xref: /openbmc/u-boot/fs/fat/fat.c (revision d928664f)
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 <config.h>
14 #include <exports.h>
15 #include <fat.h>
16 #include <asm/byteorder.h>
17 #include <part.h>
18 #include <malloc.h>
19 #include <linux/compiler.h>
20 #include <linux/ctype.h>
21 
22 #ifdef CONFIG_SUPPORT_VFAT
23 static const int vfat_enabled = 1;
24 #else
25 static const int vfat_enabled = 0;
26 #endif
27 
28 /*
29  * Convert a string to lowercase.
30  */
31 static void downcase(char *str)
32 {
33 	while (*str != '\0') {
34 		*str = tolower(*str);
35 		str++;
36 	}
37 }
38 
39 static block_dev_desc_t *cur_dev;
40 static disk_partition_t cur_part_info;
41 
42 #define DOS_BOOT_MAGIC_OFFSET	0x1fe
43 #define DOS_FS_TYPE_OFFSET	0x36
44 #define DOS_FS32_TYPE_OFFSET	0x52
45 
46 static int disk_read(__u32 block, __u32 nr_blocks, void *buf)
47 {
48 	if (!cur_dev || !cur_dev->block_read)
49 		return -1;
50 
51 	return cur_dev->block_read(cur_dev->dev,
52 			cur_part_info.start + block, nr_blocks, buf);
53 }
54 
55 int fat_set_blk_dev(block_dev_desc_t *dev_desc, disk_partition_t *info)
56 {
57 	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, dev_desc->blksz);
58 
59 	cur_dev = dev_desc;
60 	cur_part_info = *info;
61 
62 	/* Make sure it has a valid FAT header */
63 	if (disk_read(0, 1, buffer) != 1) {
64 		cur_dev = NULL;
65 		return -1;
66 	}
67 
68 	/* Check if it's actually a DOS volume */
69 	if (memcmp(buffer + DOS_BOOT_MAGIC_OFFSET, "\x55\xAA", 2)) {
70 		cur_dev = NULL;
71 		return -1;
72 	}
73 
74 	/* Check for FAT12/FAT16/FAT32 filesystem */
75 	if (!memcmp(buffer + DOS_FS_TYPE_OFFSET, "FAT", 3))
76 		return 0;
77 	if (!memcmp(buffer + DOS_FS32_TYPE_OFFSET, "FAT32", 5))
78 		return 0;
79 
80 	cur_dev = NULL;
81 	return -1;
82 }
83 
84 int fat_register_device(block_dev_desc_t *dev_desc, int part_no)
85 {
86 	disk_partition_t info;
87 
88 	/* First close any currently found FAT filesystem */
89 	cur_dev = NULL;
90 
91 	/* Read the partition table, if present */
92 	if (get_partition_info(dev_desc, part_no, &info)) {
93 		if (part_no != 0) {
94 			printf("** Partition %d not valid on device %d **\n",
95 					part_no, dev_desc->dev);
96 			return -1;
97 		}
98 
99 		info.start = 0;
100 		info.size = dev_desc->lba;
101 		info.blksz = dev_desc->blksz;
102 		info.name[0] = 0;
103 		info.type[0] = 0;
104 		info.bootable = 0;
105 #ifdef CONFIG_PARTITION_UUIDS
106 		info.uuid[0] = 0;
107 #endif
108 	}
109 
110 	return fat_set_blk_dev(dev_desc, &info);
111 }
112 
113 /*
114  * Get the first occurence of a directory delimiter ('/' or '\') in a string.
115  * Return index into string if found, -1 otherwise.
116  */
117 static int dirdelim(char *str)
118 {
119 	char *start = str;
120 
121 	while (*str != '\0') {
122 		if (ISDIRDELIM(*str))
123 			return str - start;
124 		str++;
125 	}
126 	return -1;
127 }
128 
129 /*
130  * Extract zero terminated short name from a directory entry.
