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 /* 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 inline static int index_to_handle( int index )
  58 {
  59     return (index + 1) << 2;
  60 }
  61 inline static int 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_get_fd,                       /* get_fd */
  81     no_flush,                        /* flush */
  82     no_get_file_info,                /* get_file_info */
  83     handle_table_destroy             /* destroy */
  84 };
  85
  86 /* dump a handle table */
  87 static void handle_table_dump( struct object *obj, int verbose )
  88 {
  89     int i;
  90     struct handle_table *table = (struct handle_table *)obj;
  91     struct handle_entry *entry = table->entries;
  92
  93     assert( obj->ops == &handle_table_ops );
  94
  95     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
  96              table->last, table->count, table->process );
  97     if (!verbose) return;
  98     entry = table->entries;
  99     for (i = 0; i <= table->last; i++, entry++)
 100     {
 101         if (!entry->ptr) continue;
 102         fprintf( stderr, "%9d: %p %08x ", index_to_handle(i), entry->ptr, entry->access );
 103         entry->ptr->ops->dump( entry->ptr, 0 );
 104     }
 105 }
 106
 107 /* destroy a handle table */
 108 static void handle_table_destroy( struct object *obj )
 109 {
 110     int i;
 111     struct handle_table *table = (struct handle_table *)obj;
 112     struct handle_entry *entry = table->entries;
 113
 114     assert( obj->ops == &handle_table_ops );
 115
 116     for (i = 0; i <= table->last; i++, entry++)
 117     {
 118         struct object *obj = entry->ptr;
 119         entry->ptr = NULL;
 120         if (obj) release_object( obj );
 121     }
 122     free( table->entries );
 123 }
 124
 125 /* allocate a new handle table */
 126 struct object *alloc_handle_table( struct process *process, int count )
 127 {
 128     struct handle_table *table;
 129
 130     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 131     if (!(table = alloc_object( &handle_table_ops, -1 )))
 132         return NULL;
 133     table->process = process;
 134     table->count   = count;
 135     table->last    = -1;
 136     table->free    = 0;
 137     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return &table->obj;
 138     release_object( table );
 139     return NULL;
 140 }
 141
 142 /* grow a handle table */
 143 static int grow_handle_table( struct handle_table *table )
 144 {
 145     struct handle_entry *new_entries;
 146     int count = table->count;
 147
 148     if (count >= INT_MAX / 2) return 0;
 149     count *= 2;
 150     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 151     {
 152         set_error( STATUS_NO_MEMORY );
 153         return 0;
 154     }
 155     table->entries = new_entries;
 156     table->count   = count;
 157     return 1;
 158 }
 159
 160 /* allocate the first free entry in the handle table */
 161 static int alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 162 {
 163     struct handle_entry *entry = table->entries + table->free;
 164     int i;
 165
 166     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 167     if (i >= table->count)
 168     {
 169         if (!grow_handle_table( table )) return -1;
 170         entry = table->entries + i;  /* the entries may have moved */
 171     }
 172     table->last = i;
 173  found:
 174     table->free = i + 1;
 175     entry->ptr    = grab_object( obj );
 176     entry->access = access;
 177     entry->fd     = -1;
 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( STATUS_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             ptr->fd = -1;
 275             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 276             else ptr->ptr = NULL; /* don't inherit this entry */
 277         }
 278     }
 279     /* attempt to shrink the table */
 280     shrink_handle_table( table );
 281     return &table->obj;
 282 }
 283
 284 /* close a handle and decrement the refcount of the associated object */
 285 /* return 1 if OK, 0 on error */
 286 int close_handle( struct process *process, int handle, int *fd )
 287 {
 288     struct handle_table *table;
 289     struct handle_entry *entry;
 290     struct object *obj;
 291
 292     if (!(entry = get_handle( process, handle ))) return 0;
 293     if (entry->access & RESERVED_CLOSE_PROTECT)
 294     {
 295         set_error( STATUS_INVALID_HANDLE );
 296         return 0;
 297     }
 298     obj = entry->ptr;
 299     entry->ptr = NULL;
 300     if (fd) *fd = entry->fd;
 301     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 302     entry->fd = -1;
 303     table = HANDLE_IS_GLOBAL(handle) ? global_table : (struct handle_table *)process->handles;
 304     if (entry < table->entries + table->free) table->free = entry - table->entries;
 305     if (entry == table->entries + table->last) shrink_handle_table( table );
 306     release_object( obj );
 307     return 1;
 308 }
 309
 310 /* close all the global handles */
 311 void close_global_handles(void)
 312 {
 313     if (global_table)
 314     {
 315         release_object( global_table );
 316         global_table = NULL;
 317     }
 318 }
 319
 320 /* retrieve the object corresponding to one of the magic pseudo-handles */
 321 static inline struct object *get_magic_handle( int handle )
 322 {
 323     switch(handle)
 324     {
 325         case 0xfffffffe:  /* current thread pseudo-handle */
 326             return &current->obj;
 327         case 0x7fffffff:  /* current process pseudo-handle */
 328         case 0xffffffff:  /* current process pseudo-handle */
 329             return (struct object *)current->process;
