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 <assert.h>
  22 #include <limits.h>
  23 #include <string.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26
  27 #include "winbase.h"
  28
  29 #include "handle.h"
  30 #include "process.h"
  31 #include "thread.h"
  32 #include "request.h"
  33
  34 struct handle_entry
  35 {
  36     struct object *ptr;       /* object */
  37     unsigned int   access;    /* access rights */
  38     int            fd;        /* file descriptor (in client process) */
  39 };
  40
  41 struct handle_table
  42 {
  43     struct object        obj;         /* object header */
  44     struct process      *process;     /* process owning this table */
  45     int                  count;       /* number of allocated entries */
  46     int                  last;        /* last used entry */
  47     int                  free;        /* first entry that may be free */
  48     struct handle_entry *entries;     /* handle entries */
  49 };
  50
  51 static struct handle_table *global_table;
  52
  53 /* reserved handle access rights */
  54 #define RESERVED_SHIFT         25
  55 #define RESERVED_INHERIT       (HANDLE_FLAG_INHERIT << RESERVED_SHIFT)
  56 #define RESERVED_CLOSE_PROTECT (HANDLE_FLAG_PROTECT_FROM_CLOSE << RESERVED_SHIFT)
  57 #define RESERVED_ALL           (RESERVED_INHERIT | RESERVED_CLOSE_PROTECT)
  58
  59 #define MIN_HANDLE_ENTRIES  32
  60
  61
  62 /* handle to table index conversion */
  63
  64 /* handles are a multiple of 4 under NT; handle 0 is not used */
  65 inline static handle_t index_to_handle( int index )
  66 {
  67     return (handle_t)((index + 1) << 2);
  68 }
  69 inline static int handle_to_index( handle_t handle )
  70 {
  71     return ((unsigned int)handle >> 2) - 1;
  72 }
  73
  74 /* global handle conversion */
  75
  76 #define HANDLE_OBFUSCATOR 0x544a4def
  77
  78 inline static int handle_is_global( handle_t handle)
  79 {
  80     return ((unsigned long)handle ^ HANDLE_OBFUSCATOR) < 0x10000;
  81 }
  82 inline static handle_t handle_local_to_global( handle_t handle )
  83 {
  84     if (!handle) return 0;
  85     return (handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  86 }
  87 inline static handle_t handle_global_to_local( handle_t handle )
  88 {
  89     return (handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  90 }
  91
  92
  93 static void handle_table_dump( struct object *obj, int verbose );
  94 static void handle_table_destroy( struct object *obj );
  95
  96 static const struct object_ops handle_table_ops =
  97 {
  98     sizeof(struct handle_table),     /* size */
  99     handle_table_dump,               /* dump */
 100     no_add_queue,                    /* add_queue */
 101     NULL,                            /* remove_queue */
 102     NULL,                            /* signaled */
 103     NULL,                            /* satisfied */
 104     NULL,                            /* get_poll_events */
 105     NULL,                            /* poll_event */
 106     no_get_fd,                       /* get_fd */
 107     no_flush,                        /* flush */
 108     no_get_file_info,                /* get_file_info */
 109     NULL,                            /* queue_async */
 110     handle_table_destroy             /* destroy */
 111 };
 112
 113 /* dump a handle table */
 114 static void handle_table_dump( struct object *obj, int verbose )
 115 {
 116     int i;
 117     struct handle_table *table = (struct handle_table *)obj;
 118     struct handle_entry *entry = table->entries;
 119
 120     assert( obj->ops == &handle_table_ops );
 121
 122     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
 123              table->last, table->count, table->process );
 124     if (!verbose) return;
 125     entry = table->entries;
 126     for (i = 0; i <= table->last; i++, entry++)
 127     {
 128         if (!entry->ptr) continue;
 129         fprintf( stderr, "%9u: %p %08x ",
 130                  (unsigned int)index_to_handle(i), entry->ptr, entry->access );
 131         entry->ptr->ops->dump( entry->ptr, 0 );
 132     }
 133 }
 134
 135 /* destroy a handle table */
 136 static void handle_table_destroy( struct object *obj )
 137 {
 138     int i;
 139     struct handle_table *table = (struct handle_table *)obj;
 140     struct handle_entry *entry = table->entries;
 141
 142     assert( obj->ops == &handle_table_ops );
 143
 144     for (i = 0; i <= table->last; i++, entry++)
 145     {
 146         struct object *obj = entry->ptr;
 147         entry->ptr = NULL;
 148         if (obj) release_object( obj );
 149     }
 150     free( table->entries );
 151 }
 152
 153 /* allocate a new handle table */
 154 struct object *alloc_handle_table( struct process *process, int count )
 155 {
 156     struct handle_table *table;
 157
 158     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 159     if (!(table = alloc_object( &handle_table_ops, -1 )))
 160         return NULL;
 161     table->process = process;
 162     table->count   = count;
 163     table->last    = -1;
 164     table->free    = 0;
 165     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return &table->obj;
