server/handle.c

   1 /*
   2  * Server-side handle management
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "config.h"
  22 #include "wine/port.h"
  23
  24 #include <assert.h>
  25 #include <limits.h>
  26 #include <string.h>
  27 #include <stdarg.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30
  31 #include "windef.h"
  32
  33 #include "handle.h"
  34 #include "process.h"
  35 #include "thread.h"
  36 #include "request.h"
  37
  38 struct handle_entry
  39 {
  40     struct object *ptr;       /* object */
  41     unsigned int   access;    /* access rights */
  42     int            fd;        /* file descriptor (in client process) */
  43 };
  44
  45 struct handle_table
  46 {
  47     struct object        obj;         /* object header */
  48     struct process      *process;     /* process owning this table */
  49     int                  count;       /* number of allocated entries */
  50     int                  last;        /* last used entry */
  51     int                  free;        /* first entry that may be free */
  52     struct handle_entry *entries;     /* handle entries */
  53 };
  54
  55 static struct handle_table *global_table;
  56
  57 /* reserved handle access rights */
  58 #define RESERVED_SHIFT         26
  59 #define RESERVED_INHERIT       (HANDLE_FLAG_INHERIT << RESERVED_SHIFT)
  60 #define RESERVED_CLOSE_PROTECT (HANDLE_FLAG_PROTECT_FROM_CLOSE << RESERVED_SHIFT)
  61 #define RESERVED_ALL           (RESERVED_INHERIT | RESERVED_CLOSE_PROTECT)
  62
  63 #define MIN_HANDLE_ENTRIES  32
  64
  65
  66 /* handle to table index conversion */
  67
  68 /* handles are a multiple of 4 under NT; handle 0 is not used */
  69 inline static obj_handle_t index_to_handle( int index )
  70 {
  71     return (obj_handle_t)((index + 1) << 2);
  72 }
  73 inline static int handle_to_index( obj_handle_t handle )
  74 {
  75     return ((unsigned int)handle >> 2) - 1;
  76 }
  77
  78 /* global handle conversion */
  79
  80 #define HANDLE_OBFUSCATOR 0x544a4def
  81
  82 inline static int handle_is_global( obj_handle_t handle)
  83 {
  84     return ((unsigned long)handle ^ HANDLE_OBFUSCATOR) < 0x10000;
  85 }
  86 inline static obj_handle_t handle_local_to_global( obj_handle_t handle )
  87 {
  88     if (!handle) return 0;
  89     return (obj_handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  90 }
  91 inline static obj_handle_t handle_global_to_local( obj_handle_t handle )
  92 {
  93     return (obj_handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  94 }
  95
  96
  97 static void handle_table_dump( struct object *obj, int verbose );
  98 static void handle_table_destroy( struct object *obj );
  99
 100 static const struct object_ops handle_table_ops =
 101 {
 102     sizeof(struct handle_table),     /* size */
 103     handle_table_dump,               /* dump */
 104     no_add_queue,                    /* add_queue */
 105     NULL,                            /* remove_queue */
 106     NULL,                            /* signaled */
 107     NULL,                            /* satisfied */
 108     no_signal,                       /* signal */
 109     no_get_fd,                       /* get_fd */
 110     no_close_handle,                 /* close_handle */
 111     handle_table_destroy             /* destroy */
 112 };
 113
 114 /* dump a handle table */
 115 static void handle_table_dump( struct object *obj, int verbose )
 116 {
 117     int i;
 118     struct handle_table *table = (struct handle_table *)obj;
 119     struct handle_entry *entry = table->entries;
 120
 121     assert( obj->ops == &handle_table_ops );
 122
 123     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
 124              table->last, table->count, table->process );
 125     if (!verbose) return;
 126     entry = table->entries;
 127     for (i = 0; i <= table->last; i++, entry++)
 128     {
 129         if (!entry->ptr) continue;
 130         fprintf( stderr, "%9u: %p %08x ",
 131                  (unsigned int)index_to_handle(i), entry->ptr, entry->access );
 132         entry->ptr->ops->dump( entry->ptr, 0 );
 133     }
 134 }
 135
 136 /* destroy a handle table */
 137 static void handle_table_destroy( struct object *obj )
 138 {
 139     int i;
 140     struct handle_table *table = (struct handle_table *)obj;
 141     struct handle_entry *entry;
 142
 143     assert( obj->ops == &handle_table_ops );
 144
 145     /* first notify all objects that handles are being closed */
 146     if (table->process)
 147     {
 148         for (i = 0, entry = table->entries; i <= table->last; i++, entry++)
 149         {
 150             struct object *obj = entry->ptr;
 151             if (obj) obj->ops->close_handle( obj, table->process, index_to_handle(i) );
 152         }
 153     }
 154
 155     for (i = 0, entry = table->entries; i <= table->last; i++, entry++)
 156     {
 157         struct object *obj = entry->ptr;
 158         entry->ptr = NULL;
 159         if (obj) release_object( obj );
