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