xref: /openbmc/u-boot/fs/fat/fat.c (revision 730d2544)
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 <asm/byteorder.h>
18 #include <part.h>
19 #include <malloc.h>
20 #include <memalign.h>
21 #include <linux/compiler.h>
22 #include <linux/ctype.h>
23 
24 #ifdef CONFIG_SUPPORT_VFAT
25 static const int vfat_enabled = 1;
26 #else
27 static const int vfat_enabled = 0;
28 #endif
29 
30 /*
31  * Convert a string to lowercase.
32  */
33 static void downcase(char *str)
34 {
35 	while (*str != '\0') {
36 		*str = tolower(*str);
37 		str++;
38 	}
39 }
40 
41 static struct blk_desc *cur_dev;
42 static disk_partition_t cur_part_info;
43 
44 #define DOS_BOOT_MAGIC_OFFSET	0x1fe
45 #define DOS_FS_TYPE_OFFSET	0x36
46 #define DOS_FS32_TYPE_OFFSET	0x52
47 
48 static int disk_read(__u32 block, __u32 nr_blocks, void *buf)
49 {
50 	ulong ret;
51 
52 	if (!cur_dev)
53 		return -1;
54 
55 	ret = blk_dread(cur_dev, cur_part_info.start + block, nr_blocks, buf);
56 
57 	if (nr_blocks && ret == 0)
58 		return -1;
59 
60 	return ret;
61 }
62 
63 int fat_set_blk_dev(struct blk_desc *dev_desc, disk_partition_t *info)
64 {
65 	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, dev_desc->blksz);
66 
67 	cur_dev = dev_desc;
68 	cur_part_info = *info;
69 
70 	/* Make sure it has a valid FAT header */
71 	if (disk_read(0, 1, buffer) != 1) {
72 		cur_dev = NULL;
73 		return -1;
74 	}
75 
76 	/* Check if it's actually a DOS volume */
77 	if (memcmp(buffer + DOS_BOOT_MAGIC_OFFSET, "\x55\xAA", 2)) {
78 		cur_dev = NULL;
79 		return -1;
80 	}
81 
82 	/* Check for FAT12/FAT16/FAT32 filesystem */
83 	if (!memcmp(buffer + DOS_FS_TYPE_OFFSET, "FAT", 3))
84 		return 0;
85 	if (!memcmp(buffer + DOS_FS32_TYPE_OFFSET, "FAT32", 5))
86 		return 0;
87 
88 	cur_dev = NULL;
89 	return -1;
90 }
91 
92 int fat_register_device(struct blk_desc *dev_desc, int part_no)
93 {
94 	disk_partition_t info;
95 
96 	/* First close any currently found FAT filesystem */
97 	cur_dev = NULL;
98 
99 	/* Read the partition table, if present */
100 	if (part_get_info(dev_desc, part_no, &info)) {
101 		if (part_no != 0) {
102 			printf("** Partition %d not valid on device %d **\n",
103 					part_no, dev_desc->devnum);
104 			return -1;
105 		}
106 
107 		info.start = 0;
108 		info.size = dev_desc->lba;
109 		info.blksz = dev_desc->blksz;
110 		info.name[0] = 0;
111 		info.type[0] = 0;
112 		info.bootable = 0;
113 #ifdef CONFIG_PARTITION_UUIDS
114 		info.uuid[0] = 0;
115 #endif
116 	}
117 
118 	return fat_set_blk_dev(dev_desc, &info);
119 }
120 
121 /*
122  * Get the first occurence of a directory delimiter ('/' or '\') in a string.
123  * Return index into string if found, -1 otherwise.
124  */
125 static int dirdelim(char *str)
126 {
127 	char *start = str;
128 
129 	while (*str != '\0') {
130 		if (ISDIRDELIM(*str))
131 			return str - start;
132 		str++;
133 	}
134 	return -1;
135 }
136 
137 /*
138  * Extract zero terminated short name from a directory entry.
139  */
140 static void get_name(dir_entry *dirent, char *s_name)
141 {
142 	char *ptr;
143 
144 	memcpy(s_name, dirent->name, 8);
145 	s_name[8] = '\0';
146 	ptr = s_name;
147 	while (*ptr && *ptr != ' ')
148 		ptr++;
149 	if (dirent->ext[0] && dirent->ext[0] != ' ') {
150 		*ptr = '.';
151 		ptr++;
152 		memcpy(ptr, dirent->ext, 3);
153 		ptr[3] = '\0';
154 		while (*ptr && *ptr != ' ')
155 			ptr++;
156 	}
157 	*ptr = '\0';
158 	if (*s_name == DELETED_FLAG)
159 		*s_name = '\0';
160 	else if (*s_name == aRING)
161 		*s_name = DELETED_FLAG;
162 	downcase(s_name);
163 }
164 
165 /*
166  * Get the entry at index 'entry' in a FAT (12/16/32) table.
167  * On failure 0x00 is returned.
