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dbus/dbus/dbus-list.c

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-list.c Generic linked list utility (internal to D-Bus implementation)
*
* Copyright (C) 2002 Red Hat, Inc.
*
* SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
*
* 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-list.h"
#include "dbus-mempool.h"
#include "dbus-threads-internal.h"
#include <dbus/dbus-test-tap.h>
/**
* @defgroup DBusList Linked list
* @ingroup DBusInternals
* @brief DBusList data structure
*
* Types and functions related to DBusList.
*/
/* Protected by _DBUS_LOCK (list) */
static DBusMemPool *list_pool;
/**
* @defgroup DBusListInternals Linked list implementation details
* @ingroup DBusInternals
* @brief DBusList implementation details
*
* The guts of DBusList.
*
* @{
*/
/* the mem pool is probably a speed hit, with the thread
* lock, though it does still save memory - unknown.
*/
static DBusList*
alloc_link (void *data)
{
DBusList *link;
if (!_DBUS_LOCK (list))
return FALSE;
if (list_pool == NULL)
{
list_pool = _dbus_mem_pool_new (sizeof (DBusList), TRUE);
if (list_pool == NULL)
{
_DBUS_UNLOCK (list);
return NULL;
}
link = _dbus_mem_pool_alloc (list_pool);
if (link == NULL)
{
_dbus_mem_pool_free (list_pool);
list_pool = NULL;
_DBUS_UNLOCK (list);
return NULL;
}
}
else
{
link = _dbus_mem_pool_alloc (list_pool);
}
if (link)
link->data = data;
_DBUS_UNLOCK (list);
return link;
}
static void
free_link (DBusList *link)
{
if (!_DBUS_LOCK (list))
_dbus_assert_not_reached ("we should have initialized global locks "
"before we allocated a linked-list link");
if (_dbus_mem_pool_dealloc (list_pool, link))
{
_dbus_mem_pool_free (list_pool);
list_pool = NULL;
}
_DBUS_UNLOCK (list);
}
static void
link_before (DBusList **list,
DBusList *before_this_link,
DBusList *link)
{
if (*list == NULL)
{
link->prev = link;
link->next = link;
*list = link;
}
else
{
link->next = before_this_link;
link->prev = before_this_link->prev;
before_this_link->prev = link;
link->prev->next = link;
if (before_this_link == *list)
*list = link;
}
}
static void
link_after (DBusList **list,
DBusList *after_this_link,
DBusList *link)
{
if (*list == NULL)
{
link->prev = link;
link->next = link;
*list = link;
}
else
{
link->prev = after_this_link;
link->next = after_this_link->next;
after_this_link->next = link;
link->next->prev = link;
}
}
#ifdef DBUS_ENABLE_STATS
void
_dbus_list_get_stats (dbus_uint32_t *in_use_p,
dbus_uint32_t *in_free_list_p,
dbus_uint32_t *allocated_p)
{
if (!_DBUS_LOCK (list))
{
*in_use_p = 0;
*in_free_list_p = 0;
*allocated_p = 0;
return;
}
_dbus_mem_pool_get_stats (list_pool, in_use_p, in_free_list_p, allocated_p);
_DBUS_UNLOCK (list);
}
#endif
/** @} */
/**
* @addtogroup DBusList
* @{
*/
/**
* @struct DBusList
*
* A node in a linked list.
*
* DBusList is a circular list; that is, the tail of the list
* points back to the head of the list. The empty list is
* represented by a #NULL pointer.
*/
/**
* @def _dbus_list_get_next_link
*
* Gets the next link in the list, or #NULL if
* there are no more links. Used for iteration.
*
* @code
* DBusList *link;
* link = _dbus_list_get_first_link (&list);
* while (link != NULL)
* {
* printf ("value is %p\n", link->data);
* link = _dbus_list_get_next_link (&link);
* }
* @endcode
*
* @param list address of the list head.
* @param link current link.
