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* Source/synchronization.m: Correct issue in objc_sync_remove_node()

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method where it could do a NULL dereference.  Also moved the locks on
	the tables to the highest level so to reduce the possibility of
	threading issues.


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@26877 72102866-910b-0410-8b05-ffd578937521
This commit is contained in:
gcasa 2008-09-25 04:55:42 +00:00
parent 8b51b9c39c
commit b6f7e0da8b
2 changed files with 41 additions and 13 deletions
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7
ChangeLog
View file

@ -1,3 +1,10 @@
2008-09-25 00:18-EDT Gregory John Casamento <greg_casamento@yahoo.com>
* Source/synchronization.m: Correct issue in objc_sync_remove_node()
method where it could do a NULL dereference. Also moved the locks on
the tables to the highest level so to reduce the possibility of
threading issues.
2008-09-24 17:26-EDT Gregory John Casamento <greg_casamento@yahoo.com> 2008-09-24 17:26-EDT Gregory John Casamento <greg_casamento@yahoo.com>
* Source/NSUserDefaults.m: Corrected previous change. * Source/NSUserDefaults.m: Corrected previous change.

41
Source/synchronization.m
View file

@ -74,7 +74,7 @@ static void sync_lock_init()
*/ */
lock_node_t* objc_sync_find_node(id obj) lock_node_t* objc_sync_find_node(id obj)
{ {
lock_node_t *current = NULL; lock_node_t *current = lock_list;
if(lock_list != NULL) if(lock_list != NULL)
{ {
@ -105,9 +105,6 @@ lock_node_t* objc_sync_add_node(id obj)
// get the lock... // get the lock...
sync_lock_init(); sync_lock_init();
// restrict access to the table....
objc_mutex_lock(table_lock);
// if the list hasn't been initialized, initialize it. // if the list hasn't been initialized, initialize it.
if(lock_list == NULL) if(lock_list == NULL)
{ {
@ -154,9 +151,6 @@ lock_node_t* objc_sync_add_node(id obj)
current->lock = objc_mutex_allocate(); current->lock = objc_mutex_allocate();
} }
// release access to the table...
objc_mutex_unlock(table_lock);
return current; return current;
} }
@ -182,9 +176,16 @@ lock_node_t* objc_sync_remove_node(id obj)
prev = curr->prev; prev = curr->prev;
next = curr->next; next = curr->next;
if(next != NULL)
{
next->prev = prev; next->prev = prev;
}
if(prev != NULL)
{
prev->next = next; prev->next = next;
} }
}
// return the removed node... // return the removed node...
return curr; return curr;
@ -198,6 +199,9 @@ int objc_sync_enter(id obj)
lock_node_t *node = NULL; lock_node_t *node = NULL;
int status = 0; int status = 0;
// lock access to the table until we're done....
objc_mutex_lock(table_lock);
node = objc_sync_find_node(obj); node = objc_sync_find_node(obj);
if(node == NULL) if(node == NULL)
{ {
@ -208,8 +212,15 @@ int objc_sync_enter(id obj)
} }
} }
// unlock the table....
objc_mutex_unlock(table_lock);
status = objc_mutex_lock(node->lock); status = objc_mutex_lock(node->lock);
if(status < 1) // if the status is more than one, then another thread
// has this section locked, so we abort. A status of -1
// indicates that an error occurred.
if(status > 1 || status == -1)
{ {
return OBJC_SYNC_NOT_OWNING_THREAD_ERROR; return OBJC_SYNC_NOT_OWNING_THREAD_ERROR;
} }
@ -225,20 +236,30 @@ int objc_sync_exit(id obj)
lock_node_t *node = NULL; lock_node_t *node = NULL;
int status = 0; int status = 0;
node = objc_sync_remove_node(obj); // lock access to the table until we're done....
objc_mutex_lock(table_lock);
node = objc_sync_find_node(obj);
if(node == NULL) if(node == NULL)
{ {
return OBJC_SYNC_NOT_INITIALIZED; return OBJC_SYNC_NOT_INITIALIZED;
} }
// unlock the table....
objc_mutex_unlock(table_lock);
status = objc_mutex_unlock(node->lock); status = objc_mutex_unlock(node->lock);
if(status < 1) // if the status is not zero, then we are not the sole
// owner of this node. Also if -1 is returned, this indicates and error
// condition.
if(status > 0 || status == -1)
{ {
return OBJC_SYNC_NOT_OWNING_THREAD_ERROR; return OBJC_SYNC_NOT_OWNING_THREAD_ERROR;
} }
// dealloc the node and return success. // dealloc the node and return success.
free(node); free(node);
return OBJC_SYNC_SUCCESS; return OBJC_SYNC_SUCCESS;
} }