lib/efi_loader/efi_file.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * EFI_FILE_PROTOCOL
   4  *
   5  * Copyright (c) 2017 Rob Clark
   6  */
   7
   8 #include <common.h>
   9 #include <charset.h>
  10 #include <efi_loader.h>
  11 #include <log.h>
  12 #include <malloc.h>
  13 #include <mapmem.h>
  14 #include <fs.h>
  15 #include <part.h>
  16
  17 /* GUID for file system information */
  18 const efi_guid_t efi_file_system_info_guid = EFI_FILE_SYSTEM_INFO_GUID;
  19
  20 /* GUID to obtain the volume label */
  21 const efi_guid_t efi_system_volume_label_id = EFI_FILE_SYSTEM_VOLUME_LABEL_ID;
  22
  23 struct file_system {
  24         struct efi_simple_file_system_protocol base;
  25         struct efi_device_path *dp;
  26         struct blk_desc *desc;
  27         int part;
  28 };
  29 #define to_fs(x) container_of(x, struct file_system, base)
  30
  31 struct file_handle {
  32         struct efi_file_handle base;
  33         struct file_system *fs;
  34         loff_t offset;       /* current file position/cursor */
  35         int isdir;
  36         u64 open_mode;
  37
  38         /* for reading a directory: */
  39         struct fs_dir_stream *dirs;
  40         struct fs_dirent *dent;
  41
  42         char path[0];
  43 };
  44 #define to_fh(x) container_of(x, struct file_handle, base)
  45
  46 static const struct efi_file_handle efi_file_handle_protocol;
  47
  48 static char *basename(struct file_handle *fh)
  49 {
  50         char *s = strrchr(fh->path, '/');
  51         if (s)
  52                 return s + 1;
  53         return fh->path;
  54 }
  55
  56 static int set_blk_dev(struct file_handle *fh)
  57 {
  58         return fs_set_blk_dev_with_part(fh->fs->desc, fh->fs->part);
  59 }
  60
  61 /**
  62  * is_dir() - check if file handle points to directory
  63  *
  64  * We assume that set_blk_dev(fh) has been called already.
  65  *
  66  * @fh:         file handle
  67  * Return:      true if file handle points to a directory
  68  */
  69 static int is_dir(struct file_handle *fh)
  70 {
  71         struct fs_dir_stream *dirs;
  72
  73         dirs = fs_opendir(fh->path);
  74         if (!dirs)
  75                 return 0;
  76
  77         fs_closedir(dirs);
  78
  79         return 1;
  80 }
  81
  82 /*
  83  * Normalize a path which may include either back or fwd slashes,
  84  * double slashes, . or .. entries in the path, etc.
  85  */
  86 static int sanitize_path(char *path)
  87 {
  88         char *p;
  89
  90         /* backslash to slash: */
  91         p = path;
  92         while ((p = strchr(p, '\\')))
  93                 *p++ = '/';
  94
  95         /* handle double-slashes: */
  96         p = path;
  97         while ((p = strstr(p, "//"))) {
  98                 char *src = p + 1;
  99                 memmove(p, src, strlen(src) + 1);
 100         }
 101
 102         /* handle extra /.'s */
 103         p = path;
 104         while ((p = strstr(p, "/."))) {
 105                 /*
 106                  * You'd be tempted to do this *after* handling ".."s
 107                  * below to avoid having to check if "/." is start of
 108                  * a "/..", but that won't have the correct results..