168  */
169 static __u32 get_fatent(fsdata *mydata, __u32 entry)
170 {
171 	__u32 bufnum;
172 	__u32 off16, offset;
173 	__u32 ret = 0x00;
174 	__u16 val1, val2;
175 
176 	switch (mydata->fatsize) {
177 	case 32:
178 		bufnum = entry / FAT32BUFSIZE;
179 		offset = entry - bufnum * FAT32BUFSIZE;
180 		break;
181 	case 16:
182 		bufnum = entry / FAT16BUFSIZE;
183 		offset = entry - bufnum * FAT16BUFSIZE;
184 		break;
185 	case 12:
186 		bufnum = entry / FAT12BUFSIZE;
187 		offset = entry - bufnum * FAT12BUFSIZE;
188 		break;
189 
190 	default:
191 		/* Unsupported FAT size */
192 		return ret;
193 	}
194 
195 	debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
196 	       mydata->fatsize, entry, entry, offset, offset);
197 
198 	/* Read a new block of FAT entries into the cache. */
199 	if (bufnum != mydata->fatbufnum) {
200 		__u32 getsize = FATBUFBLOCKS;
201 		__u8 *bufptr = mydata->fatbuf;
202 		__u32 fatlength = mydata->fatlength;
203 		__u32 startblock = bufnum * FATBUFBLOCKS;
204 
205 		if (startblock + getsize > fatlength)
206 			getsize = fatlength - startblock;
207 
208 		startblock += mydata->fat_sect;	/* Offset from start of disk */
209 
210 		if (disk_read(startblock, getsize, bufptr) < 0) {
211 			debug("Error reading FAT blocks\n");
212 			return ret;
213 		}
214 		mydata->fatbufnum = bufnum;
215 	}
216 
217 	/* Get the actual entry from the table */
218 	switch (mydata->fatsize) {
219 	case 32:
220 		ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
221 		break;
222 	case 16:
223 		ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
224 		break;
225 	case 12:
226 		off16 = (offset * 3) / 4;
227 
228 		switch (offset & 0x3) {
229 		case 0:
230 			ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
231 			ret &= 0xfff;
232 			break;
233 		case 1:
234 			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
235 			val1 &= 0xf000;
236 			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
237 			val2 &= 0x00ff;
238 			ret = (val2 << 4) | (val1 >> 12);
239 			break;
240 		case 2:
241 			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
242 			val1 &= 0xff00;
243 			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
244 			val2 &= 0x000f;
245 			ret = (val2 << 8) | (val1 >> 8);
246 			break;
247 		case 3:
248 			ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
249 			ret = (ret & 0xfff0) >> 4;
250 			break;
251 		default:
252 			break;
253 		}
254 		break;
255 	}
256 	debug("FAT%d: ret: %08x, offset: %04x\n",
257 	       mydata->fatsize, ret, offset);
258 
259 	return ret;
260 }
261 
262 /*
263  * Read at most 'size' bytes from the specified cluster into 'buffer'.
264  * Return 0 on success, -1 otherwise.
265  */
266 static int
267 get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
268 {
269 	__u32 idx = 0;
270 	__u32 startsect;
271 	int ret;
272 
273 	if (clustnum > 0) {
274 		startsect = mydata->data_begin +
275 				clustnum * mydata->clust_size;
276 	} else {
277 		startsect = mydata->rootdir_sect;
278 	}
279 
280 	debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect);
281 
282 	if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
283 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
284 
285 		printf("FAT: Misaligned buffer address (%p)\n", buffer);
286 
287 		while (size >= mydata->sect_size) {
288 			ret = disk_read(startsect++, 1, tmpbuf);
289 			if (ret != 1) {
290 				debug("Error reading data (got %d)\n", ret);
291 				return -1;
292 			}
293 
294 			memcpy(buffer, tmpbuf, mydata->sect_size);
295 			buffer += mydata->sect_size;
296 			size -= mydata->sect_size;
297 		}
298 	} else {
299 		idx = size / mydata->sect_size;
300 		ret = disk_read(startsect, idx, buffer);
301 		if (ret != idx) {
302 			debug("Error reading data (got %d)\n", ret);
303 			return -1;
304 		}
305 		startsect += idx;
306 		idx *= mydata->sect_size;
307 		buffer += idx;
308 		size -= idx;
309 	}
310 	if (size) {
311 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
312 
313 		ret = disk_read(startsect, 1, tmpbuf);
314 		if (ret != 1) {
315 			debug("Error reading data (got %d)\n", ret);
316 			return -1;
317 		}
318 
319 		memcpy(buffer, tmpbuf, size);
320 	}
321 
322 	return 0;
323 }
324 
325 /*
326  * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr'
327  * into 'buffer'.
328  * Update the number of bytes read in *gotsize or return -1 on fatal errors.
