/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-watch.c DBusWatch implementation
*
* Copyright (C) 2002, 2003 Red Hat Inc.
*
* Licensed under the Academic Free License version 2.1
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <config.h>
#include "dbus-internals.h"
#include "dbus-watch.h"
#include "dbus-list.h"
/**
* @defgroup DBusWatchInternals DBusWatch implementation details
* @ingroup DBusInternals
* @brief implementation details for DBusWatch
*
* @{
*/
/**
* Implementation of DBusWatch
*/
struct DBusWatch
{
int refcount; /**< Reference count */
int fd; /**< File descriptor. */
unsigned int flags; /**< Conditions to watch. */
DBusWatchHandler handler; /**< Watch handler. */
void *handler_data; /**< Watch handler data. */
DBusFreeFunction free_handler_data_function; /**< Free the watch handler data. */
void *data; /**< Application data. */
DBusFreeFunction free_data_function; /**< Free the application data. */
unsigned int enabled : 1; /**< Whether it's enabled. */
unsigned int oom_last_time : 1; /**< Whether it was OOM last time. */
};
dbus_bool_t
_dbus_watch_get_enabled (DBusWatch *watch)
{
return watch->enabled;
}
dbus_bool_t
_dbus_watch_get_oom_last_time (DBusWatch *watch)
{
return watch->oom_last_time;
}
void
_dbus_watch_set_oom_last_time (DBusWatch *watch,
dbus_bool_t oom)
{
watch->oom_last_time = oom;
}
/**
* Creates a new DBusWatch. Used to add a file descriptor to be polled
* by a main loop.
*
* @param fd the file descriptor to be watched.
* @param flags the conditions to watch for on the descriptor.
* @param enabled the initial enabled state
* @param handler the handler function
* @param data data for handler function
* @param free_data_function function to free the data
* @returns the new DBusWatch object.
*/
DBusWatch*
_dbus_watch_new (int fd,
unsigned int flags,
dbus_bool_t enabled,
DBusWatchHandler handler,
void *data,
DBusFreeFunction free_data_function)
{
DBusWatch *watch;
#define VALID_WATCH_FLAGS (DBUS_WATCH_WRITABLE | DBUS_WATCH_READABLE)
_dbus_assert ((flags & VALID_WATCH_FLAGS) == flags);
watch = dbus_new0 (DBusWatch, 1);
if (watch == NULL)
return NULL;
watch->refcount = 1;
watch->fd = fd;
watch->flags = flags;
watch->enabled = enabled;
watch->handler = handler;
watch->handler_data = data;
watch->free_handler_data_function = free_data_function;
return watch;
}
/**
* Increments the reference count of a DBusWatch object.
*
* @param watch the watch object.
* @returns the watch object.
*/
DBusWatch *
_dbus_watch_ref (DBusWatch *watch)
{
watch->refcount += 1;
return watch;
}
/**
* Decrements the reference count of a DBusWatch object
* and finalizes the object if the count reaches zero.
*
* @param watch the watch object.
*/
void
_dbus_watch_unref (DBusWatch *watch)
{
_dbus_assert (watch != NULL);
_dbus_assert (watch->refcount > 0);
watch->refcount -= 1;
if (watch->refcount == 0)
{
if (watch->fd != -1)
_dbus_warn ("this watch should have been invalidated");
dbus_watch_set_data (watch, NULL, NULL); /* call free_data_function */
if (watch->free_handler_data_function)
(* watch->free_handler_data_function) (watch->handler_data);
dbus_free (watch);
}
}
/**
* Clears the file descriptor from a now-invalid watch object so that
* no one tries to use it. This is because a watch may stay alive due
* to reference counts after the file descriptor is closed.
* Invalidation makes it easier to catch bugs. It also
* keeps people from doing dorky things like assuming file descriptors
* are unique (never recycled).
*
* @param watch the watch object.
*/
void
_dbus_watch_invalidate (DBusWatch *watch)
{
watch->fd = -1;
watch->flags = 0;
}
/**
* Sanitizes the given condition so that it only contains
* flags that the DBusWatch requested. e.g. if the
* watch is a DBUS_WATCH_READABLE watch then
* DBUS_WATCH_WRITABLE will be stripped from the condition.
*
* @param watch the watch object.
* @param condition address of the condition to sanitize.
*/
void
_dbus_watch_sanitize_condition (DBusWatch *watch,
unsigned int *condition)
{
if (!(watch->flags & DBUS_WATCH_READABLE))
*condition &= ~DBUS_WATCH_READABLE;
if (!(watch->flags & DBUS_WATCH_WRITABLE))
*condition &= ~DBUS_WATCH_WRITABLE;
}
/**
* @typedef DBusWatchList
*
* Opaque data type representing a list of watches
* and a set of DBusAddWatchFunction/DBusRemoveWatchFunction.
