server/file.c

   1 /*
   2  * Server-side file management
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  */
  20
  21 #include "config.h"
  22 #include "wine/port.h"
  23
  24 #include <assert.h>
  25 #include <fcntl.h>
  26 #include <stdarg.h>
  27 #include <stdio.h>
  28 #include <string.h>
  29 #include <stdlib.h>
  30 #include <errno.h>
  31 #ifdef HAVE_SYS_ERRNO_H
  32 #include <sys/errno.h>
  33 #endif
  34 #include <sys/stat.h>
  35 #include <sys/time.h>
  36 #include <sys/types.h>
  37 #include <time.h>
  38 #include <unistd.h>
  39 #ifdef HAVE_UTIME_H
  40 #include <utime.h>
  41 #endif
  42 #ifdef HAVE_POLL_H
  43 #include <poll.h>
  44 #endif
  45
  46 #include "ntstatus.h"
  47 #define WIN32_NO_STATUS
  48 #include "windef.h"
  49 #include "winternl.h"
  50
  51 #include "file.h"
  52 #include "handle.h"
  53 #include "thread.h"
  54 #include "request.h"
  55 #include "process.h"
  56 #include "security.h"
  57
  58 struct file
  59 {
  60     struct object       obj;        /* object header */
  61     struct fd          *fd;         /* file descriptor for this file */
  62     unsigned int        access;     /* file access (FILE_READ_DATA etc.) */
  63     mode_t              mode;       /* file stat.st_mode */
  64     uid_t               uid;        /* file stat.st_uid */
  65 };
  66
  67 static unsigned int generic_file_map_access( unsigned int access );
  68
  69 static void file_dump( struct object *obj, int verbose );
  70 static struct fd *file_get_fd( struct object *obj );
  71 static struct security_descriptor *file_get_sd( struct object *obj );
  72 static int file_set_sd( struct object *obj, const struct security_descriptor *sd, unsigned int set_info );
  73 static void file_destroy( struct object *obj );
  74
  75 static int file_get_poll_events( struct fd *fd );
  76 static void file_flush( struct fd *fd, struct event **event );
  77 static enum server_fd_type file_get_fd_type( struct fd *fd );
  78
  79 static const struct object_ops file_ops =
  80 {
  81     sizeof(struct file),          /* size */
  82     file_dump,                    /* dump */
  83     add_queue,                    /* add_queue */
  84     remove_queue,                 /* remove_queue */
  85     default_fd_signaled,          /* signaled */
  86     no_satisfied,                 /* satisfied */
  87     no_signal,                    /* signal */
  88     file_get_fd,                  /* get_fd */
  89     default_fd_map_access,        /* map_access */
  90     file_get_sd,                  /* get_sd */
  91     file_set_sd,                  /* set_sd */
  92     no_lookup_name,               /* lookup_name */
  93     no_open_file,                 /* open_file */
  94     fd_close_handle,              /* close_handle */
  95     file_destroy                  /* destroy */
  96 };
  97
  98 static const struct fd_ops file_fd_ops =
  99 {
 100     file_get_poll_events,         /* get_poll_events */
 101     default_poll_event,           /* poll_event */
 102     file_flush,                   /* flush */
 103     file_get_fd_type,             /* get_fd_type */
 104     default_fd_ioctl,             /* ioctl */
 105     default_fd_queue_async,       /* queue_async */
 106     default_fd_reselect_async,    /* reselect_async */
 107     default_fd_cancel_async       /* cancel_async */
 108 };
 109
 110 static inline int is_overlapped( const struct file *file )
 111 {
 112     return !(get_fd_options( file->fd ) & (FILE_SYNCHRONOUS_IO_ALERT | FILE_SYNCHRONOUS_IO_NONALERT));
 113 }
 114
 115 /* create a file from a file descriptor */
