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 "winerror.h"
  14 #include "winbase.h"
  15
  16 #include "handle.h"
  17 #include "process.h"
  18 #include "thread.h"
  19 #include "request.h"
  20
  21 struct handle_entry
  22 {
  23     struct object *ptr;
  24     unsigned int   access;
  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 /* global handle macros */
  46 #define HANDLE_OBFUSCATOR         0x544a4def
  47 #define HANDLE_IS_GLOBAL(h)       (((h) ^ HANDLE_OBFUSCATOR) < 0x10000)
  48 #define HANDLE_LOCAL_TO_GLOBAL(h) ((h) ^ HANDLE_OBFUSCATOR)
  49 #define HANDLE_GLOBAL_TO_LOCAL(h) ((h) ^ HANDLE_OBFUSCATOR)
  50
  51 #define MIN_HANDLE_ENTRIES  32
  52
  53
  54 static void handle_table_dump( struct object *obj, int verbose );
  55 static void handle_table_destroy( struct object *obj );
  56
  57 static const struct object_ops handle_table_ops =
  58 {
  59     sizeof(struct handle_table),
  60     handle_table_dump,
  61     no_add_queue,
  62     NULL,  /* should never get called */
  63     NULL,  /* should never get called */
  64     NULL,  /* should never get called */
  65     no_read_fd,
  66     no_write_fd,
  67     no_flush,
  68     no_get_file_info,
  69     handle_table_destroy
  70 };
  71
  72 /* dump a handle table */
  73 static void handle_table_dump( struct object *obj, int verbose )
  74 {
  75     int i;
  76     struct handle_table *table = (struct handle_table *)obj;
  77     struct handle_entry *entry = table->entries;
  78
  79     assert( obj->ops == &handle_table_ops );
  80
  81     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
  82              table->last, table->count, table->process );
  83     if (!verbose) return;
  84     entry = table->entries;
  85     for (i = 0; i <= table->last; i++, entry++)
  86     {
  87         if (!entry->ptr) continue;
  88         fprintf( stderr, "%9d: %p %08x ", i + 1, entry->ptr, entry->access );
  89         entry->ptr->ops->dump( entry->ptr, 0 );
  90     }
  91 }
  92
  93 /* destroy a handle table */
  94 static void handle_table_destroy( struct object *obj )
  95 {
  96     int i;
  97     struct handle_table *table = (struct handle_table *)obj;
  98     struct handle_entry *entry = table->entries;
  99
 100     assert( obj->ops == &handle_table_ops );
 101
 102     for (i = 0; i <= table->last; i++, entry++)
 103     {
 104         struct object *obj = entry->ptr;
 105         entry->ptr = NULL;
 106         if (obj) release_object( obj );
 107     }
 108     free( table->entries );
 109 }
 110
 111 /* allocate a new handle table */
 112 struct object *alloc_handle_table( struct process *process, int count )
 113 {
 114     struct handle_table *table;
 115
 116     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 117     if (!(table = alloc_object( &handle_table_ops )))
 118         return NULL;
 119     table->process = process;
 120     table->count   = count;
 121     table->last    = -1;
 122     table->free    = 0;
 123     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return &table->obj;
 124     release_object( table );
 125     return NULL;
 126 }
 127
 128 /* grow a handle table */
 129 static int grow_handle_table( struct handle_table *table )
 130 {
 131     struct handle_entry *new_entries;
 132     int count = table->count;
 133
 134     if (count >= INT_MAX / 2) return 0;
 135     count *= 2;
 136     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 137     {
 138         set_error( ERROR_OUTOFMEMORY );
 139         return 0;
 140     }
 141     table->entries = new_entries;
 142     table->count   = count;
 143     return 1;
 144 }
 145
 146 /* find the first free entry in the handle table */
 147 static struct handle_entry *get_free_entry( struct handle_table *table, int *phandle )
 148 {
 149     struct handle_entry *entry = table->entries + table->free;
 150     int handle;
 151
 152     for (handle = table->free; handle <= table->last; handle++, entry++)
 153         if (!entry->ptr) goto found;
 154     if (handle >= table->count)
 155     {
 156         if (!grow_handle_table( table )) return NULL;
 157         entry = table->entries + handle;  /* the entries may have moved */
 158     }
 159     table->last = handle;
 160  found:
 161     table->free = *phandle = handle + 1;  /* avoid handle 0 */
 162     return entry;
 163 }
 164
 165 /* allocate a handle for an object, incrementing its refcount */
 166 /* return the handle, or -1 on error */
 167 int alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 168 {
 169     struct handle_table *table = (struct handle_table *)process->handles;
 170     struct handle_entry *entry;
 171     int handle;
 172