* Automatically handles removing/re-adding watches
* when the DBusAddWatchFunction is updated or changed.
* Holds a reference count to each watch.
*
* Used in the implementation of both DBusServer and
* DBusClient.
*
*/
/**
* DBusWatchList implementation details. All fields
* are private.
*
*/
struct DBusWatchList
{
DBusList *watches; /**< Watch objects. */
DBusAddWatchFunction add_watch_function; /**< Callback for adding a watch. */
DBusRemoveWatchFunction remove_watch_function; /**< Callback for removing a watch. */
DBusWatchToggledFunction watch_toggled_function; /**< Callback on toggling enablement */
void *watch_data; /**< Data for watch callbacks */
DBusFreeFunction watch_free_data_function; /**< Free function for watch callback data */
};
/**
* Creates a new watch list. Returns #NULL if insufficient
* memory exists.
*
* @returns the new watch list, or #NULL on failure.
*/
DBusWatchList*
_dbus_watch_list_new (void)
{
DBusWatchList *watch_list;
watch_list = dbus_new0 (DBusWatchList, 1);
if (watch_list == NULL)
return NULL;
return watch_list;
}
/**
* Frees a DBusWatchList.
*
* @param watch_list the watch list.
*/
void
_dbus_watch_list_free (DBusWatchList *watch_list)
{
/* free watch_data and removes watches as a side effect */
_dbus_watch_list_set_functions (watch_list,
NULL, NULL, NULL, NULL, NULL);
_dbus_list_foreach (&watch_list->watches,
(DBusForeachFunction) _dbus_watch_unref,
NULL);
_dbus_list_clear (&watch_list->watches);
dbus_free (watch_list);
}
/**
* Sets the watch functions. This function is the "backend"
* for dbus_connection_set_watch_functions() and
* dbus_server_set_watch_functions().
*
* @param watch_list the watch list.
* @param add_function the add watch function.
* @param remove_function the remove watch function.
* @param toggled_function function on toggling enabled flag, or #NULL
* @param data the data for those functions.
* @param free_data_function the function to free the data.
* @returns #FALSE if not enough memory
*
*/
dbus_bool_t
_dbus_watch_list_set_functions (DBusWatchList *watch_list,
DBusAddWatchFunction add_function,
DBusRemoveWatchFunction remove_function,
DBusWatchToggledFunction toggled_function,
void *data,
DBusFreeFunction free_data_function)
{
/* Add watches with the new watch function, failing on OOM */
if (add_function != NULL)
{
DBusList *link;
link = _dbus_list_get_first_link (&watch_list->watches);
while (link != NULL)
{
DBusList *next = _dbus_list_get_next_link (&watch_list->watches,
link);
#ifdef DBUS_ENABLE_VERBOSE_MODE
{
const char *watch_type;
int flags;
flags = dbus_watch_get_flags (link->data);
if ((flags & DBUS_WATCH_READABLE) &&
(flags & DBUS_WATCH_WRITABLE))
watch_type = "readwrite";
else if (flags & DBUS_WATCH_READABLE)
watch_type = "read";
else if (flags & DBUS_WATCH_WRITABLE)
watch_type = "write";
else
watch_type = "not read or write";
_dbus_verbose ("Adding a %s watch on fd %d using newly-set add watch function\n",
watch_type,
dbus_watch_get_socket (link->data));
}
#endif /* DBUS_ENABLE_VERBOSE_MODE */
if (!(* add_function) (link->data, data))
{
/* remove it all again and return FALSE */
DBusList *link2;
link2 = _dbus_list_get_first_link (&watch_list->watches);
while (link2 != link)
{
DBusList *next = _dbus_list_get_next_link (&watch_list->watches,
link2);
_dbus_verbose ("Removing watch on fd %d using newly-set remove function because initial add failed\n",
dbus_watch_get_socket (link2->data));
(* remove_function) (link2->data, data);
link2 = next;
}
return FALSE;
}
link = next;
}
}
/* Remove all current watches from previous watch handlers */
if (watch_list->remove_watch_function != NULL)
{
_dbus_verbose ("Removing all pre-existing watches\n");
_dbus_list_foreach (&watch_list->watches,
(DBusForeachFunction) watch_list->remove_watch_function,
watch_list->watch_data);
}
if (watch_list->watch_free_data_function != NULL)
(* watch_list->watch_free_data_function) (watch_list->watch_data);
watch_list->add_watch_function = add_function;
watch_list->remove_watch_function = remove_function;
watch_list->watch_toggled_function = toggled_function;
watch_list->watch_data = data;
watch_list->watch_free_data_function = free_data_function;
return TRUE;
}
/**
* Adds a new watch to the watch list, invoking the
* application DBusAddWatchFunction if appropriate.