 116 /* if the function fails the fd is closed */
 117 static struct file *create_file_for_fd( int fd, unsigned int access, unsigned int sharing )
 118 {
 119     struct file *file;
 120     struct stat st;
 121
 122     if (fstat( fd, &st ) == -1)
 123     {
 124         file_set_error();
 125         return NULL;
 126     }
 127
 128     if ((file = alloc_object( &file_ops )))
 129     {
 130         file->mode = st.st_mode;
 131         file->access = default_fd_map_access( &file->obj, access );
 132         if (!(file->fd = create_anonymous_fd( &file_fd_ops, fd, &file->obj,
 133                                               FILE_SYNCHRONOUS_IO_NONALERT )))
 134         {
 135             release_object( file );
 136             return NULL;
 137         }
 138     }
 139     return file;
 140 }
 141
 142 static struct object *create_file_obj( struct fd *fd, unsigned int access, mode_t mode )
 143 {
 144     struct file *file = alloc_object( &file_ops );
 145
 146     if (!file) return NULL;
 147     file->access  = access;
 148     file->mode    = mode;
 149     file->fd      = fd;
 150     grab_object( fd );
 151     set_fd_user( fd, &file_fd_ops, &file->obj );
 152     return &file->obj;
 153 }
 154
 155 static struct object *create_file( const char *nameptr, data_size_t len, unsigned int access,
 156                                    unsigned int sharing, int create, unsigned int options,
 157                                    unsigned int attrs )
 158 {
 159     struct object *obj = NULL;
 160     struct fd *fd;
 161     int flags;
 162     char *name;
 163     mode_t mode;
 164
 165     if (!(name = mem_alloc( len + 1 ))) return NULL;
 166     memcpy( name, nameptr, len );
 167     name[len] = 0;
 168
 169     switch(create)
 170     {
 171     case FILE_CREATE:       flags = O_CREAT | O_EXCL; break;
 172     case FILE_OVERWRITE_IF: /* FIXME: the difference is whether we trash existing attr or not */
 173     case FILE_SUPERSEDE:    flags = O_CREAT | O_TRUNC; break;
 174     case FILE_OPEN:         flags = 0; break;
 175     case FILE_OPEN_IF:      flags = O_CREAT; break;
 176     case FILE_OVERWRITE:    flags = O_TRUNC; break;
 177     default:                set_error( STATUS_INVALID_PARAMETER ); goto done;
 178     }
 179
 180     mode = (attrs & FILE_ATTRIBUTE_READONLY) ? 0444 : 0666;
 181
 182     if (len >= 4 &&
 183         (!strcasecmp( name + len - 4, ".exe" ) || !strcasecmp( name + len - 4, ".com" )))
 184         mode |= 0111;
 185
 186     access = generic_file_map_access( access );
 187
 188     /* FIXME: should set error to STATUS_OBJECT_NAME_COLLISION if file existed before */
 189     fd = open_fd( name, flags | O_NONBLOCK | O_LARGEFILE, &mode, access, sharing, options );
 190     if (!fd) goto done;
 191
 192     if (S_ISDIR(mode))
 193         obj = create_dir_obj( fd );
 194     else if (S_ISCHR(mode) && is_serial_fd( fd ))
 195         obj = create_serial( fd );
 196     else
 197         obj = create_file_obj( fd, access, mode );
 198
 199     release_object( fd );
 200
 201 done:
 202     free( name );
 203     return obj;
 204 }
 205
 206 /* check if two file objects point to the same file */
 207 int is_same_file( struct file *file1, struct file *file2 )
 208 {
 209     return is_same_file_fd( file1->fd, file2->fd );
 210 }
 211
 212 /* create a temp file for anonymous mappings */
 213 struct file *create_temp_file( int access )
 214 {
 215     char tmpfn[16];
 216     int fd;
 217
 218     sprintf( tmpfn, "anonmap.XXXXXX" );  /* create it in the server directory */
