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efiblock.c revision 1.10.6.1
      1 /* $NetBSD: efiblock.c,v 1.10.6.1 2021/05/31 22:15:22 cjep Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2016 Kimihiro Nonaka <nonaka (at) netbsd.org>
      5  * Copyright (c) 2018 Jared McNeill <jmcneill (at) invisible.ca>
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     27  * SUCH DAMAGE.
     28  */
     29 
     30 #define FSTYPENAMES
     31 
     32 #include <sys/param.h>
     33 #include <sys/md5.h>
     34 #include <sys/uuid.h>
     35 
     36 #include <fs/cd9660/iso.h>
     37 
     38 #include "efiboot.h"
     39 #include "efiblock.h"
     40 
     41 /*
     42  * The raidframe support is basic.  Ideally, it should be expanded to
     43  * consider raid volumes a first-class citizen like the x86 efiboot does,
     44  * but for now, we simply assume each RAID is potentially bootable.
     45  */
     46 #define	RF_PROTECTED_SECTORS	64	/* XXX refer to <.../rf_optnames.h> */
     47 
     48 static EFI_HANDLE *efi_block;
     49 static UINTN efi_nblock;
     50 static struct efi_block_part *efi_block_booted = NULL;
     51 
     52 static TAILQ_HEAD(, efi_block_dev) efi_block_devs = TAILQ_HEAD_INITIALIZER(efi_block_devs);
     53 
     54 static int
     55 efi_block_parse(const char *fname, struct efi_block_part **pbpart, char **pfile)
     56 {
     57 	struct efi_block_dev *bdev;
     58 	struct efi_block_part *bpart;
     59 	char pathbuf[PATH_MAX], *default_device, *ep = NULL;
     60 	const char *full_path;
     61 	intmax_t dev;
     62 	int part;
     63 
     64 	default_device = get_default_device();
     65 	if (strchr(fname, ':') == NULL) {
     66 		if (strlen(default_device) > 0) {
     67 			snprintf(pathbuf, sizeof(pathbuf), "%s:%s", default_device, fname);
     68 			full_path = pathbuf;
     69 			*pfile = __UNCONST(fname);
     70 		} else {
     71 			return EINVAL;
     72 		}
     73 	} else {
     74 		full_path = fname;
     75 		*pfile = strchr(fname, ':') + 1;
     76 	}
     77 
     78 	if (strncasecmp(full_path, "hd", 2) != 0)
     79 		return EINVAL;
     80 	dev = strtoimax(full_path + 2, &ep, 10);
     81 	if (dev < 0 || dev >= efi_nblock)
     82 		return ENXIO;
     83 	if (ep[0] < 'a' || ep[0] >= 'a' + MAXPARTITIONS || ep[1] != ':')
     84 		return EINVAL;
     85 	part = ep[0] - 'a';
     86 	TAILQ_FOREACH(bdev, &efi_block_devs, entries) {
     87 		if (bdev->index == dev) {
     88 			TAILQ_FOREACH(bpart, &bdev->partitions, entries) {
     89 				if (bpart->index == part) {
     90 					*pbpart = bpart;
     91 					return 0;
     92 				}
     93 			}
     94 		}
     95 	}
     96 
     97 	return ENOENT;
     98 }
     99 
    100 static void
    101 efi_block_generate_hash_mbr(struct efi_block_part *bpart, struct mbr_sector *mbr)
    102 {
    103 	MD5_CTX md5ctx;
    104 
    105 	MD5Init(&md5ctx);
    106 	MD5Update(&md5ctx, (void *)mbr, sizeof(*mbr));