329  */
330 __u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
331 	__aligned(ARCH_DMA_MINALIGN);
332 
333 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
334 			__u8 *buffer, loff_t maxsize, loff_t *gotsize)
335 {
336 	loff_t filesize = FAT2CPU32(dentptr->size);
337 	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
338 	__u32 curclust = START(dentptr);
339 	__u32 endclust, newclust;
340 	loff_t actsize;
341 
342 	*gotsize = 0;
343 	debug("Filesize: %llu bytes\n", filesize);
344 
345 	if (pos >= filesize) {
346 		debug("Read position past EOF: %llu\n", pos);
347 		return 0;
348 	}
349 
350 	if (maxsize > 0 && filesize > pos + maxsize)
351 		filesize = pos + maxsize;
352 
353 	debug("%llu bytes\n", filesize);
354 
355 	actsize = bytesperclust;
356 
357 	/* go to cluster at pos */
358 	while (actsize <= pos) {
359 		curclust = get_fatent(mydata, curclust);
360 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
361 			debug("curclust: 0x%x\n", curclust);
362 			debug("Invalid FAT entry\n");
363 			return 0;
364 		}
365 		actsize += bytesperclust;
366 	}
367 
368 	/* actsize > pos */
369 	actsize -= bytesperclust;
370 	filesize -= actsize;
371 	pos -= actsize;
372 
373 	/* align to beginning of next cluster if any */
374 	if (pos) {
375 		actsize = min(filesize, (loff_t)bytesperclust);
376 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
377 				(int)actsize) != 0) {
378 			printf("Error reading cluster\n");
379 			return -1;
380 		}
381 		filesize -= actsize;
382 		actsize -= pos;
383 		memcpy(buffer, get_contents_vfatname_block + pos, actsize);
384 		*gotsize += actsize;
385 		if (!filesize)
386 			return 0;
387 		buffer += actsize;
388 
389 		curclust = get_fatent(mydata, curclust);
390 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
391 			debug("curclust: 0x%x\n", curclust);
392 			debug("Invalid FAT entry\n");
393 			return 0;
394 		}
395 	}
396 
397 	actsize = bytesperclust;
398 	endclust = curclust;
399 
400 	do {
401 		/* search for consecutive clusters */
402 		while (actsize < filesize) {
403 			newclust = get_fatent(mydata, endclust);
404 			if ((newclust - 1) != endclust)
405 				goto getit;
406 			if (CHECK_CLUST(newclust, mydata->fatsize)) {
407 				debug("curclust: 0x%x\n", newclust);
408 				debug("Invalid FAT entry\n");
409 				return 0;
410 			}
411 			endclust = newclust;
412 			actsize += bytesperclust;
413 		}
414 
415 		/* get remaining bytes */
416 		actsize = filesize;
417 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
418 			printf("Error reading cluster\n");
419 			return -1;
420 		}
421 		*gotsize += actsize;
422 		return 0;
423 getit:
424 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
425 			printf("Error reading cluster\n");
426 			return -1;
427 		}
428 		*gotsize += (int)actsize;
429 		filesize -= actsize;
430 		buffer += actsize;
431 
432 		curclust = get_fatent(mydata, endclust);
433 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
434 			debug("curclust: 0x%x\n", curclust);
435 			printf("Invalid FAT entry\n");
436 			return 0;
437 		}
438 		actsize = bytesperclust;
439 		endclust = curclust;
440 	} while (1);
441 }
442 
443 /*
444  * Extract the file name information from 'slotptr' into 'l_name',
445  * starting at l_name[*idx].
446  * Return 1 if terminator (zero byte) is found, 0 otherwise.
447  */
448 static int slot2str(dir_slot *slotptr, char *l_name, int *idx)
449 {
450 	int j;
451 
452 	for (j = 0; j <= 8; j += 2) {
453 		l_name[*idx] = slotptr->name0_4[j];
454 		if (l_name[*idx] == 0x00)
455 			return 1;
456 		(*idx)++;
457 	}
458 	for (j = 0; j <= 10; j += 2) {
459 		l_name[*idx] = slotptr->name5_10[j];
460 		if (l_name[*idx] == 0x00)
461 			return 1;
462 		(*idx)++;
463 	}
464 	for (j = 0; j <= 2; j += 2) {
465 		l_name[*idx] = slotptr->name11_12[j];
466 		if (l_name[*idx] == 0x00)
467 			return 1;
468 		(*idx)++;
469 	}
470 
471 	return 0;
472 }
473 
474 /*
475  * Extract the full long filename starting at 'retdent' (which is really
476  * a slot) into 'l_name'. If successful also copy the real directory entry
477  * into 'retdent'
478  * Return 0 on success, -1 otherwise.
479  */
480 static int
481 get_vfatname(fsdata *mydata, int curclust, __u8 *cluster,
482 	     dir_entry *retdent, char *l_name)
483 {
484 	dir_entry *realdent;
485 	dir_slot *slotptr = (dir_slot *)retdent;
486 	__u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
487 							PREFETCH_BLOCKS :
488 							mydata->clust_size);
489 	__u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
490 	int idx = 0;
491 
492 	if (counter > VFAT_MAXSEQ) {
493 		debug("Error: VFAT name is too long\n");
494 		return -1;
495 	}
496 
497 	while ((__u8 *)slotptr < buflimit) {
498 		if (counter == 0)
499 			break;
