Sweden-Number/server/thread.c

883 lines
26 KiB
C

/*
* Server-side thread management
*
* Copyright (C) 1998 Alexandre Julliard
*/
#include "config.h"
#include <assert.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_SYS_MMAN_H
#include <sys/mman.h>
#endif
#include <sys/types.h>
#ifdef HAVE_SYS_SOCKET_H
# include <sys/socket.h>
#endif
#include <sys/uio.h>
#include <unistd.h>
#include <stdarg.h>
#include "winbase.h"
#include "handle.h"
#include "process.h"
#include "thread.h"
#include "request.h"
/* thread queues */
struct thread_wait
{
int count; /* count of objects */
int flags;
struct timeval timeout;
struct timeout_user *user;
struct wait_queue_entry queues[1];
};
/* asynchronous procedure calls */
struct thread_apc
{
struct thread_apc *next; /* queue linked list */
struct thread_apc *prev;
struct object *owner; /* object that queued this apc */
void *func; /* function to call in client */
enum apc_type type; /* type of apc function */
int nb_args; /* number of arguments */
void *args[1]; /* function arguments */
};
/* thread operations */
static void dump_thread( struct object *obj, int verbose );
static int thread_signaled( struct object *obj, struct thread *thread );
extern void thread_poll_event( struct object *obj, int event );
static void destroy_thread( struct object *obj );
static struct thread_apc *thread_dequeue_apc( struct thread *thread, int system_only );
static const struct object_ops thread_ops =
{
sizeof(struct thread), /* size */
dump_thread, /* dump */
add_queue, /* add_queue */
remove_queue, /* remove_queue */
thread_signaled, /* signaled */
no_satisfied, /* satisfied */
NULL, /* get_poll_events */
thread_poll_event, /* poll_event */
no_get_fd, /* get_fd */
no_flush, /* flush */
no_get_file_info, /* get_file_info */
destroy_thread /* destroy */
};
static struct thread *first_thread;
static struct thread *booting_thread;
/* allocate the buffer for the communication with the client */
static int alloc_client_buffer( struct thread *thread )
{
union generic_request *req;
int fd = -1, fd_pipe[2], wait_pipe[2];
wait_pipe[0] = wait_pipe[1] = -1;
if (pipe( fd_pipe ) == -1)
{
file_set_error();
return 0;
}
if (pipe( wait_pipe ) == -1) goto error;
if ((fd = create_anonymous_file()) == -1) goto error;
if (ftruncate( fd, MAX_REQUEST_LENGTH ) == -1) goto error;
if ((thread->buffer = mmap( 0, MAX_REQUEST_LENGTH, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0 )) == (void*)-1) goto error;
thread->buffer_info = (struct server_buffer_info *)((char *)thread->buffer + MAX_REQUEST_LENGTH) - 1;
if (!(thread->request_fd = create_request_socket( thread ))) goto error;
thread->reply_fd = fd_pipe[1];
thread->wait_fd = wait_pipe[1];
/* make the pipes non-blocking */
fcntl( fd_pipe[1], F_SETFL, O_NONBLOCK );
fcntl( wait_pipe[1], F_SETFL, O_NONBLOCK );
/* build the first request into the buffer and send it */
req = thread->buffer;
req->get_thread_buffer.pid = get_process_id( thread->process );
req->get_thread_buffer.tid = get_thread_id( thread );
req->get_thread_buffer.boot = (thread == booting_thread);
req->get_thread_buffer.version = SERVER_PROTOCOL_VERSION;
/* add it here since send_client_fd may call kill_thread */
add_process_thread( thread->process, thread );
send_client_fd( thread, fd_pipe[0], 0 );
send_client_fd( thread, wait_pipe[0], 0 );
send_client_fd( thread, fd, 0 );
send_reply( thread, req );
close( fd_pipe[0] );
close( wait_pipe[0] );
close( fd );
return 1;
error:
file_set_error();
if (fd != -1) close( fd );
close( fd_pipe[0] );
close( fd_pipe[1] );
if (wait_pipe[0] != -1) close( wait_pipe[0] );
if (wait_pipe[1] != -1) close( wait_pipe[1] );
return 0;
}
/* create a new thread */
struct thread *create_thread( int fd, struct process *process )
{
struct thread *thread;