    107 	MD5Final(bpart->hash, &md5ctx);
    108 }
    109 
    110 static void *
    111 efi_block_allocate_device_buffer(struct efi_block_dev *bdev, UINTN size,
    112 	void **buf_start)
    113 {
    114 	void *buf;
    115 
    116 	if (bdev->bio->Media->IoAlign <= 1)
    117 		*buf_start = buf = AllocatePool(size);
    118 	else {
    119 		buf = AllocatePool(size + bdev->bio->Media->IoAlign - 1);
    120 		*buf_start = (buf == NULL) ? NULL :
    121 		    (void *)roundup2((intptr_t)buf, bdev->bio->Media->IoAlign);
    122 	}
    123 
    124 	return buf;
    125 }
    126 
    127 static int
    128 efi_block_find_partitions_cd9660(struct efi_block_dev *bdev)
    129 {
    130 	struct efi_block_part *bpart;
    131 	struct iso_primary_descriptor *vd;
    132 	void *buf, *buf_start;
    133 	EFI_STATUS status;
    134 	EFI_LBA lba;
    135 	UINT32 sz;
    136 
    137 	if (bdev->bio->Media->BlockSize != DEV_BSIZE &&
    138 	    bdev->bio->Media->BlockSize != ISO_DEFAULT_BLOCK_SIZE) {
    139 		return ENXIO;
    140 	}
    141 
    142 	sz = __MAX(sizeof(*vd), bdev->bio->Media->BlockSize);
    143 	sz = roundup(sz, bdev->bio->Media->BlockSize);
    144 	if ((buf = efi_block_allocate_device_buffer(bdev, sz, &buf_start)) == NULL) {
    145 		return ENOMEM;
    146 	}
    147 
    148 	for (lba = 16;; lba++) {
    149 		status = uefi_call_wrapper(bdev->bio->ReadBlocks, 5,
    150 		    bdev->bio,
    151 		    bdev->media_id,
    152 		    lba * ISO_DEFAULT_BLOCK_SIZE / bdev->bio->Media->BlockSize,
    153 		    sz,
    154 		    buf_start);
    155 		if (EFI_ERROR(status)) {
    156 			goto io_error;
    157 		}
    158 
    159 		vd = (struct iso_primary_descriptor *)buf_start;
    160 		if (memcmp(vd->id, ISO_STANDARD_ID, sizeof vd->id) != 0) {
    161 			goto io_error;
    162 		}
    163 		if (isonum_711(vd->type) == ISO_VD_END) {
    164 			goto io_error;
    165 		}
    166 		if (isonum_711(vd->type) == ISO_VD_PRIMARY) {
    167 			break;
    168 		}
    169 	}
    170 
    171 	if (isonum_723(vd->logical_block_size) != ISO_DEFAULT_BLOCK_SIZE) {
    172 		goto io_error;
    173 	}
    174 
    175 	bpart = alloc(sizeof(*bpart));
    176 	bpart->index = 0;
    177 	bpart->bdev = bdev;
    178 	bpart->type = EFI_BLOCK_PART_CD9660;
    179 	TAILQ_INSERT_TAIL(&bdev->partitions, bpart, entries);
    180 
    181 	FreePool(buf);
    182 	return 0;
    183 
    184 io_error:
    185 	FreePool(buf);
    186 	return EIO;
    187 }
    188 
    189 static int
    190 efi_block_find_partitions_disklabel(struct efi_block_dev *bdev, struct mbr_sector *mbr, uint32_t start, uint32_t size)
    191 {
    192 	struct efi_block_part *bpart;
    193 	struct disklabel d;
    194 	struct partition *p;
    195 	EFI_STATUS status;
    196 	EFI_LBA lba;
    197 	void *buf, *buf_start;
    198 	UINT32 sz;
    199 	int n;
    200 
    201 	sz = __MAX(sizeof(d), bdev->bio->Media->BlockSize);
    202 	sz = roundup(sz, bdev->bio->Media->BlockSize);
