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_lookup_name,                  /* lookup_name */
 112     no_close_handle,                 /* close_handle */
 113     handle_table_destroy             /* destroy */
 114 };
 115
 116 /* dump a handle table */
 117 static void handle_table_dump( struct object *obj, int verbose )
 118 {
 119     int i;
 120     struct handle_table *table = (struct handle_table *)obj;
 121     struct handle_entry *entry = table->entries;
 122
 123     assert( obj->ops == &handle_table_ops );
 124
 125     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
 126              table->last, table->count, table->process );
 127     if (!verbose) return;
 128     entry = table->entries;
 129     for (i = 0; i <= table->last; i++, entry++)
 130     {
 131         if (!entry->ptr) continue;
 132         fprintf( stderr, "    %p: %p %08x ",
 133                  index_to_handle(i), entry->ptr, entry->access );
 134         entry->ptr->ops->dump( entry->ptr, 0 );
 135     }
 136 }
 137
 138 /* destroy a handle table */
 139 static void handle_table_destroy( struct object *obj )
 140 {
 141     int i;
 142     struct handle_table *table = (struct handle_table *)obj;
 143     struct handle_entry *entry;
 144
 145     assert( obj->ops == &handle_table_ops );
 146
 147     /* first notify all objects that handles are being closed */
 148     if (table->process)
 149     {
 150         for (i = 0, entry = table->entries; i <= table->last; i++, entry++)
 151         {
 152             struct object *obj = entry->ptr;
 153             if (obj) obj->ops->close_handle( obj, table->process, index_to_handle(i) );
 154         }
 155     }
 156
 157     for (i = 0, entry = table->entries; i <= table->last; i++, entry++)
 158     {
 159         struct object *obj = entry->ptr;
 160         entry->ptr = NULL;
 161         if (obj) release_object( obj );
 162     }
 163     free( table->entries );
 164 }
 165
 166 /* allocate a new handle table */
 167 struct handle_table *alloc_handle_table( struct process *process, int count )
 168 {
 169     struct handle_table *table;
 170
 171     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 172     if (!(table = alloc_object( &handle_table_ops )))
 173         return NULL;
 174     table->process = process;
 175     table->count   = count;
 176     table->last    = -1;
 177     table->free    = 0;
 178     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return table;
 179     release_object( table );
 180     return NULL;
 181 }
 182
 183 /* grow a handle table */
 184 static int grow_handle_table( struct handle_table *table )
 185 {
 186     struct handle_entry *new_entries;
 187     int count = table->count;
 188
 189     if (count >= INT_MAX / 2) return 0;
 190     count *= 2;
 191     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 192     {
 193         set_error( STATUS_NO_MEMORY );
 194         return 0;
 195     }
 196     table->entries = new_entries;
 197     table->count   = count;
 198     return 1;
 199 }
 200
 201 /* allocate the first free entry in the handle table */
 202 static obj_handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 203 {
 204     struct handle_entry *entry = table->entries + table->free;
 205     int i;
 206
 207     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 208     if (i >= table->count)
 209     {
 210         if (!grow_handle_table( table )) return 0;
 211         entry = table->entries + i;  /* the entries may have moved */
 212     }
 213     table->last = i;
 214  found:
 215     table->free = i + 1;
 216     entry->ptr    = grab_object( obj );
 217     entry->access = access;
 218     entry->fd     = -1;
 219     return index_to_handle(i);
 220 }
 221
 222 /* allocate a handle for an object, incrementing its refcount */
 223 /* return the handle, or 0 on error */
 224 obj_handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 225 {
 226     access &= ~RESERVED_ALL;
 227     if (inherit) access |= RESERVED_INHERIT;
 228     if (!process->handles)
 229     {
 230         set_error( STATUS_NO_MEMORY );
 231         return 0;
 232     }
 233     return alloc_entry( process->handles, obj, access );
 234 }
 235
