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 <malloc.h>
  12 #include <mapmem.h>
  13 #include <fs.h>
  14
  15 /* GUID for file system information */
  16 const efi_guid_t efi_file_system_info_guid = EFI_FILE_SYSTEM_INFO_GUID;
  17
  18 struct file_system {
  19         struct efi_simple_file_system_protocol base;
  20         struct efi_device_path *dp;
  21         struct blk_desc *desc;
  22         int part;
  23 };
  24 #define to_fs(x) container_of(x, struct file_system, base)
  25
  26 struct file_handle {
  27         struct efi_file_handle base;
  28         struct file_system *fs;
  29         loff_t offset;       /* current file position/cursor */
  30         int isdir;
  31         u64 open_mode;
  32
  33         /* for reading a directory: */
  34         struct fs_dir_stream *dirs;
  35         struct fs_dirent *dent;
  36
  37         char path[0];
  38 };
  39 #define to_fh(x) container_of(x, struct file_handle, base)
  40
  41 static const struct efi_file_handle efi_file_handle_protocol;
  42
  43 static char *basename(struct file_handle *fh)
  44 {
  45         char *s = strrchr(fh->path, '/');
  46         if (s)
  47                 return s + 1;
  48         return fh->path;
  49 }
  50
  51 static int set_blk_dev(struct file_handle *fh)
  52 {
  53         return fs_set_blk_dev_with_part(fh->fs->desc, fh->fs->part);
  54 }
  55
  56 /**
  57  * is_dir() - check if file handle points to directory
  58  *
  59  * We assume that set_blk_dev(fh) has been called already.
  60  *
  61  * @fh:         file handle
  62  * Return:      true if file handle points to a directory
  63  */
  64 static int is_dir(struct file_handle *fh)
  65 {
  66         struct fs_dir_stream *dirs;
  67
  68         dirs = fs_opendir(fh->path);
  69         if (!dirs)
  70                 return 0;
  71
  72         fs_closedir(dirs);
  73
  74         return 1;
  75 }
  76
  77 /*
  78  * Normalize a path which may include either back or fwd slashes,
  79  * double slashes, . or .. entries in the path, etc.
  80  */
  81 static int sanitize_path(char *path)
  82 {
  83         char *p;
  84
  85         /* backslash to slash: */
  86         p = path;
  87         while ((p = strchr(p, '\\')))
  88                 *p++ = '/';
  89
  90         /* handle double-slashes: */
  91         p = path;
  92         while ((p = strstr(p, "//"))) {
  93                 char *src = p + 1;
  94                 memmove(p, src, strlen(src) + 1);
  95         }
  96
  97         /* handle extra /.'s */
  98         p = path;
  99         while ((p = strstr(p, "/."))) {
 100                 /*
 101                  * You'd be tempted to do this *after* handling ".."s
 102                  * below to avoid having to check if "/." is start of
 103                  * a "/..", but that won't have the correct results..
 104                  * for example, "/foo/./../bar" would get resolved to
 105                  * "/foo/bar" if you did these two passes in the other
 106                  * order
 107                  */
 108                 if (p[2] == '.') {
 109                         p += 2;
 110                         continue;
 111                 }
 112                 char *src = p + 2;
 113                 memmove(p, src, strlen(src) + 1);
 114         }
 115
 116         /* handle extra /..'s: */
 117         p = path;
 118         while ((p = strstr(p, "/.."))) {
 119                 char *src = p + 3;
 120
 121                 p--;
 122
 123                 /* find beginning of previous path entry: */
 124                 while (true) {
 125                         if (p < path)
 126                                 return -1;
 127                         if (*p == '/')
 128                                 break;
 129                         p--;
 130                 }
 131
 132                 memmove(p, src, strlen(src) + 1);
 133         }
 134
 135         return 0;
 136 }
 137
 138 /**
 139  * efi_create_file() - create file or directory
 140  *
 141  * @fh:                 file handle
 142  * @attributes:         attributes for newly created file
 143  * Returns:             0 for success
 144  */
 145 static int efi_create_file(struct file_handle *fh, u64 attributes)
 146 {
 147         loff_t actwrite;
 148         void *buffer = &actwrite;
 149
 150         if (attributes & EFI_FILE_DIRECTORY)
 151                 return fs_mkdir(fh->path);
 152         else
 153                 return fs_write(fh->path, map_to_sysmem(buffer), 0, 0,
 154                                 &actwrite);
 155 }
 156
 157 /**
 158  * file_open() - open a file handle
 159  *
 160  * @fs:                 file system
 161  * @parent:             directory relative to which the file is to be opened
 162  * @file_name:          path of the file to be opened. '\', '.', or '..' may
 163  *                      be used as modifiers. A leading backslash indicates an
 164  *                      absolute path.