*
* @param watch_list the watch list.
* @param watch the watch to add.
* @returns #TRUE on success, #FALSE if no memory.
*/
dbus_bool_t
_dbus_watch_list_add_watch (DBusWatchList *watch_list,
DBusWatch *watch)
{
if (!_dbus_list_append (&watch_list->watches, watch))
return FALSE;
_dbus_watch_ref (watch);
if (watch_list->add_watch_function != NULL)
{
_dbus_verbose ("Adding watch on fd %d\n",
dbus_watch_get_socket (watch));
if (!(* watch_list->add_watch_function) (watch,
watch_list->watch_data))
{
_dbus_list_remove_last (&watch_list->watches, watch);
_dbus_watch_unref (watch);
return FALSE;
}
}
return TRUE;
}
/**
* Removes a watch from the watch list, invoking the
* application's DBusRemoveWatchFunction if appropriate.
*
* @param watch_list the watch list.
* @param watch the watch to remove.
*/
void
_dbus_watch_list_remove_watch (DBusWatchList *watch_list,
DBusWatch *watch)
{
if (!_dbus_list_remove (&watch_list->watches, watch))
_dbus_assert_not_reached ("Nonexistent watch was removed");
if (watch_list->remove_watch_function != NULL)
{
_dbus_verbose ("Removing watch on fd %d\n",
dbus_watch_get_socket (watch));
(* watch_list->remove_watch_function) (watch,
watch_list->watch_data);
}
_dbus_watch_unref (watch);
}
/**
* Sets a watch to the given enabled state, invoking the
* application's DBusWatchToggledFunction if appropriate.
*
* @param watch_list the watch list.
* @param watch the watch to toggle.
* @param enabled #TRUE to enable
*/
void
_dbus_watch_list_toggle_watch (DBusWatchList *watch_list,
DBusWatch *watch,
dbus_bool_t enabled)
{
enabled = !!enabled;
if (enabled == watch->enabled)
return;
watch->enabled = enabled;
if (watch_list->watch_toggled_function != NULL)
{
_dbus_verbose ("Toggling watch %p on fd %d to %d\n",
watch, dbus_watch_get_socket (watch), watch->enabled);
(* watch_list->watch_toggled_function) (watch,
watch_list->watch_data);
}
}
/**
* Sets the handler for the watch.
*
* @todo this function only exists because of the weird
* way connection watches are done, see the note
* in docs for _dbus_connection_handle_watch().
*
* @param watch the watch
* @param handler the new handler
* @param data the data
* @param free_data_function free data with this
*/
void
_dbus_watch_set_handler (DBusWatch *watch,
DBusWatchHandler handler,
void *data,
DBusFreeFunction free_data_function)
{
if (watch->free_handler_data_function)
(* watch->free_handler_data_function) (watch->handler_data);
watch->handler = handler;
watch->handler_data = data;
watch->free_handler_data_function = free_data_function;
}
/** @} */
/**
* @defgroup DBusWatch DBusWatch
* @ingroup DBus
* @brief Object representing a file descriptor to be watched.
*
* Types and functions related to DBusWatch. A watch represents
* a file descriptor that the main loop needs to monitor,
* as in Qt's QSocketNotifier or GLib's g_io_add_watch().
*
* Use dbus_connection_set_watch_functions() or dbus_server_set_watch_functions()
* to be notified when libdbus needs to add or remove watches.
*
* @{
*/
/**
* @typedef DBusWatch
*
* Opaque object representing a file descriptor
* to be watched for changes in readability,
* writability, or hangup.
*/
/**
* Deprecated former name of dbus_watch_get_unix_fd().
*
* @param watch the DBusWatch object.
* @returns the file descriptor to watch.
*/
int
dbus_watch_get_fd (DBusWatch *watch)
{
_dbus_return_val_if_fail (watch != NULL, -1);
return dbus_watch_get_unix_fd(watch);
}
/**
* Returns a UNIX file descriptor to be watched,
* which may be a pipe, socket, or other type of
* descriptor. On UNIX this is preferred to
* dbus_watch_get_socket() since it works with
* more kinds of #DBusWatch.
*
* Always returns -1 on Windows. On Windows you use
* dbus_watch_get_socket() to get a Winsock socket to watch.
*
* @param watch the DBusWatch object.
* @returns the file descriptor to watch.
