server/handle.c

   1 /*
   2  * Server-side handle management
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  */
   6
   7 #include <assert.h>
   8 #include <limits.h>
   9 #include <string.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12
  13 #include "winbase.h"
  14
  15 #include "handle.h"
  16 #include "process.h"
  17 #include "thread.h"
  18 #include "request.h"
  19
  20 struct handle_entry
  21 {
  22     struct object *ptr;       /* object */
  23     unsigned int   access;    /* access rights */
  24     int            fd;        /* file descriptor (in client process) */
  25 };
  26
  27 struct handle_table
  28 {
  29     struct object        obj;         /* object header */
  30     struct process      *process;     /* process owning this table */
  31     int                  count;       /* number of allocated entries */
  32     int                  last;        /* last used entry */
  33     int                  free;        /* first entry that may be free */
  34     struct handle_entry *entries;     /* handle entries */
  35 };
  36
  37 static struct handle_table *global_table;
  38
  39 /* reserved handle access rights */
  40 #define RESERVED_SHIFT         25
  41 #define RESERVED_INHERIT       (HANDLE_FLAG_INHERIT << RESERVED_SHIFT)
  42 #define RESERVED_CLOSE_PROTECT (HANDLE_FLAG_PROTECT_FROM_CLOSE << RESERVED_SHIFT)
  43 #define RESERVED_ALL           (RESERVED_INHERIT | RESERVED_CLOSE_PROTECT)
  44
  45 #define MIN_HANDLE_ENTRIES  32
  46
  47
  48 /* handle to table index conversion */
  49
  50 /* handles are a multiple of 4 under NT; handle 0 is not used */
  51 inline static handle_t index_to_handle( int index )
  52 {
  53     return (handle_t)((index + 1) << 2);
  54 }
  55 inline static int handle_to_index( handle_t handle )
  56 {
  57     return ((unsigned int)handle >> 2) - 1;
  58 }
  59
  60 /* global handle conversion */
  61
  62 #define HANDLE_OBFUSCATOR 0x544a4def
  63
  64 inline static int handle_is_global( handle_t handle)
  65 {
  66     return ((unsigned long)handle ^ HANDLE_OBFUSCATOR) < 0x10000;
  67 }
  68 inline static handle_t handle_local_to_global( handle_t handle )
  69 {
  70     if (!handle) return 0;
  71     return (handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  72 }
  73 inline static handle_t handle_global_to_local( handle_t handle )
  74 {
  75     return (handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  76 }
  77
  78
  79 static void handle_table_dump( struct object *obj, int verbose );
  80 static void handle_table_destroy( struct object *obj );
  81
  82 static const struct object_ops handle_table_ops =
  83 {
  84     sizeof(struct handle_table),     /* size */
  85     handle_table_dump,               /* dump */
  86     no_add_queue,                    /* add_queue */
  87     NULL,                            /* remove_queue */
  88     NULL,                            /* signaled */
  89     NULL,                            /* satisfied */
  90     NULL,                            /* get_poll_events */
  91     NULL,                            /* poll_event */
  92     no_get_fd,                       /* get_fd */
  93     no_flush,                        /* flush */
  94     no_get_file_info,                /* get_file_info */
  95     handle_table_destroy             /* destroy */
  96 };
  97
  98 /* dump a handle table */
  99 static void handle_table_dump( struct object *obj, int verbose )
 100 {
 101     int i;
 102     struct handle_table *table = (struct handle_table *)obj;
 103     struct handle_entry *entry = table->entries;
 104
 105     assert( obj->ops == &handle_table_ops );
 106
 107     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
 108              table->last, table->count, table->process );
 109     if (!verbose) return;
 110     entry = table->entries;
 111     for (i = 0; i <= table->last; i++, entry++)
 112     {
 113         if (!entry->ptr) continue;
 114         fprintf( stderr, "%9u: %p %08x ",
 115                  (unsigned int)index_to_handle(i), entry->ptr, entry->access );
 116         entry->ptr->ops->dump( entry->ptr, 0 );
 117     }
 118 }
 119
 120 /* destroy a handle table */
 121 static void handle_table_destroy( struct object *obj )
 122 {
 123     int i;
 124     struct handle_table *table = (struct handle_table *)obj;
 125     struct handle_entry *entry = table->entries;