    203 	if ((buf = efi_block_allocate_device_buffer(bdev, sz, &buf_start)) == NULL)
    204 		return ENOMEM;
    205 
    206 	lba = (((EFI_LBA)start + LABELSECTOR) * DEV_BSIZE) / bdev->bio->Media->BlockSize;
    207 	status = uefi_call_wrapper(bdev->bio->ReadBlocks, 5, bdev->bio, bdev->media_id,
    208 		lba, sz, buf_start);
    209 	if (EFI_ERROR(status) || getdisklabel(buf_start, &d) != NULL) {
    210 		FreePool(buf);
    211 		return EIO;
    212 	}
    213 	FreePool(buf);
    214 
    215 	if (le32toh(d.d_magic) != DISKMAGIC || le32toh(d.d_magic2) != DISKMAGIC)
    216 		return EINVAL;
    217 	if (le16toh(d.d_npartitions) > MAXPARTITIONS)
    218 		return EINVAL;
    219 
    220 	for (n = 0; n < le16toh(d.d_npartitions); n++) {
    221 		p = &d.d_partitions[n];
    222 		switch (p->p_fstype) {
    223 		case FS_BSDFFS:
    224 		case FS_MSDOS:
    225 		case FS_BSDLFS:
    226 			break;
    227 		case FS_RAID:
    228 			p->p_size -= RF_PROTECTED_SECTORS;
    229 			p->p_offset += RF_PROTECTED_SECTORS;
    230 			break;
    231 		default:
    232 			continue;
    233 		}
    234 
    235 		bpart = alloc(sizeof(*bpart));
    236 		bpart->index = n;
    237 		bpart->bdev = bdev;
    238 		bpart->type = EFI_BLOCK_PART_DISKLABEL;
    239 		bpart->disklabel.secsize = d.d_secsize;
    240 		bpart->disklabel.part = *p;
    241 		efi_block_generate_hash_mbr(bpart, mbr);
    242 		TAILQ_INSERT_TAIL(&bdev->partitions, bpart, entries);
    243 	}
    244 
    245 	return 0;
    246 }
    247 
    248 static int
    249 efi_block_find_partitions_mbr(struct efi_block_dev *bdev)
    250 {
    251 	struct mbr_sector mbr;
    252 	struct mbr_partition *mbr_part;
    253 	EFI_STATUS status;
    254 	void *buf, *buf_start;
    255 	UINT32 sz;
    256 	int n;
    257 
    258 	sz = __MAX(sizeof(mbr), bdev->bio->Media->BlockSize);
    259 	sz = roundup(sz, bdev->bio->Media->BlockSize);
    260 	if ((buf = efi_block_allocate_device_buffer(bdev, sz, &buf_start)) == NULL)
    261 		return ENOMEM;
    262 
    263 	status = uefi_call_wrapper(bdev->bio->ReadBlocks, 5, bdev->bio, bdev->media_id,
    264 		0, sz, buf_start);
    265 	if (EFI_ERROR(status)) {
    266 		FreePool(buf);
    267 		return EIO;
    268 	}
    269 	memcpy(&mbr, buf_start, sizeof(mbr));
    270 	FreePool(buf);
    271 
    272 	if (le32toh(mbr.mbr_magic) != MBR_MAGIC)
    273 		return ENOENT;
    274 
    275 	for (n = 0; n < MBR_PART_COUNT; n++) {
    276 		mbr_part = &mbr.mbr_parts[n];
    277 		if (le32toh(mbr_part->mbrp_size) == 0)
    278 			continue;
    279 		if (mbr_part->mbrp_type == MBR_PTYPE_NETBSD) {
    280 			efi_block_find_partitions_disklabel(bdev, &mbr, le32toh(mbr_part->mbrp_start), le32toh(mbr_part->mbrp_size));
    281 			break;
    282 		}
    283 	}
    284 
    285 	return 0;
    286 }
    287 
    288 static const struct {
    289 	struct uuid guid;
    290 	uint8_t fstype;
    291 } gpt_guid_to_str[] = {
    292 	{ GPT_ENT_TYPE_NETBSD_FFS,		FS_BSDFFS },
