
+
+typedef union
+{
+    char*       stringVal;
+    int32_t     intVal;
+    bool        boolVal;
+} PrefValue;
+
+struct PrefHashEntry : PLDHashEntryHdr
+{
+    const char *key;
+    PrefValue defaultPref;
+    PrefValue userPref;
+    uint16_t  flags;
+};
+
+/*
+// <font color=blue>
+// The Init function initializes the preference context and creates
+// the preference hashtable.
+// </font>
+*/
+nsresult    PREF_Init();
+
+/*
+// Cleanup should be called at program exit to free the 
+// list of registered callbacks.
+*/
+void        PREF_Cleanup();
+void        PREF_CleanupPrefs();
+
+/*
+// <font color=blue>
+// Preference flags, including the native type of the preference
+// </font>
+*/
+
+typedef enum { PREF_INVALID = 0,
+               PREF_LOCKED = 1, PREF_USERSET = 2, PREF_CONFIG = 4, PREF_REMOTE = 8,
+               PREF_LILOCAL = 16, PREF_STRING = 32, PREF_INT = 64, PREF_BOOL = 128,
+               PREF_HAS_DEFAULT = 256,
+               PREF_VALUETYPE_MASK = (PREF_STRING | PREF_INT | PREF_BOOL)
+             } PrefType;
+
+/*
+// <font color=blue>
+// Set the various types of preferences.  These functions take a dotted
+// notation of the preference name (e.g. "browser.startup.homepage").  
+// Note that this will cause the preference to be saved to the file if
+// it is different from the default.  In other words, these are used
+// to set the _user_ preferences.
+//
+// If set_default is set to true however, it sets the default value.
+// This will only affect the program behavior if the user does not have a value
+// saved over it for the particular preference.  In addition, these will never
+// be saved out to disk.
+//
+// Each set returns PREF_VALUECHANGED if the user value changed
+// (triggering a callback), or PREF_NOERROR if the value was unchanged.
+// </font>
+*/
+nsresult PREF_SetCharPref(const char *pref,const char* value, bool set_default = false);
+nsresult PREF_SetIntPref(const char *pref,int32_t value, bool set_default = false);
+nsresult PREF_SetBoolPref(const char *pref,bool value, bool set_default = false);
+
+bool     PREF_HasUserPref(const char* pref_name);
+
+/*
+// <font color=blue>
+// Get the various types of preferences.  These functions take a dotted
+// notation of the preference name (e.g. "browser.startup.homepage")
+//
+// They also take a pointer to fill in with the return value and return an
+// error value.  At the moment, this is simply an int but it may
+// be converted to an enum once the global error strategy is worked out.
+//
+// They will perform conversion if the type doesn't match what was requested.
+// (if it is reasonably possible)
+// </font>
+*/
+nsresult PREF_GetIntPref(const char *pref,
+                           int32_t * return_int, bool get_default);	
+nsresult PREF_GetBoolPref(const char *pref, bool * return_val, bool get_default);	
+/*
+// <font color=blue>
+// These functions are similar to the above "Get" version with the significant
+// difference that the preference module will alloc the memory (e.g. XP_STRDUP) and
+// the caller will need to be responsible for freeing it...
+// </font>
+*/
+nsresult PREF_CopyCharPref(const char *pref, char ** return_buf, bool get_default);
+/*
+// <font color=blue>
+// bool function that returns whether or not the preference is locked and therefore
+// cannot be changed.
+// </font>
+*/
+bool PREF_PrefIsLocked(const char *pref_name);
+
+/*
+// <font color=blue>
+// Function that sets whether or not the preference is locked and therefore
+// cannot be changed.
+// </font>
+*/
+nsresult PREF_LockPref(const char *key, bool lockIt);
+
+PrefType PREF_GetPrefType(const char *pref_name);
+
+/*
+ * Delete a branch of the tree
+ */
+nsresult PREF_DeleteBranch(const char *branch_name);
+
+/*
+ * Clears the given pref (reverts it to its default value)
+ */
+nsresult PREF_ClearUserPref(const char *pref_name);
+
+/*
+ * Clears all user prefs
+ */
+nsresult PREF_ClearAllUserPrefs();
+
+
+/*
+// <font color=blue>
+// The callback function will get passed the pref_node which triggered the call
+// and the void * instance_data which was passed to the register callback function.
+// Return a non-zero result (nsresult) to pass an error up to the caller.
+// </font>
+*/
+/* Temporarily conditionally compile PrefChangedFunc typedef.
+** During migration from old libpref to nsIPref we need it in
+** both header files.  Eventually prefapi.h will become a private
+** file.  The two types need to be in sync for now.  Certain
+** compilers were having problems with multiple definitions.
+*/
+#ifndef have_PrefChangedFunc_typedef
+typedef void (*PrefChangedFunc) (const char *, void *);
+#define have_PrefChangedFunc_typedef
+#endif
+
+/*
+// <font color=blue>
+// Register a callback.  This takes a node in the preference tree and will
+// call the callback function if anything below that node is modified.
+// Unregister returns PREF_NOERROR if a callback was found that
+// matched all the parameters; otherwise it returns PREF_ERROR.
+// </font>
+*/
+void PREF_RegisterCallback( const char* domain,
+								PrefChangedFunc callback, void* instance_data );
+nsresult PREF_UnregisterCallback( const char* domain,
+								PrefChangedFunc callback, void* instance_data );
+
+/*
+ * Used by nsPrefService as the callback function of the 'pref' parser
+ */
+void PREF_ReaderCallback( void *closure,
+                          const char *pref,
+                          PrefValue   value,
+                          PrefType    type,
+                          bool        isDefault);
+
+#ifdef __cplusplus
+}
+#endif
+#endif