131  */
132 static void get_name(dir_entry *dirent, char *s_name)
133 {
134 	char *ptr;
135 
136 	memcpy(s_name, dirent->name, 8);
137 	s_name[8] = '\0';
138 	ptr = s_name;
139 	while (*ptr && *ptr != ' ')
140 		ptr++;
141 	if (dirent->ext[0] && dirent->ext[0] != ' ') {
142 		*ptr = '.';
143 		ptr++;
144 		memcpy(ptr, dirent->ext, 3);
145 		ptr[3] = '\0';
146 		while (*ptr && *ptr != ' ')
147 			ptr++;
148 	}
149 	*ptr = '\0';
150 	if (*s_name == DELETED_FLAG)
151 		*s_name = '\0';
152 	else if (*s_name == aRING)
153 		*s_name = DELETED_FLAG;
154 	downcase(s_name);
155 }
156 
157 /*
158  * Get the entry at index 'entry' in a FAT (12/16/32) table.
159  * On failure 0x00 is returned.
160  */
161 static __u32 get_fatent(fsdata *mydata, __u32 entry)
162 {
163 	__u32 bufnum;
164 	__u32 off16, offset;
165 	__u32 ret = 0x00;
166 	__u16 val1, val2;
167 
168 	switch (mydata->fatsize) {
169 	case 32:
170 		bufnum = entry / FAT32BUFSIZE;
171 		offset = entry - bufnum * FAT32BUFSIZE;
172 		break;
173 	case 16:
174 		bufnum = entry / FAT16BUFSIZE;
175 		offset = entry - bufnum * FAT16BUFSIZE;
176 		break;
177 	case 12:
178 		bufnum = entry / FAT12BUFSIZE;
179 		offset = entry - bufnum * FAT12BUFSIZE;
180 		break;
181 
182 	default:
183 		/* Unsupported FAT size */
184 		return ret;
185 	}
186 
187 	debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
188 	       mydata->fatsize, entry, entry, offset, offset);
189 
190 	/* Read a new block of FAT entries into the cache. */
191 	if (bufnum != mydata->fatbufnum) {
192 		__u32 getsize = FATBUFBLOCKS;
193 		__u8 *bufptr = mydata->fatbuf;
194 		__u32 fatlength = mydata->fatlength;
195 		__u32 startblock = bufnum * FATBUFBLOCKS;
196 
197 		if (startblock + getsize > fatlength)
198 			getsize = fatlength - startblock;
199 
200 		startblock += mydata->fat_sect;	/* Offset from start of disk */
201 
202 		if (disk_read(startblock, getsize, bufptr) < 0) {
203 			debug("Error reading FAT blocks\n");
204 			return ret;
205 		}
206 		mydata->fatbufnum = bufnum;
207 	}
208 
209 	/* Get the actual entry from the table */
210 	switch (mydata->fatsize) {
211 	case 32:
212 		ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
213 		break;
214 	case 16:
215 		ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
216 		break;
217 	case 12:
218 		off16 = (offset * 3) / 4;
219 
220 		switch (offset & 0x3) {
221 		case 0:
222 			ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
223 			ret &= 0xfff;
224 			break;
225 		case 1:
226 			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
227 			val1 &= 0xf000;
228 			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
229 			val2 &= 0x00ff;
230 			ret = (val2 << 4) | (val1 >> 12);
231 			break;
232 		case 2:
233 			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
234 			val1 &= 0xff00;
235 			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
236 			val2 &= 0x000f;
237 			ret = (val2 << 8) | (val1 >> 8);
238 			break;
239 		case 3:
240 			ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
241 			ret = (ret & 0xfff0) >> 4;
242 			break;
243 		default:
244 			break;
245 		}
246 		break;
247 	}
248 	debug("FAT%d: ret: %08x, offset: %04x\n",
249 	       mydata->fatsize, ret, offset);
250 
251 	return ret;
252 }
253 
254 /*
255  * Read at most 'size' bytes from the specified cluster into 'buffer'.
256  * Return 0 on success, -1 otherwise.