 173     assert( table );
 174     assert( !(access & RESERVED_ALL) );
 175     if (inherit) access |= RESERVED_INHERIT;
 176
 177     if (!(entry = get_free_entry( table, &handle ))) return -1;
 178     entry->ptr    = grab_object( obj );
 179     entry->access = access;
 180     return handle;
 181 }
 182
 183 /* allocate a global handle for an object, incrementing its refcount */
 184 /* return the handle, or -1 on error */
 185 static int alloc_global_handle( void *obj, unsigned int access )
 186 {
 187     struct handle_entry *entry;
 188     int handle;
 189
 190     if (!global_table)
 191     {
 192         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 ))) return -1;
 193     }
 194     if (!(entry = get_free_entry( global_table, &handle ))) return -1;
 195     entry->ptr    = grab_object( obj );
 196     entry->access = access;
 197     return HANDLE_LOCAL_TO_GLOBAL(handle);
 198 }
 199
 200 /* return an handle entry, or NULL if the handle is invalid */
 201 static struct handle_entry *get_handle( struct process *process, int handle )
 202 {
 203     struct handle_table *table = (struct handle_table *)process->handles;
 204     struct handle_entry *entry;
 205
 206     if (HANDLE_IS_GLOBAL(handle))
 207     {
 208         handle = HANDLE_GLOBAL_TO_LOCAL(handle);
 209         table = global_table;
 210     }
 211     if (!table) goto error;
 212     handle--;  /* handles start at 1 */
 213     if (handle < 0) goto error;
 214     if (handle > table->last) goto error;
 215     entry = table->entries + handle;
 216     if (!entry->ptr) goto error;
 217     return entry;
 218
 219  error:
 220     set_error( ERROR_INVALID_HANDLE );
 221     return NULL;
 222 }
 223
 224 /* attempt to shrink a table */
 225 static void shrink_handle_table( struct handle_table *table )
 226 {
 227     struct handle_entry *entry = table->entries + table->last;
 228     struct handle_entry *new_entries;
 229     int count = table->count;
 230
 231     while (table->last >= 0)
 232     {
 233         if (entry->ptr) break;
 234         table->last--;
 235         entry--;
 236     }
 237     if (table->last >= count / 4) return;  /* no need to shrink */
 238     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 239     count /= 2;
 240     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 241     table->count   = count;
 242     table->entries = new_entries;
 243 }
 244
 245 /* copy the handle table of the parent process */
 246 /* return 1 if OK, 0 on error */
 247 struct object *copy_handle_table( struct process *process, struct process *parent )
 248 {
 249     struct handle_table *parent_table = (struct handle_table *)parent->handles;
 250     struct handle_table *table;
 251     int i;
 252
 253     assert( parent_table );
 254     assert( parent_table->obj.ops == &handle_table_ops );
 255
 256     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 257         return NULL;
 258
 259     if ((table->last = parent_table->last) >= 0)
 260     {
 261         struct handle_entry *ptr = table->entries;
 262         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 263         for (i = 0; i <= table->last; i++, ptr++)
 264         {
 265             if (!ptr->ptr) continue;
 266             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 267             else ptr->ptr = NULL; /* don't inherit this entry */
 268         }
 269     }
 270     /* attempt to shrink the table */
 271     shrink_handle_table( table );
 272     return &table->obj;
 273 }
 274
 275 /* close a handle and decrement the refcount of the associated object */
 276 /* return 1 if OK, 0 on error */
 277 int close_handle( struct process *process, int handle )
 278 {
 279     struct handle_table *table;
 280     struct handle_entry *entry;
 281     struct object *obj;
 282
 283     if (!(entry = get_handle( process, handle ))) return 0;
 284     if (entry->access & RESERVED_CLOSE_PROTECT) return 0;  /* FIXME: error code */
 285     obj = entry->ptr;
 286     entry->ptr = NULL;
 287     table = HANDLE_IS_GLOBAL(handle) ? global_table : (struct handle_table *)process->handles;
 288     if (entry < table->entries + table->free) table->free = entry - table->entries;
 289     if (entry == table->entries + table->last) shrink_handle_table( table );
 290     release_object( obj );
 291     return 1;
 292 }
 293
 294 /* close all the global handles */
 295 void close_global_handles(void)
 296 {
 297     if (global_table)
 298     {
 299         release_object( global_table );
 300         global_table = NULL;
 301     }
 302 }
 303
 304 /* retrieve the object corresponding to a handle, incrementing its refcount */
 305 struct object *get_handle_obj( struct process *process, int handle,