 165  * @open_mode:          bit mask indicating the access mode (read, write,
 166  *                      create)
 167  * @attributes:         attributes for newly created file
 168  * Returns:             handle to the opened file or NULL
 169  */
 170 static struct efi_file_handle *file_open(struct file_system *fs,
 171                 struct file_handle *parent, u16 *file_name, u64 open_mode,
 172                 u64 attributes)
 173 {
 174         struct file_handle *fh;
 175         char f0[MAX_UTF8_PER_UTF16] = {0};
 176         int plen = 0;
 177         int flen = 0;
 178
 179         if (file_name) {
 180                 utf16_to_utf8((u8 *)f0, file_name, 1);
 181                 flen = u16_strlen(file_name);
 182         }
 183
 184         /* we could have a parent, but also an absolute path: */
 185         if (f0[0] == '\\') {
 186                 plen = 0;
 187         } else if (parent) {
 188                 plen = strlen(parent->path) + 1;
 189         }
 190
 191         /* +2 is for null and '/' */
 192         fh = calloc(1, sizeof(*fh) + plen + (flen * MAX_UTF8_PER_UTF16) + 2);
 193
 194         fh->open_mode = open_mode;
 195         fh->base = efi_file_handle_protocol;
 196         fh->fs = fs;
 197
 198         if (parent) {
 199                 char *p = fh->path;
 200                 int exists;
 201
 202                 if (plen > 0) {
 203                         strcpy(p, parent->path);
 204                         p += plen - 1;
 205                         *p++ = '/';
 206                 }
 207
 208                 utf16_to_utf8((u8 *)p, file_name, flen);
 209
 210                 if (sanitize_path(fh->path))
 211                         goto error;
 212
 213                 /* check if file exists: */
 214                 if (set_blk_dev(fh))
 215                         goto error;
 216
 217                 exists = fs_exists(fh->path);
 218                 /* fs_exists() calls fs_close(), so open file system again */
 219                 if (set_blk_dev(fh))
 220                         goto error;
 221
 222                 if (!exists) {
 223                         if (!(open_mode & EFI_FILE_MODE_CREATE) ||
 224                             efi_create_file(fh, attributes))
 225                                 goto error;
 226                         if (set_blk_dev(fh))
 227                                 goto error;
 228                 }
 229
 230                 /* figure out if file is a directory: */
 231                 fh->isdir = is_dir(fh);
 232         } else {
 233                 fh->isdir = 1;
 234                 strcpy(fh->path, "");
 235         }
 236
 237         return &fh->base;
 238
 239 error:
 240         free(fh);
 241         return NULL;
 242 }
 243
 244 static efi_status_t EFIAPI efi_file_open(struct efi_file_handle *file,
 245                 struct efi_file_handle **new_handle,
 246                 u16 *file_name, u64 open_mode, u64 attributes)
 247 {
 248         struct file_handle *fh = to_fh(file);
 249         efi_status_t ret;
 250
 251         EFI_ENTRY("%p, %p, \"%ls\", %llx, %llu", file, new_handle,
 252                   file_name, open_mode, attributes);
 253
 254         /* Check parameters */
 255         if (!file || !new_handle || !file_name) {
 256                 ret = EFI_INVALID_PARAMETER;
 257                 goto out;
 258         }
 259         if (open_mode != EFI_FILE_MODE_READ &&
 260             open_mode != (EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE) &&
 261             open_mode != (EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE |
 262                          EFI_FILE_MODE_CREATE)) {
 263                 ret = EFI_INVALID_PARAMETER;
 264                 goto out;
 265         }
 266         /*
 267          * The UEFI spec requires that attributes are only set in create mode.
