xref: /openbmc/u-boot/fs/fat/fat.c (revision fb740646)
1 /*
2  * fat.c
3  *
4  * R/O (V)FAT 12/16/32 filesystem implementation by Marcus Sundberg
5  *
6  * 2002-07-28 - rjones@nexus-tech.net - ported to ppcboot v1.1.6
7  * 2003-03-10 - kharris@nexus-tech.net - ported to uboot
8  *
9  * SPDX-License-Identifier:	GPL-2.0+
10  */
11 
12 #include <common.h>
13 #include <blk.h>
14 #include <config.h>
15 #include <exports.h>
16 #include <fat.h>
17 #include <fs.h>
18 #include <asm/byteorder.h>
19 #include <part.h>
20 #include <malloc.h>
21 #include <memalign.h>
22 #include <linux/compiler.h>
23 #include <linux/ctype.h>
24 
25 #ifdef CONFIG_SUPPORT_VFAT
26 static const int vfat_enabled = 1;
27 #else
28 static const int vfat_enabled = 0;
29 #endif
30 
31 /*
32  * Convert a string to lowercase.  Converts at most 'len' characters,
33  * 'len' may be larger than the length of 'str' if 'str' is NULL
34  * terminated.
35  */
36 static void downcase(char *str, size_t len)
37 {
38 	while (*str != '\0' && len--) {
39 		*str = tolower(*str);
40 		str++;
41 	}
42 }
43 
44 static struct blk_desc *cur_dev;
45 static disk_partition_t cur_part_info;
46 
47 #define DOS_BOOT_MAGIC_OFFSET	0x1fe
48 #define DOS_FS_TYPE_OFFSET	0x36
49 #define DOS_FS32_TYPE_OFFSET	0x52
50 
51 static int disk_read(__u32 block, __u32 nr_blocks, void *buf)
52 {
53 	ulong ret;
54 
55 	if (!cur_dev)
56 		return -1;
57 
58 	ret = blk_dread(cur_dev, cur_part_info.start + block, nr_blocks, buf);
59 
60 	if (ret != nr_blocks)
61 		return -1;
62 
63 	return ret;
64 }
65 
66 int fat_set_blk_dev(struct blk_desc *dev_desc, disk_partition_t *info)
67 {
68 	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, dev_desc->blksz);
69 
70 	cur_dev = dev_desc;
71 	cur_part_info = *info;
72 
73 	/* Make sure it has a valid FAT header */
74 	if (disk_read(0, 1, buffer) != 1) {
75 		cur_dev = NULL;
76 		return -1;
77 	}
78 
79 	/* Check if it's actually a DOS volume */
80 	if (memcmp(buffer + DOS_BOOT_MAGIC_OFFSET, "\x55\xAA", 2)) {
81 		cur_dev = NULL;
82 		return -1;
83 	}
84 
85 	/* Check for FAT12/FAT16/FAT32 filesystem */
86 	if (!memcmp(buffer + DOS_FS_TYPE_OFFSET, "FAT", 3))
87 		return 0;
88 	if (!memcmp(buffer + DOS_FS32_TYPE_OFFSET, "FAT32", 5))
89 		return 0;
90 
91 	cur_dev = NULL;
92 	return -1;
93 }
94 
95 int fat_register_device(struct blk_desc *dev_desc, int part_no)
96 {
97 	disk_partition_t info;
98 
99 	/* First close any currently found FAT filesystem */
100 	cur_dev = NULL;
101 
102 	/* Read the partition table, if present */
103 	if (part_get_info(dev_desc, part_no, &info)) {
104 		if (part_no != 0) {
105 			printf("** Partition %d not valid on device %d **\n",
106 					part_no, dev_desc->devnum);
107 			return -1;
108 		}
109 
110 		info.start = 0;
111 		info.size = dev_desc->lba;
112 		info.blksz = dev_desc->blksz;
113 		info.name[0] = 0;
114 		info.type[0] = 0;
115 		info.bootable = 0;
116 #if CONFIG_IS_ENABLED(PARTITION_UUIDS)
117 		info.uuid[0] = 0;
118 #endif
119 	}
120 
121 	return fat_set_blk_dev(dev_desc, &info);
122 }
123 
124 /*
125  * Extract zero terminated short name from a directory entry.
126  */
127 static void get_name(dir_entry *dirent, char *s_name)
128 {
129 	char *ptr;
130 
131 	memcpy(s_name, dirent->name, 8);
132 	s_name[8] = '\0';
133 	ptr = s_name;
134 	while (*ptr && *ptr != ' ')
135 		ptr++;
136 	if (dirent->lcase & CASE_LOWER_BASE)
137 		downcase(s_name, (unsigned)(ptr - s_name));
138 	if (dirent->ext[0] && dirent->ext[0] != ' ') {
139 		*ptr++ = '.';
140 		memcpy(ptr, dirent->ext, 3);
141 		if (dirent->lcase & CASE_LOWER_EXT)
142 			downcase(ptr, 3);
143 		ptr[3] = '\0';
144 		while (*ptr && *ptr != ' ')
145 			ptr++;
146 	}
147 	*ptr = '\0';
148 	if (*s_name == DELETED_FLAG)
149 		*s_name = '\0';
150 	else if (*s_name == aRING)
151 		*s_name = DELETED_FLAG;
152 }
153 
154 static int flush_dirty_fat_buffer(fsdata *mydata);
155 #if !defined(CONFIG_FAT_WRITE)
156 /* Stub for read only operation */
157 int flush_dirty_fat_buffer(fsdata *mydata)
158 {
159 	(void)(mydata);
160 	return 0;
161 }
162 #endif
163 
164 /*
165  * Get the entry at index 'entry' in a FAT (12/16/32) table.