int flags = fcntl( fd, F_GETFL, 0 );
fcntl( fd, F_SETFL, flags | O_NONBLOCK );
if (!(thread = alloc_object( &thread_ops, fd ))) return NULL;
thread->unix_pid = 0; /* not known yet */
thread->context = NULL;
thread->teb = NULL;
thread->mutex = NULL;
thread->debug_ctx = NULL;
thread->debug_event = NULL;
thread->queue = NULL;
thread->info = NULL;
thread->wait = NULL;
thread->system_apc.head = NULL;
thread->system_apc.tail = NULL;
thread->user_apc.head = NULL;
thread->user_apc.tail = NULL;
thread->error = 0;
thread->pass_fd = -1;
thread->request_fd = NULL;
thread->reply_fd = -1;
thread->wait_fd = -1;
thread->state = RUNNING;
thread->attached = 0;
thread->exit_code = 0;
thread->next = NULL;
thread->prev = NULL;
thread->priority = THREAD_PRIORITY_NORMAL;
thread->affinity = 1;
thread->suspend = 0;
thread->buffer = (void *)-1;
thread->last_req = REQ_GET_THREAD_BUFFER;
thread->process = (struct process *)grab_object( process );
if (!current) current = thread;
if (!booting_thread) /* first thread ever */
{
booting_thread = thread;
lock_master_socket(1);
}
if ((thread->next = first_thread) != NULL) thread->next->prev = thread;
first_thread = thread;
set_select_events( &thread->obj, POLLIN ); /* start listening to events */
if (!alloc_client_buffer( thread )) goto error;
return thread;
error:
release_object( thread );
return NULL;
}
/* handle a client event */
void thread_poll_event( struct object *obj, int event )
{
struct thread *thread = (struct thread *)obj;
assert( obj->ops == &thread_ops );
if (event & (POLLERR | POLLHUP)) kill_thread( thread, 0 );
else if (event & POLLIN) read_request( thread );
}
/* destroy a thread when its refcount is 0 */
static void destroy_thread( struct object *obj )
{
struct thread_apc *apc;
struct thread *thread = (struct thread *)obj;
assert( obj->ops == &thread_ops );
assert( !thread->debug_ctx ); /* cannot still be debugging something */
release_object( thread->process );
if (thread->next) thread->next->prev = thread->prev;
if (thread->prev) thread->prev->next = thread->next;
else first_thread = thread->next;
while ((apc = thread_dequeue_apc( thread, 0 ))) free( apc );
if (thread->info) release_object( thread->info );
if (thread->queue) release_object( thread->queue );
if (thread->buffer != (void *)-1) munmap( thread->buffer, MAX_REQUEST_LENGTH );
if (thread->reply_fd != -1) close( thread->reply_fd );
if (thread->wait_fd != -1) close( thread->wait_fd );
if (thread->pass_fd != -1) close( thread->pass_fd );
if (thread->request_fd) release_object( thread->request_fd );
}
/* dump a thread on stdout for debugging purposes */
static void dump_thread( struct object *obj, int verbose )
{
struct thread *thread = (struct thread *)obj;
assert( obj->ops == &thread_ops );
fprintf( stderr, "Thread pid=%d teb=%p state=%d\n",
thread->unix_pid, thread->teb, thread->state );
}
static int thread_signaled( struct object *obj, struct thread *thread )
{
struct thread *mythread = (struct thread *)obj;
return (mythread->state == TERMINATED);
}
/* get a thread pointer from a thread id (and increment the refcount) */
struct thread *get_thread_from_id( void *id )
{
struct thread *t = first_thread;
while (t && (t != id)) t = t->next;
if (t) grab_object( t );
return t;
}
/* get a thread from a handle (and increment the refcount) */
struct thread *get_thread_from_handle( handle_t handle, unsigned int access )
{
return (struct thread *)get_handle_obj( current->process, handle,
access, &thread_ops );
}
/* find a thread from a Unix pid */
struct thread *get_thread_from_pid( int pid )
{
struct thread *t = first_thread;
while (t && (t->unix_pid != pid)) t = t->next;
return t;
}
/* set all information about a thread */
static void set_thread_info( struct thread *thread,