500 		if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
501 			return -1;
502 		slotptr++;
503 		counter--;
504 	}
505 
506 	if ((__u8 *)slotptr >= buflimit) {
507 		dir_slot *slotptr2;
508 
509 		if (curclust == 0)
510 			return -1;
511 		curclust = get_fatent(mydata, curclust);
512 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
513 			debug("curclust: 0x%x\n", curclust);
514 			printf("Invalid FAT entry\n");
515 			return -1;
516 		}
517 
518 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
519 				mydata->clust_size * mydata->sect_size) != 0) {
520 			debug("Error: reading directory block\n");
521 			return -1;
522 		}
523 
524 		slotptr2 = (dir_slot *)get_contents_vfatname_block;
525 		while (counter > 0) {
526 			if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
527 			    & 0xff) != counter)
528 				return -1;
529 			slotptr2++;
530 			counter--;
531 		}
532 
533 		/* Save the real directory entry */
534 		realdent = (dir_entry *)slotptr2;
535 		while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
536 			slotptr2--;
537 			slot2str(slotptr2, l_name, &idx);
538 		}
539 	} else {
540 		/* Save the real directory entry */
541 		realdent = (dir_entry *)slotptr;
542 	}
543 
544 	do {
545 		slotptr--;
546 		if (slot2str(slotptr, l_name, &idx))
547 			break;
548 	} while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
549 
550 	l_name[idx] = '\0';
551 	if (*l_name == DELETED_FLAG)
552 		*l_name = '\0';
553 	else if (*l_name == aRING)
554 		*l_name = DELETED_FLAG;
555 	downcase(l_name);
556 
557 	/* Return the real directory entry */
558 	memcpy(retdent, realdent, sizeof(dir_entry));
559 
560 	return 0;
561 }
562 
563 /* Calculate short name checksum */
564 static __u8 mkcksum(const char name[8], const char ext[3])
565 {
566 	int i;
567 
568 	__u8 ret = 0;
569 
570 	for (i = 0; i < 8; i++)
571 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
572 	for (i = 0; i < 3; i++)
573 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
574 
575 	return ret;
576 }
577 
578 /*
579  * Get the directory entry associated with 'filename' from the directory
580  * starting at 'startsect'
581  */
582 __u8 get_dentfromdir_block[MAX_CLUSTSIZE]
583 	__aligned(ARCH_DMA_MINALIGN);
584 
585 static dir_entry *get_dentfromdir(fsdata *mydata, int startsect,
586 				  char *filename, dir_entry *retdent,
587 				  int dols)
588 {
589 	__u16 prevcksum = 0xffff;
590 	__u32 curclust = START(retdent);
591 	int files = 0, dirs = 0;
592 
593 	debug("get_dentfromdir: %s\n", filename);
594 
595 	while (1) {
596 		dir_entry *dentptr;
597 
598 		int i;
599 
600 		if (get_cluster(mydata, curclust, get_dentfromdir_block,
601 				mydata->clust_size * mydata->sect_size) != 0) {
602 			debug("Error: reading directory block\n");
603 			return NULL;
604 		}
605 
606 		dentptr = (dir_entry *)get_dentfromdir_block;
607 
608 		for (i = 0; i < DIRENTSPERCLUST; i++) {
609 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
610 
611 			l_name[0] = '\0';
612 			if (dentptr->name[0] == DELETED_FLAG) {
613 				dentptr++;
614 				continue;
615 			}
616 			if ((dentptr->attr & ATTR_VOLUME)) {
617 				if (vfat_enabled &&
618 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
619 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
620 					prevcksum = ((dir_slot *)dentptr)->alias_checksum;
621 					get_vfatname(mydata, curclust,
622 						     get_dentfromdir_block,
623 						     dentptr, l_name);
624 					if (dols) {
625 						int isdir;
626 						char dirc;
627 						int doit = 0;
628 
629 						isdir = (dentptr->attr & ATTR_DIR);
630 
631 						if (isdir) {
632 							dirs++;
633 							dirc = '/';
634 							doit = 1;
635 						} else {
636 							dirc = ' ';
637 							if (l_name[0] != 0) {
638 								files++;
639 								doit = 1;
640 							}
641 						}
642 						if (doit) {
643 							if (dirc == ' ') {
644 								printf(" %8u   %s%c\n",
645 								       FAT2CPU32(dentptr->size),
646 									l_name,
647 									dirc);
648 							} else {
649 								printf("            %s%c\n",
650 									l_name,
651 									dirc);
652 							}
653 						}
654 						dentptr++;
655 						continue;
656 					}
657 					debug("vfatname: |%s|\n", l_name);
658 				} else {
659 					/* Volume label or VFAT entry */
660 					dentptr++;
661 					continue;
662 				}
663 			}
664 			if (dentptr->name[0] == 0) {
665 				if (dols) {
666 					printf("\n%d file(s), %d dir(s)\n\n",
667 						files, dirs);
668 				}
669 				debug("Dentname == NULL - %d\n", i);
670 				return NULL;
671 			}
672 			if (vfat_enabled) {
673 				__u8 csum = mkcksum(dentptr->name, dentptr->ext);
674 				if (dols && csum == prevcksum) {
675 					prevcksum = 0xffff;
676 					dentptr++;
677 					continue;
678 				}
679 			}
680 
681 			get_name(dentptr, s_name);