166  * On failure 0x00 is returned.
167  */
168 static __u32 get_fatent(fsdata *mydata, __u32 entry)
169 {
170 	__u32 bufnum;
171 	__u32 offset, off8;
172 	__u32 ret = 0x00;
173 
174 	if (CHECK_CLUST(entry, mydata->fatsize)) {
175 		printf("Error: Invalid FAT entry: 0x%08x\n", entry);
176 		return ret;
177 	}
178 
179 	switch (mydata->fatsize) {
180 	case 32:
181 		bufnum = entry / FAT32BUFSIZE;
182 		offset = entry - bufnum * FAT32BUFSIZE;
183 		break;
184 	case 16:
185 		bufnum = entry / FAT16BUFSIZE;
186 		offset = entry - bufnum * FAT16BUFSIZE;
187 		break;
188 	case 12:
189 		bufnum = entry / FAT12BUFSIZE;
190 		offset = entry - bufnum * FAT12BUFSIZE;
191 		break;
192 
193 	default:
194 		/* Unsupported FAT size */
195 		return ret;
196 	}
197 
198 	debug("FAT%d: entry: 0x%08x = %d, offset: 0x%04x = %d\n",
199 	       mydata->fatsize, entry, entry, offset, offset);
200 
201 	/* Read a new block of FAT entries into the cache. */
202 	if (bufnum != mydata->fatbufnum) {
203 		__u32 getsize = FATBUFBLOCKS;
204 		__u8 *bufptr = mydata->fatbuf;
205 		__u32 fatlength = mydata->fatlength;
206 		__u32 startblock = bufnum * FATBUFBLOCKS;
207 
208 		/* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
209 		if (startblock + getsize > fatlength)
210 			getsize = fatlength - startblock;
211 
212 		startblock += mydata->fat_sect;	/* Offset from start of disk */
213 
214 		/* Write back the fatbuf to the disk */
215 		if (flush_dirty_fat_buffer(mydata) < 0)
216 			return -1;
217 
218 		if (disk_read(startblock, getsize, bufptr) < 0) {
219 			debug("Error reading FAT blocks\n");
220 			return ret;
221 		}
222 		mydata->fatbufnum = bufnum;
223 	}
224 
225 	/* Get the actual entry from the table */
226 	switch (mydata->fatsize) {
227 	case 32:
228 		ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
229 		break;
230 	case 16:
231 		ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
232 		break;
233 	case 12:
234 		off8 = (offset * 3) / 2;
235 		/* fatbut + off8 may be unaligned, read in byte granularity */
236 		ret = mydata->fatbuf[off8] + (mydata->fatbuf[off8 + 1] << 8);
237 
238 		if (offset & 0x1)
239 			ret >>= 4;
240 		ret &= 0xfff;
241 	}
242 	debug("FAT%d: ret: 0x%08x, entry: 0x%08x, offset: 0x%04x\n",
243 	       mydata->fatsize, ret, entry, offset);
244 
245 	return ret;
246 }
247 
248 /*
249  * Read at most 'size' bytes from the specified cluster into 'buffer'.
250  * Return 0 on success, -1 otherwise.
251  */
252 static int
253 get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
254 {
255 	__u32 idx = 0;
256 	__u32 startsect;
257 	int ret;
258 
259 	if (clustnum > 0) {
260 		startsect = clust_to_sect(mydata, clustnum);
261 	} else {
262 		startsect = mydata->rootdir_sect;
263 	}
264 
265 	debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect);
266 
267 	if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
268 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
269 
270 		printf("FAT: Misaligned buffer address (%p)\n", buffer);
271 
272 		while (size >= mydata->sect_size) {
273 			ret = disk_read(startsect++, 1, tmpbuf);
274 			if (ret != 1) {
275 				debug("Error reading data (got %d)\n", ret);
276 				return -1;
277 			}
278 
279 			memcpy(buffer, tmpbuf, mydata->sect_size);
280 			buffer += mydata->sect_size;
281 			size -= mydata->sect_size;
282 		}
283 	} else {
284 		idx = size / mydata->sect_size;
285 		ret = disk_read(startsect, idx, buffer);
286 		if (ret != idx) {
287 			debug("Error reading data (got %d)\n", ret);
288 			return -1;
289 		}
290 		startsect += idx;
291 		idx *= mydata->sect_size;
292 		buffer += idx;
293 		size -= idx;
294 	}
295 	if (size) {
296 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
297 
298 		ret = disk_read(startsect, 1, tmpbuf);
299 		if (ret != 1) {
300 			debug("Error reading data (got %d)\n", ret);
301 			return -1;
302 		}
303 
304 		memcpy(buffer, tmpbuf, size);
305 	}
306 
307 	return 0;
308 }
309 
310 /*
311  * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr'
312  * into 'buffer'.