 268          * The SCT does not care about this and sets EFI_FILE_DIRECTORY in
 269          * read mode. EDK2 does not check that attributes are zero if not in
 270          * create mode.
 271          *
 272          * So here we only check attributes in create mode and do not check
 273          * that they are zero otherwise.
 274          */
 275         if ((open_mode & EFI_FILE_MODE_CREATE) &&
 276             (attributes & (EFI_FILE_READ_ONLY | ~EFI_FILE_VALID_ATTR))) {
 277                 ret = EFI_INVALID_PARAMETER;
 278                 goto out;
 279         }
 280
 281         /* Open file */
 282         *new_handle = file_open(fh->fs, fh, file_name, open_mode, attributes);
 283         if (*new_handle) {
 284                 EFI_PRINT("file handle %p\n", *new_handle);
 285                 ret = EFI_SUCCESS;
 286         } else {
 287                 ret = EFI_NOT_FOUND;
 288         }
 289 out:
 290         return EFI_EXIT(ret);
 291 }
 292
 293 static efi_status_t file_close(struct file_handle *fh)
 294 {
 295         fs_closedir(fh->dirs);
 296         free(fh);
 297         return EFI_SUCCESS;
 298 }
 299
 300 static efi_status_t EFIAPI efi_file_close(struct efi_file_handle *file)
 301 {
 302         struct file_handle *fh = to_fh(file);
 303         EFI_ENTRY("%p", file);
 304         return EFI_EXIT(file_close(fh));
 305 }
 306
 307 static efi_status_t EFIAPI efi_file_delete(struct efi_file_handle *file)
 308 {
 309         struct file_handle *fh = to_fh(file);
 310         efi_status_t ret = EFI_SUCCESS;
 311
 312         EFI_ENTRY("%p", file);
 313
 314         if (set_blk_dev(fh) || fs_unlink(fh->path))
 315                 ret = EFI_WARN_DELETE_FAILURE;
 316
 317         file_close(fh);
 318         return EFI_EXIT(ret);
 319 }
 320
 321 static efi_status_t file_read(struct file_handle *fh, u64 *buffer_size,
 322                 void *buffer)
 323 {
 324         loff_t actread;
 325
 326         if (fs_read(fh->path, map_to_sysmem(buffer), fh->offset,
 327                     *buffer_size, &actread))
 328                 return EFI_DEVICE_ERROR;
 329
 330         *buffer_size = actread;
 331         fh->offset += actread;
 332
 333         return EFI_SUCCESS;
 334 }
 335
 336 static efi_status_t dir_read(struct file_handle *fh, u64 *buffer_size,
 337                 void *buffer)
 338 {
 339         struct efi_file_info *info = buffer;
 340         struct fs_dirent *dent;
 341         unsigned int required_size;
 342         u16 *dst;
 343
 344         if (!fh->dirs) {
 345                 assert(fh->offset == 0);
 346                 fh->dirs = fs_opendir(fh->path);
 347                 if (!fh->dirs)
 348                         return EFI_DEVICE_ERROR;
 349         }
 350
 351         /*
 352          * So this is a bit awkward.  Since fs layer is stateful and we
 353          * can't rewind an entry, in the EFI_BUFFER_TOO_SMALL case below
 354          * we might have to return without consuming the dent.. so we
 355          * have to stash it for next call.