 109                  * for example, "/foo/./../bar" would get resolved to
 110                  * "/foo/bar" if you did these two passes in the other
 111                  * order
 112                  */
 113                 if (p[2] == '.') {
 114                         p += 2;
 115                         continue;
 116                 }
 117                 char *src = p + 2;
 118                 memmove(p, src, strlen(src) + 1);
 119         }
 120
 121         /* handle extra /..'s: */
 122         p = path;
 123         while ((p = strstr(p, "/.."))) {
 124                 char *src = p + 3;
 125
 126                 p--;
 127
 128                 /* find beginning of previous path entry: */
 129                 while (true) {
 130                         if (p < path)
 131                                 return -1;
 132                         if (*p == '/')
 133                                 break;
 134                         p--;
 135                 }
 136
 137                 memmove(p, src, strlen(src) + 1);
 138         }
 139
 140         return 0;
 141 }
 142
 143 /**
 144  * efi_create_file() - create file or directory
 145  *
 146  * @fh:                 file handle
 147  * @attributes:         attributes for newly created file
 148  * Returns:             0 for success
 149  */
 150 static int efi_create_file(struct file_handle *fh, u64 attributes)
 151 {
 152         loff_t actwrite;
 153         void *buffer = &actwrite;
 154
 155         if (attributes & EFI_FILE_DIRECTORY)
 156                 return fs_mkdir(fh->path);
 157         else
 158                 return fs_write(fh->path, map_to_sysmem(buffer), 0, 0,
 159                                 &actwrite);
 160 }
 161
 162 /**
 163  * file_open() - open a file handle
 164  *
 165  * @fs:                 file system
 166  * @parent:             directory relative to which the file is to be opened
 167  * @file_name:          path of the file to be opened. '\', '.', or '..' may
 168  *                      be used as modifiers. A leading backslash indicates an
 169  *                      absolute path.
 170  * @open_mode:          bit mask indicating the access mode (read, write,
 171  *                      create)
 172  * @attributes:         attributes for newly created file
 173  * Returns:             handle to the opened file or NULL
 174  */
 175 static struct efi_file_handle *file_open(struct file_system *fs,
 176                 struct file_handle *parent, u16 *file_name, u64 open_mode,
 177                 u64 attributes)
 178 {
 179         struct file_handle *fh;
 180         char f0[MAX_UTF8_PER_UTF16] = {0};
 181         int plen = 0;
 182         int flen = 0;
 183
 184         if (file_name) {
 185                 utf16_to_utf8((u8 *)f0, file_name, 1);
 186                 flen = u16_strlen(file_name);
 187         }
 188
 189         /* we could have a parent, but also an absolute path: */
 190         if (f0[0] == '\\') {
 191                 plen = 0;
 192         } else if (parent) {
 193                 plen = strlen(parent->path) + 1;
 194         }
 195
 196         /* +2 is for null and '/' */
 197         fh = calloc(1, sizeof(*fh) + plen + (flen * MAX_UTF8_PER_UTF16) + 2);
 198
 199         fh->open_mode = open_mode;
 200         fh->base = efi_file_handle_protocol;
 201         fh->fs = fs;
 202
 203         if (parent) {
 204                 char *p = fh->path;
 205                 int exists;
 206
 207                 if (plen > 0) {
 208                         strcpy(p, parent->path);
 209                         p += plen - 1;
 210                         *p++ = '/';
 211                 }
 212
 213                 utf16_to_utf8((u8 *)p, file_name, flen);
 214
 215                 if (sanitize_path(fh->path))
 216                         goto error;
 217
 218                 /* check if file exists: */
 219                 if (set_blk_dev(fh))
 220                         goto error;
 221
 222                 exists = fs_exists(fh->path);
 223                 /* fs_exists() calls fs_close(), so open file system again */
 224                 if (set_blk_dev(fh))
 225                         goto error;
 226
 227                 if (!exists) {
 228                         if (!(open_mode & EFI_FILE_MODE_CREATE) ||
 229                             efi_create_file(fh, attributes))
 230                                 goto error;
 231                         if (set_blk_dev(fh))
 232                                 goto error;
 233                 }
 234
 235                 /* figure out if file is a directory: */
 236                 fh->isdir = is_dir(fh);
 237         } else {
 238                 fh->isdir = 1;
 239                 strcpy(fh->path, "");
 240         }
 241
 242         return &fh->base;
 243
 244 error:
 245         free(fh);
 246         return NULL;
 247 }
 248
 249 static efi_status_t EFIAPI efi_file_open(struct efi_file_handle *file,
 250                 struct efi_file_handle **new_handle,
 251                 u16 *file_name, u64 open_mode, u64 attributes)
 252 {
 253         struct file_handle *fh = to_fh(file);
 254         efi_status_t ret;
 255
 256         EFI_ENTRY("%p, %p, \"%ls\", %llx, %llu", file, new_handle,
 257                   file_name, open_mode, attributes);
 258
 259         /* Check parameters */
 260         if (!file || !new_handle || !file_name) {
 261                 ret = EFI_INVALID_PARAMETER;
 262                 goto out;
 263         }
 264         if (open_mode != EFI_FILE_MODE_READ &&
 265             open_mode != (EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE) &&
 266             open_mode != (EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE |
 267                          EFI_FILE_MODE_CREATE)) {
 268                 ret = EFI_INVALID_PARAMETER;
 269                 goto out;
 270         }
 271         /*
 272          * The UEFI spec requires that attributes are only set in create mode.