struct set_thread_info_request *req )
{
if (req->mask & SET_THREAD_INFO_PRIORITY)
thread->priority = req->priority;
if (req->mask & SET_THREAD_INFO_AFFINITY)
{
if (req->affinity != 1) set_error( STATUS_INVALID_PARAMETER );
else thread->affinity = req->affinity;
}
}
/* suspend a thread */
int suspend_thread( struct thread *thread, int check_limit )
{
int old_count = thread->suspend;
if (thread->suspend < MAXIMUM_SUSPEND_COUNT || !check_limit)
{
if (!(thread->process->suspend + thread->suspend++)) stop_thread( thread );
}
else set_error( STATUS_SUSPEND_COUNT_EXCEEDED );
return old_count;
}
/* resume a thread */
int resume_thread( struct thread *thread )
{
int old_count = thread->suspend;
if (thread->suspend > 0)
{
if (!(--thread->suspend + thread->process->suspend)) continue_thread( thread );
}
return old_count;
}
/* suspend all threads but the current */
void suspend_all_threads( void )
{
struct thread *thread;
for ( thread = first_thread; thread; thread = thread->next )
if ( thread != current )
suspend_thread( thread, 0 );
}
/* resume all threads but the current */
void resume_all_threads( void )
{
struct thread *thread;
for ( thread = first_thread; thread; thread = thread->next )
if ( thread != current )
resume_thread( thread );
}
/* add a thread to an object wait queue; return 1 if OK, 0 on error */
int add_queue( struct object *obj, struct wait_queue_entry *entry )
{
grab_object( obj );
entry->obj = obj;
entry->prev = obj->tail;
entry->next = NULL;
if (obj->tail) obj->tail->next = entry;
else obj->head = entry;
obj->tail = entry;
return 1;
}
/* remove a thread from an object wait queue */
void remove_queue( struct object *obj, struct wait_queue_entry *entry )
{
if (entry->next) entry->next->prev = entry->prev;
else obj->tail = entry->prev;
if (entry->prev) entry->prev->next = entry->next;
else obj->head = entry->next;
release_object( obj );
}
/* finish waiting */
static void end_wait( struct thread *thread )
{
struct thread_wait *wait = thread->wait;
struct wait_queue_entry *entry;
int i;
assert( wait );
for (i = 0, entry = wait->queues; i < wait->count; i++, entry++)
entry->obj->ops->remove_queue( entry->obj, entry );
if (wait->user) remove_timeout_user( wait->user );
free( wait );
thread->wait = NULL;
}
/* build the thread wait structure */
static int wait_on( int count, struct object *objects[], int flags, int sec, int usec )
{
struct thread_wait *wait;
struct wait_queue_entry *entry;
int i;
if (!(wait = mem_alloc( sizeof(*wait) + (count-1) * sizeof(*entry) ))) return 0;
current->wait = wait;
wait->count = count;
wait->flags = flags;
wait->user = NULL;
if (flags & SELECT_TIMEOUT)
{
wait->timeout.tv_sec = sec;
wait->timeout.tv_usec = usec;
}
for (i = 0, entry = wait->queues; i < count; i++, entry++)
{
struct object *obj = objects[i];
entry->thread = current;
if (!obj->ops->add_queue( obj, entry ))
{
wait->count = i;
end_wait( current );
return 0;
}
}
return 1;
}
/* check if the thread waiting condition is satisfied */
static int check_wait( struct thread *thread )
{
int i, signaled;
struct thread_wait *wait = thread->wait;
struct wait_queue_entry *entry = wait->queues;
assert( wait );
if (wait->flags & SELECT_ALL)
{
int not_ok = 0;
/* Note: we must check them all anyway, as some objects may
* want to do something when signaled, even if others are not */
for (i = 0, entry = wait->queues; i < wait->count; i++, entry++)
not_ok |= !entry->obj->ops->signaled( entry->obj, thread );
if (not_ok) goto other_checks;
/* Wait satisfied: tell it to all objects */
signaled = 0;
for (i = 0, entry = wait->queues; i < wait->count; i++, entry++)
if (entry->obj->ops->satisfied( entry->obj, thread ))
signaled = STATUS_ABANDONED_WAIT_0;
return signaled;
}
else
{
for (i = 0, entry = wait->queues; i < wait->count; i++, entry++)
