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