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Diffstat (limited to 'libhurd-cap-server/client-release.c')
| -rw-r--r-- | libhurd-cap-server/client-release.c | 192 |
1 files changed, 0 insertions, 192 deletions
diff --git a/libhurd-cap-server/client-release.c b/libhurd-cap-server/client-release.c deleted file mode 100644 index 57d3796..0000000 --- a/libhurd-cap-server/client-release.c +++ /dev/null @@ -1,192 +0,0 @@ -/* client-release.c - Release a capability client. - Copyright (C) 2004 Free Software Foundation, Inc. - Written by Marcus Brinkmann <marcus@gnu.org> - - This file is part of the GNU Hurd. - - This program is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 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 - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA - 02111-1307 USA. */ - -#if HAVE_CONFIG_H -#include <config.h> -#endif - -#include <errno.h> -#include <pthread.h> -#include <stdlib.h> - -#include <compiler.h> - -#include "cap-server-intern.h" - - -/* Deallocate the connection client CLIENT. */ -void -_hurd_cap_client_dealloc (hurd_cap_bucket_t bucket, _hurd_cap_client_t client) -{ - unsigned int nr_caps = 0; - - /* This function is only invoked if the reference count for the - client entry in the client table of the class drops to 0, and - after the table entry was removed. Usually, the last reference - is removed by the task death notification handler. - - At that point, there are no more pending RPCs for this client (if - there were, there would be a reference for each of them). This - also means that all capability IDs have at most one internal - reference, the one for all external references. */ - - /* Note that although the client has been removed from the clients - table in the class, there are still back-references for each and - every capability object in our capability table caps. These - capability entries all count as references to ourself. They are - used for example if a capability is revoked. It is important to - realize that such a revocation can happen anytime as long as - there are still valid capability objects in the caps table of the - client. - - So, to correctly release those references, we have to look up - each capability object properly, acquiring our own internal - reference for it, then we have to unlock the client to lock the - capability object, to finally revoke our own capability and - release the capability object reference. Only then can we - reacquire our own lock and go on to the next capability. While - we do not hold our lock, more capabilities can be revoked by - other concurrent operations. However, no new capabilities are - added, so one pass through the table is enough. */ - - pthread_mutex_lock (&client->lock); - - /* Release all capability objects held by this user. Because we - have to honor the locking order, this takes a while. */ - HURD_TABLE_ITERATE (&client->caps, idx) - { - _hurd_cap_obj_entry_t entry; - - entry = *((_hurd_cap_obj_entry_t *) - HURD_TABLE_LOOKUP (&client->caps, idx)); - - /* If there were no external references, the last internal - reference would have been released before we get here. */ - assert (entry->external_refs); - - nr_caps++; - - /* The number of internal references is either one or zero. If - it is one, then the capability is not revoked yet, so we have - to do it. If it is zero, then the capability is revoked - (dead), and we only have to clear the table entry. */ - if (!entry->dead) - { - hurd_cap_obj_t cap_obj = entry->cap_obj; - - assert (entry->internal_refs == 1); - - /* Acquire an internal reference to prevent that our own - reference to the capability object is removed by a - concurrent revocation as soon as we unlock the client. - After all, the existing internal reference belongs to the - capability object, and not to us. */ - entry->internal_refs++; - pthread_mutex_unlock (&client->lock); - - pthread_mutex_lock (&cap_obj->lock); - /* Check if we should revoke it, or if somebody else did already. */ - if (!entry->dead) - { - int found; - - /* We should revoke it. */ - pthread_mutex_lock (&client->lock); - found = hurd_ihash_remove (&client->caps_reverse, - (hurd_ihash_key_t) cap_obj); - assert (found); - entry->dead = 1; - - assert (entry->internal_refs == 2); - entry->internal_refs--; - pthread_mutex_unlock (&client->lock); - - /* FIXME: Remove it from the capabilities client list. */ - } - pthread_mutex_unlock (&cap_obj->lock); - - pthread_mutex_lock (&client->lock); - /* Now we can drop the capability object below. */ - assert (entry->dead); - assert (entry->internal_refs == 1); - assert (entry->external_refs); - } - else - { - /* If the capability is dead, we can simply drop it below. */ - assert (entry->internal_refs == 0); - entry->internal_refs = 1; - } - - entry->dead = 0; - /* ENTRY->internal_refs is 1. */ - entry->external_refs = 1; - - /* Remove the entry. */ - hurd_slab_dealloc (&_hurd_cap_obj_entry_space, entry); - hurd_table_remove (&client->caps, idx); - } - - /* After all this ugly work, the rest is trivial. */ - if (client->state != _HURD_CAP_STATE_GREEN) - client->state = _HURD_CAP_STATE_GREEN; - - assert (client->pending_rpcs == NULL); - - /* FIXME: Release the task info capability here. */ - - /* FIXME: It would be a good idea to shrink the empty table and - empty hash here, to reclaim resources and be able to eventually - enforce a per-client quota. */ - pthread_mutex_unlock (&client->lock); - - pthread_mutex_lock (&bucket->lock); - bucket->nr_caps -= nr_caps; - pthread_mutex_unlock (&bucket->lock); - - hurd_slab_dealloc (&_hurd_cap_client_space, client); -} - - -/* Release a reference for the client with the ID IDX in bucket - BUCKET. */ -void -_hurd_cap_client_release (hurd_cap_bucket_t bucket, _hurd_cap_client_id_t idx) -{ - _hurd_cap_client_t client; - - pthread_mutex_lock (&bucket->lock); - client = *(_hurd_cap_client_t *) HURD_TABLE_LOOKUP (&bucket->clients, idx); - - if (EXPECT_TRUE (client->refs > 1)) - { - client->refs--; - pthread_mutex_unlock (&bucket->lock); - } - else - { - hurd_table_remove (&bucket->clients, idx); - hurd_ihash_locp_remove (&bucket->clients_reverse, client->locp); - - pthread_mutex_unlock (&bucket->lock); - _hurd_cap_client_dealloc (bucket, client); - } -} |