 236 /* allocate a global handle for an object, incrementing its refcount */
 237 /* return the handle, or 0 on error */
 238 static obj_handle_t alloc_global_handle( void *obj, unsigned int access )
 239 {
 240     if (!global_table)
 241     {
 242         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 243             return 0;
 244     }
 245     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 246 }
 247
 248 /* return a handle entry, or NULL if the handle is invalid */
 249 static struct handle_entry *get_handle( struct process *process, obj_handle_t handle )
 250 {
 251     struct handle_table *table = process->handles;
 252     struct handle_entry *entry;
 253     int index;
 254
 255     if (handle_is_global(handle))
 256     {
 257         handle = handle_global_to_local(handle);
 258         table = global_table;
 259     }
 260     if (!table) goto error;
 261     index = handle_to_index( handle );
 262     if (index < 0) goto error;
 263     if (index > table->last) goto error;
 264     entry = table->entries + index;
 265     if (!entry->ptr) goto error;
 266     return entry;
 267
 268  error:
 269     set_error( STATUS_INVALID_HANDLE );
 270     return NULL;
 271 }
 272
 273 /* attempt to shrink a table */
 274 static void shrink_handle_table( struct handle_table *table )
 275 {
 276     struct handle_entry *entry = table->entries + table->last;
 277     struct handle_entry *new_entries;
 278     int count = table->count;
 279
 280     while (table->last >= 0)
 281     {
 282         if (entry->ptr) break;
 283         table->last--;
 284         entry--;
 285     }
 286     if (table->last >= count / 4) return;  /* no need to shrink */
 287     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 288     count /= 2;
 289     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 290     table->count   = count;
 291     table->entries = new_entries;
 292 }
 293
 294 /* copy the handle table of the parent process */
 295 /* return 1 if OK, 0 on error */
 296 struct handle_table *copy_handle_table( struct process *process, struct process *parent )
 297 {
 298     struct handle_table *parent_table = parent->handles;
 299     struct handle_table *table;
 300     int i;
 301
 302     assert( parent_table );
 303     assert( parent_table->obj.ops == &handle_table_ops );
 304
 305     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 306         return NULL;
 307
 308     if ((table->last = parent_table->last) >= 0)
 309     {
 310         struct handle_entry *ptr = table->entries;
 311         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 312         for (i = 0; i <= table->last; i++, ptr++)
 313         {
 314             if (!ptr->ptr) continue;
 315             ptr->fd = -1;
 316             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 317             else ptr->ptr = NULL; /* don't inherit this entry */
 318         }
 319     }
 320     /* attempt to shrink the table */
 321     shrink_handle_table( table );
 322     return table;
 323 }
 324
 325 /* close a handle and decrement the refcount of the associated object */
 326 /* return 1 if OK, 0 on error */
 327 int close_handle( struct process *process, obj_handle_t handle, int *fd )
 328 {
 329     struct handle_table *table;
 330     struct handle_entry *entry;
 331     struct object *obj;
 332
 333     if (!(entry = get_handle( process, handle ))) return 0;
 334     if (entry->access & RESERVED_CLOSE_PROTECT)
 335     {
 336         set_error( STATUS_HANDLE_NOT_CLOSABLE );
 337         return 0;
 338     }
 339     obj = entry->ptr;
 340     if (!obj->ops->close_handle( obj, process, handle ))
 341     {
 342         set_error( STATUS_HANDLE_NOT_CLOSABLE );
 343         return 0;
 344     }
 345     entry->ptr = NULL;
 346     if (fd) *fd = entry->fd;
 347     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 348     entry->fd = -1;
 349     table = handle_is_global(handle) ? global_table : process->handles;
 350     if (entry < table->entries + table->free) table->free = entry - table->entries;
 351     if (entry == table->entries + table->last) shrink_handle_table( table );
 352     release_object( obj );
 353     return 1;
 354 }
 355
