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         25
  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     handle_table_destroy             /* destroy */
 112 };
 113
 114 /* dump a handle table */
 115 static void handle_table_dump( struct object *obj, int verbose )
 116 {
 117     int i;
 118     struct handle_table *table = (struct handle_table *)obj;
 119     struct handle_entry *entry = table->entries;
 120
 121     assert( obj->ops == &handle_table_ops );
 122
 123     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
 124              table->last, table->count, table->process );
 125     if (!verbose) return;
 126     entry = table->entries;
 127     for (i = 0; i <= table->last; i++, entry++)
 128     {
 129         if (!entry->ptr) continue;
 130         fprintf( stderr, "%9u: %p %08x ",
 131                  (unsigned int)index_to_handle(i), entry->ptr, entry->access );
 132         entry->ptr->ops->dump( entry->ptr, 0 );
 133     }
 134 }
 135
 136 /* destroy a handle table */
 137 static void handle_table_destroy( struct object *obj )
 138 {
 139     int i;
 140     struct handle_table *table = (struct handle_table *)obj;
 141     struct handle_entry *entry = table->entries;
 142
 143     assert( obj->ops == &handle_table_ops );
 144
 145     for (i = 0; i <= table->last; i++, entry++)
 146     {
 147         struct object *obj = entry->ptr;
 148         entry->ptr = NULL;
 149         if (obj) release_object( obj );
 150     }
 151     free( table->entries );
 152 }
 153
 154 /* allocate a new handle table */
 155 struct handle_table *alloc_handle_table( struct process *process, int count )
 156 {
 157     struct handle_table *table;
 158
 159     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 160     if (!(table = alloc_object( &handle_table_ops )))
 161         return NULL;
 162     table->process = process;
 163     table->count   = count;
 164     table->last    = -1;
 165     table->free    = 0;
 166     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return table;
 167     release_object( table );
 168     return NULL;
 169 }
 170
 171 /* grow a handle table */
 172 static int grow_handle_table( struct handle_table *table )
 173 {
 174     struct handle_entry *new_entries;
 175     int count = table->count;
 176
 177     if (count >= INT_MAX / 2) return 0;
 178     count *= 2;
 179     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 180     {
 181         set_error( STATUS_NO_MEMORY );
 182         return 0;
 183     }
 184     table->entries = new_entries;
 185     table->count   = count;
 186     return 1;
 187 }
 188
 189 /* allocate the first free entry in the handle table */
 190 static obj_handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 191 {
 192     struct handle_entry *entry = table->entries + table->free;
 193     int i;
 194
 195     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 196     if (i >= table->count)
 197     {
 198         if (!grow_handle_table( table )) return 0;
 199         entry = table->entries + i;  /* the entries may have moved */
 200     }
 201     table->last = i;
 202  found:
 203     table->free = i + 1;
 204     entry->ptr    = grab_object( obj );
 205     entry->access = access;
 206     entry->fd     = -1;
 207     return index_to_handle(i);
 208 }
 209
 210 /* allocate a handle for an object, incrementing its refcount */
 211 /* return the handle, or 0 on error */
 212 obj_handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 213 {
 214     struct handle_table *table = process->handles;
 215
 216     assert( table );
 217     assert( !(access & RESERVED_ALL) );
 218     if (inherit) access |= RESERVED_INHERIT;
 219     return alloc_entry( table, obj, access );
 220 }
 221
 222 /* allocate a global handle for an object, incrementing its refcount */
 223 /* return the handle, or 0 on error */
 224 static obj_handle_t alloc_global_handle( void *obj, unsigned int access )
 225 {
 226     if (!global_table)
 227     {
 228         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 229             return 0;
 230     }
 231     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 232 }
 233
 234 /* return a handle entry, or NULL if the handle is invalid */
 235 static struct handle_entry *get_handle( struct process *process, obj_handle_t handle )
 236 {
 237     struct handle_table *table = process->handles;
 238     struct handle_entry *entry;
 239     int index;
 240
 241     if (handle_is_global(handle))
 242     {
 243         handle = handle_global_to_local(handle);
 244         table = global_table;
 245     }
 246     if (!table) goto error;
 247     index = handle_to_index( handle );
 248     if (index < 0) goto error;
 249     if (index > table->last) goto error;
 250     entry = table->entries + index;
 251     if (!entry->ptr) goto error;
 252     return entry;
 253
 254  error:
 255     set_error( STATUS_INVALID_HANDLE );
 256     return NULL;
 257 }
 258
 259 /* attempt to shrink a table */
 260 static void shrink_handle_table( struct handle_table *table )
 261 {
 262     struct handle_entry *entry = table->entries + table->last;
 263     struct handle_entry *new_entries;
 264     int count = table->count;
 265
 266     while (table->last >= 0)
 267     {
 268         if (entry->ptr) break;
 269         table->last--;
 270         entry--;
 271     }
