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     NULL,                            /* queue_async */
  96     handle_table_destroy             /* destroy */
  97 };
  98
  99 /* dump a handle table */
 100 static void handle_table_dump( struct object *obj, int verbose )
 101 {
 102     int i;
 103     struct handle_table *table = (struct handle_table *)obj;
 104     struct handle_entry *entry = table->entries;
 105
 106     assert( obj->ops == &handle_table_ops );
 107
 108     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
 109              table->last, table->count, table->process );
 110     if (!verbose) return;
 111     entry = table->entries;
 112     for (i = 0; i <= table->last; i++, entry++)
 113     {
 114         if (!entry->ptr) continue;
 115         fprintf( stderr, "%9u: %p %08x ",
 116                  (unsigned int)index_to_handle(i), entry->ptr, entry->access );
 117         entry->ptr->ops->dump( entry->ptr, 0 );
 118     }
 119 }
 120
 121 /* destroy a handle table */
 122 static void handle_table_destroy( struct object *obj )
 123 {
 124     int i;
 125     struct handle_table *table = (struct handle_table *)obj;
 126     struct handle_entry *entry = table->entries;
 127
 128     assert( obj->ops == &handle_table_ops );
 129
 130     for (i = 0; i <= table->last; i++, entry++)
 131     {
 132         struct object *obj = entry->ptr;
 133         entry->ptr = NULL;
 134         if (obj) release_object( obj );
 135     }
 136     free( table->entries );
 137 }
 138
 139 /* allocate a new handle table */
 140 struct object *alloc_handle_table( struct process *process, int count )
 141 {
 142     struct handle_table *table;
 143
 144     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 145     if (!(table = alloc_object( &handle_table_ops, -1 )))
 146         return NULL;
 147     table->process = process;
 148     table->count   = count;
 149     table->last    = -1;
 150     table->free    = 0;
 151     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return &table->obj;
 152     release_object( table );
 153     return NULL;
 154 }
 155
 156 /* grow a handle table */
 157 static int grow_handle_table( struct handle_table *table )
 158 {
 159     struct handle_entry *new_entries;
 160     int count = table->count;
 161
 162     if (count >= INT_MAX / 2) return 0;
 163     count *= 2;
 164     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 165     {
 166         set_error( STATUS_NO_MEMORY );
 167         return 0;
 168     }
 169     table->entries = new_entries;
 170     table->count   = count;
 171     return 1;
 172 }
 173
 174 /* allocate the first free entry in the handle table */
 175 static handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 176 {
 177     struct handle_entry *entry = table->entries + table->free;
 178     int i;
 179
 180     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 181     if (i >= table->count)
 182     {
 183         if (!grow_handle_table( table )) return 0;
 184         entry = table->entries + i;  /* the entries may have moved */
 185     }
 186     table->last = i;
 187  found:
 188     table->free = i + 1;
 189     entry->ptr    = grab_object( obj );
 190     entry->access = access;
 191     entry->fd     = -1;
 192     return index_to_handle(i);
 193 }
 194
 195 /* allocate a handle for an object, incrementing its refcount */
 196 /* return the handle, or 0 on error */
 197 handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 198 {
 199     struct handle_table *table = (struct handle_table *)process->handles;
 200
 201     assert( table );
 202     assert( !(access & RESERVED_ALL) );
 203     if (inherit) access |= RESERVED_INHERIT;
 204     return alloc_entry( table, obj, access );
 205 }
 206
 207 /* allocate a global handle for an object, incrementing its refcount */
 208 /* return the handle, or 0 on error */
 209 static handle_t alloc_global_handle( void *obj, unsigned int access )
 210 {
 211     if (!global_table)
 212     {
 213         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 214             return 0;
 215     }
 216     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 217 }
 218
 219 /* return a handle entry, or NULL if the handle is invalid */
 220 static struct handle_entry *get_handle( struct process *process, handle_t handle )
 221 {
 222     struct handle_table *table = (struct handle_table *)process->handles;
 223     struct handle_entry *entry;
 224     int index;
 225
 226     if (handle_is_global(handle))
 227     {
 228         handle = handle_global_to_local(handle);
 229         table = global_table;
 230     }
 231     if (!table) goto error;
 232     index = handle_to_index( handle );
 233     if (index < 0) goto error;
 234     if (index > table->last) goto error;