 273          * The SCT does not care about this and sets EFI_FILE_DIRECTORY in
 274          * read mode. EDK2 does not check that attributes are zero if not in
 275          * create mode.
 276          *
 277          * So here we only check attributes in create mode and do not check
 278          * that they are zero otherwise.
 279          */
 280         if ((open_mode & EFI_FILE_MODE_CREATE) &&
 281             (attributes & (EFI_FILE_READ_ONLY | ~EFI_FILE_VALID_ATTR))) {
 282                 ret = EFI_INVALID_PARAMETER;
 283                 goto out;
 284         }
 285
 286         /* Open file */
 287         *new_handle = file_open(fh->fs, fh, file_name, open_mode, attributes);
 288         if (*new_handle) {
 289                 EFI_PRINT("file handle %p\n", *new_handle);
 290                 ret = EFI_SUCCESS;
 291         } else {
 292                 ret = EFI_NOT_FOUND;
 293         }
 294 out:
 295         return EFI_EXIT(ret);
 296 }
 297
 298 static efi_status_t file_close(struct file_handle *fh)
 299 {
 300         fs_closedir(fh->dirs);
 301         free(fh);
 302         return EFI_SUCCESS;
 303 }
 304
 305 static efi_status_t EFIAPI efi_file_close(struct efi_file_handle *file)
 306 {
 307         struct file_handle *fh = to_fh(file);
 308         EFI_ENTRY("%p", file);
 309         return EFI_EXIT(file_close(fh));
 310 }
 311
 312 static efi_status_t EFIAPI efi_file_delete(struct efi_file_handle *file)
 313 {
 314         struct file_handle *fh = to_fh(file);
 315         efi_status_t ret = EFI_SUCCESS;
 316
 317         EFI_ENTRY("%p", file);
 318
 319         if (set_blk_dev(fh) || fs_unlink(fh->path))
 320                 ret = EFI_WARN_DELETE_FAILURE;
 321
 322         file_close(fh);
 323         return EFI_EXIT(ret);
 324 }
 325
 326 /**
 327  * efi_get_file_size() - determine the size of a file
 328  *
 329  * @fh:         file handle
 330  * @file_size:  pointer to receive file size
 331  * Return:      status code
 332  */
 333 static efi_status_t efi_get_file_size(struct file_handle *fh,
 334                                       loff_t *file_size)
 335 {
 336         if (set_blk_dev(fh))
 337                 return EFI_DEVICE_ERROR;
 338
 339         if (fs_size(fh->path, file_size))
 340                 return EFI_DEVICE_ERROR;
 341
 342         return EFI_SUCCESS;
 343 }
 344
 345 static efi_status_t file_read(struct file_handle *fh, u64 *buffer_size,
 346                 void *buffer)
 347 {
 348         loff_t actread;
 349         efi_status_t ret;
 350         loff_t file_size;
 351
 352         if (!buffer) {
 353                 ret = EFI_INVALID_PARAMETER;
 354                 return ret;
 355         }
 356
 357         ret = efi_get_file_size(fh, &file_size);
 358         if (ret != EFI_SUCCESS)
 359                 return ret;
 360         if (file_size < fh->offset) {
 361                 ret = EFI_DEVICE_ERROR;
 362                 return ret;
 363         }
 364
 365         if (set_blk_dev(fh))
 366                 return EFI_DEVICE_ERROR;
 367         if (fs_read(fh->path, map_to_sysmem(buffer), fh->offset,
 368                     *buffer_size, &actread))
 369                 return EFI_DEVICE_ERROR;
 370
 371         *buffer_size = actread;
 372         fh->offset += actread;
 373