 160     }
 161     free( table->entries );
 162 }
 163
 164 /* allocate a new handle table */
 165 struct handle_table *alloc_handle_table( struct process *process, int count )
 166 {
 167     struct handle_table *table;
 168
 169     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 170     if (!(table = alloc_object( &handle_table_ops )))
 171         return NULL;
 172     table->process = process;
 173     table->count   = count;
 174     table->last    = -1;
 175     table->free    = 0;
 176     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return table;
 177     release_object( table );
 178     return NULL;
 179 }
 180
 181 /* grow a handle table */
 182 static int grow_handle_table( struct handle_table *table )
 183 {
 184     struct handle_entry *new_entries;
 185     int count = table->count;
 186
 187     if (count >= INT_MAX / 2) return 0;
 188     count *= 2;
 189     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 190     {
 191         set_error( STATUS_NO_MEMORY );
 192         return 0;
 193     }
 194     table->entries = new_entries;
 195     table->count   = count;
 196     return 1;
 197 }
 198
 199 /* allocate the first free entry in the handle table */
 200 static obj_handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 201 {
 202     struct handle_entry *entry = table->entries + table->free;
 203     int i;
 204
 205     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 206     if (i >= table->count)
 207     {
 208         if (!grow_handle_table( table )) return 0;
 209         entry = table->entries + i;  /* the entries may have moved */
 210     }
 211     table->last = i;
 212  found:
 213     table->free = i + 1;
 214     entry->ptr    = grab_object( obj );
 215     entry->access = access;
 216     entry->fd     = -1;
 217     return index_to_handle(i);
 218 }
 219
 220 /* allocate a handle for an object, incrementing its refcount */
 221 /* return the handle, or 0 on error */
 222 obj_handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 223 {
 224     access &= ~RESERVED_ALL;
 225     if (inherit) access |= RESERVED_INHERIT;
 226     if (!process->handles)
 227     {
 228         set_error( STATUS_NO_MEMORY );
 229         return 0;
 230     }
 231     return alloc_entry( process->handles, obj, access );
 232 }
 233
 234 /* allocate a global handle for an object, incrementing its refcount */
 235 /* return the handle, or 0 on error */
 236 static obj_handle_t alloc_global_handle( void *obj, unsigned int access )
 237 {
 238     if (!global_table)
 239     {
 240         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 241             return 0;
 242     }
 243     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 244 }
 245
 246 /* return a handle entry, or NULL if the handle is invalid */
 247 static struct handle_entry *get_handle( struct process *process, obj_handle_t handle )
 248 {
 249     struct handle_table *table = process->handles;
 250     struct handle_entry *entry;
 251     int index;
 252
 253     if (handle_is_global(handle))
 254     {
 255         handle = handle_global_to_local(handle);
 256         table = global_table;
 257     }
 258     if (!table) goto error;
 259     index = handle_to_index( handle );
 260     if (index < 0) goto error;
 261     if (index > table->last) goto error;
 262     entry = table->entries + index;
 263     if (!entry->ptr) goto error;
 264     return entry;
 265
 266  error:
 267     set_error( STATUS_INVALID_HANDLE );
 268     return NULL;
 269 }
 270
 271 /* attempt to shrink a table */
 272 static void shrink_handle_table( struct handle_table *table )
 273 {
 274     struct handle_entry *entry = table->entries + table->last;
 275     struct handle_entry *new_entries;
 276     int count = table->count;
 277
 278     while (table->last >= 0)
 279     {
 280         if (entry->ptr) break;
 281         table->last--;
 282         entry--;
 283     }
 284     if (table->last >= count / 4) return;  /* no need to shrink */
 285     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 286     count /= 2;
 287     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 288     table->count   = count;
 289     table->entries = new_entries;
 290 }
 291
 292 /* copy the handle table of the parent process */
 293 /* return 1 if OK, 0 on error */
 294 struct handle_table *copy_handle_table( struct process *process, struct process *parent )
 295 {
 296     struct handle_table *parent_table = parent->handles;
 297     struct handle_table *table;
 298     int i;
 299
 300     assert( parent_table );
 301     assert( parent_table->obj.ops == &handle_table_ops );
 302
 303     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 304         return NULL;
 305
 306     if ((table->last = parent_table->last) >= 0)
 307     {
 308         struct handle_entry *ptr = table->entries;
 309         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 310         for (i = 0; i <= table->last; i++, ptr++)
