SystemConfiguration.fproj/SCDynamicStorePrivate.h

   1 /*
   2  * Copyright (c) 2000, 2001, 2004, 2005, 2010, 2011 Apple Inc. All rights reserved.
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   8  * Version 2.0 (the 'License'). You may not use this file except in
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  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
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  13  * The Original Code and all software distributed under the License are
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  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  23
  24 #ifndef _SCDYNAMICSTOREPRIVATE_H
  25 #define _SCDYNAMICSTOREPRIVATE_H
  26
  27 #include <sys/cdefs.h>
  28 #include <mach/message.h>
  29 #include <CoreFoundation/CoreFoundation.h>
  30 #include <SystemConfiguration/SCDynamicStore.h>
  31
  32 /*!
  33         @header SCDynamicStorePrivate
  34         @discussion The SCDynamicStore APIs provide access to a key-value
  35                 dictionary maintained by a server process.  The dictionary is
  36                 accessible by all processes on the system.  The APIs allow you
  37                 to list the current key-value pairs, add or remove key-value
  38                 pairs, add or change the values associated with a key, and
  39                 request change notifications.
  40
  41                 The SCDynamicStore is not "persistent" (the store content
  42                 starts off empty and is not saved across boot).
  43
  44                 All interaction with the SCDynamicStore [server] is via Mach
  45                 IPC (MiG) messages.
  46
  47                 A client process, using the SCDynamicStoreSetNotificationKeys
  48                 API, specifies a list of specific keys of interest and/or a
  49                 list of regex(3) pattern strings that will be matched on
  50                 current (and future) keys in the store.  Any matched keys that
  51                 are added, updated, or removed will trigger a notification.
  52                 The notification is delivered to the monitoring session via
  53                 a "something has changed" Mach IPC message.  The callback
  54                 notification, as part of its implementation, issues a request
  55                 to the server to identify the specific list of changes and
  56                 this list is passed along as part of the callback.  Any
  57                 subsequent changes to the SCDynamicStore will trigger a new
  58                 "something has changed" Mach IPC message and an additional
  59                 callback.
  60
  61                 Note: the list (array) of changed keys passed to the
  62                       notification callback will be always be non-NULL
  63                       and non-empty with one exception.  That exception
  64                       is when the SCDynamicStore server has been restarted.
  65                       In that case, if no reconnect callback was setup
  66                       with the SCDynamicStoreSetReconnectCallBack API
  67                       then a non-NULL but empty array will be passed.
  68
  69                 Disconnect/reconnect considerations:
  70
  71                 1. We don't expect the SCDynamicStore server to fail but one
  72                    should always be prepared for the unexpected.
  73
  74                 2. Processes that write to the SCDynamicStore should be
  75                    prepared to repost any content when/if the server fails.
  76                    A callout, registered with the SCDynamicStoreSetReconnectCallBack
  77                    API, should be used to post any updates the SCDynamicStore
  78                    after a failure.
  79
  80                 3. Processes that cache SCDynamicStore content (or otherwise
  81                    maintain state based on previous notifications) should be
  82                    aware that all store content is lost when/if the server
  83                    fails.  After handling a SCDynamicStore notification with
  84                    no keys or a disconnect/reconnect callout, your code should
  85                    assume that any cached content is no longer valid.
  86
  87                 Performance considerations:
  88
  89                 1. We recommend that any code trying to capture a snapshot of
  90                    more than one SCDynamicStore key should use the SCDynamicStoreCopyMultiple
  91                    API (and not make multiple calls to SCDynamicStoreCopyValue).
  92
  93                 2. We recommend that any code making multiple (and related)
  94                    changes to the SCDynamicStore should batch them into a
  95                    single call using the SCDynamicStoreSetMultiple API (and
  96                    not make multiple calls to SCDynamicStoreSetValue).
  97  */
  98
  99 /*!
 100         @typedef SCDynamicStoreDisconnectCallBack
 101         @discussion Type of callback function used when notification of
 102                 the dynamic store session being disconnected is delivered.
 103         @param store The dynamic store session.
 104         @param info A C pointer to a user-specified block of data.
 105  */
 106 typedef void (*SCDynamicStoreDisconnectCallBack)        (
 107                                                          SCDynamicStoreRef      store,
 108                                                          void                   *info
 109                                                          );
 110
 111
 112 __BEGIN_DECLS
 113
 114 /*!
 115         @function SCDynamicStoreAddWatchedKey
 116         @discussion Adds the specified key to the list of "dynamic store"
 117                 values that are being monitored for changes.
 118         @param store The "dynamic store" session being watched.
 119         @param key The key to be monitored.
 120         @param isRegex A booolean indicating whether a specific key should
 121                 be monitored or if it consists of a regex(3) pattern string
 122                 of keys.
