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 "winternl.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, "    %p: %p %08x ",
 132                  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     access &= ~RESERVED_ALL;
 226     if (inherit) access |= RESERVED_INHERIT;
 227     if (!process->handles)
 228     {
 229         set_error( STATUS_NO_MEMORY );
 230         return 0;
 231     }
 232     return alloc_entry( process->handles, obj, access );
 233 }
 234
 235 /* allocate a global handle for an object, incrementing its refcount */
 236 /* return the handle, or 0 on error */
 237 static obj_handle_t alloc_global_handle( void *obj, unsigned int access )
 238 {
 239     if (!global_table)
 240     {
 241         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 242             return 0;
 243     }
 244     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 245 }
 246
 247 /* return a handle entry, or NULL if the handle is invalid */
 248 static struct handle_entry *get_handle( struct process *process, obj_handle_t handle )
 249 {
 250     struct handle_table *table = process->handles;
 251     struct handle_entry *entry;
 252     int index;
 253
 254     if (handle_is_global(handle))
 255     {
 256         handle = handle_global_to_local(handle);
 257         table = global_table;
 258     }
 259     if (!table) goto error;
 260     index = handle_to_index( handle );
 261     if (index < 0) goto error;
 262     if (index > table->last) goto error;
 263     entry = table->entries + index;
 264     if (!entry->ptr) goto error;
 265     return entry;
 266
 267  error:
 268     set_error( STATUS_INVALID_HANDLE );
 269     return NULL;
 270 }
 271
 272 /* attempt to shrink a table */
 273 static void shrink_handle_table( struct handle_table *table )
 274 {
 275     struct handle_entry *entry = table->entries + table->last;
 276     struct handle_entry *new_entries;
 277     int count = table->count;
 278
 279     while (table->last >= 0)
 280     {
 281         if (entry->ptr) break;
 282         table->last--;
 283         entry--;
 284     }
 285     if (table->last >= count / 4) return;  /* no need to shrink */
 286     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 287     count /= 2;
 288     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 289     table->count   = count;
 290     table->entries = new_entries;
 291 }
 292
 293 /* copy the handle table of the parent process */
 294 /* return 1 if OK, 0 on error */
 295 struct handle_table *copy_handle_table( struct process *process, struct process *parent )
 296 {
 297     struct handle_table *parent_table = parent->handles;
 298     struct handle_table *table;
 299     int i;
 300
 301     assert( parent_table );
 302     assert( parent_table->obj.ops == &handle_table_ops );
 303
 304     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 305         return NULL;
 306
 307     if ((table->last = parent_table->last) >= 0)
 308     {
 309         struct handle_entry *ptr = table->entries;
 310         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 311         for (i = 0; i <= table->last; i++, ptr++)
 312         {
 313             if (!ptr->ptr) continue;
 314             ptr->fd = -1;
 315             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 316             else ptr->ptr = NULL; /* don't inherit this entry */
 317         }
 318     }
 319     /* attempt to shrink the table */
 320     shrink_handle_table( table );
 321     return table;
 322 }
 323
 324 /* close a handle and decrement the refcount of the associated object */
 325 /* return 1 if OK, 0 on error */
 326 int close_handle( struct process *process, obj_handle_t handle, int *fd )
 327 {
 328     struct handle_table *table;
 329     struct handle_entry *entry;
 330     struct object *obj;
 331
 332     if (!(entry = get_handle( process, handle ))) return 0;
 333     if (entry->access & RESERVED_CLOSE_PROTECT)
 334     {
 335         set_error( STATUS_HANDLE_NOT_CLOSABLE );
 336         return 0;
 337     }
 338     obj = entry->ptr;
 339     if (!obj->ops->close_handle( obj, process, handle ))
 340     {
 341         set_error( STATUS_HANDLE_NOT_CLOSABLE );
 342         return 0;
 343     }
 344     entry->ptr = NULL;
 345     if (fd) *fd = entry->fd;
 346     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 347     entry->fd = -1;