 311         {
 312             if (!ptr->ptr) continue;
 313             ptr->fd = -1;
 314             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 315             else ptr->ptr = NULL; /* don't inherit this entry */
 316         }
 317     }
 318     /* attempt to shrink the table */
 319     shrink_handle_table( table );
 320     return table;
 321 }
 322
 323 /* close a handle and decrement the refcount of the associated object */
 324 /* return 1 if OK, 0 on error */
 325 int close_handle( struct process *process, obj_handle_t handle, int *fd )
 326 {
 327     struct handle_table *table;
 328     struct handle_entry *entry;
 329     struct object *obj;
 330
 331     if (!(entry = get_handle( process, handle ))) return 0;
 332     if (entry->access & RESERVED_CLOSE_PROTECT)
 333     {
 334         set_error( STATUS_HANDLE_NOT_CLOSABLE );
 335         return 0;
 336     }
 337     obj = entry->ptr;
 338     if (!obj->ops->close_handle( obj, process, handle ))
 339     {
 340         set_error( STATUS_HANDLE_NOT_CLOSABLE );
 341         return 0;
 342     }
 343     entry->ptr = NULL;
 344     if (fd) *fd = entry->fd;
 345     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 346     entry->fd = -1;
 347     table = handle_is_global(handle) ? global_table : process->handles;
 348     if (entry < table->entries + table->free) table->free = entry - table->entries;
 349     if (entry == table->entries + table->last) shrink_handle_table( table );
 350     release_object( obj );
 351     return 1;
 352 }
 353
 354 /* close all the global handles */
 355 void close_global_handles(void)
 356 {
 357     if (global_table)
 358     {
 359         release_object( global_table );
 360         global_table = NULL;
 361     }
 362 }
 363
 364 /* retrieve the object corresponding to one of the magic pseudo-handles */
 365 static inline struct object *get_magic_handle( obj_handle_t handle )
 366 {
 367     switch((unsigned long)handle)
 368     {
 369         case 0xfffffffe:  /* current thread pseudo-handle */
 370             return &current->obj;
 371         case 0x7fffffff:  /* current process pseudo-handle */
 372         case 0xffffffff:  /* current process pseudo-handle */
 373             return (struct object *)current->process;
 374         default:
 375             return NULL;
 376     }
 377 }
 378
 379 /* retrieve the object corresponding to a handle, incrementing its refcount */
 380 struct object *get_handle_obj( struct process *process, obj_handle_t handle,
 381                                unsigned int access, const struct object_ops *ops )
 382 {
 383     struct handle_entry *entry;
 384     struct object *obj;
 385
 386     if (!(obj = get_magic_handle( handle )))
 387     {
 388         if (!(entry = get_handle( process, handle ))) return NULL;
 389         if ((entry->access & access) != access)
 390         {
 391             set_error( STATUS_ACCESS_DENIED );
 392             return NULL;
 393         }
 394         obj = entry->ptr;
 395     }
 396     if (ops && (obj->ops != ops))
 397     {
 398         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 399         return NULL;
 400     }
 401     return grab_object( obj );
 402 }
 403
 404 /* retrieve the access rights of a given handle */
 405 unsigned int get_handle_access( struct process *process, obj_handle_t handle )
 406 {
 407     struct handle_entry *entry;
 408
 409     if (get_magic_handle( handle )) return ~0U;  /* magic handles have all access rights */
 410     if (!(entry = get_handle( process, handle ))) return 0;
 411     return entry->access;
 412 }
 413
 414 /* retrieve the cached fd for a given handle */
 415 int get_handle_unix_fd( struct process *process, obj_handle_t handle, unsigned int access )
 416 {
 417     struct handle_entry *entry;
 418
 419     if (!(entry = get_handle( process, handle ))) return -1;
 420     if ((entry->access & access) != access)
 421     {
 422         set_error( STATUS_ACCESS_DENIED );
 423         return -1;
 424     }
 425     return entry->fd;
 426 }
 427
 428 /* set the cached fd for a handle if not set already, and return the current value */
 429 int set_handle_unix_fd( struct process *process, obj_handle_t handle, int fd )
 430 {
 431     struct handle_entry *entry;
 432
 433     if (handle_is_global( handle )) return -1;  /* no fd cache for global handles */
 434     if (!(entry = get_handle( process, handle ))) return -1;
 435     /* if no current fd set it, otherwise return current fd */
 436     if (entry->fd == -1) entry->fd = fd;
 437     return entry->fd;
 438 }
 439
 440 /* remove the cached fd and return it */
 441 int flush_cached_fd( struct process *process, obj_handle_t handle )
 442 {
 443     struct handle_entry *entry = get_handle( process, handle );
 444     int fd = -1;
 445
 446     if (entry)
 447     {
 448         fd = entry->fd;
 449         entry->fd = -1;
 450     }
 451     return fd;
 452 }
 453