* @returns the next link, or %NULL if none.
*
*/
/**
* @def _dbus_list_get_prev_link
*
* Gets the previous link in the list, or #NULL if
* there are no more links. Used for iteration.
*
* @code
* DBusList *link;
* link = _dbus_list_get_last_link (&list);
* while (link != NULL)
* {
* printf ("value is %p\n", link->data);
* link = _dbus_list_get_prev_link (&link);
* }
* @endcode
*
* @param list address of the list head.
* @param link current link.
* @returns the previous link, or %NULL if none.
*
*/
/**
* Allocates a linked list node. Useful for preallocating
* nodes and using _dbus_list_append_link() to avoid
* allocations.
*
* @param data the value to store in the link.
* @returns a newly allocated link.
*/
DBusList*
_dbus_list_alloc_link (void *data)
{
return alloc_link (data);
}
/**
* Frees a linked list node allocated with _dbus_list_alloc_link.
* Does not free the data in the node.
*
* @param link the list node
*/
void
_dbus_list_free_link (DBusList *link)
{
free_link (link);
}
/**
* Appends a value to the list. May return #FALSE
* if insufficient memory exists to add a list link.
* This is a constant-time operation.
*
* @param list address of the list head.
* @param data the value to append.
* @returns #TRUE on success.
*/
dbus_bool_t
_dbus_list_append (DBusList **list,
void *data)
{
if (!_dbus_list_prepend (list, data))
return FALSE;
/* Now cycle the list forward one so the prepended node is the tail */
*list = (*list)->next;
return TRUE;
}
/**
* Prepends a value to the list. May return #FALSE
* if insufficient memory exists to add a list link.
* This is a constant-time operation.
*
* @param list address of the list head.
* @param data the value to prepend.
* @returns #TRUE on success.
*/
dbus_bool_t
_dbus_list_prepend (DBusList **list,
void *data)
{
DBusList *link;
link = alloc_link (data);
if (link == NULL)
return FALSE;
link_before (list, *list, link);
return TRUE;
}
/**
* Appends a link to the list.
* Cannot fail due to out of memory.
* This is a constant-time operation.
*
* @param list address of the list head.
* @param link the link to append.
*/
void
_dbus_list_append_link (DBusList **list,
DBusList *link)
{
_dbus_list_prepend_link (list, link);
/* Now cycle the list forward one so the prepended node is the tail */
*list = (*list)->next;
}
/**
* Prepends a link to the list.
* Cannot fail due to out of memory.
* This is a constant-time operation.
*
* @param list address of the list head.
* @param link the link to prepend.
*/
void
_dbus_list_prepend_link (DBusList **list,
DBusList *link)
{
link_before (list, *list, link);
}
/**
* Inserts data into the list after the given existing link.
*
* @param list the list to modify
* @param after_this_link existing link to insert after, or #NULL to prepend
* @param data the value to insert
* @returns #TRUE on success, #FALSE if memory allocation fails
*/
dbus_bool_t
_dbus_list_insert_after (DBusList **list,
DBusList *after_this_link,
void *data)
{
DBusList *link;
if (after_this_link == NULL)
return _dbus_list_prepend (list, data);
else
{
link = alloc_link (data);
if (link == NULL)
return FALSE;
link_after (list, after_this_link, link);
}
return TRUE;
}
/**
* Inserts a link into the list before the given existing link.
*
* @param list the list to modify
* @param before_this_link existing link to insert before, or #NULL to append
* @param link the link to insert
*/
void
_dbus_list_insert_before_link (DBusList **list,
DBusList *before_this_link,
DBusList *link)
{
if (before_this_link == NULL)
_dbus_list_append_link (list, link);
else
link_before (list, before_this_link, link);
}
/**
* Inserts a link into the list after the given existing link.