 330         default:
 331             return NULL;
 332     }
 333 }
 334
 335 /* retrieve the object corresponding to a handle, incrementing its refcount */
 336 struct object *get_handle_obj( struct process *process, int handle,
 337                                unsigned int access, const struct object_ops *ops )
 338 {
 339     struct handle_entry *entry;
 340     struct object *obj;
 341
 342     if (!(obj = get_magic_handle( handle )))
 343     {
 344         if (!(entry = get_handle( process, handle ))) return NULL;
 345         if ((entry->access & access) != access)
 346         {
 347             set_error( STATUS_ACCESS_DENIED );
 348             return NULL;
 349         }
 350         obj = entry->ptr;
 351     }
 352     if (ops && (obj->ops != ops))
 353     {
 354         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 355         return NULL;
 356     }
 357     return grab_object( obj );
 358 }
 359
 360 /* retrieve the cached fd for a given handle */
 361 int get_handle_fd( struct process *process, int handle, unsigned int access )
 362 {
 363     struct handle_entry *entry;
 364
 365     if (!(entry = get_handle( process, handle ))) return -1;
 366     if ((entry->access & access) != access)
 367     {
 368         set_error( STATUS_ACCESS_DENIED );
 369         return -1;
 370     }
 371     return entry->fd;
 372 }
 373
 374 /* get/set the handle reserved flags */
 375 /* return the old flags (or -1 on error) */
 376 static int set_handle_info( struct process *process, int handle, int mask, int flags, int *fd )
 377 {
 378     struct handle_entry *entry;
 379     unsigned int old_access;
 380
 381     if (get_magic_handle( handle ))
 382     {
 383         /* we can retrieve but not set info for magic handles */
 384         if (mask) set_error( STATUS_ACCESS_DENIED );
 385         return 0;
 386     }
 387     if (!(entry = get_handle( process, handle ))) return -1;
 388     old_access = entry->access;
 389     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 390     flags = (flags << RESERVED_SHIFT) & mask;
 391     entry->access = (entry->access & ~mask) | flags;
 392     /* if no current fd set it, otherwise return current fd */
 393     if (entry->fd == -1) entry->fd = *fd;
 394     *fd = entry->fd;
 395     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 396 }
 397
 398 /* duplicate a handle */
 399 int duplicate_handle( struct process *src, int src_handle, struct process *dst,
 400                       unsigned int access, int inherit, int options )
 401 {
 402     int res;
 403     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 404
 405     if (!obj) return -1;
 406     if (options & DUP_HANDLE_SAME_ACCESS)
 407     {
 408         struct handle_entry *entry = get_handle( src, src_handle );
 409         if (entry)
 410             access = entry->access;
 411         else  /* pseudo-handle, give it full access */
 412         {
 413             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 414             clear_error();
 415         }
 416     }
 417     access &= ~RESERVED_ALL;
 418     if (options & DUP_HANDLE_MAKE_GLOBAL)
 419         res = alloc_global_handle( obj, access );
 420     else
 421         res = alloc_handle( dst, obj, access, inherit );
 422     release_object( obj );
 423     return res;
 424 }
 425
 426 /* open a new handle to an existing object */
 427 int open_object( const WCHAR *name, size_t len, const struct object_ops *ops,
 428                  unsigned int access, int inherit )
 429 {
 430     int handle = -1;
 431     struct object *obj = find_object( name, len );
 432     if (obj)
 433     {
 434         if (ops && obj->ops != ops)
 435             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 436         else
 437             handle = alloc_handle( current->process, obj, access, inherit );
 438         release_object( obj );
 439     }
 440     else
 441         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 442     return handle;
 443 }
 444
 445 /* close a handle */
 446 DECL_HANDLER(close_handle)
 447 {
 448     close_handle( current->process, req->handle, &req->fd );
 449 }
 450
 451 /* set a handle information */
 452 DECL_HANDLER(set_handle_info)
 453 {
 454     int fd = req->fd;
 455
 456     if (HANDLE_IS_GLOBAL(req->handle)) fd = -1;  /* no fd cache for global handles */
 457     req->old_flags = set_handle_info( current->process, req->handle, req->mask, req->flags, &fd );
 458     req->cur_fd = fd;
 459 }
 460
 461 /* duplicate a handle */
 462 DECL_HANDLER(dup_handle)
 463 {
 464     struct process *src, *dst;
 465
 466     req->handle = -1;
 467     req->fd = -1;
 468     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 469     {
 470         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 471         {
 472             req->handle = duplicate_handle( src, req->src_handle, NULL,
 473                                             req->access, req->inherit, req->options );
 474         }
 475         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 476         {
 477             req->handle = duplicate_handle( src, req->src_handle, dst,
 478                                             req->access, req->inherit, req->options );
 479             release_object( dst );
 480         }
 481         /* close the handle no matter what happened */
 482         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 483         {
 484             if (src == current->process) close_handle( src, req->src_handle, &req->fd );
 485             else close_handle( src, req->src_handle, NULL );
 486         }
 487         release_object( src );
 488     }
 489 }