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