682 			if (dols) {
683 				int isdir = (dentptr->attr & ATTR_DIR);
684 				char dirc;
685 				int doit = 0;
686 
687 				if (isdir) {
688 					dirs++;
689 					dirc = '/';
690 					doit = 1;
691 				} else {
692 					dirc = ' ';
693 					if (s_name[0] != 0) {
694 						files++;
695 						doit = 1;
696 					}
697 				}
698 
699 				if (doit) {
700 					if (dirc == ' ') {
701 						printf(" %8u   %s%c\n",
702 						       FAT2CPU32(dentptr->size),
703 							s_name, dirc);
704 					} else {
705 						printf("            %s%c\n",
706 							s_name, dirc);
707 					}
708 				}
709 
710 				dentptr++;
711 				continue;
712 			}
713 
714 			if (strcmp(filename, s_name)
715 			    && strcmp(filename, l_name)) {
716 				debug("Mismatch: |%s|%s|\n", s_name, l_name);
717 				dentptr++;
718 				continue;
719 			}
720 
721 			memcpy(retdent, dentptr, sizeof(dir_entry));
722 
723 			debug("DentName: %s", s_name);
724 			debug(", start: 0x%x", START(dentptr));
725 			debug(", size:  0x%x %s\n",
726 			      FAT2CPU32(dentptr->size),
727 			      (dentptr->attr & ATTR_DIR) ? "(DIR)" : "");
728 
729 			return retdent;
730 		}
731 
732 		curclust = get_fatent(mydata, curclust);
733 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
734 			debug("curclust: 0x%x\n", curclust);
735 			printf("Invalid FAT entry\n");
736 			return NULL;
737 		}
738 	}
739 
740 	return NULL;
741 }
742 
743 /*
744  * Read boot sector and volume info from a FAT filesystem
745  */
746 static int
747 read_bootsectandvi(boot_sector *bs, volume_info *volinfo, int *fatsize)
748 {
749 	__u8 *block;
750 	volume_info *vistart;
751 	int ret = 0;
752 
753 	if (cur_dev == NULL) {
754 		debug("Error: no device selected\n");
755 		return -1;
756 	}
757 
758 	block = memalign(ARCH_DMA_MINALIGN, cur_dev->blksz);
759 	if (block == NULL) {
760 		debug("Error: allocating block\n");
761 		return -1;
762 	}
763 
764 	if (disk_read(0, 1, block) < 0) {
765 		debug("Error: reading block\n");
766 		goto fail;
767 	}
768 
769 	memcpy(bs, block, sizeof(boot_sector));
770 	bs->reserved = FAT2CPU16(bs->reserved);
771 	bs->fat_length = FAT2CPU16(bs->fat_length);
772 	bs->secs_track = FAT2CPU16(bs->secs_track);
773 	bs->heads = FAT2CPU16(bs->heads);
774 	bs->total_sect = FAT2CPU32(bs->total_sect);
775 
776 	/* FAT32 entries */
777 	if (bs->fat_length == 0) {
778 		/* Assume FAT32 */
779 		bs->fat32_length = FAT2CPU32(bs->fat32_length);
780 		bs->flags = FAT2CPU16(bs->flags);
781 		bs->root_cluster = FAT2CPU32(bs->root_cluster);
782 		bs->info_sector = FAT2CPU16(bs->info_sector);
783 		bs->backup_boot = FAT2CPU16(bs->backup_boot);
784 		vistart = (volume_info *)(block + sizeof(boot_sector));
785 		*fatsize = 32;
786 	} else {
787 		vistart = (volume_info *)&(bs->fat32_length);
788 		*fatsize = 0;
789 	}
790 	memcpy(volinfo, vistart, sizeof(volume_info));
791 
792 	if (*fatsize == 32) {
793 		if (strncmp(FAT32_SIGN, vistart->fs_type, SIGNLEN) == 0)
794 			goto exit;
795 	} else {
796 		if (strncmp(FAT12_SIGN, vistart->fs_type, SIGNLEN) == 0) {
797 			*fatsize = 12;
798 			goto exit;
799 		}
800 		if (strncmp(FAT16_SIGN, vistart->fs_type, SIGNLEN) == 0) {
801 			*fatsize = 16;
802 			goto exit;
803 		}
804 	}
805 
806 	debug("Error: broken fs_type sign\n");
807 fail:
808 	ret = -1;
809 exit:
810 	free(block);
811 	return ret;
812 }
813 
814 __u8 do_fat_read_at_block[MAX_CLUSTSIZE]
815 	__aligned(ARCH_DMA_MINALIGN);
816 
817 int do_fat_read_at(const char *filename, loff_t pos, void *buffer,
818 		   loff_t maxsize, int dols, int dogetsize, loff_t *size)
819 {
820 	char fnamecopy[2048];
821 	boot_sector bs;
822 	volume_info volinfo;
823 	fsdata datablock;
824 	fsdata *mydata = &datablock;
825 	dir_entry *dentptr = NULL;
826 	__u16 prevcksum = 0xffff;
827 	char *subname = "";
828 	__u32 cursect;
829 	int idx, isdir = 0;
830 	int files = 0, dirs = 0;
831 	int ret = -1;
832 	int firsttime;
833 	__u32 root_cluster = 0;
834 	__u32 read_blk;
835 	int rootdir_size = 0;
836 	int buffer_blk_cnt;
837 	int do_read;
838 	__u8 *dir_ptr;
839 
840 	if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
841 		debug("Error: reading boot sector\n");
842 		return -1;
843 	}
844 
845 	if (mydata->fatsize == 32) {
846 		root_cluster = bs.root_cluster;
847 		mydata->fatlength = bs.fat32_length;
848 	} else {
849 		mydata->fatlength = bs.fat_length;
850 	}
851 
852 	mydata->fat_sect = bs.reserved;
853 
854 	cursect = mydata->rootdir_sect
855 		= mydata->fat_sect + mydata->fatlength * bs.fats;
856 
857 	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
858 	mydata->clust_size = bs.cluster_size;
859 	if (mydata->sect_size != cur_part_info.blksz) {
860 		printf("Error: FAT sector size mismatch (fs=%hu, dev=%lu)\n",
861 				mydata->sect_size, cur_part_info.blksz);
862 		return -1;