{
if (!entry->obj->ops->signaled( entry->obj, thread )) continue;
/* Wait satisfied: tell it to the object */
signaled = i;
if (entry->obj->ops->satisfied( entry->obj, thread ))
signaled = i + STATUS_ABANDONED_WAIT_0;
return signaled;
}
}
other_checks:
if ((wait->flags & SELECT_INTERRUPTIBLE) && thread->system_apc.head) return STATUS_USER_APC;
if ((wait->flags & SELECT_ALERTABLE) && thread->user_apc.head) return STATUS_USER_APC;
if (wait->flags & SELECT_TIMEOUT)
{
struct timeval now;
gettimeofday( &now, NULL );
if (!time_before( &now, &wait->timeout )) return STATUS_TIMEOUT;
}
return -1;
}
/* attempt to wake up a thread */
/* return 1 if OK, 0 if the wait condition is still not satisfied */
static int wake_thread( struct thread *thread )
{
int signaled;
if ((signaled = check_wait( thread )) == -1) return 0;
if (debug_level) fprintf( stderr, "%08x: *wakeup* object=%d\n",
(unsigned int)thread, signaled );
end_wait( thread );
send_thread_wakeup( thread, signaled );
return 1;
}
/* thread wait timeout */
static void thread_timeout( void *ptr )
{
struct thread *thread = ptr;
if (debug_level) fprintf( stderr, "%08x: *timeout*\n", (unsigned int)thread );
assert( thread->wait );
thread->wait->user = NULL;
end_wait( thread );
send_thread_wakeup( thread, STATUS_TIMEOUT );
}
/* select on a list of handles */
static void select_on( int count, handle_t *handles, int flags, int sec, int usec )
{
int ret, i;
struct object *objects[MAXIMUM_WAIT_OBJECTS];
assert( !current->wait );
if ((count < 0) || (count > MAXIMUM_WAIT_OBJECTS))
{
set_error( STATUS_INVALID_PARAMETER );
return;
}
for (i = 0; i < count; i++)
{
if (!(objects[i] = get_handle_obj( current->process, handles[i], SYNCHRONIZE, NULL )))
break;
}
if (i < count) goto done;
if (!wait_on( count, objects, flags, sec, usec )) goto done;
if ((ret = check_wait( current )) != -1)
{
/* condition is already satisfied */
end_wait( current );
set_error( ret );
goto done;
}
/* now we need to wait */
if (flags & SELECT_TIMEOUT)
{
if (!(current->wait->user = add_timeout_user( &current->wait->timeout,
thread_timeout, current )))
{
end_wait( current );
goto done;
}
}
set_error( STATUS_PENDING );
done:
while (--i >= 0) release_object( objects[i] );
}
/* attempt to wake threads sleeping on the object wait queue */
void wake_up( struct object *obj, int max )
{
struct wait_queue_entry *entry = obj->head;
while (entry)
{
struct thread *thread = entry->thread;
entry = entry->next;
if (wake_thread( thread ))
{
if (max && !--max) break;
}
}
}
/* queue an async procedure call */
int thread_queue_apc( struct thread *thread, struct object *owner, void *func,
enum apc_type type, int system, int nb_args, ... )
{
struct thread_apc *apc;
struct apc_queue *queue = system ? &thread->system_apc : &thread->user_apc;
/* cancel a possible previous APC with the same owner */
if (owner) thread_cancel_apc( thread, owner, system );
if (!(apc = mem_alloc( sizeof(*apc) + (nb_args-1)*sizeof(apc->args[0]) ))) return 0;
apc->prev = queue->tail;
apc->next = NULL;
apc->owner = owner;
apc->func = func;
apc->type = type;
apc->nb_args = nb_args;
if (nb_args)
{
int i;
va_list args;
va_start( args, nb_args );
for (i = 0; i < nb_args; i++) apc->args[i] = va_arg( args, void * );
va_end( args );
}
queue->tail = apc;
if (!apc->prev) /* first one */
{
queue->head = apc;
if (thread->wait) wake_thread( thread );
}
return 1;
}
/* cancel the async procedure call owned by a specific object */
void thread_cancel_apc( struct thread *thread, struct object *owner, int system )
{
struct thread_apc *apc;
struct apc_queue *queue = system ? &thread->system_apc : &thread->user_apc;
for (apc = queue->head; apc; apc = apc->next)
{
if (apc->owner != owner) continue;
if (apc->next) apc->next->prev = apc->prev;