*/
int
dbus_watch_get_unix_fd (DBusWatch *watch)
{
_dbus_return_val_if_fail (watch != NULL, -1);
/* FIXME remove #ifdef and do this on a lower level
* (watch should have set_socket and set_unix_fd and track
* which it has, and the transport should provide the
* appropriate watch type)
*/
#ifdef DBUS_UNIX
return watch->fd;
#else
return dbus_watch_get_socket( watch );
#endif
}
/**
* Returns a socket to be watched, on UNIX this will return -1 if our
* transport is not socket-based so dbus_watch_get_unix_fd() is
* preferred.
*
* On Windows, dbus_watch_get_unix_fd() returns -1 but this function
* returns a Winsock socket (assuming the transport is socket-based,
* as it always is for now).
*
* @param watch the DBusWatch object.
* @returns the socket to watch.
*/
int
dbus_watch_get_socket (DBusWatch *watch)
{
_dbus_return_val_if_fail (watch != NULL, -1);
return watch->fd;
}
/**
* Gets flags from DBusWatchFlags indicating
* what conditions should be monitored on the
* file descriptor.
*
* The flags returned will only contain DBUS_WATCH_READABLE
* and DBUS_WATCH_WRITABLE, never DBUS_WATCH_HANGUP or
* DBUS_WATCH_ERROR; all watches implicitly include a watch
* for hangups, errors, and other exceptional conditions.
*
* @param watch the DBusWatch object.
* @returns the conditions to watch.
*/
unsigned int
dbus_watch_get_flags (DBusWatch *watch)
{
_dbus_return_val_if_fail (watch != NULL, 0);
_dbus_assert ((watch->flags & VALID_WATCH_FLAGS) == watch->flags);
return watch->flags;
}
/**
* Gets data previously set with dbus_watch_set_data()
* or #NULL if none.
*
* @param watch the DBusWatch object.
* @returns previously-set data.
*/
void*
dbus_watch_get_data (DBusWatch *watch)
{
_dbus_return_val_if_fail (watch != NULL, NULL);
return watch->data;
}
/**
* Sets data which can be retrieved with dbus_watch_get_data().
* Intended for use by the DBusAddWatchFunction and
* DBusRemoveWatchFunction to store their own data. For example with
* Qt you might store the QSocketNotifier for this watch and with GLib
* you might store a GSource.
*
* @param watch the DBusWatch object.
* @param data the data.
* @param free_data_function function to be called to free the data.
*/
void
dbus_watch_set_data (DBusWatch *watch,
void *data,
DBusFreeFunction free_data_function)
{
_dbus_return_if_fail (watch != NULL);
_dbus_verbose ("Setting watch fd %d data to data = %p function = %p from data = %p function = %p\n",
dbus_watch_get_socket (watch),
data, free_data_function, watch->data, watch->free_data_function);
if (watch->free_data_function != NULL)
(* watch->free_data_function) (watch->data);
watch->data = data;
watch->free_data_function = free_data_function;
}
/**
* Returns whether a watch is enabled or not. If not
* enabled, it should not be polled by the main loop.
*
* @param watch the DBusWatch object
* @returns #TRUE if the watch is enabled
*/
dbus_bool_t
dbus_watch_get_enabled (DBusWatch *watch)
{
_dbus_return_val_if_fail (watch != NULL, FALSE);
return watch->enabled;
}
/**
* Called to notify the D-Bus library when a previously-added watch is
* ready for reading or writing, or has an exception such as a hangup.
*
* If this function returns #FALSE, then the file descriptor may still
* be ready for reading or writing, but more memory is needed in order
* to do the reading or writing. If you ignore the #FALSE return, your
* application may spin in a busy loop on the file descriptor until
* memory becomes available, but nothing more catastrophic should
* happen.
*
* dbus_watch_handle() cannot be called during the
* DBusAddWatchFunction, as the connection will not be ready to handle
* that watch yet.
*
* It is not allowed to reference a DBusWatch after it has been passed
* to remove_function.
*
* @param watch the DBusWatch object.
* @param flags the poll condition using #DBusWatchFlags values
* @returns #FALSE if there wasn't enough memory
*/
dbus_bool_t
dbus_watch_handle (DBusWatch *watch,
unsigned int flags)
{
_dbus_return_val_if_fail (watch != NULL, FALSE);
#ifndef DBUS_DISABLE_CHECKS
if (watch->fd < 0 || watch->flags == 0)
{
_dbus_warn_check_failed ("Watch is invalid, it should have been removed\n");
return TRUE;
}
#endif
_dbus_return_val_if_fail (watch->fd >= 0 /* fails if watch was removed */, TRUE);
_dbus_watch_sanitize_condition (watch, &flags);
if (flags == 0)
{
_dbus_verbose ("After sanitization, watch flags on fd %d were 0\n",
watch->fd);
return TRUE;
}
else
return (* watch->handler) (watch, flags,
watch->handler_data);
}
/** @} */