 219     fd = mkstemps( tmpfn, 0 );
 220     if (fd == -1)
 221     {
 222         file_set_error();
 223         return NULL;
 224     }
 225     unlink( tmpfn );
 226     return create_file_for_fd( fd, access, 0 );
 227 }
 228
 229 static void file_dump( struct object *obj, int verbose )
 230 {
 231     struct file *file = (struct file *)obj;
 232     assert( obj->ops == &file_ops );
 233     fprintf( stderr, "File fd=%p\n", file->fd );
 234 }
 235
 236 static int file_get_poll_events( struct fd *fd )
 237 {
 238     struct file *file = get_fd_user( fd );
 239     int events = 0;
 240     assert( file->obj.ops == &file_ops );
 241     if (file->access & FILE_UNIX_READ_ACCESS) events |= POLLIN;
 242     if (file->access & FILE_UNIX_WRITE_ACCESS) events |= POLLOUT;
 243     return events;
 244 }
 245
 246 static void file_flush( struct fd *fd, struct event **event )
 247 {
 248     int unix_fd = get_unix_fd( fd );
 249     if (unix_fd != -1 && fsync( unix_fd ) == -1) file_set_error();
 250 }
 251
 252 static enum server_fd_type file_get_fd_type( struct fd *fd )
 253 {
 254     struct file *file = get_fd_user( fd );
 255
 256     if (S_ISREG(file->mode) || S_ISBLK(file->mode)) return FD_TYPE_FILE;
 257     if (S_ISDIR(file->mode)) return FD_TYPE_DIR;
 258     return FD_TYPE_CHAR;
 259 }
 260
 261 static struct fd *file_get_fd( struct object *obj )
 262 {
 263     struct file *file = (struct file *)obj;
 264     assert( obj->ops == &file_ops );
 265     return (struct fd *)grab_object( file->fd );
 266 }
 267
 268 static unsigned int generic_file_map_access( unsigned int access )
 269 {
 270     if (access & GENERIC_READ)    access |= FILE_GENERIC_READ;
 271     if (access & GENERIC_WRITE)   access |= FILE_GENERIC_WRITE;
 272     if (access & GENERIC_EXECUTE) access |= FILE_GENERIC_EXECUTE;
 273     if (access & GENERIC_ALL)     access |= FILE_ALL_ACCESS;
 274     return access & ~(GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE | GENERIC_ALL);
 275 }
 276
 277 static struct security_descriptor *file_get_sd( struct object *obj )
 278 {
 279     struct file *file = (struct file *)obj;
 280     struct stat st;
 281     int unix_fd;
 282     struct security_descriptor *sd;
 283     const SID *user;
 284     const SID *group;
 285     size_t dacl_size;
 286     ACCESS_ALLOWED_ACE *aaa;
 287     ACL *dacl;
 288     SID *sid;
 289     char *ptr;
 290     const SID *world_sid = security_world_sid;
 291     const SID *local_system_sid = security_local_system_sid;
 292
 293     assert( obj->ops == &file_ops );
 294
 295     unix_fd = get_file_unix_fd( file );
 296
 297     if (unix_fd == -1) return obj->sd;
 298
 299     if (fstat( unix_fd, &st ) == -1)
 300         return obj->sd;
 301
 302     /* mode and uid the same? if so, no need to re-generate security descriptor */
 303     if (obj->sd && (st.st_mode & (S_IRWXU|S_IRWXO)) == (file->mode & (S_IRWXU|S_IRWXO)) &&
 304         (st.st_uid == file->uid))
 305         return obj->sd;
 306
 307     user = security_unix_uid_to_sid( st.st_uid );
 308     group = token_get_primary_group( current->process->token );
 309
 310     dacl_size = sizeof(ACL) + FIELD_OFFSET(ACCESS_ALLOWED_ACE, SidStart) +
 311         FIELD_OFFSET(SID, SubAuthority[local_system_sid->SubAuthorityCount]);
 312     if (st.st_mode & S_IRWXU)
 313         dacl_size += FIELD_OFFSET(ACCESS_ALLOWED_ACE, SidStart) +
 314             FIELD_OFFSET(SID, SubAuthority[user->SubAuthorityCount]);
 315     if (st.st_mode & S_IRWXO)
 316         dacl_size += FIELD_OFFSET(ACCESS_ALLOWED_ACE, SidStart) +