 306                                unsigned int access, const struct object_ops *ops )
 307 {
 308     struct handle_entry *entry;
 309     struct object *obj;
 310
 311     switch( handle )
 312     {
 313     case 0xfffffffe:  /* current thread pseudo-handle */
 314         obj = &current->obj;
 315         break;
 316     case 0x7fffffff:  /* current process pseudo-handle */
 317         obj = (struct object *)current->process;
 318         break;
 319     default:
 320         if (!(entry = get_handle( process, handle ))) return NULL;
 321         if ((entry->access & access) != access)
 322         {
 323             set_error( ERROR_ACCESS_DENIED );
 324             return NULL;
 325         }
 326         obj = entry->ptr;
 327         break;
 328     }
 329     if (ops && (obj->ops != ops))
 330     {
 331         set_error( ERROR_INVALID_HANDLE );  /* not the right type */
 332         return NULL;
 333     }
 334     return grab_object( obj );
 335 }
 336
 337 /* get/set the handle reserved flags */
 338 /* return the new flags (or -1 on error) */
 339 static int set_handle_info( struct process *process, int handle, int mask, int flags )
 340 {
 341     struct handle_entry *entry;
 342
 343     if (!(entry = get_handle( process, handle ))) return -1;
 344     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 345     flags = (flags << RESERVED_SHIFT) & mask;
 346     entry->access = (entry->access & ~mask) | flags;
 347     return (entry->access & RESERVED_ALL) >> RESERVED_SHIFT;
 348 }
 349
 350 /* duplicate a handle */
 351 int duplicate_handle( struct process *src, int src_handle, struct process *dst,
 352                       unsigned int access, int inherit, int options )
 353 {
 354     int res;
 355     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 356
 357     if (!obj) return -1;
 358     if (options & DUP_HANDLE_SAME_ACCESS)
 359     {
 360         struct handle_entry *entry = get_handle( src, src_handle );
 361         if (entry)
 362             access = entry->access;
 363         else  /* pseudo-handle, give it full access */
 364         {
 365             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 366             clear_error();
 367         }
 368     }
 369     access &= ~RESERVED_ALL;
 370     if (options & DUP_HANDLE_MAKE_GLOBAL)
 371         res = alloc_global_handle( obj, access );
 372     else
 373         res = alloc_handle( dst, obj, access, inherit );
 374     release_object( obj );
 375     return res;
 376 }
 377
 378 /* open a new handle to an existing object */
 379 int open_object( const char *name, size_t len, const struct object_ops *ops,
 380                  unsigned int access, int inherit )
 381 {
 382     struct object *obj = find_object( name, len );
 383     if (!obj)
 384     {
 385         set_error( ERROR_FILE_NOT_FOUND );
 386         return -1;
 387     }
 388     if (ops && obj->ops != ops)
 389     {
 390         release_object( obj );
 391         set_error( ERROR_INVALID_HANDLE );  /* FIXME: not the right type */
 392         return -1;
 393     }
 394     return alloc_handle( current->process, obj, access, inherit );
 395 }
 396
 397 /* close a handle */
 398 DECL_HANDLER(close_handle)
 399 {
 400     close_handle( current->process, req->handle );
 401 }
 402
 403 /* get information about a handle */
 404 DECL_HANDLER(get_handle_info)
 405 {
 406     req->flags = set_handle_info( current->process, req->handle, 0, 0 );
 407 }
 408
 409 /* set a handle information */
 410 DECL_HANDLER(set_handle_info)
 411 {
 412     set_handle_info( current->process, req->handle, req->mask, req->flags );
 413 }
 414
 415 /* duplicate a handle */
 416 DECL_HANDLER(dup_handle)
 417 {
 418     struct process *src, *dst;
 419
 420     req->handle = -1;
 421     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 422     {
 423         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 424         {
 425             req->handle = duplicate_handle( src, req->src_handle, NULL,
 426                                             req->access, req->inherit, req->options );
 427         }
 428         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 429         {
 430             req->handle = duplicate_handle( src, req->src_handle, dst,
 431                                             req->access, req->inherit, req->options );
 432             release_object( dst );
 433         }
 434         /* close the handle no matter what happened */
 435         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 436             close_handle( src, req->src_handle );
 437         release_object( src );
 438     }
 439 }