 348     table = handle_is_global(handle) ? global_table : process->handles;
 349     if (entry < table->entries + table->free) table->free = entry - table->entries;
 350     if (entry == table->entries + table->last) shrink_handle_table( table );
 351     release_object( obj );
 352     return 1;
 353 }
 354
 355 /* close all the global handles */
 356 void close_global_handles(void)
 357 {
 358     if (global_table)
 359     {
 360         release_object( global_table );
 361         global_table = NULL;
 362     }
 363 }
 364
 365 /* retrieve the object corresponding to one of the magic pseudo-handles */
 366 static inline struct object *get_magic_handle( obj_handle_t handle )
 367 {
 368     switch((unsigned long)handle)
 369     {
 370         case 0xfffffffe:  /* current thread pseudo-handle */
 371             return &current->obj;
 372         case 0x7fffffff:  /* current process pseudo-handle */
 373         case 0xffffffff:  /* current process pseudo-handle */
 374             return (struct object *)current->process;
 375         default:
 376             return NULL;
 377     }
 378 }
 379
 380 /* retrieve the object corresponding to a handle, incrementing its refcount */
 381 struct object *get_handle_obj( struct process *process, obj_handle_t handle,
 382                                unsigned int access, const struct object_ops *ops )
 383 {
 384     struct handle_entry *entry;
 385     struct object *obj;
 386
 387     if (!(obj = get_magic_handle( handle )))
 388     {
 389         if (!(entry = get_handle( process, handle ))) return NULL;
 390         if ((entry->access & access) != access)
 391         {
 392             set_error( STATUS_ACCESS_DENIED );
 393             return NULL;
 394         }
 395         obj = entry->ptr;
 396     }
 397     if (ops && (obj->ops != ops))
 398     {
 399         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 400         return NULL;
 401     }
 402     return grab_object( obj );
 403 }
 404
 405 /* retrieve the access rights of a given handle */
 406 unsigned int get_handle_access( struct process *process, obj_handle_t handle )
 407 {
 408     struct handle_entry *entry;
 409
 410     if (get_magic_handle( handle )) return ~0U;  /* magic handles have all access rights */
 411     if (!(entry = get_handle( process, handle ))) return 0;
 412     return entry->access;
 413 }
 414
 415 /* retrieve the cached fd for a given handle */
 416 int get_handle_unix_fd( struct process *process, obj_handle_t handle, unsigned int access )
 417 {
 418     struct handle_entry *entry;
 419
 420     if (!(entry = get_handle( process, handle ))) return -1;
 421     if ((entry->access & access) != access)
 422     {
 423         set_error( STATUS_ACCESS_DENIED );
 424         return -1;
 425     }
 426     return entry->fd;
 427 }
 428
 429 /* set the cached fd for a handle if not set already, and return the current value */
 430 int set_handle_unix_fd( struct process *process, obj_handle_t handle, int fd )
 431 {
 432     struct handle_entry *entry;
 433
 434     if (handle_is_global( handle )) return -1;  /* no fd cache for global handles */
 435     if (!(entry = get_handle( process, handle ))) return -1;
 436     /* if no current fd set it, otherwise return current fd */
 437     if (entry->fd == -1) entry->fd = fd;
 438     return entry->fd;
 439 }
 440
 441 /* remove the cached fd and return it */
 442 int flush_cached_fd( struct process *process, obj_handle_t handle )
 443 {
 444     struct handle_entry *entry = get_handle( process, handle );
 445     int fd = -1;
 446
 447     if (entry)
 448     {
 449         fd = entry->fd;
 450         entry->fd = -1;
 451     }
 452     return fd;
 453 }
 454
 455 /* find the first inherited handle of the given type */
 456 /* this is needed for window stations and desktops (don't ask...) */
 457 obj_handle_t find_inherited_handle( struct process *process, const struct object_ops *ops )
 458 {
 459     struct handle_table *table = process->handles;
 460     struct handle_entry *ptr;
 461     int i;
 462
 463     if (!table) return 0;
 464
 465     for (i = 0, ptr = table->entries; i <= table->last; i++, ptr++)
 466     {
 467         if (!ptr->ptr) continue;
 468         if (ptr->ptr->ops != ops) continue;
 469         if (ptr->access & RESERVED_INHERIT) return index_to_handle(i);
 470     }
 471     return 0;