 317             FIELD_OFFSET(SID, SubAuthority[world_sid->SubAuthorityCount]);
 318
 319     sd = mem_alloc( sizeof(struct security_descriptor) +
 320                     FIELD_OFFSET(SID, SubAuthority[user->SubAuthorityCount]) +
 321                     FIELD_OFFSET(SID, SubAuthority[group->SubAuthorityCount]) +
 322                     dacl_size );
 323     if (!sd) return obj->sd;
 324
 325     sd->control = SE_DACL_PRESENT;
 326     sd->owner_len = FIELD_OFFSET(SID, SubAuthority[user->SubAuthorityCount]);
 327     sd->group_len = FIELD_OFFSET(SID, SubAuthority[group->SubAuthorityCount]);
 328     sd->sacl_len = 0;
 329     sd->dacl_len = dacl_size;
 330
 331     ptr = (char *)(sd + 1);
 332     memcpy( ptr, user, sd->owner_len );
 333     ptr += sd->owner_len;
 334     memcpy( ptr, group, sd->group_len );
 335     ptr += sd->group_len;
 336
 337     dacl = (ACL *)ptr;
 338     dacl->AclRevision = ACL_REVISION;
 339     dacl->Sbz1 = 0;
 340     dacl->AclSize = dacl_size;
 341     dacl->AceCount = 1 + (st.st_mode & S_IRWXU ? 1 : 0) + (st.st_mode & S_IRWXO ? 1 : 0);
 342     dacl->Sbz2 = 0;
 343
 344     /* always give FILE_ALL_ACCESS for Local System */
 345     aaa = (ACCESS_ALLOWED_ACE *)(dacl + 1);
 346     aaa->Header.AceType = ACCESS_ALLOWED_ACE_TYPE;
 347     aaa->Header.AceFlags = 0;
 348     aaa->Header.AceSize = FIELD_OFFSET(ACCESS_ALLOWED_ACE, SidStart) +
 349         FIELD_OFFSET(SID, SubAuthority[local_system_sid->SubAuthorityCount]);
 350     aaa->Mask = FILE_ALL_ACCESS;
 351     sid = (SID *)&aaa->SidStart;
 352     memcpy( sid, local_system_sid, FIELD_OFFSET(SID, SubAuthority[local_system_sid->SubAuthorityCount]) );
 353
 354     if (st.st_mode & S_IRWXU)
 355     {
 356         /* appropriate access rights for the user */
 357         aaa = (ACCESS_ALLOWED_ACE *)ace_next( &aaa->Header );
 358         aaa->Header.AceType = ACCESS_ALLOWED_ACE_TYPE;
 359         aaa->Header.AceFlags = 0;
 360         aaa->Header.AceSize = FIELD_OFFSET(ACCESS_ALLOWED_ACE, SidStart) +
 361                               FIELD_OFFSET(SID, SubAuthority[user->SubAuthorityCount]);
 362         aaa->Mask = WRITE_DAC | WRITE_OWNER;
 363         if (st.st_mode & S_IRUSR)
 364             aaa->Mask |= FILE_GENERIC_READ;
 365         if (st.st_mode & S_IWUSR)
 366             aaa->Mask |= FILE_GENERIC_WRITE | DELETE;
 367         if (st.st_mode & S_IXUSR)
 368             aaa->Mask |= FILE_GENERIC_EXECUTE;
 369         sid = (SID *)&aaa->SidStart;
 370         memcpy( sid, user, FIELD_OFFSET(SID, SubAuthority[user->SubAuthorityCount]) );
 371     }
 372     if (st.st_mode & S_IRWXO)
 373     {
 374         /* appropriate access rights for Everyone */
 375         aaa = (ACCESS_ALLOWED_ACE *)ace_next( &aaa->Header );
 376         aaa->Header.AceType = ACCESS_ALLOWED_ACE_TYPE;
 377         aaa->Header.AceFlags = 0;
 378         aaa->Header.AceSize = FIELD_OFFSET(ACCESS_ALLOWED_ACE, SidStart) +
 379                              FIELD_OFFSET(SID, SubAuthority[world_sid->SubAuthorityCount]);
 380         aaa->Mask = 0;
 381         if (st.st_mode & S_IROTH)
 382             aaa->Mask |= FILE_GENERIC_READ;
 383         if (st.st_mode & S_IWOTH)
 384             aaa->Mask |= FILE_GENERIC_WRITE | DELETE;
 385         if (st.st_mode & S_IXOTH)
 386             aaa->Mask |= FILE_GENERIC_EXECUTE;
 387         sid = (SID *)&aaa->SidStart;
 388         memcpy( sid, world_sid, FIELD_OFFSET(SID, SubAuthority[world_sid->SubAuthorityCount]) );
 389     }
 390
 391     file->mode = st.st_mode;
 392     file->uid = st.st_uid;
 393     free( obj->sd );