863 	}
864 
865 	if (mydata->fatsize == 32) {
866 		mydata->data_begin = mydata->rootdir_sect -
867 					(mydata->clust_size * 2);
868 	} else {
869 		rootdir_size = ((bs.dir_entries[1]  * (int)256 +
870 				 bs.dir_entries[0]) *
871 				 sizeof(dir_entry)) /
872 				 mydata->sect_size;
873 		mydata->data_begin = mydata->rootdir_sect +
874 					rootdir_size -
875 					(mydata->clust_size * 2);
876 	}
877 
878 	mydata->fatbufnum = -1;
879 	mydata->fat_dirty = 0;
880 	mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
881 	if (mydata->fatbuf == NULL) {
882 		debug("Error: allocating memory\n");
883 		return -1;
884 	}
885 
886 	if (vfat_enabled)
887 		debug("VFAT Support enabled\n");
888 
889 	debug("FAT%d, fat_sect: %d, fatlength: %d\n",
890 	       mydata->fatsize, mydata->fat_sect, mydata->fatlength);
891 	debug("Rootdir begins at cluster: %d, sector: %d, offset: %x\n"
892 	       "Data begins at: %d\n",
893 	       root_cluster,
894 	       mydata->rootdir_sect,
895 	       mydata->rootdir_sect * mydata->sect_size, mydata->data_begin);
896 	debug("Sector size: %d, cluster size: %d\n", mydata->sect_size,
897 	      mydata->clust_size);
898 
899 	/* "cwd" is always the root... */
900 	while (ISDIRDELIM(*filename))
901 		filename++;
902 
903 	/* Make a copy of the filename and convert it to lowercase */
904 	strcpy(fnamecopy, filename);
905 	downcase(fnamecopy);
906 
907 root_reparse:
908 	if (*fnamecopy == '\0') {
909 		if (!dols)
910 			goto exit;
911 
912 		dols = LS_ROOT;
913 	} else if ((idx = dirdelim(fnamecopy)) >= 0) {
914 		isdir = 1;
915 		fnamecopy[idx] = '\0';
916 		subname = fnamecopy + idx + 1;
917 
918 		/* Handle multiple delimiters */
919 		while (ISDIRDELIM(*subname))
920 			subname++;
921 	} else if (dols) {
922 		isdir = 1;
923 	}
924 
925 	buffer_blk_cnt = 0;
926 	firsttime = 1;
927 	while (1) {
928 		int i;
929 
930 		if (mydata->fatsize == 32 || firsttime) {
931 			dir_ptr = do_fat_read_at_block;
932 			firsttime = 0;
933 		} else {
934 			/**
935 			 * FAT16 sector buffer modification:
936 			 * Each loop, the second buffered block is moved to
937 			 * the buffer begin, and two next sectors are read
938 			 * next to the previously moved one. So the sector
939 			 * buffer keeps always 3 sectors for fat16.
940 			 * And the current sector is the buffer second sector
941 			 * beside the "firsttime" read, when it is the first one.
942 			 *
943 			 * PREFETCH_BLOCKS is 2 for FAT16 == loop[0:1]
944 			 * n = computed root dir sector
945 			 * loop |  cursect-1  | cursect    | cursect+1  |
946 			 *   0  |  sector n+0 | sector n+1 | none       |
947 			 *   1  |  none       | sector n+0 | sector n+1 |
948 			 *   0  |  sector n+1 | sector n+2 | sector n+3 |
949 			 *   1  |  sector n+3 | ...
950 			*/
951 			dir_ptr = (do_fat_read_at_block + mydata->sect_size);
952 			memcpy(do_fat_read_at_block, dir_ptr, mydata->sect_size);
953 		}
954 
955 		do_read = 1;
956 
957 		if (mydata->fatsize == 32 && buffer_blk_cnt)
958 			do_read = 0;
959 
960 		if (do_read) {
961 			read_blk = (mydata->fatsize == 32) ?
962 				    mydata->clust_size : PREFETCH_BLOCKS;
963 
964 			debug("FAT read(sect=%d, cnt:%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n",
965 				cursect, read_blk, mydata->clust_size, DIRENTSPERBLOCK);
966 
967 			if (disk_read(cursect, read_blk, dir_ptr) < 0) {
968 				debug("Error: reading rootdir block\n");
969 				goto exit;
970 			}
971 
972 			dentptr = (dir_entry *)dir_ptr;
973 		}
974 
975 		for (i = 0; i < DIRENTSPERBLOCK; i++) {
976 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
977 			__u8 csum;
978 
979 			l_name[0] = '\0';
980 			if (dentptr->name[0] == DELETED_FLAG) {
981 				dentptr++;
982 				continue;
983 			}
984 
985 			if (vfat_enabled)
986 				csum = mkcksum(dentptr->name, dentptr->ext);
987 
988 			if (dentptr->attr & ATTR_VOLUME) {
989 				if (vfat_enabled &&
990 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
991 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
992 					prevcksum =
993 						((dir_slot *)dentptr)->alias_checksum;
994 
995 					get_vfatname(mydata,
996 						     root_cluster,
997 						     dir_ptr,
998 						     dentptr, l_name);
999 
1000 					if (dols == LS_ROOT) {
1001 						char dirc;
1002 						int doit = 0;
1003 						int isdir =
1004 							(dentptr->attr & ATTR_DIR);
1005 
1006 						if (isdir) {
1007 							dirs++;
1008 							dirc = '/';
1009 							doit = 1;
1010 						} else {
1011 							dirc = ' ';
1012 							if (l_name[0] != 0) {
1013 								files++;
1014 								doit = 1;
1015 							}
1016 						}
1017 						if (doit) {
1018 							if (dirc == ' ') {
1019 								printf(" %8u   %s%c\n",
1020 								       FAT2CPU32(dentptr->size),
1021 									l_name,
1022 									dirc);