 472 }
 473
 474 /* get/set the handle reserved flags */
 475 /* return the old flags (or -1 on error) */
 476 static int set_handle_flags( struct process *process, obj_handle_t handle, int mask, int flags )
 477 {
 478     struct handle_entry *entry;
 479     unsigned int old_access;
 480
 481     if (get_magic_handle( handle ))
 482     {
 483         /* we can retrieve but not set info for magic handles */
 484         if (mask) set_error( STATUS_ACCESS_DENIED );
 485         return 0;
 486     }
 487     if (!(entry = get_handle( process, handle ))) return -1;
 488     old_access = entry->access;
 489     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 490     flags = (flags << RESERVED_SHIFT) & mask;
 491     entry->access = (entry->access & ~mask) | flags;
 492     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 493 }
 494
 495 /* duplicate a handle */
 496 obj_handle_t duplicate_handle( struct process *src, obj_handle_t src_handle, struct process *dst,
 497                            unsigned int access, int inherit, int options )
 498 {
 499     obj_handle_t res;
 500     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 501
 502     if (!obj) return 0;
 503     if (options & DUP_HANDLE_SAME_ACCESS)
 504     {
 505         struct handle_entry *entry = get_handle( src, src_handle );
 506         if (entry)
 507             access = entry->access;
 508         else  /* pseudo-handle, give it full access */
 509         {
 510             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 511             clear_error();
 512         }
 513     }
 514     access &= ~RESERVED_ALL;
 515     if (options & DUP_HANDLE_MAKE_GLOBAL)
 516         res = alloc_global_handle( obj, access );
 517     else
 518         res = alloc_handle( dst, obj, access, inherit );
 519     release_object( obj );
 520     return res;
 521 }
 522
 523 /* open a new handle to an existing object */
 524 obj_handle_t open_object( const struct namespace *namespace, const WCHAR *name, size_t len,
 525                           const struct object_ops *ops, unsigned int access, unsigned int attr )
 526 {
 527     obj_handle_t handle = 0;
 528     struct object *obj = find_object( namespace, name, len, attr );
 529     if (obj)
 530     {
 531         if (ops && obj->ops != ops)
 532             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 533         else
 534             handle = alloc_handle( current->process, obj, access, attr & OBJ_INHERIT );
 535         release_object( obj );
 536     }
 537     else
 538         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 539     return handle;
 540 }
 541
 542 /* return the size of the handle table of a given process */
 543 unsigned int get_handle_table_count( struct process *process )
 544 {
 545     if (!process->handles) return 0;
 546     return process->handles->count;
 547 }
 548
 549 /* close a handle */
 550 DECL_HANDLER(close_handle)
 551 {
 552     close_handle( current->process, req->handle, &reply->fd );
 553 }
 554
 555 /* set a handle information */
 556 DECL_HANDLER(set_handle_info)
 557 {
 558     reply->old_flags = set_handle_flags( current->process, req->handle, req->mask, req->flags );
 559 }
 560
 561 /* duplicate a handle */
 562 DECL_HANDLER(dup_handle)
 563 {
 564     struct process *src, *dst;
 565
 566     reply->handle = 0;
 567     reply->fd = -1;
 568     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 569     {
 570         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 571         {
 572             reply->handle = duplicate_handle( src, req->src_handle, NULL,
 573                                               req->access, req->inherit, req->options );
 574         }
 575         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 576         {
 577             reply->handle = duplicate_handle( src, req->src_handle, dst,
 578                                               req->access, req->inherit, req->options );
 579             release_object( dst );
 580         }
 581         /* close the handle no matter what happened */
 582         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 583         {
 584             if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
 585             else close_handle( src, req->src_handle, NULL );
 586         }
 587         release_object( src );
 588     }
 589 }