    293 	{ GPT_ENT_TYPE_NETBSD_LFS,		FS_BSDLFS },
    294 	{ GPT_ENT_TYPE_NETBSD_RAIDFRAME,	FS_RAID },
    295 	{ GPT_ENT_TYPE_NETBSD_CCD,		FS_CCD },
    296 	{ GPT_ENT_TYPE_NETBSD_CGD,		FS_CGD },
    297 	{ GPT_ENT_TYPE_MS_BASIC_DATA,		FS_MSDOS },	/* or NTFS? ambiguous */
    298 	{ GPT_ENT_TYPE_EFI,			FS_MSDOS },
    299 };
    300 
    301 static int
    302 efi_block_find_partitions_gpt_entry(struct efi_block_dev *bdev, struct gpt_hdr *hdr, struct gpt_ent *ent, UINT32 index)
    303 {
    304 	struct efi_block_part *bpart;
    305 	uint8_t fstype = FS_UNUSED;
    306 	struct uuid uuid;
    307 	int n;
    308 
    309 	memcpy(&uuid, ent->ent_type, sizeof(uuid));
    310 	for (n = 0; n < __arraycount(gpt_guid_to_str); n++)
    311 		if (memcmp(ent->ent_type, &gpt_guid_to_str[n].guid, sizeof(ent->ent_type)) == 0) {
    312 			fstype = gpt_guid_to_str[n].fstype;
    313 			break;
    314 		}
    315 	if (fstype == FS_UNUSED)
    316 		return 0;
    317 
    318 	bpart = alloc(sizeof(*bpart));
    319 	bpart->index = index;
    320 	bpart->bdev = bdev;
    321 	bpart->type = EFI_BLOCK_PART_GPT;
    322 	bpart->gpt.fstype = fstype;
    323 	bpart->gpt.ent = *ent;
    324 	if (fstype == FS_RAID) {
    325 		bpart->gpt.ent.ent_lba_start += RF_PROTECTED_SECTORS;
    326 		bpart->gpt.ent.ent_lba_end -= RF_PROTECTED_SECTORS;
    327 	}
    328 	memcpy(bpart->hash, ent->ent_guid, sizeof(bpart->hash));
    329 	TAILQ_INSERT_TAIL(&bdev->partitions, bpart, entries);
    330 
    331 	return 0;
    332 }
    333 
    334 static int
    335 efi_block_find_partitions_gpt(struct efi_block_dev *bdev)
    336 {
    337 	struct gpt_hdr hdr;
    338 	struct gpt_ent ent;
    339 	EFI_STATUS status;
    340 	void *buf, *buf_start;
    341 	UINT32 sz, entry;
    342 
    343 	sz = __MAX(sizeof(hdr), bdev->bio->Media->BlockSize);
    344 	sz = roundup(sz, bdev->bio->Media->BlockSize);
    345 	if ((buf = efi_block_allocate_device_buffer(bdev, sz, &buf_start)) == NULL)
    346 		return ENOMEM;
    347 
    348 	status = uefi_call_wrapper(bdev->bio->ReadBlocks, 5, bdev->bio, bdev->media_id,
    349 		GPT_HDR_BLKNO, sz, buf_start);
    350 	if (EFI_ERROR(status)) {
    351 		FreePool(buf);
    352 		return EIO;
    353 	}
    354 	memcpy(&hdr, buf_start, sizeof(hdr));
    355 	FreePool(buf);
    356 
    357 	if (memcmp(hdr.hdr_sig, GPT_HDR_SIG, sizeof(hdr.hdr_sig)) != 0)
    358 		return ENOENT;
    359 	if (le32toh(hdr.hdr_entsz) < sizeof(ent))
    360 		return EINVAL;
    361 
    362 	sz = __MAX(le32toh(hdr.hdr_entsz) * le32toh(hdr.hdr_entries), bdev->bio->Media->BlockSize);
    363 	sz = roundup(sz, bdev->bio->Media->BlockSize);
    364 	if ((buf = efi_block_allocate_device_buffer(bdev, sz, &buf_start)) == NULL)
    365 		return ENOMEM;
    366 
    367 	status = uefi_call_wrapper(bdev->bio->ReadBlocks, 5, bdev->bio, bdev->media_id,
    368 		le64toh(hdr.hdr_lba_table), sz, buf_start);
    369 	if (EFI_ERROR(status)) {
    370 		FreePool(buf);
    371 		return EIO;