 374         return EFI_SUCCESS;
 375 }
 376
 377 static efi_status_t dir_read(struct file_handle *fh, u64 *buffer_size,
 378                 void *buffer)
 379 {
 380         struct efi_file_info *info = buffer;
 381         struct fs_dirent *dent;
 382         u64 required_size;
 383         u16 *dst;
 384
 385         if (set_blk_dev(fh))
 386                 return EFI_DEVICE_ERROR;
 387
 388         if (!fh->dirs) {
 389                 assert(fh->offset == 0);
 390                 fh->dirs = fs_opendir(fh->path);
 391                 if (!fh->dirs)
 392                         return EFI_DEVICE_ERROR;
 393                 fh->dent = NULL;
 394         }
 395
 396         /*
 397          * So this is a bit awkward.  Since fs layer is stateful and we
 398          * can't rewind an entry, in the EFI_BUFFER_TOO_SMALL case below
 399          * we might have to return without consuming the dent.. so we
 400          * have to stash it for next call.
 401          */
 402         if (fh->dent) {
 403                 dent = fh->dent;
 404         } else {
 405                 dent = fs_readdir(fh->dirs);
 406         }
 407
 408         if (!dent) {
 409                 /* no more files in directory */
 410                 *buffer_size = 0;
 411                 return EFI_SUCCESS;
 412         }
 413
 414         /* check buffer size: */
 415         required_size = sizeof(*info) +
 416                         2 * (utf8_utf16_strlen(dent->name) + 1);
 417         if (*buffer_size < required_size) {
 418                 *buffer_size = required_size;
 419                 fh->dent = dent;
 420                 return EFI_BUFFER_TOO_SMALL;
 421         }
 422         if (!buffer)
 423                 return EFI_INVALID_PARAMETER;
 424         fh->dent = NULL;
 425
 426         *buffer_size = required_size;
 427         memset(info, 0, required_size);
 428
 429         info->size = required_size;
 430         info->file_size = dent->size;
 431         info->physical_size = dent->size;
 432
 433         if (dent->type == FS_DT_DIR)
 434                 info->attribute |= EFI_FILE_DIRECTORY;
 435
 436         dst = info->file_name;
 437         utf8_utf16_strcpy(&dst, dent->name);
 438
 439         fh->offset++;
 440
 441         return EFI_SUCCESS;
 442 }
 443
 444 static efi_status_t EFIAPI efi_file_read(struct efi_file_handle *file,
 445                                          efi_uintn_t *buffer_size, void *buffer)
 446 {
 447         struct file_handle *fh = to_fh(file);
 448         efi_status_t ret = EFI_SUCCESS;
 449         u64 bs;
 450
 451         EFI_ENTRY("%p, %p, %p", file, buffer_size, buffer);
 452
 453         if (!buffer_size) {
 454                 ret = EFI_INVALID_PARAMETER;
 455                 goto error;
 456         }
 457
 458         bs = *buffer_size;
 459         if (fh->isdir)
 460                 ret = dir_read(fh, &bs, buffer);
 461         else
 462                 ret = file_read(fh, &bs, buffer);
 463         if (bs <= SIZE_MAX)
 464                 *buffer_size = bs;
 465         else
 466                 *buffer_size = SIZE_MAX;
 467
 468 error:
 469         return EFI_EXIT(ret);
 470 }
 471
 472 /**
 473  * efi_file_write() - write to file
 474  *
 475  * This function implements the Write() service of the EFI_FILE_PROTOCOL.