 126
 127     assert( obj->ops == &handle_table_ops );
 128
 129     for (i = 0; i <= table->last; i++, entry++)
 130     {
 131         struct object *obj = entry->ptr;
 132         entry->ptr = NULL;
 133         if (obj) release_object( obj );
 134     }
 135     free( table->entries );
 136 }
 137
 138 /* allocate a new handle table */
 139 struct object *alloc_handle_table( struct process *process, int count )
 140 {
 141     struct handle_table *table;
 142
 143     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 144     if (!(table = alloc_object( &handle_table_ops, -1 )))
 145         return NULL;
 146     table->process = process;
 147     table->count   = count;
 148     table->last    = -1;
 149     table->free    = 0;
 150     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return &table->obj;
 151     release_object( table );
 152     return NULL;
 153 }
 154
 155 /* grow a handle table */
 156 static int grow_handle_table( struct handle_table *table )
 157 {
 158     struct handle_entry *new_entries;
 159     int count = table->count;
 160
 161     if (count >= INT_MAX / 2) return 0;
 162     count *= 2;
 163     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 164     {
 165         set_error( STATUS_NO_MEMORY );
 166         return 0;
 167     }
 168     table->entries = new_entries;
 169     table->count   = count;
 170     return 1;
 171 }
 172
 173 /* allocate the first free entry in the handle table */
 174 static handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 175 {
 176     struct handle_entry *entry = table->entries + table->free;
 177     int i;
 178
 179     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 180     if (i >= table->count)
 181     {
 182         if (!grow_handle_table( table )) return 0;
 183         entry = table->entries + i;  /* the entries may have moved */
 184     }
 185     table->last = i;
 186  found:
 187     table->free = i + 1;
 188     entry->ptr    = grab_object( obj );
 189     entry->access = access;
 190     entry->fd     = -1;
 191     return index_to_handle(i);
 192 }
 193
 194 /* allocate a handle for an object, incrementing its refcount */
 195 /* return the handle, or 0 on error */
 196 handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 197 {
 198     struct handle_table *table = (struct handle_table *)process->handles;
 199
 200     assert( table );
 201     assert( !(access & RESERVED_ALL) );
 202     if (inherit) access |= RESERVED_INHERIT;
 203     return alloc_entry( table, obj, access );
 204 }
 205
 206 /* allocate a global handle for an object, incrementing its refcount */
 207 /* return the handle, or 0 on error */
 208 static handle_t alloc_global_handle( void *obj, unsigned int access )
 209 {
 210     if (!global_table)
 211     {
 212         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 213             return 0;
 214     }
 215     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 216 }
 217
 218 /* return a handle entry, or NULL if the handle is invalid */
 219 static struct handle_entry *get_handle( struct process *process, handle_t handle )
 220 {
 221     struct handle_table *table = (struct handle_table *)process->handles;
 222     struct handle_entry *entry;
 223     int index;
 224
 225     if (handle_is_global(handle))
 226     {
 227         handle = handle_global_to_local(handle);
 228         table = global_table;
 229     }
 230     if (!table) goto error;
 231     index = handle_to_index( handle );
 232     if (index < 0) goto error;
 233     if (index > table->last) goto error;
 234     entry = table->entries + index;
 235     if (!entry->ptr) goto error;
 236     return entry;
 237
 238  error:
 239     set_error( STATUS_INVALID_HANDLE );
 240     return NULL;
 241 }
 242
 243 /* attempt to shrink a table */
 244 static void shrink_handle_table( struct handle_table *table )
 245 {
 246     struct handle_entry *entry = table->entries + table->last;
 247     struct handle_entry *new_entries;
 248     int count = table->count;
 249
 250     while (table->last >= 0)
 251     {
 252         if (entry->ptr) break;
 253         table->last--;
 254         entry--;
 255     }
 256     if (table->last >= count / 4) return;  /* no need to shrink */
 257     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 258     count /= 2;