 272     if (table->last >= count / 4) return;  /* no need to shrink */
 273     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 274     count /= 2;
 275     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 276     table->count   = count;
 277     table->entries = new_entries;
 278 }
 279
 280 /* copy the handle table of the parent process */
 281 /* return 1 if OK, 0 on error */
 282 struct handle_table *copy_handle_table( struct process *process, struct process *parent )
 283 {
 284     struct handle_table *parent_table = parent->handles;
 285     struct handle_table *table;
 286     int i;
 287
 288     assert( parent_table );
 289     assert( parent_table->obj.ops == &handle_table_ops );
 290
 291     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 292         return NULL;
 293
 294     if ((table->last = parent_table->last) >= 0)
 295     {
 296         struct handle_entry *ptr = table->entries;
 297         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 298         for (i = 0; i <= table->last; i++, ptr++)
 299         {
 300             if (!ptr->ptr) continue;
 301             ptr->fd = -1;
 302             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 303             else ptr->ptr = NULL; /* don't inherit this entry */
 304         }
 305     }
 306     /* attempt to shrink the table */
 307     shrink_handle_table( table );
 308     return table;
 309 }
 310
 311 /* close a handle and decrement the refcount of the associated object */
 312 /* return 1 if OK, 0 on error */
 313 int close_handle( struct process *process, obj_handle_t handle, int *fd )
 314 {
 315     struct handle_table *table;
 316     struct handle_entry *entry;
 317     struct object *obj;
 318
 319     if (!(entry = get_handle( process, handle ))) return 0;
 320     if (entry->access & RESERVED_CLOSE_PROTECT)
 321     {
 322         set_error( STATUS_INVALID_HANDLE );
 323         return 0;
 324     }
 325     obj = entry->ptr;
 326     entry->ptr = NULL;
 327     if (fd) *fd = entry->fd;
 328     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 329     entry->fd = -1;
 330     table = handle_is_global(handle) ? global_table : process->handles;
 331     if (entry < table->entries + table->free) table->free = entry - table->entries;
 332     if (entry == table->entries + table->last) shrink_handle_table( table );
 333     /* hack: windows seems to treat registry handles differently */
 334     registry_close_handle( obj, handle );
 335     release_object( obj );
 336     return 1;
 337 }
 338
 339 /* close all the global handles */
 340 void close_global_handles(void)
 341 {
 342     if (global_table)
 343     {
 344         release_object( global_table );
 345         global_table = NULL;
 346     }
 347 }
 348
 349 /* retrieve the object corresponding to one of the magic pseudo-handles */
 350 static inline struct object *get_magic_handle( obj_handle_t handle )
 351 {
 352     switch((unsigned long)handle)
 353     {
 354         case 0xfffffffe:  /* current thread pseudo-handle */
 355             return &current->obj;
 356         case 0x7fffffff:  /* current process pseudo-handle */
 357         case 0xffffffff:  /* current process pseudo-handle */
 358             return (struct object *)current->process;
 359         default:
 360             return NULL;
 361     }
 362 }
 363
 364 /* retrieve the object corresponding to a handle, incrementing its refcount */
 365 struct object *get_handle_obj( struct process *process, obj_handle_t handle,
 366                                unsigned int access, const struct object_ops *ops )
 367 {
 368     struct handle_entry *entry;
 369     struct object *obj;
 370
 371     if (!(obj = get_magic_handle( handle )))
 372     {
 373         if (!(entry = get_handle( process, handle ))) return NULL;
 374         if ((entry->access & access) != access)
 375         {
 376             set_error( STATUS_ACCESS_DENIED );
 377             return NULL;
 378         }
 379         obj = entry->ptr;
 380     }
 381     if (ops && (obj->ops != ops))
 382     {
 383         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 384         return NULL;
 385     }
 386     return grab_object( obj );
 387 }
 388
 389 /* retrieve the access rights of a given handle */
 390 unsigned int get_handle_access( struct process *process, obj_handle_t handle )
 391 {
 392     struct handle_entry *entry;
 393
 394     if (get_magic_handle( handle )) return ~0U;  /* magic handles have all access rights */
 395     if (!(entry = get_handle( process, handle ))) return 0;
 396     return entry->access;
 397 }
 398
 399 /* retrieve the cached fd for a given handle */
 400 int get_handle_unix_fd( struct process *process, obj_handle_t handle, unsigned int access )
 401 {
 402     struct handle_entry *entry;
 403
 404     if (!(entry = get_handle( process, handle ))) return -1;
 405     if ((entry->access & access) != access)
 406     {
 407         set_error( STATUS_ACCESS_DENIED );
 408         return -1;
 409     }
 410     return entry->fd;
 411 }
 412
 413 /* remove the cached fd and return it */
 414 int flush_cached_fd( struct process *process, obj_handle_t handle )
 415 {
 416     struct handle_entry *entry = get_handle( process, handle );
 417     int fd = -1;
 418
 419     if (entry)
 420     {
 421         fd = entry->fd;
 422         entry->fd = -1;