313  * Update the number of bytes read in *gotsize or return -1 on fatal errors.
314  */
315 __u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
316 	__aligned(ARCH_DMA_MINALIGN);
317 
318 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
319 			__u8 *buffer, loff_t maxsize, loff_t *gotsize)
320 {
321 	loff_t filesize = FAT2CPU32(dentptr->size);
322 	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
323 	__u32 curclust = START(dentptr);
324 	__u32 endclust, newclust;
325 	loff_t actsize;
326 
327 	*gotsize = 0;
328 	debug("Filesize: %llu bytes\n", filesize);
329 
330 	if (pos >= filesize) {
331 		debug("Read position past EOF: %llu\n", pos);
332 		return 0;
333 	}
334 
335 	if (maxsize > 0 && filesize > pos + maxsize)
336 		filesize = pos + maxsize;
337 
338 	debug("%llu bytes\n", filesize);
339 
340 	actsize = bytesperclust;
341 
342 	/* go to cluster at pos */
343 	while (actsize <= pos) {
344 		curclust = get_fatent(mydata, curclust);
345 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
346 			debug("curclust: 0x%x\n", curclust);
347 			debug("Invalid FAT entry\n");
348 			return 0;
349 		}
350 		actsize += bytesperclust;
351 	}
352 
353 	/* actsize > pos */
354 	actsize -= bytesperclust;
355 	filesize -= actsize;
356 	pos -= actsize;
357 
358 	/* align to beginning of next cluster if any */
359 	if (pos) {
360 		actsize = min(filesize, (loff_t)bytesperclust);
361 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
362 				(int)actsize) != 0) {
363 			printf("Error reading cluster\n");
364 			return -1;
365 		}
366 		filesize -= actsize;
367 		actsize -= pos;
368 		memcpy(buffer, get_contents_vfatname_block + pos, actsize);
369 		*gotsize += actsize;
370 		if (!filesize)
371 			return 0;
372 		buffer += actsize;
373 
374 		curclust = get_fatent(mydata, curclust);
375 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
376 			debug("curclust: 0x%x\n", curclust);
377 			debug("Invalid FAT entry\n");
378 			return 0;
379 		}
380 	}
381 
382 	actsize = bytesperclust;
383 	endclust = curclust;
384 
385 	do {
386 		/* search for consecutive clusters */
387 		while (actsize < filesize) {
388 			newclust = get_fatent(mydata, endclust);
389 			if ((newclust - 1) != endclust)
390 				goto getit;
391 			if (CHECK_CLUST(newclust, mydata->fatsize)) {
392 				debug("curclust: 0x%x\n", newclust);
393 				debug("Invalid FAT entry\n");
394 				return 0;
395 			}
396 			endclust = newclust;
397 			actsize += bytesperclust;
398 		}
399 
400 		/* get remaining bytes */
401 		actsize = filesize;
402 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
403 			printf("Error reading cluster\n");
404 			return -1;
405 		}
406 		*gotsize += actsize;
407 		return 0;
408 getit:
409 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
410 			printf("Error reading cluster\n");
411 			return -1;
412 		}
413 		*gotsize += (int)actsize;
414 		filesize -= actsize;
415 		buffer += actsize;
416 
417 		curclust = get_fatent(mydata, endclust);
418 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
419 			debug("curclust: 0x%x\n", curclust);
420 			printf("Invalid FAT entry\n");
421 			return 0;
422 		}
423 		actsize = bytesperclust;
424 		endclust = curclust;
425 	} while (1);
426 }
427 
428 /*
429  * Extract the file name information from 'slotptr' into 'l_name',
430  * starting at l_name[*idx].
431  * Return 1 if terminator (zero byte) is found, 0 otherwise.