 476  *
 477  * See the Unified Extensible Firmware Interface (UEFI) specification for
 478  * details.
 479  *
 480  * @file:               file handle
 481  * @buffer_size:        number of bytes to write
 482  * @buffer:             buffer with the bytes to write
 483  * Return:              status code
 484  */
 485 static efi_status_t EFIAPI efi_file_write(struct efi_file_handle *file,
 486                                           efi_uintn_t *buffer_size,
 487                                           void *buffer)
 488 {
 489         struct file_handle *fh = to_fh(file);
 490         efi_status_t ret = EFI_SUCCESS;
 491         loff_t actwrite;
 492
 493         EFI_ENTRY("%p, %p, %p", file, buffer_size, buffer);
 494
 495         if (!file || !buffer_size || !buffer) {
 496                 ret = EFI_INVALID_PARAMETER;
 497                 goto out;
 498         }
 499         if (fh->isdir) {
 500                 ret = EFI_UNSUPPORTED;
 501                 goto out;
 502         }
 503         if (!(fh->open_mode & EFI_FILE_MODE_WRITE)) {
 504                 ret = EFI_ACCESS_DENIED;
 505                 goto out;
 506         }
 507
 508         if (!*buffer_size)
 509                 goto out;
 510
 511         if (set_blk_dev(fh)) {
 512                 ret = EFI_DEVICE_ERROR;
 513                 goto out;
 514         }
 515         if (fs_write(fh->path, map_to_sysmem(buffer), fh->offset, *buffer_size,
 516                      &actwrite)) {
 517                 ret = EFI_DEVICE_ERROR;
 518                 goto out;
 519         }
 520         *buffer_size = actwrite;
 521         fh->offset += actwrite;
 522
 523 out:
 524         return EFI_EXIT(ret);
 525 }
 526
 527 /**
 528  * efi_file_getpos() - get current position in file
 529  *
 530  * This function implements the GetPosition service of the EFI file protocol.
 531  * See the UEFI spec for details.
 532  *
 533  * @file:       file handle
 534  * @pos:        pointer to file position
 535  * Return:      status code
 536  */
 537 static efi_status_t EFIAPI efi_file_getpos(struct efi_file_handle *file,
 538                                            u64 *pos)
 539 {
 540         efi_status_t ret = EFI_SUCCESS;
 541         struct file_handle *fh = to_fh(file);
 542
 543         EFI_ENTRY("%p, %p", file, pos);
 544
 545         if (fh->isdir) {
 546                 ret = EFI_UNSUPPORTED;
 547                 goto out;
 548         }
 549
 550         *pos = fh->offset;
 551 out:
 552         return EFI_EXIT(ret);
 553 }
 554
 555 /**
 556  * efi_file_setpos() - set current position in file
 557  *
 558  * This function implements the SetPosition service of the EFI file protocol.
 559  * See the UEFI spec for details.