else queue->tail = apc->prev;
if (apc->prev) apc->prev->next = apc->next;
else queue->head = apc->next;
free( apc );
return;
}
}
/* remove the head apc from the queue; the returned pointer must be freed by the caller */
static struct thread_apc *thread_dequeue_apc( struct thread *thread, int system_only )
{
struct thread_apc *apc;
struct apc_queue *queue = &thread->system_apc;
if (!queue->head && !system_only) queue = &thread->user_apc;
if ((apc = queue->head))
{
if (apc->next) apc->next->prev = NULL;
else queue->tail = NULL;
queue->head = apc->next;
}
return apc;
}
/* retrieve an LDT selector entry */
static void get_selector_entry( struct thread *thread, int entry,
unsigned int *base, unsigned int *limit,
unsigned char *flags )
{
if (!thread->process->ldt_copy)
{
set_error( STATUS_ACCESS_DENIED );
return;
}
if (entry >= 8192)
{
set_error( STATUS_INVALID_PARAMETER ); /* FIXME */
return;
}
if (suspend_for_ptrace( thread ))
{
unsigned char flags_buf[4];
int *addr = (int *)thread->process->ldt_copy + entry;
if (read_thread_int( thread, addr, base ) == -1) goto done;
if (read_thread_int( thread, addr + 8192, limit ) == -1) goto done;
addr = (int *)thread->process->ldt_copy + 2*8192 + (entry >> 2);
if (read_thread_int( thread, addr, (int *)flags_buf ) == -1) goto done;
*flags = flags_buf[entry & 3];
done:
resume_thread( thread );
}
}
/* kill a thread on the spot */
void kill_thread( struct thread *thread, int violent_death )
{
if (thread->state == TERMINATED) return; /* already killed */
thread->state = TERMINATED;
if (current == thread) current = NULL;
if (debug_level)
fprintf( stderr,"%08x: *killed* exit_code=%d\n",
(unsigned int)thread, thread->exit_code );
if (thread->wait)
{
end_wait( thread );
/* if it is waiting on the socket, we don't need to send a SIGTERM */
violent_death = 0;
}
debug_exit_thread( thread );
abandon_mutexes( thread );
remove_process_thread( thread->process, thread );
wake_up( &thread->obj, 0 );
detach_thread( thread, violent_death ? SIGTERM : 0 );
remove_select_user( &thread->obj );
release_object( thread->request_fd );
close( thread->reply_fd );
close( thread->wait_fd );
munmap( thread->buffer, MAX_REQUEST_LENGTH );
thread->request_fd = NULL;
thread->reply_fd = -1;
thread->wait_fd = -1;
thread->buffer = (void *)-1;
release_object( thread );
}
/* take a snapshot of currently running threads */
struct thread_snapshot *thread_snap( int *count )
{
struct thread_snapshot *snapshot, *ptr;
struct thread *thread;
int total = 0;
for (thread = first_thread; thread; thread = thread->next)
if (thread->state != TERMINATED) total++;
if (!total || !(snapshot = mem_alloc( sizeof(*snapshot) * total ))) return NULL;
ptr = snapshot;
for (thread = first_thread; thread; thread = thread->next)
{
if (thread->state == TERMINATED) continue;
ptr->thread = thread;
ptr->count = thread->obj.refcount;
ptr->priority = thread->priority;
grab_object( thread );
ptr++;
}
*count = total;
return snapshot;
}
/* signal that we are finished booting on the client side */
DECL_HANDLER(boot_done)
{
debug_level = max( debug_level, req->debug_level );
/* Make sure last_req is initialized */
current->last_req = REQ_BOOT_DONE;
if (current == booting_thread)
{
booting_thread = (struct thread *)~0UL; /* make sure it doesn't match other threads */
lock_master_socket(0); /* allow other clients now */
}
}
/* create a new thread */
DECL_HANDLER(new_thread)
{
struct thread *thread;
int sock[2];
if (socketpair( AF_UNIX, SOCK_STREAM, 0, sock ) != -1)
{
if ((thread = create_thread( sock[0], current->process )))
{
if (req->suspend) thread->suspend++;
req->tid = thread;
if ((req->handle = alloc_handle( current->process, thread,
THREAD_ALL_ACCESS, req->inherit )))
{
send_client_fd( current, sock[1], req->handle );