257  */
258 static int
259 get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
260 {
261 	__u32 idx = 0;
262 	__u32 startsect;
263 	int ret;
264 
265 	if (clustnum > 0) {
266 		startsect = mydata->data_begin +
267 				clustnum * mydata->clust_size;
268 	} else {
269 		startsect = mydata->rootdir_sect;
270 	}
271 
272 	debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect);
273 
274 	if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
275 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
276 
277 		printf("FAT: Misaligned buffer address (%p)\n", buffer);
278 
279 		while (size >= mydata->sect_size) {
280 			ret = disk_read(startsect++, 1, tmpbuf);
281 			if (ret != 1) {
282 				debug("Error reading data (got %d)\n", ret);
283 				return -1;
284 			}
285 
286 			memcpy(buffer, tmpbuf, mydata->sect_size);
287 			buffer += mydata->sect_size;
288 			size -= mydata->sect_size;
289 		}
290 	} else {
291 		idx = size / mydata->sect_size;
292 		ret = disk_read(startsect, idx, buffer);
293 		if (ret != idx) {
294 			debug("Error reading data (got %d)\n", ret);
295 			return -1;
296 		}
297 		startsect += idx;
298 		idx *= mydata->sect_size;
299 		buffer += idx;
300 		size -= idx;
301 	}
302 	if (size) {
303 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
304 
305 		ret = disk_read(startsect, 1, tmpbuf);
306 		if (ret != 1) {
307 			debug("Error reading data (got %d)\n", ret);
308 			return -1;
309 		}
310 
311 		memcpy(buffer, tmpbuf, size);
312 	}
313 
314 	return 0;
315 }
316 
317 /*
318  * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr'
319  * into 'buffer'.
320  * Update the number of bytes read in *gotsize or return -1 on fatal errors.
321  */
322 __u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
323 	__aligned(ARCH_DMA_MINALIGN);
324 
325 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
326 			__u8 *buffer, loff_t maxsize, loff_t *gotsize)
327 {
328 	loff_t filesize = FAT2CPU32(dentptr->size);
329 	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
330 	__u32 curclust = START(dentptr);
331 	__u32 endclust, newclust;
332 	loff_t actsize;
333 
334 	*gotsize = 0;
335 	debug("Filesize: %llu bytes\n", filesize);
336 
337 	if (pos >= filesize) {
338 		debug("Read position past EOF: %llu\n", pos);
339 		return 0;
340 	}
341 
342 	if (maxsize > 0 && filesize > pos + maxsize)
343 		filesize = pos + maxsize;
344 
345 	debug("%llu bytes\n", filesize);
346 
347 	actsize = bytesperclust;
348 
349 	/* go to cluster at pos */
350 	while (actsize <= pos) {
351 		curclust = get_fatent(mydata, curclust);
352 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
353 			debug("curclust: 0x%x\n", curclust);
354 			debug("Invalid FAT entry\n");
355 			return 0;
356 		}
357 		actsize += bytesperclust;
358 	}
359 
360 	/* actsize > pos */
361 	actsize -= bytesperclust;
362 	filesize -= actsize;
363 	pos -= actsize;
364 
365 	/* align to beginning of next cluster if any */
366 	if (pos) {
367 		actsize = min(filesize, (loff_t)bytesperclust);
368 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
369 				(int)actsize) != 0) {
370 			printf("Error reading cluster\n");
371 			return -1;
372 		}
373 		filesize -= actsize;
374 		actsize -= pos;
375 		memcpy(buffer, get_contents_vfatname_block + pos, actsize);
376 		*gotsize += actsize;
377 		if (!filesize)
378 			return 0;
379 		buffer += actsize;
380 
381 		curclust = get_fatent(mydata, curclust);
382 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
383 			debug("curclust: 0x%x\n", curclust);
384 			debug("Invalid FAT entry\n");
385 			return 0;
386 		}
387 	}
388 
389 	actsize = bytesperclust;
390 	endclust = curclust;
391 
392 	do {
393 		/* search for consecutive clusters */
394 		while (actsize < filesize) {
395 			newclust = get_fatent(mydata, endclust);
396 			if ((newclust - 1) != endclust)
397 				goto getit;
398 			if (CHECK_CLUST(newclust, mydata->fatsize)) {
399 				debug("curclust: 0x%x\n", newclust);
400 				debug("Invalid FAT entry\n");
401 				return 0;
402 			}
403 			endclust = newclust;
404 			actsize += bytesperclust;
405 		}
406 
407 		/* get remaining bytes */
408 		actsize = filesize;
409 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
410 			printf("Error reading cluster\n");
411 			return -1;
412 		}
413 		*gotsize += actsize;
414 		return 0;
415 getit:
416 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
417 			printf("Error reading cluster\n");
418 			return -1;
419 		}
420 		*gotsize += (int)actsize;
421 		filesize -= actsize;
422 		buffer += actsize;
423 
424 		curclust = get_fatent(mydata, endclust);
425 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
426 			debug("curclust: 0x%x\n", curclust);
427 			printf("Invalid FAT entry\n");
428 			return 0;
429 		}
430 		actsize = bytesperclust;
431 		endclust = curclust;
432 	} while (1);
433 }
434 
435 /*
436  * Extract the file name information from 'slotptr' into 'l_name',
437  * starting at l_name[*idx].