 560  *
 561  * @file:       file handle
 562  * @pos:        new file position
 563  * Return:      status code
 564  */
 565 static efi_status_t EFIAPI efi_file_setpos(struct efi_file_handle *file,
 566                                            u64 pos)
 567 {
 568         struct file_handle *fh = to_fh(file);
 569         efi_status_t ret = EFI_SUCCESS;
 570
 571         EFI_ENTRY("%p, %llu", file, pos);
 572
 573         if (fh->isdir) {
 574                 if (pos != 0) {
 575                         ret = EFI_UNSUPPORTED;
 576                         goto error;
 577                 }
 578                 fs_closedir(fh->dirs);
 579                 fh->dirs = NULL;
 580         }
 581
 582         if (pos == ~0ULL) {
 583                 loff_t file_size;
 584
 585                 ret = efi_get_file_size(fh, &file_size);
 586                 if (ret != EFI_SUCCESS)
 587                         goto error;
 588                 pos = file_size;
 589         }
 590
 591         fh->offset = pos;
 592
 593 error:
 594         return EFI_EXIT(ret);
 595 }
 596
 597 static efi_status_t EFIAPI efi_file_getinfo(struct efi_file_handle *file,
 598                                             const efi_guid_t *info_type,
 599                                             efi_uintn_t *buffer_size,
 600                                             void *buffer)
 601 {
 602         struct file_handle *fh = to_fh(file);
 603         efi_status_t ret = EFI_SUCCESS;
 604         u16 *dst;
 605
 606         EFI_ENTRY("%p, %pUl, %p, %p", file, info_type, buffer_size, buffer);
 607
 608         if (!file || !info_type || !buffer_size ||
 609             (*buffer_size && !buffer)) {
 610                 ret = EFI_INVALID_PARAMETER;
 611                 goto error;
 612         }
 613
 614         if (!guidcmp(info_type, &efi_file_info_guid)) {
 615                 struct efi_file_info *info = buffer;
 616                 char *filename = basename(fh);
 617                 unsigned int required_size;
 618                 loff_t file_size;
 619
 620                 /* check buffer size: */
 621                 required_size = sizeof(*info) +
 622                                 2 * (utf8_utf16_strlen(filename) + 1);
 623                 if (*buffer_size < required_size) {
 624                         *buffer_size = required_size;
 625                         ret = EFI_BUFFER_TOO_SMALL;
 626                         goto error;
 627                 }
 628
 629                 ret = efi_get_file_size(fh, &file_size);
 630                 if (ret != EFI_SUCCESS)
 631                         goto error;
 632
 633                 memset(info, 0, required_size);
 634
 635                 info->size = required_size;
 636                 info->file_size = file_size;
 637                 info->physical_size = file_size;
 638
 639                 if (fh->isdir)
 640                         info->attribute |= EFI_FILE_DIRECTORY;
 641
 642                 dst = info->file_name;
 643                 utf8_utf16_strcpy(&dst, filename);
 644         } else if (!guidcmp(info_type, &efi_file_system_info_guid)) {
 645                 struct efi_file_system_info *info = buffer;
 646                 struct disk_partition part;
 647                 efi_uintn_t required_size;
 648                 int r;
 649
 650                 if (fh->fs->part >= 1)
 651                         r = part_get_info(fh->fs->desc, fh->fs->part, &part);
 652                 else
 653                         r = part_get_info_whole_disk(fh->fs->desc, &part);
 654                 if (r < 0) {
 655                         ret = EFI_DEVICE_ERROR;
 656                         goto error;
 657                 }
 658                 required_size = sizeof(*info) + 2;
 659                 if (*buffer_size < required_size) {
 660                         *buffer_size = required_size;
 661                         ret = EFI_BUFFER_TOO_SMALL;
 662                         goto error;
 663                 }
 664
 665                 memset(info, 0, required_size);
 666
 667                 info->size = required_size;
 668                 /*
 669                  * TODO: We cannot determine if the volume can be written to.
 670                  */
 671                 info->read_only = false;
 672                 info->volume_size = part.size * part.blksz;
 673                 /*
 674                  * TODO: We currently have no function to determine the free
 675                  * space. The volume size is the best upper bound we have.
 676                  */
 677                 info->free_space = info->volume_size;
 678                 info->block_size = part.blksz;
 679                 /*
 680                  * TODO: The volume label is not available in U-Boot.