 394     obj->sd = sd;
 395     return sd;
 396 }
 397
 398 static int file_set_sd( struct object *obj, const struct security_descriptor *sd,
 399                         unsigned int set_info )
 400 {
 401     struct file *file = (struct file *)obj;
 402     mode_t new_mode;
 403     mode_t denied_mode = 0;
 404     const SID *owner;
 405     int unix_fd;
 406
 407     assert( obj->ops == &file_ops );
 408
 409     unix_fd = get_file_unix_fd( file );
 410
 411     if (unix_fd == -1) return 1;
 412
 413     if (set_info & OWNER_SECURITY_INFORMATION)
 414     {
 415         owner = sd_get_owner( sd );
 416         if (!owner)
 417         {
 418             set_error( STATUS_INVALID_SECURITY_DESCR );
 419             return 0;
 420         }
 421         if (!obj->sd || !security_equal_sid( owner, sd_get_owner( obj->sd ) ))
 422         {
 423             /* FIXME: get Unix uid and call fchown */
 424         }
 425     }
 426     else if (obj->sd)
 427         owner = sd_get_owner( obj->sd );
 428     else
 429         owner = token_get_user( current->process->token );
 430
 431     /* group and sacl not supported */
 432
 433     /* keep the bits that we don't map to access rights in the ACL */
 434     new_mode = file->mode & (S_ISUID|S_ISGID|S_ISVTX|S_IRWXG);
 435
 436     if (set_info & DACL_SECURITY_INFORMATION)
 437     {
 438         if (sd->control & SE_DACL_PRESENT)
 439         {
 440             const ACL *dacl = (const ACL *)((char *)sd + sd->owner_len + sd->group_len + sd->sacl_len);
 441             const ACE_HEADER *ace = (const ACE_HEADER *)(dacl + 1);
 442             ULONG i;
 443             for (i = 0; i < dacl->AceCount; i++)
 444             {
 445                 const ACCESS_ALLOWED_ACE *aa_ace;
 446                 const ACCESS_DENIED_ACE *ad_ace;
 447                 const SID *sid;
 448                 switch (ace->AceType)
 449                 {
 450                 case ACCESS_DENIED_ACE_TYPE:
 451                     ad_ace = (const ACCESS_DENIED_ACE *)ace;
 452                     sid = (const SID *)&ad_ace->SidStart;
 453                     if (security_equal_sid( sid, security_world_sid ))
 454                     {
 455                         unsigned int access = generic_file_map_access( ad_ace->Mask );
 456                         if (access & FILE_READ_DATA)
 457                             denied_mode |= S_IROTH;
 458                         if (access & FILE_WRITE_DATA)
 459                             denied_mode |= S_IWOTH;
 460                         if (access & FILE_EXECUTE)
 461                             denied_mode |= S_IXOTH;
 462                     }
 463                     else if (security_equal_sid( sid, owner ))
 464                     {
 465                         unsigned int access = generic_file_map_access( ad_ace->Mask );
 466                         if (access & FILE_READ_DATA)
 467                             denied_mode |= S_IRUSR;
 468                         if (access & FILE_WRITE_DATA)
 469                             denied_mode |= S_IWUSR;
 470                         if (access & FILE_EXECUTE)
 471                             denied_mode |= S_IXUSR;
 472                     }
 473                     break;
 474                 case ACCESS_ALLOWED_ACE_TYPE:
 475                     aa_ace = (const ACCESS_ALLOWED_ACE *)ace;
 476                     sid = (const SID *)&aa_ace->SidStart;
 477                     if (security_equal_sid( sid, security_world_sid ))
 478                     {
 479                         unsigned int access = generic_file_map_access( aa_ace->Mask );
