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