 681                  */
 682                 info->volume_label[0] = 0;
 683         } else if (!guidcmp(info_type, &efi_system_volume_label_id)) {
 684                 if (*buffer_size < 2) {
 685                         *buffer_size = 2;
 686                         ret = EFI_BUFFER_TOO_SMALL;
 687                         goto error;
 688                 }
 689                 *(u16 *)buffer = 0;
 690         } else {
 691                 ret = EFI_UNSUPPORTED;
 692         }
 693
 694 error:
 695         return EFI_EXIT(ret);
 696 }
 697
 698 static efi_status_t EFIAPI efi_file_setinfo(struct efi_file_handle *file,
 699                                             const efi_guid_t *info_type,
 700                                             efi_uintn_t buffer_size,
 701                                             void *buffer)
 702 {
 703         struct file_handle *fh = to_fh(file);
 704         efi_status_t ret = EFI_UNSUPPORTED;
 705
 706         EFI_ENTRY("%p, %pUl, %zu, %p", file, info_type, buffer_size, buffer);
 707
 708         if (!guidcmp(info_type, &efi_file_info_guid)) {
 709                 struct efi_file_info *info = (struct efi_file_info *)buffer;
 710                 char *filename = basename(fh);
 711                 char *new_file_name, *pos;
 712                 loff_t file_size;
 713
 714                 /* The buffer will always contain a file name. */
 715                 if (buffer_size < sizeof(struct efi_file_info) + 2 ||
 716                     buffer_size < info->size) {
 717                         ret = EFI_BAD_BUFFER_SIZE;
 718                         goto out;
 719                 }
 720                 /* We cannot change the directory attribute */
 721                 if (!fh->isdir != !(info->attribute & EFI_FILE_DIRECTORY)) {
 722                         ret = EFI_ACCESS_DENIED;
 723                         goto out;
 724                 }
 725                 /* Check for renaming */
 726                 new_file_name = malloc(utf16_utf8_strlen(info->file_name));
 727                 if (!new_file_name) {
 728                         ret = EFI_OUT_OF_RESOURCES;
 729                         goto out;
 730                 }
 731                 pos = new_file_name;
 732                 utf16_utf8_strcpy(&pos, info->file_name);
 733                 if (strcmp(new_file_name, filename)) {
 734                         /* TODO: we do not support renaming */
 735                         EFI_PRINT("Renaming not supported\n");
 736                         free(new_file_name);
 737                         ret = EFI_ACCESS_DENIED;
 738                         goto out;
 739                 }
 740                 free(new_file_name);
 741                 /* Check for truncation */
 742                 ret = efi_get_file_size(fh, &file_size);
 743                 if (ret != EFI_SUCCESS)
 744                         goto out;
 745                 if (file_size != info->file_size) {
 746                         /* TODO: we do not support truncation */
 747                         EFI_PRINT("Truncation not supported\n");
 748                         ret = EFI_ACCESS_DENIED;
 749                         goto out;
 750                 }
 751                 /*
 752                  * We do not care for the other attributes
 753                  * TODO: Support read only
 754                  */
 755                 ret = EFI_SUCCESS;
 756         } else {
 757                 /* TODO: We do not support changing the volume label */
 758                 ret = EFI_UNSUPPORTED;
 759         }
 760 out:
 761         return EFI_EXIT(ret);
 762 }
 763
 764 static efi_status_t EFIAPI efi_file_flush(struct efi_file_handle *file)
 765 {
 766         EFI_ENTRY("%p", file);
 767         return EFI_EXIT(EFI_SUCCESS);
 768 }
 769
 770 static efi_status_t EFIAPI efi_file_open_ex(struct efi_file_handle *file,
 771                         struct efi_file_handle **new_handle,
 772                         u16 *file_name, u64 open_mode, u64 attributes,
 773                         struct efi_file_io_token *token)
 774 {
 775         return EFI_UNSUPPORTED;
 776 }
 777
 778 static efi_status_t EFIAPI efi_file_read_ex(struct efi_file_handle *file,