 423     }
 424     return fd;
 425 }
 426
 427 /* find the first inherited handle of the given type */
 428 /* this is needed for window stations and desktops (don't ask...) */
 429 obj_handle_t find_inherited_handle( struct process *process, const struct object_ops *ops )
 430 {
 431     struct handle_table *table = process->handles;
 432     struct handle_entry *ptr;
 433     int i;
 434
 435     if (!table) return 0;
 436
 437     for (i = 0, ptr = table->entries; i <= table->last; i++, ptr++)
 438     {
 439         if (!ptr->ptr) continue;
 440         if (ptr->ptr->ops != ops) continue;
 441         if (ptr->access & RESERVED_INHERIT) return index_to_handle(i);
 442     }
 443     return 0;
 444 }
 445
 446 /* get/set the handle reserved flags */
 447 /* return the old flags (or -1 on error) */
 448 int set_handle_info( struct process *process, obj_handle_t handle, int mask, int flags, int *fd )
 449 {
 450     struct handle_entry *entry;
 451     unsigned int old_access;
 452
 453     if (get_magic_handle( handle ))
 454     {
 455         /* we can retrieve but not set info for magic handles */
 456         if (mask) set_error( STATUS_ACCESS_DENIED );
 457         return 0;
 458     }
 459     if (!(entry = get_handle( process, handle ))) return -1;
 460     old_access = entry->access;
 461     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 462     flags = (flags << RESERVED_SHIFT) & mask;
 463     entry->access = (entry->access & ~mask) | flags;
 464     /* if no current fd set it, otherwise return current fd */
 465     if (entry->fd == -1) entry->fd = *fd;
 466     *fd = entry->fd;
 467     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 468 }
 469
 470 /* duplicate a handle */
 471 obj_handle_t duplicate_handle( struct process *src, obj_handle_t src_handle, struct process *dst,
 472                            unsigned int access, int inherit, int options )
 473 {
 474     obj_handle_t res;
 475     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 476
 477     if (!obj) return 0;
 478     if (options & DUP_HANDLE_SAME_ACCESS)
 479     {
 480         struct handle_entry *entry = get_handle( src, src_handle );
 481         if (entry)
 482             access = entry->access;
 483         else  /* pseudo-handle, give it full access */
 484         {
 485             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 486             clear_error();
 487         }
 488     }
 489     access &= ~RESERVED_ALL;
 490     if (options & DUP_HANDLE_MAKE_GLOBAL)
 491         res = alloc_global_handle( obj, access );
 492     else
 493         res = alloc_handle( dst, obj, access, inherit );
 494     release_object( obj );
 495     return res;
 496 }
 497
 498 /* open a new handle to an existing object */
 499 obj_handle_t open_object( const struct namespace *namespace, const WCHAR *name, size_t len,
 500                           const struct object_ops *ops, unsigned int access, int inherit )
 501 {
 502     obj_handle_t handle = 0;
 503     struct object *obj = find_object( namespace, name, len );
 504     if (obj)
 505     {
 506         if (ops && obj->ops != ops)
 507             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 508         else
 509             handle = alloc_handle( current->process, obj, access, inherit );
 510         release_object( obj );
 511     }
 512     else
 513         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 514     return handle;
 515 }
 516
 517 /* return the size of the handle table of a given process */
 518 unsigned int get_handle_table_count( struct process *process )
 519 {
 520     return process->handles->count;
 521 }
 522
 523 /* close a handle */
 524 DECL_HANDLER(close_handle)
 525 {
 526     close_handle( current->process, req->handle, &reply->fd );
 527 }
 528
 529 /* set a handle information */
 530 DECL_HANDLER(set_handle_info)
 531 {
 532     int fd = req->fd;
 533
 534     if (handle_is_global(req->handle)) fd = -1;  /* no fd cache for global handles */
 535     reply->old_flags = set_handle_info( current->process, req->handle,
 536                                         req->mask, req->flags, &fd );
 537     reply->cur_fd = fd;
 538 }
 539
 540 /* duplicate a handle */
 541 DECL_HANDLER(dup_handle)
 542 {
 543     struct process *src, *dst;
 544
 545     reply->handle = 0;
 546     reply->fd = -1;
 547     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 548     {
 549         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 550         {
 551             reply->handle = duplicate_handle( src, req->src_handle, NULL,
 552                                               req->access, req->inherit, req->options );
 553         }
 554         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 555         {
 556             reply->handle = duplicate_handle( src, req->src_handle, dst,
 557                                               req->access, req->inherit, req->options );
 558             release_object( dst );
 559         }
 560         /* close the handle no matter what happened */
 561         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 562         {
 563             if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
 564             else close_handle( src, req->src_handle, NULL );
 565         }
 566         release_object( src );
 567     }
 568 }