*
* @param list the list to modify
* @param after_this_link existing link to insert after, or #NULL to prepend
* @param link the link to insert
*/
void
_dbus_list_insert_after_link (DBusList **list,
DBusList *after_this_link,
DBusList *link)
{
if (after_this_link == NULL)
_dbus_list_prepend_link (list, link);
else
link_after (list, after_this_link, link);
}
/**
* Removes a value from the list. Only removes the
* first value equal to the given data pointer,
* even if multiple values exist which match.
* This is a linear-time operation.
*
* @param list address of the list head.
* @param data the value to remove.
* @returns #TRUE if a value was found to remove.
*/
dbus_bool_t
_dbus_list_remove (DBusList **list,
void *data)
{
DBusList *link;
link = *list;
while (link != NULL)
{
if (link->data == data)
{
_dbus_list_remove_link (list, link);
return TRUE;
}
link = _dbus_list_get_next_link (list, link);
}
return FALSE;
}
/**
* Removes a value from the list. Only removes the
* last value equal to the given data pointer,
* even if multiple values exist which match.
* This is a linear-time operation.
*
* @param list address of the list head.
* @param data the value to remove.
* @returns #TRUE if a value was found to remove.
*/
dbus_bool_t
_dbus_list_remove_last (DBusList **list,
void *data)
{
DBusList *link;
link = _dbus_list_find_last (list, data);
if (link)
{
_dbus_list_remove_link (list, link);
return TRUE;
}
else
return FALSE;
}
/**
* Finds a value in the list. Returns the last link
* with value equal to the given data pointer.
* This is a linear-time operation.
* Returns #NULL if no value found that matches.
*
* @param list address of the list head.
* @param data the value to find.
* @returns the link if found
*/
DBusList*
_dbus_list_find_last (DBusList **list,
void *data)
{
DBusList *link;
link = _dbus_list_get_last_link (list);
while (link != NULL)
{
if (link->data == data)
return link;
link = _dbus_list_get_prev_link (list, link);
}
return NULL;
}
/**
* Removes the given link from the list, but doesn't
* free it. _dbus_list_remove_link() both removes the
* link and also frees it.
*
* @param list the list
* @param link the link in the list
*/
void
_dbus_list_unlink (DBusList **list,
DBusList *link)
{
if (link->next == link)
{
/* one-element list */
*list = NULL;
}
else
{
link->prev->next = link->next;
link->next->prev = link->prev;
if (*list == link)
*list = link->next;
}
link->next = NULL;
link->prev = NULL;
}
/**
* Removes a link from the list. This is a constant-time operation.
*
* @param list address of the list head.
* @param link the list link to remove.
*/
void
_dbus_list_remove_link (DBusList **list,
DBusList *link)
{
_dbus_list_unlink (list, link);
free_link (link);
}
/**
* Frees all links in the list and sets the list head to #NULL. Does
* not free the data in each link, for obvious reasons. This is a
* linear-time operation.
*
* @param list address of the list head.
*/
void
_dbus_list_clear (DBusList **list)
{
DBusList *link;
link = *list;
while (link != NULL)
{
DBusList *next = _dbus_list_get_next_link (list, link);
free_link (link);
link = next;
}
*list = NULL;
}
/**
* Free every link and every element in the list.
*
* @param list address of the head of the list.
* @param function free-function to call for each element.
*
*/
void
_dbus_list_clear_full (DBusList **list,
DBusFreeFunction function)
{
DBusList *link;
link = *list;
while (link != NULL)
{
DBusList *next = _dbus_list_get_next_link (list, link);
function (link->data);
free_link (link);
link = next;
}
*list = NULL;
}
/**
* Gets the first link in the list.
* This is a constant-time operation.
*
* @param list address of the list head.
* @returns the first link, or #NULL for an empty list.
*/
DBusList*
_dbus_list_get_first_link (DBusList **list)
{
return *list;
}
/**
* Gets the last link in the list.
* This is a constant-time operation.
*
* @param list address of the list head.
* @returns the last link, or #NULL for an empty list.