438  * Return 1 if terminator (zero byte) is found, 0 otherwise.
439  */
440 static int slot2str(dir_slot *slotptr, char *l_name, int *idx)
441 {
442 	int j;
443 
444 	for (j = 0; j <= 8; j += 2) {
445 		l_name[*idx] = slotptr->name0_4[j];
446 		if (l_name[*idx] == 0x00)
447 			return 1;
448 		(*idx)++;
449 	}
450 	for (j = 0; j <= 10; j += 2) {
451 		l_name[*idx] = slotptr->name5_10[j];
452 		if (l_name[*idx] == 0x00)
453 			return 1;
454 		(*idx)++;
455 	}
456 	for (j = 0; j <= 2; j += 2) {
457 		l_name[*idx] = slotptr->name11_12[j];
458 		if (l_name[*idx] == 0x00)
459 			return 1;
460 		(*idx)++;
461 	}
462 
463 	return 0;
464 }
465 
466 /*
467  * Extract the full long filename starting at 'retdent' (which is really
468  * a slot) into 'l_name'. If successful also copy the real directory entry
469  * into 'retdent'
470  * Return 0 on success, -1 otherwise.
471  */
472 static int
473 get_vfatname(fsdata *mydata, int curclust, __u8 *cluster,
474 	     dir_entry *retdent, char *l_name)
475 {
476 	dir_entry *realdent;
477 	dir_slot *slotptr = (dir_slot *)retdent;
478 	__u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
479 							PREFETCH_BLOCKS :
480 							mydata->clust_size);
481 	__u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
482 	int idx = 0;
483 
484 	if (counter > VFAT_MAXSEQ) {
485 		debug("Error: VFAT name is too long\n");
486 		return -1;
487 	}
488 
489 	while ((__u8 *)slotptr < buflimit) {
490 		if (counter == 0)
491 			break;
492 		if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
493 			return -1;
494 		slotptr++;
495 		counter--;
496 	}
497 
498 	if ((__u8 *)slotptr >= buflimit) {
499 		dir_slot *slotptr2;
500 
501 		if (curclust == 0)
502 			return -1;
503 		curclust = get_fatent(mydata, curclust);
504 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
505 			debug("curclust: 0x%x\n", curclust);
506 			printf("Invalid FAT entry\n");
507 			return -1;
508 		}
509 
510 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
511 				mydata->clust_size * mydata->sect_size) != 0) {
512 			debug("Error: reading directory block\n");
513 			return -1;
514 		}
515 
516 		slotptr2 = (dir_slot *)get_contents_vfatname_block;
517 		while (counter > 0) {
518 			if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
519 			    & 0xff) != counter)
520 				return -1;
521 			slotptr2++;
522 			counter--;
523 		}
524 
525 		/* Save the real directory entry */
526 		realdent = (dir_entry *)slotptr2;
527 		while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
528 			slotptr2--;
529 			slot2str(slotptr2, l_name, &idx);
530 		}
531 	} else {
532 		/* Save the real directory entry */
533 		realdent = (dir_entry *)slotptr;
534 	}
535 
536 	do {
537 		slotptr--;
538 		if (slot2str(slotptr, l_name, &idx))
539 			break;
540 	} while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
541 
542 	l_name[idx] = '\0';
543 	if (*l_name == DELETED_FLAG)
544 		*l_name = '\0';
545 	else if (*l_name == aRING)
546 		*l_name = DELETED_FLAG;
547 	downcase(l_name);
548 
549 	/* Return the real directory entry */
550 	memcpy(retdent, realdent, sizeof(dir_entry));
551 
552 	return 0;
553 }
554 
555 /* Calculate short name checksum */