432  */
433 static int slot2str(dir_slot *slotptr, char *l_name, int *idx)
434 {
435 	int j;
436 
437 	for (j = 0; j <= 8; j += 2) {
438 		l_name[*idx] = slotptr->name0_4[j];
439 		if (l_name[*idx] == 0x00)
440 			return 1;
441 		(*idx)++;
442 	}
443 	for (j = 0; j <= 10; j += 2) {
444 		l_name[*idx] = slotptr->name5_10[j];
445 		if (l_name[*idx] == 0x00)
446 			return 1;
447 		(*idx)++;
448 	}
449 	for (j = 0; j <= 2; j += 2) {
450 		l_name[*idx] = slotptr->name11_12[j];
451 		if (l_name[*idx] == 0x00)
452 			return 1;
453 		(*idx)++;
454 	}
455 
456 	return 0;
457 }
458 
459 /* Calculate short name checksum */
460 static __u8 mkcksum(const char name[8], const char ext[3])
461 {
462 	int i;
463 
464 	__u8 ret = 0;
465 
466 	for (i = 0; i < 8; i++)
467 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
468 	for (i = 0; i < 3; i++)
469 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
470 
471 	return ret;
472 }
473 
474 /*
475  * TODO these should go away once fat_write is reworked to use the
476  * directory iterator
477  */
478 __u8 get_dentfromdir_block[MAX_CLUSTSIZE]
479 	__aligned(ARCH_DMA_MINALIGN);
480 __u8 do_fat_read_at_block[MAX_CLUSTSIZE]
481 	__aligned(ARCH_DMA_MINALIGN);
482 
483 /*
484  * Read boot sector and volume info from a FAT filesystem
485  */
486 static int
487 read_bootsectandvi(boot_sector *bs, volume_info *volinfo, int *fatsize)
488 {
489 	__u8 *block;
490 	volume_info *vistart;
491 	int ret = 0;
492 
493 	if (cur_dev == NULL) {
494 		debug("Error: no device selected\n");
495 		return -1;
496 	}
497 
498 	block = memalign(ARCH_DMA_MINALIGN, cur_dev->blksz);
499 	if (block == NULL) {
500 		debug("Error: allocating block\n");
501 		return -1;
502 	}
503 
504 	if (disk_read(0, 1, block) < 0) {
505 		debug("Error: reading block\n");
506 		goto fail;
507 	}
508 
509 	memcpy(bs, block, sizeof(boot_sector));
510 	bs->reserved = FAT2CPU16(bs->reserved);
511 	bs->fat_length = FAT2CPU16(bs->fat_length);
512 	bs->secs_track = FAT2CPU16(bs->secs_track);
513 	bs->heads = FAT2CPU16(bs->heads);
514 	bs->total_sect = FAT2CPU32(bs->total_sect);
515 
516 	/* FAT32 entries */
517 	if (bs->fat_length == 0) {
518 		/* Assume FAT32 */
519 		bs->fat32_length = FAT2CPU32(bs->fat32_length);
520 		bs->flags = FAT2CPU16(bs->flags);
521 		bs->root_cluster = FAT2CPU32(bs->root_cluster);
522 		bs->info_sector = FAT2CPU16(bs->info_sector);
523 		bs->backup_boot = FAT2CPU16(bs->backup_boot);
524 		vistart = (volume_info *)(block + sizeof(boot_sector));
525 		*fatsize = 32;
526 	} else {
527 		vistart = (volume_info *)&(bs->fat32_length);
528 		*fatsize = 0;
529 	}
530 	memcpy(volinfo, vistart, sizeof(volume_info));
531 
532 	if (*fatsize == 32) {
533 		if (strncmp(FAT32_SIGN, vistart->fs_type, SIGNLEN) == 0)
534 			goto exit;
535 	} else {
536 		if (strncmp(FAT12_SIGN, vistart->fs_type, SIGNLEN) == 0) {
537 			*fatsize = 12;
538 			goto exit;
539 		}
540 		if (strncmp(FAT16_SIGN, vistart->fs_type, SIGNLEN) == 0) {
541 			*fatsize = 16;
542 			goto exit;
543 		}
544 	}
545 
546 	debug("Error: broken fs_type sign\n");
547 fail:
548 	ret = -1;
549 exit:
550 	free(block);
551 	return ret;
552 }
553 
554 static int get_fs_info(fsdata *mydata)
555 {
556 	boot_sector bs;
557 	volume_info volinfo;
558 	int ret;
559 
560 	ret = read_bootsectandvi(&bs, &volinfo, &mydata->fatsize);
561 	if (ret) {
562 		debug("Error: reading boot sector\n");
563 		return ret;
564 	}
565 
566 	if (mydata->fatsize == 32) {
567 		mydata->fatlength = bs.fat32_length;
568 	} else {
569 		mydata->fatlength = bs.fat_length;
570 	}
571 
572 	mydata->fat_sect = bs.reserved;
573 
574 	mydata->rootdir_sect = mydata->fat_sect + mydata->fatlength * bs.fats;
575 
576 	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
577 	mydata->clust_size = bs.cluster_size;
578 	if (mydata->sect_size != cur_part_info.blksz) {
579 		printf("Error: FAT sector size mismatch (fs=%hu, dev=%lu)\n",
580 				mydata->sect_size, cur_part_info.blksz);
581 		return -1;
582 	}
583 
584 	if (mydata->fatsize == 32) {
585 		mydata->data_begin = mydata->rootdir_sect -
586 					(mydata->clust_size * 2);
587 		mydata->root_cluster = bs.root_cluster;
588 	} else {
589 		mydata->rootdir_size = ((bs.dir_entries[1]  * (int)256 +
590 					 bs.dir_entries[0]) *
591 					 sizeof(dir_entry)) /
592 					 mydata->sect_size;
593 		mydata->data_begin = mydata->rootdir_sect +
594 					mydata->rootdir_size -
595 					(mydata->clust_size * 2);
596 		mydata->root_cluster =
597 			sect_to_clust(mydata, mydata->rootdir_sect);
598 	}
599 
600 	mydata->fatbufnum = -1;
601 	mydata->fat_dirty = 0;
602 	mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
603 	if (mydata->fatbuf == NULL) {
604 		debug("Error: allocating memory\n");
605 		return -1;
606 	}
607 
608 	if (vfat_enabled)
609 		debug("VFAT Support enabled\n");
610 
611 	debug("FAT%d, fat_sect: %d, fatlength: %d\n",
612 	       mydata->fatsize, mydata->fat_sect, mydata->fatlength);
613 	debug("Rootdir begins at cluster: %d, sector: %d, offset: %x\n"
614 	       "Data begins at: %d\n",
615 	       mydata->root_cluster,
616 	       mydata->rootdir_sect,
617 	       mydata->rootdir_sect * mydata->sect_size, mydata->data_begin);
618 	debug("Sector size: %d, cluster size: %d\n", mydata->sect_size,
619 	      mydata->clust_size);
620 
621 	return 0;
622 }
623 
624 
625 /*
626  * Directory iterator, to simplify filesystem traversal
627  *
628  * Implements an iterator pattern to traverse directory tables,
629  * transparently handling directory tables split across multiple
630  * clusters, and the difference between FAT12/FAT16 root directory
631  * (contiguous) and subdirectories + FAT32 root (chained).