 356          */
 357         if (fh->dent) {
 358                 dent = fh->dent;
 359                 fh->dent = NULL;
 360         } else {
 361                 dent = fs_readdir(fh->dirs);
 362         }
 363
 364
 365         if (!dent) {
 366                 /* no more files in directory: */
 367                 /* workaround shim.efi bug/quirk.. as find_boot_csv()
 368                  * loops through directory contents, it initially calls
 369                  * read w/ zero length buffer to find out how much mem
 370                  * to allocate for the EFI_FILE_INFO, then allocates,
 371                  * and then calls a 2nd time.  If we return size of
 372                  * zero the first time, it happily passes that to
 373                  * AllocateZeroPool(), and when that returns NULL it
 374                  * thinks it is EFI_OUT_OF_RESOURCES.  So on first
 375                  * call return a non-zero size:
 376                  */
 377                 if (*buffer_size == 0)
 378                         *buffer_size = sizeof(*info);
 379                 else
 380                         *buffer_size = 0;
 381                 return EFI_SUCCESS;
 382         }
 383
 384         /* check buffer size: */
 385         required_size = sizeof(*info) +
 386                         2 * (utf8_utf16_strlen(dent->name) + 1);
 387         if (*buffer_size < required_size) {
 388                 *buffer_size = required_size;
 389                 fh->dent = dent;
 390                 return EFI_BUFFER_TOO_SMALL;
 391         }
 392
 393         *buffer_size = required_size;
 394         memset(info, 0, required_size);
 395
 396         info->size = required_size;
 397         info->file_size = dent->size;
 398         info->physical_size = dent->size;
 399
 400         if (dent->type == FS_DT_DIR)
 401                 info->attribute |= EFI_FILE_DIRECTORY;
 402
 403         dst = info->file_name;
 404         utf8_utf16_strcpy(&dst, dent->name);
 405
 406         fh->offset++;
 407
 408         return EFI_SUCCESS;
 409 }
 410
 411 static efi_status_t EFIAPI efi_file_read(struct efi_file_handle *file,
 412                                          efi_uintn_t *buffer_size, void *buffer)
 413 {
 414         struct file_handle *fh = to_fh(file);
 415         efi_status_t ret = EFI_SUCCESS;
 416         u64 bs;
 417
 418         EFI_ENTRY("%p, %p, %p", file, buffer_size, buffer);
 419
 420         if (!buffer_size || !buffer) {
 421                 ret = EFI_INVALID_PARAMETER;
 422                 goto error;
 423         }
 424
 425         if (set_blk_dev(fh)) {
 426                 ret = EFI_DEVICE_ERROR;
 427                 goto error;
 428         }
 429
 430         bs = *buffer_size;
 431         if (fh->isdir)
 432                 ret = dir_read(fh, &bs, buffer);
 433         else
 434                 ret = file_read(fh, &bs, buffer);
 435         if (bs <= SIZE_MAX)
 436                 *buffer_size = bs;
 437         else
 438                 *buffer_size = SIZE_MAX;
 439
 440 error:
 441         return EFI_EXIT(ret);
 442 }
 443
 444 /**
 445  * efi_file_write() - write to file
 446  *
 447  * This function implements the Write() service of the EFI_FILE_PROTOCOL.
 448  *
 449  * See the Unified Extensible Firmware Interface (UEFI) specification for
 450  * details.
 451  *
 452  * @file:               file handle
 453  * @buffer_size:        number of bytes to write
 454  * @buffer:             buffer with the bytes to write
 455  * Return:              status code
 456  */
 457 static efi_status_t EFIAPI efi_file_write(struct efi_file_handle *file,
 458                                           efi_uintn_t *buffer_size,
 459                                           void *buffer)
 460 {
 461         struct file_handle *fh = to_fh(file);
 462         efi_status_t ret = EFI_SUCCESS;
 463         loff_t actwrite;
 464
 465         EFI_ENTRY("%p, %p, %p", file, buffer_size, buffer);
 466
 467         if (!file || !buffer_size || !buffer) {
 468                 ret = EFI_INVALID_PARAMETER;
 469                 goto out;
 470         }
 471         if (fh->isdir) {
 472                 ret = EFI_UNSUPPORTED;
 473                 goto out;
 474         }
 475         if (!(fh->open_mode & EFI_FILE_MODE_WRITE)) {
 476                 ret = EFI_ACCESS_DENIED;
 477                 goto out;
 478         }
 479
 480         if (!*buffer_size)
 481                 goto out;
 482
 483         if (set_blk_dev(fh)) {
 484                 ret = EFI_DEVICE_ERROR;
 485                 goto out;
 486         }
 487         if (fs_write(fh->path, map_to_sysmem(buffer), fh->offset, *buffer_size,
 488                      &actwrite)) {
 489                 ret = EFI_DEVICE_ERROR;
 490                 goto out;
 491         }
 492         *buffer_size = actwrite;
 493         fh->offset += actwrite;
 494
 495 out:
 496         return EFI_EXIT(ret);
 497 }
 498
 499 /**
 500  * efi_file_getpos() - get current position in file
 501  *
 502  * This function implements the GetPosition service of the EFI file protocol.