556 static __u8 mkcksum(const char name[8], const char ext[3])
557 {
558 	int i;
559 
560 	__u8 ret = 0;
561 
562 	for (i = 0; i < 8; i++)
563 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
564 	for (i = 0; i < 3; i++)
565 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
566 
567 	return ret;
568 }
569 
570 /*
571  * Get the directory entry associated with 'filename' from the directory
572  * starting at 'startsect'
573  */
574 __u8 get_dentfromdir_block[MAX_CLUSTSIZE]
575 	__aligned(ARCH_DMA_MINALIGN);
576 
577 static dir_entry *get_dentfromdir(fsdata *mydata, int startsect,
578 				  char *filename, dir_entry *retdent,
579 				  int dols)
580 {
581 	__u16 prevcksum = 0xffff;
582 	__u32 curclust = START(retdent);
583 	int files = 0, dirs = 0;
584 
585 	debug("get_dentfromdir: %s\n", filename);
586 
587 	while (1) {
588 		dir_entry *dentptr;
589 
590 		int i;
591 
592 		if (get_cluster(mydata, curclust, get_dentfromdir_block,
593 				mydata->clust_size * mydata->sect_size) != 0) {
594 			debug("Error: reading directory block\n");
595 			return NULL;
596 		}
597 
598 		dentptr = (dir_entry *)get_dentfromdir_block;
599 
600 		for (i = 0; i < DIRENTSPERCLUST; i++) {
601 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
602 
603 			l_name[0] = '\0';
604 			if (dentptr->name[0] == DELETED_FLAG) {
605 				dentptr++;
606 				continue;
607 			}
608 			if ((dentptr->attr & ATTR_VOLUME)) {
609 				if (vfat_enabled &&
610 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
611 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
612 					prevcksum = ((dir_slot *)dentptr)->alias_checksum;
613 					get_vfatname(mydata, curclust,
614 						     get_dentfromdir_block,
615 						     dentptr, l_name);
616 					if (dols) {
617 						int isdir;
618 						char dirc;
619 						int doit = 0;
620 
621 						isdir = (dentptr->attr & ATTR_DIR);
622 
623 						if (isdir) {
624 							dirs++;
625 							dirc = '/';
626 							doit = 1;
627 						} else {
628 							dirc = ' ';
629 							if (l_name[0] != 0) {
630 								files++;
631 								doit = 1;
632 							}
633 						}
634 						if (doit) {
635 							if (dirc == ' ') {
636 								printf(" %8u   %s%c\n",
637 								       FAT2CPU32(dentptr->size),
638 									l_name,
639 									dirc);
640 							} else {
641 								printf("            %s%c\n",
642 									l_name,
643 									dirc);
644 							}
645 						}
646 						dentptr++;
647 						continue;
648 					}
649 					debug("vfatname: |%s|\n", l_name);
650 				} else {
651 					/* Volume label or VFAT entry */
652 					dentptr++;
653 					continue;
654 				}
655 			}
656 			if (dentptr->name[0] == 0) {
657 				if (dols) {
658 					printf("\n%d file(s), %d dir(s)\n\n",
659 						files, dirs);
660 				}
661 				debug("Dentname == NULL - %d\n", i);
662 				return NULL;
663 			}
664 			if (vfat_enabled) {
665 				__u8 csum = mkcksum(dentptr->name, dentptr->ext);
666 				if (dols && csum == prevcksum) {
667 					prevcksum = 0xffff;
668 					dentptr++;
669 					continue;
670 				}
671 			}
672 
673 			get_name(dentptr, s_name);
674 			if (dols) {
675 				int isdir = (dentptr->attr & ATTR_DIR);
676 				char dirc;