*/
DBusList*
_dbus_list_get_last_link (DBusList **list)
{
if (*list == NULL)
return NULL;
else
return (*list)->prev;
}
/**
* Gets the last data in the list.
* This is a constant-time operation.
*
* @param list address of the list head.
* @returns the last data in the list, or #NULL for an empty list.
*/
void*
_dbus_list_get_last (DBusList **list)
{
if (*list == NULL)
return NULL;
else
return (*list)->prev->data;
}
/**
* Gets the first data in the list.
* This is a constant-time operation.
*
* @param list address of the list head.
* @returns the first data in the list, or #NULL for an empty list.
*/
void*
_dbus_list_get_first (DBusList **list)
{
if (*list == NULL)
return NULL;
else
return (*list)->data;
}
/**
* Removes the first link in the list and returns it. This is a
* constant-time operation.
*
* @param list address of the list head.
* @returns the first link in the list, or #NULL for an empty list.
*/
DBusList*
_dbus_list_pop_first_link (DBusList **list)
{
DBusList *link;
link = _dbus_list_get_first_link (list);
if (link == NULL)
return NULL;
_dbus_list_unlink (list, link);
return link;
}
/**
* Removes the first value in the list and returns it. This is a
* constant-time operation.
*
* @param list address of the list head.
* @returns the first data in the list, or #NULL for an empty list.
*/
void*
_dbus_list_pop_first (DBusList **list)
{
DBusList *link;
void *data;
link = _dbus_list_get_first_link (list);
if (link == NULL)
return NULL;
data = link->data;
_dbus_list_remove_link (list, link);
return data;
}
/**
* Removes the last value in the list and returns it. This is a
* constant-time operation.
*
* @param list address of the list head.
* @returns the last data in the list, or #NULL for an empty list.
*/
void*
_dbus_list_pop_last (DBusList **list)
{
DBusList *link;
void *data;
link = _dbus_list_get_last_link (list);
if (link == NULL)
return NULL;
data = link->data;
_dbus_list_remove_link (list, link);
return data;
}
/**
* Copies a list. This is a linear-time operation. If there isn't
* enough memory to copy the entire list, the destination list will be
* set to #NULL.
*
* @param list address of the head of the list to copy.
* @param dest address where the copied list should be placed.
* @returns #TRUE on success, #FALSE if not enough memory.
*/
dbus_bool_t
_dbus_list_copy (DBusList **list,
DBusList **dest)
{
DBusList *link;
_dbus_assert (list != dest);
*dest = NULL;
link = *list;
while (link != NULL)
{
if (!_dbus_list_append (dest, link->data))
{
/* free what we have so far */
_dbus_list_clear (dest);
return FALSE;
}
link = _dbus_list_get_next_link (list, link);
}
return TRUE;
}
/**
* Gets the length of a list. This is a linear-time
* operation.
*
* @param list address of the head of the list
* @returns number of elements in the list.
*/
int
_dbus_list_get_length (DBusList **list)
{
DBusList *link;
int length;
length = 0;
link = *list;
while (link != NULL)
{
++length;
link = _dbus_list_get_next_link (list, link);
}
return length;
}
/**
* Calls the given function for each element in the list. The
* function is passed the list element as its first argument, and the
* given data as its second argument.
*
* @param list address of the head of the list.
* @param function function to call for each element.
* @param data extra data for the function.
*
*/
void
_dbus_list_foreach (DBusList **list,
DBusForeachFunction function,
void *data)
{
DBusList *link;
link = *list;
while (link != NULL)
{
DBusList *next = _dbus_list_get_next_link (list, link);
(* function) (link->data, data);
link = next;
}
}
/**
* Check whether length is exactly one.
*
* @param list the list
* @returns #TRUE if length is exactly one
*/
dbus_bool_t
_dbus_list_length_is_one (DBusList **list)
{
return (*list != NULL &&
(*list)->next == *list);
}
/** @} */
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