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