 480                         if (access & FILE_READ_DATA)
 481                             new_mode |= S_IROTH;
 482                         if (access & FILE_WRITE_DATA)
 483                             new_mode |= S_IWOTH;
 484                         if (access & FILE_EXECUTE)
 485                             new_mode |= S_IXOTH;
 486                     }
 487                     else if (security_equal_sid( sid, owner ))
 488                     {
 489                         unsigned int access = generic_file_map_access( aa_ace->Mask );
 490                         if (access & FILE_READ_DATA)
 491                             new_mode |= S_IRUSR;
 492                         if (access & FILE_WRITE_DATA)
 493                             new_mode |= S_IWUSR;
 494                         if (access & FILE_EXECUTE)
 495                             new_mode |= S_IXUSR;
 496                     }
 497                     break;
 498                 }
 499                 ace = ace_next( ace );
 500             }
 501         }
 502         else
 503             /* no ACL means full access rights to anyone */
 504             new_mode |= S_IRWXU | S_IRWXO;
 505
 506         if (file->mode != (new_mode & ~denied_mode))
 507         {
 508             if (fchmod( unix_fd, new_mode & ~denied_mode ) == -1)
 509             {
 510                 file_set_error();
 511                 return 0;
 512             }
 513
 514             file->mode = new_mode & ~denied_mode;
 515         }
 516     }
 517     return 1;
 518 }
 519
 520 static void file_destroy( struct object *obj )
 521 {
 522     struct file *file = (struct file *)obj;
 523     assert( obj->ops == &file_ops );
 524
 525     if (file->fd) release_object( file->fd );
 526 }
 527
 528 /* set the last error depending on errno */
 529 void file_set_error(void)
 530 {
 531     switch (errno)
 532     {
 533     case ETXTBSY:
 534     case EAGAIN:    set_error( STATUS_SHARING_VIOLATION ); break;
 535     case EBADF:     set_error( STATUS_INVALID_HANDLE ); break;
 536     case ENOSPC:    set_error( STATUS_DISK_FULL ); break;
 537     case EACCES:
 538     case ESRCH:
 539     case EPERM:     set_error( STATUS_ACCESS_DENIED ); break;
 540     case EROFS:     set_error( STATUS_MEDIA_WRITE_PROTECTED ); break;
 541     case EBUSY:     set_error( STATUS_FILE_LOCK_CONFLICT ); break;
 542     case ENOENT:    set_error( STATUS_NO_SUCH_FILE ); break;
 543     case EISDIR:    set_error( STATUS_FILE_IS_A_DIRECTORY ); break;
 544     case ENFILE:
 545     case EMFILE:    set_error( STATUS_TOO_MANY_OPENED_FILES ); break;
 546     case EEXIST:    set_error( STATUS_OBJECT_NAME_COLLISION ); break;
 547     case EINVAL:    set_error( STATUS_INVALID_PARAMETER ); break;
 548     case ESPIPE:    set_error( STATUS_ILLEGAL_FUNCTION ); break;
 549     case ENOTEMPTY: set_error( STATUS_DIRECTORY_NOT_EMPTY ); break;
 550     case EIO:       set_error( STATUS_ACCESS_VIOLATION ); break;
 551     case ENOTDIR:   set_error( STATUS_NOT_A_DIRECTORY ); break;
 552     case EFBIG:     set_error( STATUS_SECTION_TOO_BIG ); break;
 553     case ENODEV:    set_error( STATUS_NO_SUCH_DEVICE ); break;
 554     case ENXIO:     set_error( STATUS_NO_SUCH_DEVICE ); break;
 555 #ifdef EOVERFLOW
 556     case EOVERFLOW: set_error( STATUS_INVALID_PARAMETER ); break;
 557 #endif
 558     default:
 559         perror("wineserver: file_set_error() can't map error");
 560         set_error( STATUS_UNSUCCESSFUL );
 561         break;
 562     }
 563 }
 564