 503  * See the UEFI spec for details.
 504  *
 505  * @file:       file handle
 506  * @pos:        pointer to file position
 507  * Return:      status code
 508  */
 509 static efi_status_t EFIAPI efi_file_getpos(struct efi_file_handle *file,
 510                                            u64 *pos)
 511 {
 512         efi_status_t ret = EFI_SUCCESS;
 513         struct file_handle *fh = to_fh(file);
 514
 515         EFI_ENTRY("%p, %p", file, pos);
 516
 517         if (fh->isdir) {
 518                 ret = EFI_UNSUPPORTED;
 519                 goto out;
 520         }
 521
 522         *pos = fh->offset;
 523 out:
 524         return EFI_EXIT(ret);
 525 }
 526
 527 /**
 528  * efi_file_setpos() - set current position in file
 529  *
 530  * This function implements the SetPosition service of the EFI file protocol.
 531  * See the UEFI spec for details.
 532  *
 533  * @file:       file handle
 534  * @pos:        new file position
 535  * Return:      status code
 536  */
 537 static efi_status_t EFIAPI efi_file_setpos(struct efi_file_handle *file,
 538                                            u64 pos)
 539 {
 540         struct file_handle *fh = to_fh(file);
 541         efi_status_t ret = EFI_SUCCESS;
 542
 543         EFI_ENTRY("%p, %llu", file, pos);
 544
 545         if (fh->isdir) {
 546                 if (pos != 0) {
 547                         ret = EFI_UNSUPPORTED;
 548                         goto error;
 549                 }
 550                 fs_closedir(fh->dirs);
 551                 fh->dirs = NULL;
 552         }
 553
 554         if (pos == ~0ULL) {
 555                 loff_t file_size;
 556
 557                 if (set_blk_dev(fh)) {
 558                         ret = EFI_DEVICE_ERROR;
 559                         goto error;
 560                 }
 561
 562                 if (fs_size(fh->path, &file_size)) {
 563                         ret = EFI_DEVICE_ERROR;
 564                         goto error;
 565                 }
 566
 567                 pos = file_size;
 568         }
 569
 570         fh->offset = pos;
 571
 572 error:
 573         return EFI_EXIT(ret);
 574 }
 575
 576 static efi_status_t EFIAPI efi_file_getinfo(struct efi_file_handle *file,
 577                                             const efi_guid_t *info_type,
 578                                             efi_uintn_t *buffer_size,
 579                                             void *buffer)
 580 {
 581         struct file_handle *fh = to_fh(file);
 582         efi_status_t ret = EFI_SUCCESS;
 583         u16 *dst;
 584
 585         EFI_ENTRY("%p, %pUl, %p, %p", file, info_type, buffer_size, buffer);
 586
 587         if (!guidcmp(info_type, &efi_file_info_guid)) {
 588                 struct efi_file_info *info = buffer;
 589                 char *filename = basename(fh);
 590                 unsigned int required_size;
 591                 loff_t file_size;
 592
 593                 /* check buffer size: */
 594                 required_size = sizeof(*info) +
 595                                 2 * (utf8_utf16_strlen(filename) + 1);
 596                 if (*buffer_size < required_size) {
 597                         *buffer_size = required_size;
 598                         ret = EFI_BUFFER_TOO_SMALL;
 599                         goto error;
 600                 }
 601
 602                 if (set_blk_dev(fh)) {
 603                         ret = EFI_DEVICE_ERROR;
 604                         goto error;
 605                 }
 606
 607                 if (fs_size(fh->path, &file_size)) {
 608                         ret = EFI_DEVICE_ERROR;
 609                         goto error;
 610                 }
 611
 612                 memset(info, 0, required_size);
 613
 614                 info->size = required_size;
 615                 info->file_size = file_size;
 616                 info->physical_size = file_size;
 617
 618                 if (fh->isdir)
 619                         info->attribute |= EFI_FILE_DIRECTORY;
 620
 621                 dst = info->file_name;
 622                 utf8_utf16_strcpy(&dst, filename);
 623         } else if (!guidcmp(info_type, &efi_file_system_info_guid)) {
 624                 struct efi_file_system_info *info = buffer;
 625                 disk_partition_t part;
 626                 efi_uintn_t required_size;
 627                 int r;
 628
 629                 if (fh->fs->part >= 1)
 630                         r = part_get_info(fh->fs->desc, fh->fs->part, &part);
 631                 else
 632                         r = part_get_info_whole_disk(fh->fs->desc, &part);
 633                 if (r < 0) {
 634                         ret = EFI_DEVICE_ERROR;
 635                         goto error;
 636                 }
 637                 required_size = sizeof(*info) + 2 *
 638                                 (utf8_utf16_strlen((const char *)part.name) +
 639                                  1);
 640                 if (*buffer_size < required_size) {
 641                         *buffer_size = required_size;
 642                         ret = EFI_BUFFER_TOO_SMALL;
 643                         goto error;
 644                 }
 645
 646                 memset(info, 0, required_size);
 647
 648                 info->size = required_size;
 649                 info->read_only = true;
 650                 info->volume_size = part.size * part.blksz;
 651                 info->free_space = 0;
 652                 info->block_size = part.blksz;
 653                 /*
 654                  * TODO: The volume label is not available in U-Boot.