632  *
633  * Rough usage:
634  *
635  *   for (fat_itr_root(&itr, fsdata); fat_itr_next(&itr); ) {
636  *      // to traverse down to a subdirectory pointed to by
637  *      // current iterator position:
638  *      fat_itr_child(&itr, &itr);
639  *   }
640  *
641  * For more complete example, see fat_itr_resolve()
642  */
643 
644 typedef struct {
645 	fsdata    *fsdata;        /* filesystem parameters */
646 	unsigned   clust;         /* current cluster */
647 	int        last_cluster;  /* set once we've read last cluster */
648 	int        is_root;       /* is iterator at root directory */
649 	int        remaining;     /* remaining dent's in current cluster */
650 
651 	/* current iterator position values: */
652 	dir_entry *dent;          /* current directory entry */
653 	char       l_name[VFAT_MAXLEN_BYTES];    /* long (vfat) name */
654 	char       s_name[14];    /* short 8.3 name */
655 	char      *name;          /* l_name if there is one, else s_name */
656 
657 	/* storage for current cluster in memory: */
658 	u8         block[MAX_CLUSTSIZE] __aligned(ARCH_DMA_MINALIGN);
659 } fat_itr;
660 
661 static int fat_itr_isdir(fat_itr *itr);
662 
663 /**
664  * fat_itr_root() - initialize an iterator to start at the root
665  * directory
666  *
667  * @itr: iterator to initialize
668  * @fsdata: filesystem data for the partition
669  * @return 0 on success, else -errno
670  */
671 static int fat_itr_root(fat_itr *itr, fsdata *fsdata)
672 {
673 	if (get_fs_info(fsdata))
674 		return -ENXIO;
675 
676 	itr->fsdata = fsdata;
677 	itr->clust = fsdata->root_cluster;
678 	itr->dent = NULL;
679 	itr->remaining = 0;
680 	itr->last_cluster = 0;
681 	itr->is_root = 1;
682 
683 	return 0;
684 }
685 
686 /**
687  * fat_itr_child() - initialize an iterator to descend into a sub-
688  * directory
689  *
690  * Initializes 'itr' to iterate the contents of the directory at
691  * the current cursor position of 'parent'.  It is an error to
692  * call this if the current cursor of 'parent' is pointing at a
693  * regular file.
694  *
695  * Note that 'itr' and 'parent' can be the same pointer if you do
696  * not need to preserve 'parent' after this call, which is useful
697  * for traversing directory structure to resolve a file/directory.
698  *
699  * @itr: iterator to initialize
700  * @parent: the iterator pointing at a directory entry in the
701  *    parent directory of the directory to iterate
702  */
703 static void fat_itr_child(fat_itr *itr, fat_itr *parent)
704 {
705 	fsdata *mydata = parent->fsdata;  /* for silly macros */
706 	unsigned clustnum = START(parent->dent);
707 
708 	assert(fat_itr_isdir(parent));
709 
710 	itr->fsdata = parent->fsdata;
711 	if (clustnum > 0) {
712 		itr->clust = clustnum;
713 	} else {
714 		itr->clust = parent->fsdata->root_cluster;
715 	}
716 	itr->dent = NULL;
717 	itr->remaining = 0;
718 	itr->last_cluster = 0;
719 	itr->is_root = 0;
720 }
721 
722 static void *next_cluster(fat_itr *itr)
723 {
724 	fsdata *mydata = itr->fsdata;  /* for silly macros */
725 	int ret;
726 	u32 sect;
727 
728 	/* have we reached the end? */
729 	if (itr->last_cluster)
730 		return NULL;
731 
732 	sect = clust_to_sect(itr->fsdata, itr->clust);
733 
734 	debug("FAT read(sect=%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n",
735 	      sect, itr->fsdata->clust_size, DIRENTSPERBLOCK);
736 
737 	/*
738 	 * NOTE: do_fat_read_at() had complicated logic to deal w/
739 	 * vfat names that span multiple clusters in the fat16 case,
740 	 * which get_dentfromdir() probably also needed (and was
741 	 * missing).  And not entirely sure what fat32 didn't have
742 	 * the same issue..  We solve that by only caring about one
743 	 * dent at a time and iteratively constructing the vfat long
744 	 * name.