 166     release_object( table );
 167     return NULL;
 168 }
 169
 170 /* grow a handle table */
 171 static int grow_handle_table( struct handle_table *table )
 172 {
 173     struct handle_entry *new_entries;
 174     int count = table->count;
 175
 176     if (count >= INT_MAX / 2) return 0;
 177     count *= 2;
 178     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 179     {
 180         set_error( STATUS_NO_MEMORY );
 181         return 0;
 182     }
 183     table->entries = new_entries;
 184     table->count   = count;
 185     return 1;
 186 }
 187
 188 /* allocate the first free entry in the handle table */
 189 static handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 190 {
 191     struct handle_entry *entry = table->entries + table->free;
 192     int i;
 193
 194     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 195     if (i >= table->count)
 196     {
 197         if (!grow_handle_table( table )) return 0;
 198         entry = table->entries + i;  /* the entries may have moved */
 199     }
 200     table->last = i;
 201  found:
 202     table->free = i + 1;
 203     entry->ptr    = grab_object( obj );
 204     entry->access = access;
 205     entry->fd     = -1;
 206     return index_to_handle(i);
 207 }
 208
 209 /* allocate a handle for an object, incrementing its refcount */
 210 /* return the handle, or 0 on error */
 211 handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 212 {
 213     struct handle_table *table = (struct handle_table *)process->handles;
 214
 215     assert( table );
 216     assert( !(access & RESERVED_ALL) );
 217     if (inherit) access |= RESERVED_INHERIT;
 218     return alloc_entry( table, obj, access );
 219 }
 220
 221 /* allocate a global handle for an object, incrementing its refcount */
 222 /* return the handle, or 0 on error */
 223 static handle_t alloc_global_handle( void *obj, unsigned int access )
 224 {
 225     if (!global_table)
 226     {
 227         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 228             return 0;
 229     }
 230     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 231 }
 232
 233 /* return a handle entry, or NULL if the handle is invalid */
 234 static struct handle_entry *get_handle( struct process *process, handle_t handle )
 235 {
 236     struct handle_table *table = (struct handle_table *)process->handles;
 237     struct handle_entry *entry;
 238     int index;
 239
 240     if (handle_is_global(handle))
 241     {
 242         handle = handle_global_to_local(handle);
 243         table = global_table;
 244     }
 245     if (!table) goto error;
 246     index = handle_to_index( handle );
 247     if (index < 0) goto error;
 248     if (index > table->last) goto error;
 249     entry = table->entries + index;
 250     if (!entry->ptr) goto error;
 251     return entry;
 252
 253  error:
 254     set_error( STATUS_INVALID_HANDLE );
 255     return NULL;
 256 }
 257
 258 /* attempt to shrink a table */
 259 static void shrink_handle_table( struct handle_table *table )
 260 {
 261     struct handle_entry *entry = table->entries + table->last;
 262     struct handle_entry *new_entries;
 263     int count = table->count;
 264
 265     while (table->last >= 0)
 266     {
 267         if (entry->ptr) break;
 268         table->last--;
 269         entry--;
 270     }
 271     if (table->last >= count / 4) return;  /* no need to shrink */
 272     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 273     count /= 2;
 274     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 275     table->count   = count;
 276     table->entries = new_entries;
 277 }
 278
 279 /* copy the handle table of the parent process */
 280 /* return 1 if OK, 0 on error */
 281 struct object *copy_handle_table( struct process *process, struct process *parent )
 282 {
 283     struct handle_table *parent_table = (struct handle_table *)parent->handles;
 284     struct handle_table *table;
 285     int i;
 286
 287     assert( parent_table );
 288     assert( parent_table->obj.ops == &handle_table_ops );
 289
 290     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 291         return NULL;
 292
 293     if ((table->last = parent_table->last) >= 0)
 294     {
 295         struct handle_entry *ptr = table->entries;
 296         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 297         for (i = 0; i <= table->last; i++, ptr++)
 298         {
 299             if (!ptr->ptr) continue;
 300             ptr->fd = -1;
 301             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 302             else ptr->ptr = NULL; /* don't inherit this entry */
 303         }
 304     }
 305     /* attempt to shrink the table */
 306     shrink_handle_table( table );
 307     return &table->obj;
 308 }
 309
 310 /* close a handle and decrement the refcount of the associated object */
 311 /* return 1 if OK, 0 on error */
 312 int close_handle( struct process *process, handle_t handle, int *fd )
 313 {
 314     struct handle_table *table;
 315     struct handle_entry *entry;
 316     struct object *obj;
 317
 318     if (!(entry = get_handle( process, handle ))) return 0;
 319     if (entry->access & RESERVED_CLOSE_PROTECT)