 259     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 260     table->count   = count;
 261     table->entries = new_entries;
 262 }
 263
 264 /* copy the handle table of the parent process */
 265 /* return 1 if OK, 0 on error */
 266 struct object *copy_handle_table( struct process *process, struct process *parent )
 267 {
 268     struct handle_table *parent_table = (struct handle_table *)parent->handles;
 269     struct handle_table *table;
 270     int i;
 271
 272     assert( parent_table );
 273     assert( parent_table->obj.ops == &handle_table_ops );
 274
 275     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 276         return NULL;
 277
 278     if ((table->last = parent_table->last) >= 0)
 279     {
 280         struct handle_entry *ptr = table->entries;
 281         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 282         for (i = 0; i <= table->last; i++, ptr++)
 283         {
 284             if (!ptr->ptr) continue;
 285             ptr->fd = -1;
 286             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 287             else ptr->ptr = NULL; /* don't inherit this entry */
 288         }
 289     }
 290     /* attempt to shrink the table */
 291     shrink_handle_table( table );
 292     return &table->obj;
 293 }
 294
 295 /* close a handle and decrement the refcount of the associated object */
 296 /* return 1 if OK, 0 on error */
 297 int close_handle( struct process *process, handle_t handle, int *fd )
 298 {
 299     struct handle_table *table;
 300     struct handle_entry *entry;
 301     struct object *obj;
 302
 303     if (!(entry = get_handle( process, handle ))) return 0;
 304     if (entry->access & RESERVED_CLOSE_PROTECT)
 305     {
 306         set_error( STATUS_INVALID_HANDLE );
 307         return 0;
 308     }
 309     obj = entry->ptr;
 310     entry->ptr = NULL;
 311     if (fd) *fd = entry->fd;
 312     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 313     entry->fd = -1;
 314     table = handle_is_global(handle) ? global_table : (struct handle_table *)process->handles;
 315     if (entry < table->entries + table->free) table->free = entry - table->entries;
 316     if (entry == table->entries + table->last) shrink_handle_table( table );
 317     release_object( obj );
 318     return 1;
 319 }
 320
 321 /* close all the global handles */
 322 void close_global_handles(void)
 323 {
 324     if (global_table)
 325     {
 326         release_object( global_table );
 327         global_table = NULL;
 328     }
 329 }
 330
 331 /* retrieve the object corresponding to one of the magic pseudo-handles */
 332 static inline struct object *get_magic_handle( handle_t handle )
 333 {
 334     switch((unsigned long)handle)
 335     {
 336         case 0xfffffffe:  /* current thread pseudo-handle */
 337             return &current->obj;
 338         case 0x7fffffff:  /* current process pseudo-handle */
 339         case 0xffffffff:  /* current process pseudo-handle */
 340             return (struct object *)current->process;
 341         default:
 342             return NULL;
 343     }
 344 }
 345
 346 /* retrieve the object corresponding to a handle, incrementing its refcount */
 347 struct object *get_handle_obj( struct process *process, handle_t handle,
 348                                unsigned int access, const struct object_ops *ops )
 349 {
 350     struct handle_entry *entry;
 351     struct object *obj;
 352
 353     if (!(obj = get_magic_handle( handle )))
 354     {
 355         if (!(entry = get_handle( process, handle ))) return NULL;
 356         if ((entry->access & access) != access)
 357         {
 358             set_error( STATUS_ACCESS_DENIED );
 359             return NULL;
 360         }
 361         obj = entry->ptr;
 362     }
 363     if (ops && (obj->ops != ops))
 364     {
 365         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 366         return NULL;
 367     }
 368     return grab_object( obj );
 369 }
 370
 371 /* retrieve the cached fd for a given handle */
 372 int get_handle_fd( struct process *process, handle_t handle, unsigned int access )
 373 {
 374     struct handle_entry *entry;
 375
 376     if (!(entry = get_handle( process, handle ))) return -1;
 377     if ((entry->access & access) != access)
 378     {
 379         set_error( STATUS_ACCESS_DENIED );
 380         return -1;
 381     }
 382     return entry->fd;