 779                         struct efi_file_io_token *token)
 780 {
 781         return EFI_UNSUPPORTED;
 782 }
 783
 784 static efi_status_t EFIAPI efi_file_write_ex(struct efi_file_handle *file,
 785                         struct efi_file_io_token *token)
 786 {
 787         return EFI_UNSUPPORTED;
 788 }
 789
 790 static efi_status_t EFIAPI efi_file_flush_ex(struct efi_file_handle *file,
 791                         struct efi_file_io_token *token)
 792 {
 793         return EFI_UNSUPPORTED;
 794 }
 795
 796 static const struct efi_file_handle efi_file_handle_protocol = {
 797         .rev = EFI_FILE_PROTOCOL_REVISION2,
 798         .open = efi_file_open,
 799         .close = efi_file_close,
 800         .delete = efi_file_delete,
 801         .read = efi_file_read,
 802         .write = efi_file_write,
 803         .getpos = efi_file_getpos,
 804         .setpos = efi_file_setpos,
 805         .getinfo = efi_file_getinfo,
 806         .setinfo = efi_file_setinfo,
 807         .flush = efi_file_flush,
 808         .open_ex = efi_file_open_ex,
 809         .read_ex = efi_file_read_ex,
 810         .write_ex = efi_file_write_ex,
 811         .flush_ex = efi_file_flush_ex,
 812 };
 813
 814 /**
 815  * efi_file_from_path() - open file via device path
 816  *
 817  * @fp:         device path
 818  * @return:     EFI_FILE_PROTOCOL for the file or NULL
 819  */
 820 struct efi_file_handle *efi_file_from_path(struct efi_device_path *fp)
 821 {
 822         struct efi_simple_file_system_protocol *v;
 823         struct efi_file_handle *f;
 824         efi_status_t ret;
 825
 826         v = efi_fs_from_path(fp);
 827         if (!v)
 828                 return NULL;
 829
 830         EFI_CALL(ret = v->open_volume(v, &f));
 831         if (ret != EFI_SUCCESS)
 832                 return NULL;
 833
 834         /* Skip over device-path nodes before the file path. */
 835         while (fp && !EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH))
 836                 fp = efi_dp_next(fp);
 837
 838         /*
 839          * Step through the nodes of the directory path until the actual file
 840          * node is reached which is the final node in the device path.
 841          */
 842         while (fp) {
 843                 struct efi_device_path_file_path *fdp =
 844                         container_of(fp, struct efi_device_path_file_path, dp);
 845                 struct efi_file_handle *f2;
 846                 u16 *filename;
 847
 848                 if (!EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH)) {
 849                         printf("bad file path!\n");
 850                         f->close(f);
 851                         return NULL;
 852                 }
 853
 854                 filename = u16_strdup(fdp->str);
 855                 if (!filename)
 856                         return NULL;
 857                 EFI_CALL(ret = f->open(f, &f2, filename,
 858                                        EFI_FILE_MODE_READ, 0));
 859                 free(filename);
 860                 if (ret != EFI_SUCCESS)
 861                         return NULL;
 862
 863                 fp = efi_dp_next(fp);
 864
 865                 EFI_CALL(f->close(f));
 866                 f = f2;
 867         }
 868
 869         return f;
 870 }
 871
 872 static efi_status_t EFIAPI
 873 efi_open_volume(struct efi_simple_file_system_protocol *this,
 874                 struct efi_file_handle **root)
 875 {
 876         struct file_system *fs = to_fs(this);
 877
 878         EFI_ENTRY("%p, %p", this, root);
 879
 880         *root = file_open(fs, NULL, NULL, 0, 0);
 881
 882         return EFI_EXIT(EFI_SUCCESS);
 883 }
 884
 885 struct efi_simple_file_system_protocol *
 886 efi_simple_file_system(struct blk_desc *desc, int part,
 887                        struct efi_device_path *dp)
 888 {
 889         struct file_system *fs;
 890
 891         fs = calloc(1, sizeof(*fs));
 892         fs->base.rev = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_REVISION;
 893         fs->base.open_volume = efi_open_volume;
 894         fs->desc = desc;
 895         fs->part = part;
 896         fs->dp = dp;
 897
 898         return &fs->base;
 899 }