745 	 */
746 	ret = disk_read(sect, itr->fsdata->clust_size,
747 			itr->block);
748 	if (ret < 0) {
749 		debug("Error: reading block\n");
750 		return NULL;
751 	}
752 
753 	if (itr->is_root && itr->fsdata->fatsize != 32) {
754 		itr->clust++;
755 		sect = clust_to_sect(itr->fsdata, itr->clust);
756 		if (sect - itr->fsdata->rootdir_sect >=
757 		    itr->fsdata->rootdir_size) {
758 			debug("cursect: 0x%x\n", itr->clust);
759 			itr->last_cluster = 1;
760 		}
761 	} else {
762 		itr->clust = get_fatent(itr->fsdata, itr->clust);
763 		if (CHECK_CLUST(itr->clust, itr->fsdata->fatsize)) {
764 			debug("cursect: 0x%x\n", itr->clust);
765 			itr->last_cluster = 1;
766 		}
767 	}
768 
769 	return itr->block;
770 }
771 
772 static dir_entry *next_dent(fat_itr *itr)
773 {
774 	if (itr->remaining == 0) {
775 		struct dir_entry *dent = next_cluster(itr);
776 		unsigned nbytes = itr->fsdata->sect_size *
777 			itr->fsdata->clust_size;
778 
779 		/* have we reached the last cluster? */
780 		if (!dent)
781 			return NULL;
782 
783 		itr->remaining = nbytes / sizeof(dir_entry) - 1;
784 		itr->dent = dent;
785 	} else {
786 		itr->remaining--;
787 		itr->dent++;
788 	}
789 
790 	/* have we reached the last valid entry? */
791 	if (itr->dent->name[0] == 0)
792 		return NULL;
793 
794 	return itr->dent;
795 }
796 
797 static dir_entry *extract_vfat_name(fat_itr *itr)
798 {
799 	struct dir_entry *dent = itr->dent;
800 	int seqn = itr->dent->name[0] & ~LAST_LONG_ENTRY_MASK;
801 	u8 chksum, alias_checksum = ((dir_slot *)dent)->alias_checksum;
802 	int n = 0;
803 
804 	while (seqn--) {
805 		char buf[13];
806 		int idx = 0;
807 
808 		slot2str((dir_slot *)dent, buf, &idx);
809 
810 		/* shift accumulated long-name up and copy new part in: */
811 		memmove(itr->l_name + idx, itr->l_name, n);
812 		memcpy(itr->l_name, buf, idx);
813 		n += idx;
814 
815 		dent = next_dent(itr);
816 		if (!dent)
817 			return NULL;
818 	}
819 
820 	itr->l_name[n] = '\0';
821 
822 	chksum = mkcksum(dent->name, dent->ext);
823 
824 	/* checksum mismatch could mean deleted file, etc.. skip it: */
825 	if (chksum != alias_checksum) {
826 		debug("** chksum=%x, alias_checksum=%x, l_name=%s, s_name=%8s.%3s\n",
827 		      chksum, alias_checksum, itr->l_name, dent->name, dent->ext);
828 		return NULL;
829 	}
830 
831 	return dent;
832 }
833 
834 /**
835  * fat_itr_next() - step to the next entry in a directory
836  *
837  * Must be called once on a new iterator before the cursor is valid.
838  *
839  * @itr: the iterator to iterate
840  * @return boolean, 1 if success or 0 if no more entries in the
841  *    current directory
842  */
843 static int fat_itr_next(fat_itr *itr)
844 {
845 	dir_entry *dent;
846 
847 	itr->name = NULL;
848 
849 	while (1) {
850 		dent = next_dent(itr);
851 		if (!dent)
852 			return 0;
853 
854 		if (dent->name[0] == DELETED_FLAG ||
855 		    dent->name[0] == aRING)
856 			continue;
857 
858 		if (dent->attr & ATTR_VOLUME) {
859 			if (vfat_enabled &&
860 			    (dent->attr & ATTR_VFAT) == ATTR_VFAT &&
861 			    (dent->name[0] & LAST_LONG_ENTRY_MASK)) {
862 				dent = extract_vfat_name(itr);
863 				if (!dent)
864 					continue;
865 				itr->name = itr->l_name;
866 				break;
867 			} else {
868 				/* Volume label or VFAT entry, skip */
869 				continue;
870 			}
871 		}
872 
873 		break;
874 	}
875 
876 	get_name(dent, itr->s_name);
877 	if (!itr->name)
878 		itr->name = itr->s_name;
879 
880 	return 1;
881 }
882 
883 /**
884  * fat_itr_isdir() - is current cursor position pointing to a directory
885  *
886  * @itr: the iterator
887  * @return true if cursor is at a directory
888  */
889 static int fat_itr_isdir(fat_itr *itr)
890 {
891 	return !!(itr->dent->attr & ATTR_DIR);
892 }
893 
894 /*
895  * Helpers:
896  */
897 
898 #define TYPE_FILE 0x1
899 #define TYPE_DIR  0x2
900 #define TYPE_ANY  (TYPE_FILE | TYPE_DIR)
901 
902 /**
903  * fat_itr_resolve() - traverse directory structure to resolve the
904  * requested path.