    372 	}
    373 
    374 	for (entry = 0; entry < le32toh(hdr.hdr_entries); entry++) {
    375 		memcpy(&ent, buf_start + (entry * le32toh(hdr.hdr_entsz)),
    376 			sizeof(ent));
    377 		efi_block_find_partitions_gpt_entry(bdev, &hdr, &ent, entry);
    378 	}
    379 
    380 	FreePool(buf);
    381 
    382 	return 0;
    383 }
    384 
    385 static int
    386 efi_block_find_partitions(struct efi_block_dev *bdev)
    387 {
    388 	int error;
    389 
    390 	error = efi_block_find_partitions_gpt(bdev);
    391 	if (error)
    392 		error = efi_block_find_partitions_mbr(bdev);
    393 	if (error)
    394 		error = efi_block_find_partitions_cd9660(bdev);
    395 
    396 	return error;
    397 }
    398 
    399 void
    400 efi_block_probe(void)
    401 {
    402 	struct efi_block_dev *bdev;
    403 	struct efi_block_part *bpart;
    404 	EFI_BLOCK_IO *bio;
    405 	EFI_STATUS status;
    406 	uint16_t devindex = 0;
    407 	int depth = -1;
    408 	int n;
    409 
    410 	status = LibLocateHandle(ByProtocol, &BlockIoProtocol, NULL, &efi_nblock, &efi_block);
    411 	if (EFI_ERROR(status))
    412 		return;
    413 
    414 	if (efi_bootdp) {
    415 		depth = efi_device_path_depth(efi_bootdp, MEDIA_DEVICE_PATH);
    416 		if (depth == 0)
    417 			depth = 1;
    418 		else if (depth == -1)
    419 			depth = 2;
    420 	}
    421 
    422 	for (n = 0; n < efi_nblock; n++) {
    423 		status = uefi_call_wrapper(BS->HandleProtocol, 3, efi_block[n], &BlockIoProtocol, (void **)&bio);
    424 		if (EFI_ERROR(status) || !bio->Media->MediaPresent)
    425 			continue;
    426 
    427 		if (bio->Media->LogicalPartition)
    428 			continue;
    429 
    430 		bdev = alloc(sizeof(*bdev));
    431 		bdev->index = devindex++;
    432 		bdev->bio = bio;
    433 		bdev->media_id = bio->Media->MediaId;
    434 		bdev->path = DevicePathFromHandle(efi_block[n]);
    435 		TAILQ_INIT(&bdev->partitions);
    436 		TAILQ_INSERT_TAIL(&efi_block_devs, bdev, entries);
    437 
    438 		efi_block_find_partitions(bdev);
    439 
    440 		if (depth > 0 && efi_device_path_ncmp(efi_bootdp, DevicePathFromHandle(efi_block[n]), depth) == 0) {
    441 			TAILQ_FOREACH(bpart, &bdev->partitions, entries) {
    442 				uint8_t fstype = FS_UNUSED;
    443 				switch (bpart->type) {
    444 				case EFI_BLOCK_PART_DISKLABEL:
    445 					fstype = bpart->disklabel.part.p_fstype;
    446 					break;
    447 				case EFI_BLOCK_PART_GPT:
    448 					fstype = bpart->gpt.fstype;
    449 					break;
    450 				case EFI_BLOCK_PART_CD9660:
    451 					fstype = FS_ISO9660;
    452 					break;
    453 				}
    454 				if (fstype == FS_BSDFFS || fstype == FS_ISO9660 || fstype == FS_RAID) {
    455 					char devname[9];
    456 					snprintf(devname, sizeof(devname), "hd%u%c", bdev->index, bpart->index + 'a');
    457 					set_default_device(devname);
    458 					set_default_fstype(fstype);
    459 					break;
    460 				}
    461 			}
    462 		}