 655                  * Use the partition name as substitute.
 656                  */
 657                 dst = info->volume_label;
 658                 utf8_utf16_strcpy(&dst, (const char *)part.name);
 659         } else {
 660                 ret = EFI_UNSUPPORTED;
 661         }
 662
 663 error:
 664         return EFI_EXIT(ret);
 665 }
 666
 667 static efi_status_t EFIAPI efi_file_setinfo(struct efi_file_handle *file,
 668                                             const efi_guid_t *info_type,
 669                                             efi_uintn_t buffer_size,
 670                                             void *buffer)
 671 {
 672         struct file_handle *fh = to_fh(file);
 673         efi_status_t ret = EFI_UNSUPPORTED;
 674
 675         EFI_ENTRY("%p, %pUl, %zu, %p", file, info_type, buffer_size, buffer);
 676
 677         if (!guidcmp(info_type, &efi_file_info_guid)) {
 678                 struct efi_file_info *info = (struct efi_file_info *)buffer;
 679                 char *filename = basename(fh);
 680                 char *new_file_name, *pos;
 681                 loff_t file_size;
 682
 683                 if (buffer_size < sizeof(struct efi_file_info)) {
 684                         ret = EFI_BAD_BUFFER_SIZE;
 685                         goto out;
 686                 }
 687                 /* We cannot change the directory attribute */
 688                 if (!fh->isdir != !(info->attribute & EFI_FILE_DIRECTORY)) {
 689                         ret = EFI_ACCESS_DENIED;
 690                         goto out;
 691                 }
 692                 /* Check for renaming */
 693                 new_file_name = malloc(utf16_utf8_strlen(info->file_name));
 694                 if (!new_file_name) {
 695                         ret = EFI_OUT_OF_RESOURCES;
 696                         goto out;
 697                 }
 698                 pos = new_file_name;
 699                 utf16_utf8_strcpy(&pos, info->file_name);
 700                 if (strcmp(new_file_name, filename)) {
 701                         /* TODO: we do not support renaming */
 702                         EFI_PRINT("Renaming not supported\n");
 703                         free(new_file_name);
 704                         ret = EFI_ACCESS_DENIED;
 705                         goto out;
 706                 }
 707                 free(new_file_name);
 708                 /* Check for truncation */
 709                 if (set_blk_dev(fh)) {
 710                         ret = EFI_DEVICE_ERROR;
 711                         goto out;
 712                 }
 713                 if (fs_size(fh->path, &file_size)) {
 714                         ret = EFI_DEVICE_ERROR;
 715                         goto out;
 716                 }
 717                 if (file_size != info->file_size) {
 718                         /* TODO: we do not support truncation */
 719                         EFI_PRINT("Truncation not supported\n");
 720                         ret = EFI_ACCESS_DENIED;
 721                         goto out;
 722                 }
 723                 /*
 724                  * We do not care for the other attributes
 725                  * TODO: Support read only
 726                  */
 727                 ret = EFI_SUCCESS;
 728         } else if (!guidcmp(info_type, &efi_file_system_info_guid)) {
 729                 if (buffer_size < sizeof(struct efi_file_system_info)) {
 730                         ret = EFI_BAD_BUFFER_SIZE;
 731                         goto out;
 732                 }
 733         } else {
 734                 ret = EFI_UNSUPPORTED;
 735         }
 736 out:
 737         return EFI_EXIT(ret);
 738 }
 739
 740 static efi_status_t EFIAPI efi_file_flush(struct efi_file_handle *file)
 741 {
 742         EFI_ENTRY("%p", file);
 743         return EFI_EXIT(EFI_SUCCESS);
 744 }
 745
 746 static const struct efi_file_handle efi_file_handle_protocol = {
 747         /*
 748          * TODO: We currently only support EFI file protocol revision 0x00010000
 749          *       while UEFI specs 2.4 - 2.7 prescribe revision 0x00020000.