 356 /* close all the global handles */
 357 void close_global_handles(void)
 358 {
 359     if (global_table)
 360     {
 361         release_object( global_table );
 362         global_table = NULL;
 363     }
 364 }
 365
 366 /* retrieve the object corresponding to one of the magic pseudo-handles */
 367 static inline struct object *get_magic_handle( obj_handle_t handle )
 368 {
 369     switch((unsigned long)handle)
 370     {
 371         case 0xfffffffe:  /* current thread pseudo-handle */
 372             return &current->obj;
 373         case 0x7fffffff:  /* current process pseudo-handle */
 374         case 0xffffffff:  /* current process pseudo-handle */
 375             return (struct object *)current->process;
 376         default:
 377             return NULL;
 378     }
 379 }
 380
 381 /* retrieve the object corresponding to a handle, incrementing its refcount */
 382 struct object *get_handle_obj( struct process *process, obj_handle_t handle,
 383                                unsigned int access, const struct object_ops *ops )
 384 {
 385     struct handle_entry *entry;
 386     struct object *obj;
 387
 388     if (!(obj = get_magic_handle( handle )))
 389     {
 390         if (!(entry = get_handle( process, handle ))) return NULL;
 391         if ((entry->access & access) != access)
 392         {
 393             set_error( STATUS_ACCESS_DENIED );
 394             return NULL;
 395         }
 396         obj = entry->ptr;
 397     }
 398     if (ops && (obj->ops != ops))
 399     {
 400         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 401         return NULL;
 402     }
 403     return grab_object( obj );
 404 }
 405
 406 /* retrieve the access rights of a given handle */
 407 unsigned int get_handle_access( struct process *process, obj_handle_t handle )
 408 {
 409     struct handle_entry *entry;
 410
 411     if (get_magic_handle( handle )) return ~0U;  /* magic handles have all access rights */
 412     if (!(entry = get_handle( process, handle ))) return 0;
 413     return entry->access;
 414 }
 415
 416 /* retrieve the cached fd for a given handle */
 417 int get_handle_unix_fd( struct process *process, obj_handle_t handle, unsigned int access )
 418 {
 419     struct handle_entry *entry;
 420
 421     if (!(entry = get_handle( process, handle ))) return -1;
 422     if ((entry->access & access) != access)
 423     {
 424         set_error( STATUS_ACCESS_DENIED );
 425         return -1;
 426     }
 427     return entry->fd;
 428 }
 429
 430 /* set the cached fd for a handle if not set already, and return the current value */
 431 int set_handle_unix_fd( struct process *process, obj_handle_t handle, int fd )
 432 {
 433     struct handle_entry *entry;
 434
 435     if (handle_is_global( handle )) return -1;  /* no fd cache for global handles */
 436     if (!(entry = get_handle( process, handle ))) return -1;
 437     /* if no current fd set it, otherwise return current fd */
 438     if (entry->fd == -1) entry->fd = fd;
 439     return entry->fd;
 440 }
 441
 442 /* remove the cached fd and return it */
 443 int flush_cached_fd( struct process *process, obj_handle_t handle )
 444 {
 445     struct handle_entry *entry = get_handle( process, handle );
 446     int fd = -1;
 447
 448     if (entry)
 449     {
 450         fd = entry->fd;
 451         entry->fd = -1;
 452     }
 453     return fd;
 454 }
 455
 456 /* find the first inherited handle of the given type */
 457 /* this is needed for window stations and desktops (don't ask...) */
 458 obj_handle_t find_inherited_handle( struct process *process, const struct object_ops *ops )
 459 {
 460     struct handle_table *table = process->handles;
 461     struct handle_entry *ptr;
 462     int i;
 463
 464     if (!table) return 0;
 465
 466     for (i = 0, ptr = table->entries; i <= table->last; i++, ptr++)
 467     {
 468         if (!ptr->ptr) continue;
 469         if (ptr->ptr->ops != ops) continue;
 470         if (ptr->access & RESERVED_INHERIT) return index_to_handle(i);
 471     }
 472     return 0;
 473 }
 474
 475 /* get/set the handle reserved flags */
 476 /* return the old flags (or -1 on error) */