    463 	}
    464 }
    465 
    466 static void
    467 print_guid(const uint8_t *guid)
    468 {
    469 	const int index[] = { 3, 2, 1, 0, 5, 4, 7, 6, 8, 9, 10, 11, 12, 13, 14, 15 };
    470 	int i;
    471 
    472 	for (i = 0; i < 16; i++) {
    473 		printf("%02x", guid[index[i]]);
    474 		if (i == 3 || i == 5 || i == 7 || i == 9)
    475 			printf("-");
    476 	}
    477 }
    478 
    479 void
    480 efi_block_show(void)
    481 {
    482 	struct efi_block_dev *bdev;
    483 	struct efi_block_part *bpart;
    484 	uint64_t size;
    485 	CHAR16 *path;
    486 
    487 	TAILQ_FOREACH(bdev, &efi_block_devs, entries) {
    488 		printf("hd%u (", bdev->index);
    489 
    490 		/* Size in MB */
    491 		size = ((bdev->bio->Media->LastBlock + 1) * bdev->bio->Media->BlockSize) / (1024 * 1024);
    492 		if (size >= 10000)
    493 			printf("%"PRIu64" GB", size / 1024);
    494 		else
    495 			printf("%"PRIu64" MB", size);
    496 		printf("): ");
    497 
    498 		path = DevicePathToStr(bdev->path);
    499 		Print(L"%s", path);
    500 		FreePool(path);
    501 
    502 		printf("\n");
    503 
    504 		TAILQ_FOREACH(bpart, &bdev->partitions, entries) {
    505 			switch (bpart->type) {
    506 			case EFI_BLOCK_PART_DISKLABEL:
    507 				printf("  hd%u%c (", bdev->index, bpart->index + 'a');
    508 
    509 				/* Size in MB */
    510 				size = ((uint64_t)bpart->disklabel.secsize * bpart->disklabel.part.p_size) / (1024 * 1024);
    511 				if (size >= 10000)
    512 					printf("%"PRIu64" GB", size / 1024);
    513 				else
    514 					printf("%"PRIu64" MB", size);
    515 				printf("): ");
    516 
    517 				printf("%s\n", fstypenames[bpart->disklabel.part.p_fstype]);
    518 				break;
    519 			case EFI_BLOCK_PART_GPT:
    520 				printf("  hd%u%c ", bdev->index, bpart->index + 'a');
    521 
    522 				if (bpart->gpt.ent.ent_name[0] == 0x0000) {
    523 					printf("\"");
    524 					print_guid(bpart->gpt.ent.ent_guid);
    525 					printf("\"");
    526 				} else {
    527 					Print(L"\"%s\"", bpart->gpt.ent.ent_name);
    528 				}
    529 
    530 				/* Size in MB */
    531 				size = (le64toh(bpart->gpt.ent.ent_lba_end) - le64toh(bpart->gpt.ent.ent_lba_start)) * bdev->bio->Media->BlockSize;
    532 				size /= (1024 * 1024);
    533 				if (size >= 10000)
    534 					printf(" (%"PRIu64" GB): ", size / 1024);
    535 				else
    536 					printf(" (%"PRIu64" MB): ", size);
    537 
    538 				printf("%s\n", fstypenames[bpart->gpt.fstype]);
    539 				break;
    540 			case EFI_BLOCK_PART_CD9660:
    541 				printf("  hd%u%c %s\n", bdev->index, bpart->index + 'a', fstypenames[FS_ISO9660]);
    542 				break;
    543 			default:
    544 				break;
    545 			}
    546 		}
    547 	}
    548 }
    549 
    550 struct efi_block_part *
    551 efi_block_boot_part(void)
    552 {
    553 	return efi_block_booted;
    554 }
    555 
    556 int
    557 efi_block_open(struct open_file *f, ...)