 750          */
 751         .rev = EFI_FILE_PROTOCOL_REVISION,
 752         .open = efi_file_open,
 753         .close = efi_file_close,
 754         .delete = efi_file_delete,
 755         .read = efi_file_read,
 756         .write = efi_file_write,
 757         .getpos = efi_file_getpos,
 758         .setpos = efi_file_setpos,
 759         .getinfo = efi_file_getinfo,
 760         .setinfo = efi_file_setinfo,
 761         .flush = efi_file_flush,
 762 };
 763
 764 /**
 765  * efi_file_from_path() - open file via device path
 766  *
 767  * @fp:         device path
 768  * @return:     EFI_FILE_PROTOCOL for the file or NULL
 769  */
 770 struct efi_file_handle *efi_file_from_path(struct efi_device_path *fp)
 771 {
 772         struct efi_simple_file_system_protocol *v;
 773         struct efi_file_handle *f;
 774         efi_status_t ret;
 775
 776         v = efi_fs_from_path(fp);
 777         if (!v)
 778                 return NULL;
 779
 780         EFI_CALL(ret = v->open_volume(v, &f));
 781         if (ret != EFI_SUCCESS)
 782                 return NULL;
 783
 784         /* Skip over device-path nodes before the file path. */
 785         while (fp && !EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH))
 786                 fp = efi_dp_next(fp);
 787
 788         /*
 789          * Step through the nodes of the directory path until the actual file
 790          * node is reached which is the final node in the device path.
 791          */
 792         while (fp) {
 793                 struct efi_device_path_file_path *fdp =
 794                         container_of(fp, struct efi_device_path_file_path, dp);
 795                 struct efi_file_handle *f2;
 796                 u16 *filename;
 797
 798                 if (!EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH)) {
 799                         printf("bad file path!\n");
 800                         f->close(f);
 801                         return NULL;
 802                 }
 803
 804                 filename = u16_strdup(fdp->str);
 805                 if (!filename)
 806                         return NULL;
 807                 EFI_CALL(ret = f->open(f, &f2, filename,
 808                                        EFI_FILE_MODE_READ, 0));
 809                 free(filename);
 810                 if (ret != EFI_SUCCESS)
 811                         return NULL;
 812
 813                 fp = efi_dp_next(fp);
 814
 815                 EFI_CALL(f->close(f));
 816                 f = f2;
 817         }
 818
 819         return f;
 820 }
 821
 822 static efi_status_t EFIAPI
 823 efi_open_volume(struct efi_simple_file_system_protocol *this,
 824                 struct efi_file_handle **root)
 825 {
 826         struct file_system *fs = to_fs(this);
 827
 828         EFI_ENTRY("%p, %p", this, root);
 829
 830         *root = file_open(fs, NULL, NULL, 0, 0);
 831
 832         return EFI_EXIT(EFI_SUCCESS);
 833 }
 834
 835 struct efi_simple_file_system_protocol *
 836 efi_simple_file_system(struct blk_desc *desc, int part,
 837                        struct efi_device_path *dp)
 838 {
 839         struct file_system *fs;
 840
 841         fs = calloc(1, sizeof(*fs));
 842         fs->base.rev = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_REVISION;
 843         fs->base.open_volume = efi_open_volume;
 844         fs->desc = desc;
 845         fs->part = part;
 846         fs->dp = dp;
 847
 848         return &fs->base;
 849 }