905  *
906  * Traverse directory structure to the requested path.  If the specified
907  * path is to a directory, this will descend into the directory and
908  * leave it iterator at the start of the directory.  If the path is to a
909  * file, it will leave the iterator in the parent directory with current
910  * cursor at file's entry in the directory.
911  *
912  * @itr: iterator initialized to root
913  * @path: the requested path
914  * @type: bitmask of allowable file types
915  * @return 0 on success or -errno
916  */
917 static int fat_itr_resolve(fat_itr *itr, const char *path, unsigned type)
918 {
919 	const char *next;
920 
921 	/* chomp any extra leading slashes: */
922 	while (path[0] && ISDIRDELIM(path[0]))
923 		path++;
924 
925 	/* are we at the end? */
926 	if (strlen(path) == 0) {
927 		if (!(type & TYPE_DIR))
928 			return -ENOENT;
929 		return 0;
930 	}
931 
932 	/* find length of next path entry: */
933 	next = path;
934 	while (next[0] && !ISDIRDELIM(next[0]))
935 		next++;
936 
937 	while (fat_itr_next(itr)) {
938 		int match = 0;
939 		unsigned n = max(strlen(itr->name), (size_t)(next - path));
940 
941 		/* check both long and short name: */
942 		if (!strncasecmp(path, itr->name, n))
943 			match = 1;
944 		else if (itr->name != itr->s_name &&
945 			 !strncasecmp(path, itr->s_name, n))
946 			match = 1;
947 
948 		if (!match)
949 			continue;
950 
951 		if (fat_itr_isdir(itr)) {
952 			/* recurse into directory: */
953 			fat_itr_child(itr, itr);
954 			return fat_itr_resolve(itr, next, type);
955 		} else if (next[0]) {
956 			/*
957 			 * If next is not empty then we have a case
958 			 * like: /path/to/realfile/nonsense
959 			 */
960 			debug("bad trailing path: %s\n", next);
961 			return -ENOENT;
962 		} else if (!(type & TYPE_FILE)) {
963 			return -ENOTDIR;
964 		} else {
965 			return 0;
966 		}
967 	}
968 
969 	return -ENOENT;
970 }
971 
972 int file_fat_detectfs(void)
973 {
974 	boot_sector bs;
975 	volume_info volinfo;
976 	int fatsize;
977 	char vol_label[12];
978 
979 	if (cur_dev == NULL) {
980 		printf("No current device\n");
981 		return 1;
982 	}
983 
984 #if defined(CONFIG_IDE) || \
985     defined(CONFIG_SATA) || \
986     defined(CONFIG_SCSI) || \
987     defined(CONFIG_CMD_USB) || \
988     defined(CONFIG_MMC)
989 	printf("Interface:  ");
990 	switch (cur_dev->if_type) {
991 	case IF_TYPE_IDE:
992 		printf("IDE");
993 		break;
994 	case IF_TYPE_SATA:
995 		printf("SATA");
996 		break;
997 	case IF_TYPE_SCSI:
998 		printf("SCSI");
999 		break;
1000 	case IF_TYPE_ATAPI:
1001 		printf("ATAPI");
1002 		break;
1003 	case IF_TYPE_USB:
1004 		printf("USB");
1005 		break;
1006 	case IF_TYPE_DOC:
1007 		printf("DOC");
1008 		break;
1009 	case IF_TYPE_MMC:
1010 		printf("MMC");
1011 		break;
1012 	default:
1013 		printf("Unknown");
1014 	}
1015 
1016 	printf("\n  Device %d: ", cur_dev->devnum);
1017 	dev_print(cur_dev);
1018 #endif
1019 
1020 	if (read_bootsectandvi(&bs, &volinfo, &fatsize)) {
1021 		printf("\nNo valid FAT fs found\n");
1022 		return 1;
1023 	}
1024 
1025 	memcpy(vol_label, volinfo.volume_label, 11);
1026 	vol_label[11] = '\0';
1027 	volinfo.fs_type[5] = '\0';
1028 
1029 	printf("Filesystem: %s \"%s\"\n", volinfo.fs_type, vol_label);
1030 
1031 	return 0;
1032 }
1033 
1034 int fat_exists(const char *filename)
1035 {
1036 	fsdata fsdata;
1037 	fat_itr *itr;
1038 	int ret;
1039 
1040 	itr = malloc(sizeof(fat_itr));
1041 	ret = fat_itr_root(itr, &fsdata);
1042 	if (ret)
1043 		return 0;
1044 