close( sock[1] );
/* thread object will be released when the thread gets killed */
return;
}
kill_thread( thread, 1 );
}
close( sock[1] );
}
else file_set_error();
}
/* retrieve the thread buffer file descriptor */
DECL_HANDLER(get_thread_buffer)
{
fatal_protocol_error( current, "get_thread_buffer: should never get called directly\n" );
}
/* initialize a new thread */
DECL_HANDLER(init_thread)
{
if (current->unix_pid)
{
fatal_protocol_error( current, "init_thread: already running\n" );
return;
}
current->unix_pid = req->unix_pid;
current->teb = req->teb;
if (current->suspend + current->process->suspend > 0) stop_thread( current );
if (current->process->running_threads > 1)
generate_debug_event( current, CREATE_THREAD_DEBUG_EVENT, req->entry );
}
/* terminate a thread */
DECL_HANDLER(terminate_thread)
{
struct thread *thread;
req->self = 0;
req->last = 0;
if ((thread = get_thread_from_handle( req->handle, THREAD_TERMINATE )))
{
thread->exit_code = req->exit_code;
if (thread != current) kill_thread( thread, 1 );
else
{
req->self = 1;
req->last = (thread->process->running_threads == 1);
}
release_object( thread );
}
}
/* fetch information about a thread */
DECL_HANDLER(get_thread_info)
{
struct thread *thread;
handle_t handle = req->handle;
if (!handle) thread = get_thread_from_id( req->tid_in );
else thread = get_thread_from_handle( req->handle, THREAD_QUERY_INFORMATION );
if (thread)
{
req->tid = get_thread_id( thread );
req->teb = thread->teb;
req->exit_code = (thread->state == TERMINATED) ? thread->exit_code : STILL_ACTIVE;
req->priority = thread->priority;
release_object( thread );
}
}
/* set information about a thread */
DECL_HANDLER(set_thread_info)
{
struct thread *thread;
if ((thread = get_thread_from_handle( req->handle, THREAD_SET_INFORMATION )))
{
set_thread_info( thread, req );
release_object( thread );
}
}
/* suspend a thread */
DECL_HANDLER(suspend_thread)
{
struct thread *thread;
if ((thread = get_thread_from_handle( req->handle, THREAD_SUSPEND_RESUME )))
{
req->count = suspend_thread( thread, 1 );
release_object( thread );
}
}
/* resume a thread */
DECL_HANDLER(resume_thread)
{
struct thread *thread;
if ((thread = get_thread_from_handle( req->handle, THREAD_SUSPEND_RESUME )))
{
req->count = resume_thread( thread );
release_object( thread );
}
}
/* select on a handle list */
DECL_HANDLER(select)
{
int count = get_req_data_size(req) / sizeof(int);
select_on( count, get_req_data(req), req->flags, req->sec, req->usec );
}
/* queue an APC for a thread */
DECL_HANDLER(queue_apc)
{
struct thread *thread;
if ((thread = get_thread_from_handle( req->handle, THREAD_SET_CONTEXT )))
{
thread_queue_apc( thread, NULL, req->func, APC_USER, !req->user, 1, req->param );
release_object( thread );
}
}
/* get next APC to call */
DECL_HANDLER(get_apc)
{
struct thread_apc *apc;
size_t size;
for (;;)
{
if (!(apc = thread_dequeue_apc( current, !req->alertable )))
{
/* no more APCs */
req->func = NULL;
req->type = APC_NONE;
set_req_data_size( req, 0 );
return;
}
/* Optimization: ignore APCs that have a NULL func; they are only used
* to wake up a thread, but since we got here the thread woke up already.
*/
if (apc->func) break;
free( apc );
}
size = apc->nb_args * sizeof(apc->args[0]);
if (size > get_req_data_size(req)) size = get_req_data_size(req);
req->func = apc->func;
req->type = apc->type;
memcpy( get_req_data(req), apc->args, size );
set_req_data_size( req, size );
free( apc );
}
/* fetch a selector entry for a thread */
DECL_HANDLER(get_selector_entry)
{
struct thread *thread;
if ((thread = get_thread_from_handle( req->handle, THREAD_QUERY_INFORMATION )))
{
get_selector_entry( thread, req->entry, &req->base, &req->limit, &req->flags );
release_object( thread );
}
}