1023 							} else {
1024 								printf("            %s%c\n",
1025 									l_name,
1026 									dirc);
1027 							}
1028 						}
1029 						dentptr++;
1030 						continue;
1031 					}
1032 					debug("Rootvfatname: |%s|\n",
1033 					       l_name);
1034 				} else {
1035 					/* Volume label or VFAT entry */
1036 					dentptr++;
1037 					continue;
1038 				}
1039 			} else if (dentptr->name[0] == 0) {
1040 				debug("RootDentname == NULL - %d\n", i);
1041 				if (dols == LS_ROOT) {
1042 					printf("\n%d file(s), %d dir(s)\n\n",
1043 						files, dirs);
1044 					ret = 0;
1045 				}
1046 				goto exit;
1047 			}
1048 			else if (vfat_enabled &&
1049 				 dols == LS_ROOT && csum == prevcksum) {
1050 				prevcksum = 0xffff;
1051 				dentptr++;
1052 				continue;
1053 			}
1054 
1055 			get_name(dentptr, s_name);
1056 
1057 			if (dols == LS_ROOT) {
1058 				int isdir = (dentptr->attr & ATTR_DIR);
1059 				char dirc;
1060 				int doit = 0;
1061 
1062 				if (isdir) {
1063 					dirc = '/';
1064 					if (s_name[0] != 0) {
1065 						dirs++;
1066 						doit = 1;
1067 					}
1068 				} else {
1069 					dirc = ' ';
1070 					if (s_name[0] != 0) {
1071 						files++;
1072 						doit = 1;
1073 					}
1074 				}
1075 				if (doit) {
1076 					if (dirc == ' ') {
1077 						printf(" %8u   %s%c\n",
1078 						       FAT2CPU32(dentptr->size),
1079 							s_name, dirc);
1080 					} else {
1081 						printf("            %s%c\n",
1082 							s_name, dirc);
1083 					}
1084 				}
1085 				dentptr++;
1086 				continue;
1087 			}
1088 
1089 			if (strcmp(fnamecopy, s_name)
1090 			    && strcmp(fnamecopy, l_name)) {
1091 				debug("RootMismatch: |%s|%s|\n", s_name,
1092 				       l_name);
1093 				dentptr++;
1094 				continue;
1095 			}
1096 
1097 			if (isdir && !(dentptr->attr & ATTR_DIR))
1098 				goto exit;
1099 
1100 			debug("RootName: %s", s_name);
1101 			debug(", start: 0x%x", START(dentptr));
1102 			debug(", size:  0x%x %s\n",
1103 			       FAT2CPU32(dentptr->size),
1104 			       isdir ? "(DIR)" : "");
1105 
1106 			goto rootdir_done;	/* We got a match */
1107 		}
1108 		debug("END LOOP: buffer_blk_cnt=%d   clust_size=%d\n", buffer_blk_cnt,
1109 		       mydata->clust_size);
1110 
1111 		/*
1112 		 * On FAT32 we must fetch the FAT entries for the next
1113 		 * root directory clusters when a cluster has been
1114 		 * completely processed.
1115 		 */
1116 		++buffer_blk_cnt;
1117 		int rootdir_end = 0;
1118 		if (mydata->fatsize == 32) {
1119 			if (buffer_blk_cnt == mydata->clust_size) {
1120 				int nxtsect = 0;
1121 				int nxt_clust = 0;
1122 
1123 				nxt_clust = get_fatent(mydata, root_cluster);
1124 				rootdir_end = CHECK_CLUST(nxt_clust, 32);
1125 
1126 				nxtsect = mydata->data_begin +
1127 					(nxt_clust * mydata->clust_size);
1128 
1129 				root_cluster = nxt_clust;
1130 
1131 				cursect = nxtsect;
1132 				buffer_blk_cnt = 0;
1133 			}
1134 		} else {
1135 			if (buffer_blk_cnt == PREFETCH_BLOCKS)
1136 				buffer_blk_cnt = 0;
1137 
1138 			rootdir_end = (++cursect - mydata->rootdir_sect >=
1139 				       rootdir_size);
1140 		}
1141 
1142 		/* If end of rootdir reached */
1143 		if (rootdir_end) {
1144 			if (dols == LS_ROOT) {
1145 				printf("\n%d file(s), %d dir(s)\n\n",
1146 				       files, dirs);
1147 				*size = 0;
1148 			}
1149 			goto exit;
1150 		}
1151 	}
1152 rootdir_done:
1153 
1154 	firsttime = 1;
1155 
1156 	while (isdir) {
1157 		int startsect = mydata->data_begin
1158 			+ START(dentptr) * mydata->clust_size;
1159 		dir_entry dent;
1160 		char *nextname = NULL;
1161 
1162 		dent = *dentptr;
1163 		dentptr = &dent;
1164 
1165 		idx = dirdelim(subname);
1166 
1167 		if (idx >= 0) {
1168 			subname[idx] = '\0';
1169 			nextname = subname + idx + 1;
1170 			/* Handle multiple delimiters */
1171 			while (ISDIRDELIM(*nextname))
1172 				nextname++;
1173 			if (dols && *nextname == '\0')
1174 				firsttime = 0;
1175 		} else {
1176 			if (dols && firsttime) {
1177 				firsttime = 0;
1178 			} else {
1179 				isdir = 0;
1180 			}
1181 		}
1182 
1183 		if (get_dentfromdir(mydata, startsect, subname, dentptr,
1184 				     isdir ? 0 : dols) == NULL) {
1185 			if (dols && !isdir)
1186 				*size = 0;
1187 			goto exit;
1188 		}
1189 
1190 		if (isdir && !(dentptr->attr & ATTR_DIR))
1191 			goto exit;
1192 
1193 		/*
1194 		 * If we are looking for a directory, and found a directory
1195 		 * type entry, and the entry is for the root directory (as
1196 		 * denoted by a cluster number of 0), jump back to the start
1197 		 * of the function, since at least on FAT12/16, the root dir
1198 		 * lives in a hard-coded location and needs special handling
1199 		 * to parse, rather than simply following the cluster linked
1200 		 * list in the FAT, like other directories.