    558 {
    559 	struct efi_block_part *bpart;
    560 	const char *fname;
    561 	char **file;
    562 	char *path;
    563 	va_list ap;
    564 	int rv, n;
    565 
    566 	va_start(ap, f);
    567 	fname = va_arg(ap, const char *);
    568 	file = va_arg(ap, char **);
    569 	va_end(ap);
    570 
    571 	rv = efi_block_parse(fname, &bpart, &path);
    572 	if (rv != 0)
    573 		return rv;
    574 
    575 	for (n = 0; n < ndevs; n++)
    576 		if (strcmp(DEV_NAME(&devsw[n]), "efiblock") == 0) {
    577 			f->f_dev = &devsw[n];
    578 			break;
    579 		}
    580 	if (n == ndevs)
    581 		return ENXIO;
    582 
    583 	f->f_devdata = bpart;
    584 
    585 	*file = path;
    586 
    587 	efi_block_booted = bpart;
    588 
    589 	return 0;
    590 }
    591 
    592 int
    593 efi_block_close(struct open_file *f)
    594 {
    595 	return 0;
    596 }
    597 
    598 int
    599 efi_block_strategy(void *devdata, int rw, daddr_t dblk, size_t size, void *buf, size_t *rsize)
    600 {
    601 	struct efi_block_part *bpart = devdata;
    602 	EFI_STATUS status;
    603 	void *allocated_buf, *aligned_buf;
    604 
    605 	if (rw != F_READ)
    606 		return EROFS;
    607 
    608 	switch (bpart->type) {
    609 	case EFI_BLOCK_PART_DISKLABEL:
    610 		if (bpart->bdev->bio->Media->BlockSize != bpart->disklabel.secsize) {
    611 			printf("%s: unsupported block size %d (expected %d)\n", __func__,
    612 			    bpart->bdev->bio->Media->BlockSize, bpart->disklabel.secsize);
    613 			return EIO;
    614 		}
    615 		dblk += bpart->disklabel.part.p_offset;
    616 		break;
    617 	case EFI_BLOCK_PART_GPT:
    618 		if (bpart->bdev->bio->Media->BlockSize != DEV_BSIZE) {
    619 			printf("%s: unsupported block size %d (expected %d)\n", __func__,
    620 			    bpart->bdev->bio->Media->BlockSize, DEV_BSIZE);
    621 			return EIO;
    622 		}
    623 		dblk += le64toh(bpart->gpt.ent.ent_lba_start);
    624 		break;
    625 	case EFI_BLOCK_PART_CD9660:
    626 		dblk *= ISO_DEFAULT_BLOCK_SIZE / bpart->bdev->bio->Media->BlockSize;
    627 		break;
    628 	default:
    629 		return EINVAL;
    630 	}
    631 
    632 	if ((bpart->bdev->bio->Media->IoAlign <= 1) ||
    633 		((intptr_t)buf & (bpart->bdev->bio->Media->IoAlign - 1)) == 0) {
    634 		allocated_buf = NULL;
    635 		aligned_buf = buf;
    636 	} else if ((allocated_buf = efi_block_allocate_device_buffer(bpart->bdev,
    637 		size, &aligned_buf)) == NULL) {
    638 		return ENOMEM;
    639 	}
    640 
    641 	status = uefi_call_wrapper(bpart->bdev->bio->ReadBlocks, 5,
    642 		bpart->bdev->bio, bpart->bdev->media_id, dblk, size, aligned_buf);
    643 	if (EFI_ERROR(status)) {
    644 		if (allocated_buf != NULL)
    645 			FreePool(allocated_buf);
    646 		return EIO;
    647 	}
    648 	if (allocated_buf != NULL) {
    649 		memcpy(buf, aligned_buf, size);
    650 		FreePool(allocated_buf);
    651 	}
    652 
    653 	*rsize = size;
    654 
    655 	return 0;
    656 }
    657