 320     {
 321         set_error( STATUS_INVALID_HANDLE );
 322         return 0;
 323     }
 324     obj = entry->ptr;
 325     entry->ptr = NULL;
 326     if (fd) *fd = entry->fd;
 327     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 328     entry->fd = -1;
 329     table = handle_is_global(handle) ? global_table : (struct handle_table *)process->handles;
 330     if (entry < table->entries + table->free) table->free = entry - table->entries;
 331     if (entry == table->entries + table->last) shrink_handle_table( table );
 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( 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, 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_fd( struct process *process, 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 /* get/set the handle reserved flags */
 401 /* return the old flags (or -1 on error) */
 402 static int set_handle_info( struct process *process, handle_t handle,
 403                             int mask, int flags, int *fd )
 404 {
 405     struct handle_entry *entry;
 406     unsigned int old_access;
 407
 408     if (get_magic_handle( handle ))
 409     {
 410         /* we can retrieve but not set info for magic handles */
 411         if (mask) set_error( STATUS_ACCESS_DENIED );
 412         return 0;
 413     }
 414     if (!(entry = get_handle( process, handle ))) return -1;
 415     old_access = entry->access;
 416     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 417     flags = (flags << RESERVED_SHIFT) & mask;
 418     entry->access = (entry->access & ~mask) | flags;
 419     /* if no current fd set it, otherwise return current fd */
 420     if (entry->fd == -1) entry->fd = *fd;
 421     *fd = entry->fd;
 422     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 423 }
 424
 425 /* duplicate a handle */
 426 handle_t duplicate_handle( struct process *src, handle_t src_handle, struct process *dst,
 427                            unsigned int access, int inherit, int options )
 428 {
 429     handle_t res;
 430     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 431
 432     if (!obj) return 0;
 433     if (options & DUP_HANDLE_SAME_ACCESS)
 434     {
 435         struct handle_entry *entry = get_handle( src, src_handle );
 436         if (entry)
 437             access = entry->access;
 438         else  /* pseudo-handle, give it full access */
 439         {
 440             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 441             clear_error();
 442         }
 443     }
 444     access &= ~RESERVED_ALL;
 445     if (options & DUP_HANDLE_MAKE_GLOBAL)
 446         res = alloc_global_handle( obj, access );
 447     else
 448         res = alloc_handle( dst, obj, access, inherit );
 449     release_object( obj );
 450     return res;
 451 }
 452
 453 /* open a new handle to an existing object */
 454 handle_t open_object( const WCHAR *name, size_t len, const struct object_ops *ops,
 455                       unsigned int access, int inherit )
 456 {
 457     handle_t handle = 0;
 458     struct object *obj = find_object( name, len );
 459     if (obj)
 460     {
 461         if (ops && obj->ops != ops)
 462             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 463         else
 464             handle = alloc_handle( current->process, obj, access, inherit );
 465         release_object( obj );
 466     }
 467     else
 468         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 469     return handle;
 470 }
 471
 472 /* close a handle */
 473 DECL_HANDLER(close_handle)
 474 {
 475     close_handle( current->process, req->handle, &reply->fd );
 476 }
 477
 478 /* set a handle information */
 479 DECL_HANDLER(set_handle_info)
 480 {
 481     int fd = req->fd;
 482
 483     if (handle_is_global(req->handle)) fd = -1;  /* no fd cache for global handles */
 484     reply->old_flags = set_handle_info( current->process, req->handle,
 485                                         req->mask, req->flags, &fd );
 486     reply->cur_fd = fd;
 487 }
 488
 489 /* duplicate a handle */
 490 DECL_HANDLER(dup_handle)
 491 {
 492     struct process *src, *dst;
 493
 494     reply->handle = 0;
 495     reply->fd = -1;
 496     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 497     {
 498         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 499         {
 500             reply->handle = duplicate_handle( src, req->src_handle, NULL,
 501                                               req->access, req->inherit, req->options );
 502         }
 503         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 504         {
 505             reply->handle = duplicate_handle( src, req->src_handle, dst,
 506                                               req->access, req->inherit, req->options );
 507             release_object( dst );
 508         }
 509         /* close the handle no matter what happened */
 510         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 511         {
 512             if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
 513             else close_handle( src, req->src_handle, NULL );
 514         }
 515         release_object( src );
 516     }
 517 }