 477 static int set_handle_flags( struct process *process, obj_handle_t handle, int mask, int flags )
 478 {
 479     struct handle_entry *entry;
 480     unsigned int old_access;
 481
 482     if (get_magic_handle( handle ))
 483     {
 484         /* we can retrieve but not set info for magic handles */
 485         if (mask) set_error( STATUS_ACCESS_DENIED );
 486         return 0;
 487     }
 488     if (!(entry = get_handle( process, handle ))) return -1;
 489     old_access = entry->access;
 490     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 491     flags = (flags << RESERVED_SHIFT) & mask;
 492     entry->access = (entry->access & ~mask) | flags;
 493     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 494 }
 495
 496 /* duplicate a handle */
 497 obj_handle_t duplicate_handle( struct process *src, obj_handle_t src_handle, struct process *dst,
 498                            unsigned int access, int inherit, int options )
 499 {
 500     obj_handle_t res;
 501     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 502
 503     if (!obj) return 0;
 504     if (options & DUP_HANDLE_SAME_ACCESS)
 505     {
 506         struct handle_entry *entry = get_handle( src, src_handle );
 507         if (entry)
 508             access = entry->access;
 509         else  /* pseudo-handle, give it full access */
 510         {
 511             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 512             clear_error();
 513         }
 514     }
 515     access &= ~RESERVED_ALL;
 516     if (options & DUP_HANDLE_MAKE_GLOBAL)
 517         res = alloc_global_handle( obj, access );
 518     else
 519         res = alloc_handle( dst, obj, access, inherit );
 520     release_object( obj );
 521     return res;
 522 }
 523
 524 /* open a new handle to an existing object */
 525 obj_handle_t open_object( const struct namespace *namespace, const struct unicode_str *name,
 526                           const struct object_ops *ops, unsigned int access, unsigned int attr )
 527 {
 528     obj_handle_t handle = 0;
 529     struct object *obj = find_object( namespace, name, attr );
 530     if (obj)
 531     {
 532         if (ops && obj->ops != ops)
 533             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 534         else
 535             handle = alloc_handle( current->process, obj, access, attr & OBJ_INHERIT );
 536         release_object( obj );
 537     }
 538     else
 539         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 540     return handle;
 541 }
 542
 543 /* return the size of the handle table of a given process */
 544 unsigned int get_handle_table_count( struct process *process )
 545 {
 546     if (!process->handles) return 0;
 547     return process->handles->count;
 548 }
 549
 550 /* close a handle */
 551 DECL_HANDLER(close_handle)
 552 {
 553     close_handle( current->process, req->handle, &reply->fd );
 554 }
 555
 556 /* set a handle information */
 557 DECL_HANDLER(set_handle_info)
 558 {
 559     reply->old_flags = set_handle_flags( current->process, req->handle, req->mask, req->flags );
 560 }
 561
 562 /* duplicate a handle */
 563 DECL_HANDLER(dup_handle)
 564 {
 565     struct process *src, *dst;
 566
 567     reply->handle = 0;
 568     reply->fd = -1;
 569     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 570     {
 571         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 572         {
 573             reply->handle = duplicate_handle( src, req->src_handle, NULL,
 574                                               req->access, req->inherit, req->options );
 575         }
 576         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 577         {
 578             reply->handle = duplicate_handle( src, req->src_handle, dst,
 579                                               req->access, req->inherit, req->options );
 580             release_object( dst );
 581         }
 582         /* close the handle no matter what happened */
 583         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 584         {
 585             if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
 586             else close_handle( src, req->src_handle, NULL );
 587         }
 588         release_object( src );
 589     }
 590 }