1201 		 */
1202 		if (isdir && (dentptr->attr & ATTR_DIR) && !START(dentptr)) {
1203 			/*
1204 			 * Modify the filename to remove the prefix that gets
1205 			 * back to the root directory, so the initial root dir
1206 			 * parsing code can continue from where we are without
1207 			 * confusion.
1208 			 */
1209 			strcpy(fnamecopy, nextname ?: "");
1210 			/*
1211 			 * Set up state the same way as the function does when
1212 			 * first started. This is required for the root dir
1213 			 * parsing code operates in its expected environment.
1214 			 */
1215 			subname = "";
1216 			cursect = mydata->rootdir_sect;
1217 			isdir = 0;
1218 			goto root_reparse;
1219 		}
1220 
1221 		if (idx >= 0)
1222 			subname = nextname;
1223 	}
1224 
1225 	if (dogetsize) {
1226 		*size = FAT2CPU32(dentptr->size);
1227 		ret = 0;
1228 	} else {
1229 		ret = get_contents(mydata, dentptr, pos, buffer, maxsize, size);
1230 	}
1231 	debug("Size: %u, got: %llu\n", FAT2CPU32(dentptr->size), *size);
1232 
1233 exit:
1234 	free(mydata->fatbuf);
1235 	return ret;
1236 }
1237 
1238 int do_fat_read(const char *filename, void *buffer, loff_t maxsize, int dols,
1239 		loff_t *actread)
1240 {
1241 	return do_fat_read_at(filename, 0, buffer, maxsize, dols, 0, actread);
1242 }
1243 
1244 int file_fat_detectfs(void)
1245 {
1246 	boot_sector bs;
1247 	volume_info volinfo;
1248 	int fatsize;
1249 	char vol_label[12];
1250 
1251 	if (cur_dev == NULL) {
1252 		printf("No current device\n");
1253 		return 1;
1254 	}
1255 
1256 #if defined(CONFIG_CMD_IDE) || \
1257     defined(CONFIG_CMD_SATA) || \
1258     defined(CONFIG_SCSI) || \
1259     defined(CONFIG_CMD_USB) || \
1260     defined(CONFIG_MMC)
1261 	printf("Interface:  ");
1262 	switch (cur_dev->if_type) {
1263 	case IF_TYPE_IDE:
1264 		printf("IDE");
1265 		break;
1266 	case IF_TYPE_SATA:
1267 		printf("SATA");
1268 		break;
1269 	case IF_TYPE_SCSI:
1270 		printf("SCSI");
1271 		break;
1272 	case IF_TYPE_ATAPI:
1273 		printf("ATAPI");
1274 		break;
1275 	case IF_TYPE_USB:
1276 		printf("USB");
1277 		break;
1278 	case IF_TYPE_DOC:
1279 		printf("DOC");
1280 		break;
1281 	case IF_TYPE_MMC:
1282 		printf("MMC");
1283 		break;
1284 	default:
1285 		printf("Unknown");
1286 	}
1287 
1288 	printf("\n  Device %d: ", cur_dev->devnum);
1289 	dev_print(cur_dev);
1290 #endif
1291 
1292 	if (read_bootsectandvi(&bs, &volinfo, &fatsize)) {
1293 		printf("\nNo valid FAT fs found\n");
1294 		return 1;
1295 	}
1296 
1297 	memcpy(vol_label, volinfo.volume_label, 11);
1298 	vol_label[11] = '\0';
1299 	volinfo.fs_type[5] = '\0';
1300 
1301 	printf("Filesystem: %s \"%s\"\n", volinfo.fs_type, vol_label);
1302 
1303 	return 0;
1304 }
1305 
1306 int file_fat_ls(const char *dir)
1307 {
1308 	loff_t size;
1309 
1310 	return do_fat_read(dir, NULL, 0, LS_YES, &size);
1311 }
1312 
1313 int fat_exists(const char *filename)
1314 {
1315 	int ret;
1316 	loff_t size;
1317 
1318 	ret = do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, &size);
1319 	return ret == 0;
1320 }
1321 
1322 int fat_size(const char *filename, loff_t *size)
1323 {
1324 	return do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, size);
1325 }
1326 
1327 int file_fat_read_at(const char *filename, loff_t pos, void *buffer,
1328 		     loff_t maxsize, loff_t *actread)
1329 {
1330 	printf("reading %s\n", filename);
1331 	return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO, 0,
1332 			      actread);
1333 }
1334 
1335 int file_fat_read(const char *filename, void *buffer, int maxsize)
1336 {
1337 	loff_t actread;
1338 	int ret;
1339 
1340 	ret =  file_fat_read_at(filename, 0, buffer, maxsize, &actread);
1341 	if (ret)
1342 		return ret;
1343 	else
1344 		return actread;
1345 }
1346 
1347 int fat_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
1348 		  loff_t *actread)
1349 {
1350 	int ret;
1351 
1352 	ret = file_fat_read_at(filename, offset, buf, len, actread);
1353 	if (ret)
1354 		printf("** Unable to read file %s **\n", filename);
1355 
1356 	return ret;
1357 }
1358 
1359 void fat_close(void)
1360 {
1361 }
1362