 235     entry = table->entries + index;
 236     if (!entry->ptr) goto error;
 237     return entry;
 238
 239  error:
 240     set_error( STATUS_INVALID_HANDLE );
 241     return NULL;
 242 }
 243
 244 /* attempt to shrink a table */
 245 static void shrink_handle_table( struct handle_table *table )
 246 {
 247     struct handle_entry *entry = table->entries + table->last;
 248     struct handle_entry *new_entries;
 249     int count = table->count;
 250
 251     while (table->last >= 0)
 252     {
 253         if (entry->ptr) break;
 254         table->last--;
 255         entry--;
 256     }
 257     if (table->last >= count / 4) return;  /* no need to shrink */
 258     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 259     count /= 2;
 260     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 261     table->count   = count;
 262     table->entries = new_entries;
 263 }
 264
 265 /* copy the handle table of the parent process */
 266 /* return 1 if OK, 0 on error */
 267 struct object *copy_handle_table( struct process *process, struct process *parent )
 268 {
 269     struct handle_table *parent_table = (struct handle_table *)parent->handles;
 270     struct handle_table *table;
 271     int i;
 272
 273     assert( parent_table );
 274     assert( parent_table->obj.ops == &handle_table_ops );
 275
 276     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 277         return NULL;
 278
 279     if ((table->last = parent_table->last) >= 0)
 280     {
 281         struct handle_entry *ptr = table->entries;
 282         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 283         for (i = 0; i <= table->last; i++, ptr++)
 284         {
 285             if (!ptr->ptr) continue;
 286             ptr->fd = -1;
 287             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 288             else ptr->ptr = NULL; /* don't inherit this entry */
 289         }
 290     }
 291     /* attempt to shrink the table */
 292     shrink_handle_table( table );
 293     return &table->obj;
 294 }
 295
 296 /* close a handle and decrement the refcount of the associated object */
 297 /* return 1 if OK, 0 on error */
 298 int close_handle( struct process *process, handle_t handle, int *fd )
 299 {
 300     struct handle_table *table;
 301     struct handle_entry *entry;
 302     struct object *obj;
 303
 304     if (!(entry = get_handle( process, handle ))) return 0;
 305     if (entry->access & RESERVED_CLOSE_PROTECT)
 306     {
 307         set_error( STATUS_INVALID_HANDLE );
 308         return 0;
 309     }
 310     obj = entry->ptr;
 311     entry->ptr = NULL;
 312     if (fd) *fd = entry->fd;
 313     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 314     entry->fd = -1;
 315     table = handle_is_global(handle) ? global_table : (struct handle_table *)process->handles;
 316     if (entry < table->entries + table->free) table->free = entry - table->entries;
 317     if (entry == table->entries + table->last) shrink_handle_table( table );
 318     release_object( obj );
 319     return 1;
 320 }
 321
 322 /* close all the global handles */
 323 void close_global_handles(void)
 324 {
 325     if (global_table)
 326     {
 327         release_object( global_table );
 328         global_table = NULL;
 329     }
 330 }
 331
 332 /* retrieve the object corresponding to one of the magic pseudo-handles */
 333 static inline struct object *get_magic_handle( handle_t handle )
 334 {
 335     switch((unsigned long)handle)
 336     {
 337         case 0xfffffffe:  /* current thread pseudo-handle */
 338             return &current->obj;
 339         case 0x7fffffff:  /* current process pseudo-handle */
 340         case 0xffffffff:  /* current process pseudo-handle */
 341             return (struct object *)current->process;
 342         default:
 343             return NULL;
 344     }
 345 }
 346
 347 /* retrieve the object corresponding to a handle, incrementing its refcount */
 348 struct object *get_handle_obj( struct process *process, handle_t handle,
 349                                unsigned int access, const struct object_ops *ops )
 350 {
 351     struct handle_entry *entry;
 352     struct object *obj;
 353
 354     if (!(obj = get_magic_handle( handle )))
 355     {
 356         if (!(entry = get_handle( process, handle ))) return NULL;
 357         if ((entry->access & access) != access)
 358         {
 359             set_error( STATUS_ACCESS_DENIED );
 360             return NULL;
 361         }
 362         obj = entry->ptr;
 363     }
 364     if (ops && (obj->ops != ops))
 365     {
 366         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 367         return NULL;
 368     }
 369     return grab_object( obj );
 370 }
 371
 372 /* retrieve the cached fd for a given handle */