1045 	ret = fat_itr_resolve(itr, filename, TYPE_ANY);
1046 	free(fsdata.fatbuf);
1047 	free(itr);
1048 	return ret == 0;
1049 }
1050 
1051 int fat_size(const char *filename, loff_t *size)
1052 {
1053 	fsdata fsdata;
1054 	fat_itr *itr;
1055 	int ret;
1056 
1057 	itr = malloc(sizeof(fat_itr));
1058 	ret = fat_itr_root(itr, &fsdata);
1059 	if (ret)
1060 		return ret;
1061 
1062 	ret = fat_itr_resolve(itr, filename, TYPE_FILE);
1063 	if (ret) {
1064 		/*
1065 		 * Directories don't have size, but fs_size() is not
1066 		 * expected to fail if passed a directory path:
1067 		 */
1068 		free(fsdata.fatbuf);
1069 		fat_itr_root(itr, &fsdata);
1070 		if (!fat_itr_resolve(itr, filename, TYPE_DIR)) {
1071 			*size = 0;
1072 			ret = 0;
1073 		}
1074 		goto out;
1075 	}
1076 
1077 	*size = FAT2CPU32(itr->dent->size);
1078 	free(fsdata.fatbuf);
1079 out:
1080 	free(itr);
1081 	return ret;
1082 }
1083 
1084 int file_fat_read_at(const char *filename, loff_t pos, void *buffer,
1085 		     loff_t maxsize, loff_t *actread)
1086 {
1087 	fsdata fsdata;
1088 	fat_itr *itr;
1089 	int ret;
1090 
1091 	itr = malloc(sizeof(fat_itr));
1092 	ret = fat_itr_root(itr, &fsdata);
1093 	if (ret)
1094 		return ret;
1095 
1096 	ret = fat_itr_resolve(itr, filename, TYPE_FILE);
1097 	if (ret)
1098 		goto out;
1099 
1100 	printf("reading %s\n", filename);
1101 	ret = get_contents(&fsdata, itr->dent, pos, buffer, maxsize, actread);
1102 
1103 out:
1104 	free(fsdata.fatbuf);
1105 	free(itr);
1106 	return ret;
1107 }
1108 
1109 int file_fat_read(const char *filename, void *buffer, int maxsize)
1110 {
1111 	loff_t actread;
1112 	int ret;
1113 
1114 	ret =  file_fat_read_at(filename, 0, buffer, maxsize, &actread);
1115 	if (ret)
1116 		return ret;
1117 	else
1118 		return actread;
1119 }
1120 
1121 int fat_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
1122 		  loff_t *actread)
1123 {
1124 	int ret;
1125 
1126 	ret = file_fat_read_at(filename, offset, buf, len, actread);
1127 	if (ret)
1128 		printf("** Unable to read file %s **\n", filename);
1129 
1130 	return ret;
1131 }
1132 
1133 typedef struct {
1134 	struct fs_dir_stream parent;
1135 	struct fs_dirent dirent;
1136 	fsdata fsdata;
1137 	fat_itr itr;
1138 } fat_dir;
1139 
1140 int fat_opendir(const char *filename, struct fs_dir_stream **dirsp)
1141 {
1142 	fat_dir *dir = calloc(1, sizeof(*dir));
1143 	int ret;
1144 
1145 	if (!dir)
1146 		return -ENOMEM;
1147 
1148 	ret = fat_itr_root(&dir->itr, &dir->fsdata);
1149 	if (ret)
1150 		goto fail;
1151 
1152 	ret = fat_itr_resolve(&dir->itr, filename, TYPE_DIR);
1153 	if (ret)
1154 		goto fail;
1155 
1156 	*dirsp = (struct fs_dir_stream *)dir;
1157 	return 0;
1158 
1159 fail:
1160 	free(dir->fsdata.fatbuf);
1161 	free(dir);
1162 	return ret;
1163 }
1164 
1165 int fat_readdir(struct fs_dir_stream *dirs, struct fs_dirent **dentp)
1166 {
1167 	fat_dir *dir = (fat_dir *)dirs;
1168 	struct fs_dirent *dent = &dir->dirent;
1169 
1170 	if (!fat_itr_next(&dir->itr))
1171 		return -ENOENT;
1172 
1173 	memset(dent, 0, sizeof(*dent));
1174 	strcpy(dent->name, dir->itr.name);
1175 
1176 	if (fat_itr_isdir(&dir->itr)) {
1177 		dent->type = FS_DT_DIR;
1178 	} else {
1179 		dent->type = FS_DT_REG;
1180 		dent->size = FAT2CPU32(dir->itr.dent->size);
1181 	}
1182 
1183 	*dentp = dent;
1184 
1185 	return 0;
1186 }
1187 
1188 void fat_closedir(struct fs_dir_stream *dirs)
1189 {
1190 	fat_dir *dir = (fat_dir *)dirs;
1191 	free(dir->fsdata.fatbuf);
1192 	free(dir);
1193 }
1194 
1195 void fat_close(void)
1196 {
1197 }
1198