 565 struct file *get_file_obj( struct process *process, obj_handle_t handle, unsigned int access )
 566 {
 567     return (struct file *)get_handle_obj( process, handle, access, &file_ops );
 568 }
 569
 570 int get_file_unix_fd( struct file *file )
 571 {
 572     return get_unix_fd( file->fd );
 573 }
 574
 575 struct file *grab_file_unless_removable( struct file *file )
 576 {
 577     if (is_fd_removable( file->fd )) return NULL;
 578     return (struct file *)grab_object( file );
 579 }
 580
 581 /* extend a file beyond the current end of file */
 582 static int extend_file( struct file *file, file_pos_t new_size )
 583 {
 584     static const char zero;
 585     int unix_fd = get_file_unix_fd( file );
 586     off_t size = new_size;
 587
 588     if (unix_fd == -1) return 0;
 589
 590     if (sizeof(new_size) > sizeof(size) && size != new_size)
 591     {
 592         set_error( STATUS_INVALID_PARAMETER );
 593         return 0;
 594     }
 595     /* extend the file one byte beyond the requested size and then truncate it */
 596     /* this should work around ftruncate implementations that can't extend files */
 597     if (pwrite( unix_fd, &zero, 1, size ) != -1)
 598     {
 599         ftruncate( unix_fd, size );
 600         return 1;
 601     }
 602     file_set_error();
 603     return 0;
 604 }
 605
 606 /* try to grow the file to the specified size */
 607 int grow_file( struct file *file, file_pos_t size )
 608 {
 609     struct stat st;
 610     int unix_fd = get_file_unix_fd( file );
 611
 612     if (unix_fd == -1) return 0;
 613
 614     if (fstat( unix_fd, &st ) == -1)
 615     {
 616         file_set_error();
 617         return 0;
 618     }
 619     if (st.st_size >= size) return 1;  /* already large enough */
 620     return extend_file( file, size );
 621 }
 622
 623 /* create a file */
 624 DECL_HANDLER(create_file)
 625 {
 626     struct object *file;
 627
 628     reply->handle = 0;
 629     if ((file = create_file( get_req_data(), get_req_data_size(), req->access,
 630                              req->sharing, req->create, req->options, req->attrs )))
 631     {
 632         reply->handle = alloc_handle( current->process, file, req->access, req->attributes );
 633         release_object( file );
 634     }
 635 }
 636
 637 /* allocate a file handle for a Unix fd */
 638 DECL_HANDLER(alloc_file_handle)
 639 {
 640     struct file *file;
 641     int fd;
 642
 643     reply->handle = 0;
 644     if ((fd = thread_get_inflight_fd( current, req->fd )) == -1)
 645     {
 646         set_error( STATUS_INVALID_HANDLE );
 647         return;
 648     }
 649     if ((file = create_file_for_fd( fd, req->access, FILE_SHARE_READ | FILE_SHARE_WRITE )))
 650     {
 651         reply->handle = alloc_handle( current->process, file, req->access, req->attributes );
 652         release_object( file );
 653     }
 654 }
 655
 656 /* lock a region of a file */
 657 DECL_HANDLER(lock_file)
 658 {
 659     struct file *file;
 660
 661     if ((file = get_file_obj( current->process, req->handle, 0 )))
 662     {
 663         reply->handle = lock_fd( file->fd, req->offset, req->count, req->shared, req->wait );
 664         reply->overlapped = is_overlapped( file );
 665         release_object( file );
 666     }
 667 }
 668
 669 /* unlock a region of a file */
 670 DECL_HANDLER(unlock_file)
 671 {
 672     struct file *file;
 673
 674     if ((file = get_file_obj( current->process, req->handle, 0 )))
 675     {
 676         unlock_fd( file->fd, req->offset, req->count );
 677         release_object( file );
 678     }
 679 }