 123         @result TRUE if the key was successfully added to the "watch"
 124                 list; FALSE if an error was encountered.
 125  */
 126 Boolean
 127 SCDynamicStoreAddWatchedKey             (SCDynamicStoreRef              store,
 128                                          CFStringRef                    key,
 129                                          Boolean                        isRegex);
 130
 131 /*!
 132         @function SCDynamicStoreRemoveWatchedKey
 133         @discussion Removes the specified key from the list of "dynamic store"
 134                 values that are being monitored for changes.
 135         @param store The "dynamic store" session being watched.
 136         @param key The key that should no longer be monitored.
 137         @param isRegex A booolean indicating whether a specific key should
 138                 be monitored or if it consists of a regex(3) pattern string
 139                 of keys.
 140         @result TRUE if the key was successfully removed from the "watch"
 141                 list; FALSE if an error was encountered.
 142  */
 143 Boolean
 144 SCDynamicStoreRemoveWatchedKey          (SCDynamicStoreRef              store,
 145                                          CFStringRef                    key,
 146                                          Boolean                        isRegex);
 147
 148 /*!
 149         @function SCDynamicStoreNotifyFileDescriptor
 150         @discussion Allocates a file descriptor that can be used to detect changes
 151                 to one of the system configuration data entries associated with the
 152                 current session's notifier keys. When a change is detected, the
 153                 specified identifier (4 bytes) will be delivered to the calling
 154                 application via the allocated file descriptor.
 155
 156         @param store An SCDynamicStoreRef that should be used for communication with the server.
 157         @param identifier A (4 byte) integer that can be used to identify this
 158                 notification.
 159         @param fd A pointer to a file descriptor.  Upon return, fd will
 160                 contain the file descriptor that will be used for any notifications.
 161         @result A boolean indicating the success (or failure) of the call.
 162  */
 163 Boolean
 164 SCDynamicStoreNotifyFileDescriptor      (SCDynamicStoreRef              store,
 165                                          int32_t                        identifier,
 166                                          int                            *fd);
 167
 168 /*!
 169         @function SCDynamicStoreNotifySignal
 170         @discussion Requests that the specified BSD signal be sent to the process
 171                 with the indicated process id whenever a change has been detected
 172                 to one of the system configuration data entries associated with the
 173                 current session's notifier keys.
 174
 175                 Note: this function is not valid for "configd" plug-ins.
 176
 177         @param store An SCDynamicStoreRef that should be used for communication with the server.
 178         @param pid A UNIX process ID that should be signalled for any notifications.
 179         @param sig A signal number to be used.
 180         @result A boolean indicating the success (or failure) of the call.
 181  */
 182 Boolean
 183 SCDynamicStoreNotifySignal              (SCDynamicStoreRef              store,
 184                                          pid_t                          pid,
 185                                          int                            sig);
 186
 187 /*!
 188         @function SCDynamicStoreNotifyWait
 189         @discussion Waits for a change to be made to a value in the
 190                 "dynamic store" that is being monitored.
 191         @param store The "dynamic store" session.
 192         @result TRUE if a change has been detected; FALSE if an error was encountered.
 193  */
 194 Boolean
 195 SCDynamicStoreNotifyWait                (SCDynamicStoreRef              store);
 196
 197 /*!
 198         @function SCDynamicStoreNotifyCancel
 199         @discussion Cancels any outstanding notification requests for
 200                 this "dynamic store" session.
 201
 202         @param store The "dynamic store" session.
 203         @result TRUE if all notifications have been cancelled; FALSE if an
 204                 error was encountered.
 205  */
 206 Boolean
 207 SCDynamicStoreNotifyCancel              (SCDynamicStoreRef              store);
 208
 209 /*!
 210         @function SCDynamicStoreSetDisconnectCallBack
 211         @discussion Assigns a callback to a SCDynamicStore session.  The function
 212                 is called when the session has been disconnected.  The callback
 213                 should be established before a client writes any content to the
 214                 SCDynamicStore to ensure that the information can be re-posted
 215                 when/if a disconnect is detected.
 216         @param store A reference to the dynamic store session.
 217         @param callout The function to be called when the session was disconnected.
 218                 If NULL, the current callback is removed.
 219         @result Returns TRUE on success, FALSE on failure.
 220  */
 221 Boolean
 222 SCDynamicStoreSetDisconnectCallBack     (
 223                                          SCDynamicStoreRef                      store,
 224                                          SCDynamicStoreDisconnectCallBack       callout
 225                                         )                               __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0/*SPI*/);
 226
 227 Boolean
 228 SCDynamicStoreSnapshot                  (SCDynamicStoreRef              store);
 229
 230 __END_DECLS
 231
 232 #endif /* _SCDYNAMICSTOREPRIVATE_H */