 454 /* find the first inherited handle of the given type */
 455 /* this is needed for window stations and desktops (don't ask...) */
 456 obj_handle_t find_inherited_handle( struct process *process, const struct object_ops *ops )
 457 {
 458     struct handle_table *table = process->handles;
 459     struct handle_entry *ptr;
 460     int i;
 461
 462     if (!table) return 0;
 463
 464     for (i = 0, ptr = table->entries; i <= table->last; i++, ptr++)
 465     {
 466         if (!ptr->ptr) continue;
 467         if (ptr->ptr->ops != ops) continue;
 468         if (ptr->access & RESERVED_INHERIT) return index_to_handle(i);
 469     }
 470     return 0;
 471 }
 472
 473 /* get/set the handle reserved flags */
 474 /* return the old flags (or -1 on error) */
 475 static int set_handle_flags( struct process *process, obj_handle_t handle, int mask, int flags )
 476 {
 477     struct handle_entry *entry;
 478     unsigned int old_access;
 479
 480     if (get_magic_handle( handle ))
 481     {
 482         /* we can retrieve but not set info for magic handles */
 483         if (mask) set_error( STATUS_ACCESS_DENIED );
 484         return 0;
 485     }
 486     if (!(entry = get_handle( process, handle ))) return -1;
 487     old_access = entry->access;
 488     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 489     flags = (flags << RESERVED_SHIFT) & mask;
 490     entry->access = (entry->access & ~mask) | flags;
 491     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 492 }
 493
 494 /* duplicate a handle */
 495 obj_handle_t duplicate_handle( struct process *src, obj_handle_t src_handle, struct process *dst,
 496                            unsigned int access, int inherit, int options )
 497 {
 498     obj_handle_t res;
 499     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 500
 501     if (!obj) return 0;
 502     if (options & DUP_HANDLE_SAME_ACCESS)
 503     {
 504         struct handle_entry *entry = get_handle( src, src_handle );
 505         if (entry)
 506             access = entry->access;
 507         else  /* pseudo-handle, give it full access */
 508         {
 509             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 510             clear_error();
 511         }
 512     }
 513     access &= ~RESERVED_ALL;
 514     if (options & DUP_HANDLE_MAKE_GLOBAL)
 515         res = alloc_global_handle( obj, access );
 516     else
 517         res = alloc_handle( dst, obj, access, inherit );
 518     release_object( obj );
 519     return res;
 520 }
 521
 522 /* open a new handle to an existing object */
 523 obj_handle_t open_object( const struct namespace *namespace, const WCHAR *name, size_t len,
 524                           const struct object_ops *ops, unsigned int access, int inherit )
 525 {
 526     obj_handle_t handle = 0;
 527     struct object *obj = find_object( namespace, name, len );
 528     if (obj)
 529     {
 530         if (ops && obj->ops != ops)
 531             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 532         else
 533             handle = alloc_handle( current->process, obj, access, inherit );
 534         release_object( obj );
 535     }
 536     else
 537         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 538     return handle;
 539 }
 540
 541 /* return the size of the handle table of a given process */
 542 unsigned int get_handle_table_count( struct process *process )
 543 {
 544     if (!process->handles) return 0;
 545     return process->handles->count;
 546 }
 547
 548 /* close a handle */
 549 DECL_HANDLER(close_handle)
 550 {
 551     close_handle( current->process, req->handle, &reply->fd );
 552 }
 553
 554 /* set a handle information */
 555 DECL_HANDLER(set_handle_info)
 556 {
 557     reply->old_flags = set_handle_flags( current->process, req->handle, req->mask, req->flags );
 558 }
 559
 560 /* duplicate a handle */
 561 DECL_HANDLER(dup_handle)
 562 {
 563     struct process *src, *dst;
 564
 565     reply->handle = 0;
 566     reply->fd = -1;
 567     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 568     {
 569         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 570         {
 571             reply->handle = duplicate_handle( src, req->src_handle, NULL,
 572                                               req->access, req->inherit, req->options );
 573         }
 574         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 575         {
 576             reply->handle = duplicate_handle( src, req->src_handle, dst,
 577                                               req->access, req->inherit, req->options );
 578             release_object( dst );
 579         }
 580         /* close the handle no matter what happened */
 581         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 582         {
 583             if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
 584             else close_handle( src, req->src_handle, NULL );
 585         }
 586         release_object( src );
 587     }
 588 }