 373 int get_handle_fd( struct process *process, handle_t handle, unsigned int access )
 374 {
 375     struct handle_entry *entry;
 376
 377     if (!(entry = get_handle( process, handle ))) return -1;
 378     if ((entry->access & access) != access)
 379     {
 380         set_error( STATUS_ACCESS_DENIED );
 381         return -1;
 382     }
 383     return entry->fd;
 384 }
 385
 386 /* get/set the handle reserved flags */
 387 /* return the old flags (or -1 on error) */
 388 static int set_handle_info( struct process *process, handle_t handle,
 389                             int mask, int flags, int *fd )
 390 {
 391     struct handle_entry *entry;
 392     unsigned int old_access;
 393
 394     if (get_magic_handle( handle ))
 395     {
 396         /* we can retrieve but not set info for magic handles */
 397         if (mask) set_error( STATUS_ACCESS_DENIED );
 398         return 0;
 399     }
 400     if (!(entry = get_handle( process, handle ))) return -1;
 401     old_access = entry->access;
 402     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 403     flags = (flags << RESERVED_SHIFT) & mask;
 404     entry->access = (entry->access & ~mask) | flags;
 405     /* if no current fd set it, otherwise return current fd */
 406     if (entry->fd == -1) entry->fd = *fd;
 407     *fd = entry->fd;
 408     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 409 }
 410
 411 /* duplicate a handle */
 412 handle_t duplicate_handle( struct process *src, handle_t src_handle, struct process *dst,
 413                            unsigned int access, int inherit, int options )
 414 {
 415     handle_t res;
 416     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 417
 418     if (!obj) return 0;
 419     if (options & DUP_HANDLE_SAME_ACCESS)
 420     {
 421         struct handle_entry *entry = get_handle( src, src_handle );
 422         if (entry)
 423             access = entry->access;
 424         else  /* pseudo-handle, give it full access */
 425         {
 426             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 427             clear_error();
 428         }
 429     }
 430     access &= ~RESERVED_ALL;
 431     if (options & DUP_HANDLE_MAKE_GLOBAL)
 432         res = alloc_global_handle( obj, access );
 433     else
 434         res = alloc_handle( dst, obj, access, inherit );
 435     release_object( obj );
 436     return res;
 437 }
 438
 439 /* open a new handle to an existing object */
 440 handle_t open_object( const WCHAR *name, size_t len, const struct object_ops *ops,
 441                       unsigned int access, int inherit )
 442 {
 443     handle_t handle = 0;
 444     struct object *obj = find_object( name, len );
 445     if (obj)
 446     {
 447         if (ops && obj->ops != ops)
 448             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 449         else
 450             handle = alloc_handle( current->process, obj, access, inherit );
 451         release_object( obj );
 452     }
 453     else
 454         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 455     return handle;
 456 }
 457
 458 /* close a handle */
 459 DECL_HANDLER(close_handle)
 460 {
 461     close_handle( current->process, req->handle, &reply->fd );
 462 }
 463
 464 /* set a handle information */
 465 DECL_HANDLER(set_handle_info)
 466 {
 467     int fd = req->fd;
 468
 469     if (handle_is_global(req->handle)) fd = -1;  /* no fd cache for global handles */
 470     reply->old_flags = set_handle_info( current->process, req->handle,
 471                                         req->mask, req->flags, &fd );
 472     reply->cur_fd = fd;
 473 }
 474
 475 /* duplicate a handle */
 476 DECL_HANDLER(dup_handle)
 477 {
 478     struct process *src, *dst;
 479
 480     reply->handle = 0;
 481     reply->fd = -1;
 482     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 483     {
 484         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 485         {
 486             reply->handle = duplicate_handle( src, req->src_handle, NULL,
 487                                               req->access, req->inherit, req->options );
 488         }
 489         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 490         {
 491             reply->handle = duplicate_handle( src, req->src_handle, dst,
 492                                               req->access, req->inherit, req->options );
 493             release_object( dst );
 494         }
 495         /* close the handle no matter what happened */
 496         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 497         {
 498             if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
 499             else close_handle( src, req->src_handle, NULL );
 500         }
 501         release_object( src );
 502     }
 503 }