 383 }
 384
 385 /* get/set the handle reserved flags */
 386 /* return the old flags (or -1 on error) */
 387 static int set_handle_info( struct process *process, handle_t handle,
 388                             int mask, int flags, int *fd )
 389 {
 390     struct handle_entry *entry;
 391     unsigned int old_access;
 392
 393     if (get_magic_handle( handle ))
 394     {
 395         /* we can retrieve but not set info for magic handles */
 396         if (mask) set_error( STATUS_ACCESS_DENIED );
 397         return 0;
 398     }
 399     if (!(entry = get_handle( process, handle ))) return -1;
 400     old_access = entry->access;
 401     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 402     flags = (flags << RESERVED_SHIFT) & mask;
 403     entry->access = (entry->access & ~mask) | flags;
 404     /* if no current fd set it, otherwise return current fd */
 405     if (entry->fd == -1) entry->fd = *fd;
 406     *fd = entry->fd;
 407     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 408 }
 409
 410 /* duplicate a handle */
 411 handle_t duplicate_handle( struct process *src, handle_t src_handle, struct process *dst,
 412                            unsigned int access, int inherit, int options )
 413 {
 414     handle_t res;
 415     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 416
 417     if (!obj) return 0;
 418     if (options & DUP_HANDLE_SAME_ACCESS)
 419     {
 420         struct handle_entry *entry = get_handle( src, src_handle );
 421         if (entry)
 422             access = entry->access;
 423         else  /* pseudo-handle, give it full access */
 424         {
 425             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 426             clear_error();
 427         }
 428     }
 429     access &= ~RESERVED_ALL;
 430     if (options & DUP_HANDLE_MAKE_GLOBAL)
 431         res = alloc_global_handle( obj, access );
 432     else
 433         res = alloc_handle( dst, obj, access, inherit );
 434     release_object( obj );
 435     return res;
 436 }
 437
 438 /* open a new handle to an existing object */
 439 handle_t open_object( const WCHAR *name, size_t len, const struct object_ops *ops,
 440                       unsigned int access, int inherit )
 441 {
 442     handle_t handle = 0;
 443     struct object *obj = find_object( name, len );
 444     if (obj)
 445     {
 446         if (ops && obj->ops != ops)
 447             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 448         else
 449             handle = alloc_handle( current->process, obj, access, inherit );
 450         release_object( obj );
 451     }
 452     else
 453         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 454     return handle;
 455 }
 456
 457 /* close a handle */
 458 DECL_HANDLER(close_handle)
 459 {
 460     close_handle( current->process, req->handle, &req->fd );
 461 }
 462
 463 /* set a handle information */
 464 DECL_HANDLER(set_handle_info)
 465 {
 466     int fd = req->fd;
 467
 468     if (handle_is_global(req->handle)) fd = -1;  /* no fd cache for global handles */
 469     req->old_flags = set_handle_info( current->process, req->handle, req->mask, req->flags, &fd );
 470     req->cur_fd = fd;
 471 }
 472
 473 /* duplicate a handle */
 474 DECL_HANDLER(dup_handle)
 475 {
 476     struct process *src, *dst;
 477
 478     req->handle = 0;
 479     req->fd = -1;
 480     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 481     {
 482         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 483         {
 484             req->handle = duplicate_handle( src, req->src_handle, NULL,
 485                                             req->access, req->inherit, req->options );
 486         }
 487         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 488         {
 489             req->handle = duplicate_handle( src, req->src_handle, dst,
 490                                             req->access, req->inherit, req->options );
 491             release_object( dst );
 492         }
 493         /* close the handle no matter what happened */
 494         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 495         {
 496             if (src == current->process) close_handle( src, req->src_handle, &req->fd );
 497             else close_handle( src, req->src_handle, NULL );
 498         }
 499         release_object( src );
 500     }
 501 }