677 				int doit = 0;
678 
679 				if (isdir) {
680 					dirs++;
681 					dirc = '/';
682 					doit = 1;
683 				} else {
684 					dirc = ' ';
685 					if (s_name[0] != 0) {
686 						files++;
687 						doit = 1;
688 					}
689 				}
690 
691 				if (doit) {
692 					if (dirc == ' ') {
693 						printf(" %8u   %s%c\n",
694 						       FAT2CPU32(dentptr->size),
695 							s_name, dirc);
696 					} else {
697 						printf("            %s%c\n",
698 							s_name, dirc);
699 					}
700 				}
701 
702 				dentptr++;
703 				continue;
704 			}
705 
706 			if (strcmp(filename, s_name)
707 			    && strcmp(filename, l_name)) {
708 				debug("Mismatch: |%s|%s|\n", s_name, l_name);
709 				dentptr++;
710 				continue;
711 			}
712 
713 			memcpy(retdent, dentptr, sizeof(dir_entry));
714 
715 			debug("DentName: %s", s_name);
716 			debug(", start: 0x%x", START(dentptr));
717 			debug(", size:  0x%x %s\n",
718 			      FAT2CPU32(dentptr->size),
719 			      (dentptr->attr & ATTR_DIR) ? "(DIR)" : "");
720 
721 			return retdent;
722 		}
723 
724 		curclust = get_fatent(mydata, curclust);
725 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
726 			debug("curclust: 0x%x\n", curclust);
727 			printf("Invalid FAT entry\n");
728 			return NULL;
729 		}
730 	}
731 
732 	return NULL;
733 }
734 
735 /*
736  * Read boot sector and volume info from a FAT filesystem
737  */
738 static int
739 read_bootsectandvi(boot_sector *bs, volume_info *volinfo, int *fatsize)
740 {
741 	__u8 *block;
742 	volume_info *vistart;
743 	int ret = 0;
744 
745 	if (cur_dev == NULL) {
746 		debug("Error: no device selected\n");
747 		return -1;
748 	}
749 
750 	block = memalign(ARCH_DMA_MINALIGN, cur_dev->blksz);
751 	if (block == NULL) {
752 		debug("Error: allocating block\n");
753 		return -1;
754 	}
755 
756 	if (disk_read(0, 1, block) < 0) {
757 		debug("Error: reading block\n");
758 		goto fail;
759 	}
760 
761 	memcpy(bs, block, sizeof(boot_sector));
762 	bs->reserved = FAT2CPU16(bs->reserved);
763 	bs->fat_length = FAT2CPU16(bs->fat_length);
764 	bs->secs_track = FAT2CPU16(bs->secs_track);
765 	bs->heads = FAT2CPU16(bs->heads);
766 	bs->total_sect = FAT2CPU32(bs->total_sect);
767 
768 	/* FAT32 entries */
769 	if (bs->fat_length == 0) {
770 		/* Assume FAT32 */
771 		bs->fat32_length = FAT2CPU32(bs->fat32_length);
772 		bs->flags = FAT2CPU16(bs->flags);
773 		bs->root_cluster = FAT2CPU32(bs->root_cluster);
774 		bs->info_sector = FAT2CPU16(bs->info_sector);
775 		bs->backup_boot = FAT2CPU16(bs->backup_boot);
776 		vistart = (volume_info *)(block + sizeof(boot_sector));
777 		*fatsize = 32;
778 	} else {
779 		vistart = (volume_info *)&(bs->fat32_length);
780 		*fatsize = 0;
781 	}
782 	memcpy(volinfo, vistart, sizeof(volume_info));
783 
784 	if (*fatsize == 32) {
785 		if (strncmp(FAT32_SIGN, vistart->fs_type, SIGNLEN) == 0)
786 			goto exit;
787 	} else {
788 		if (strncmp(FAT12_SIGN, vistart->fs_type, SIGNLEN) == 0) {
789 			*fatsize = 12;
790 			goto exit;
791 		}
792 		if (strncmp(FAT16_SIGN, vistart->fs_type, SIGNLEN) == 0) {
793 			*fatsize = 16;
794 			goto exit;
795 		}
796 	}
797 
798 	debug("Error: broken fs_type sign\n");
799 fail:
800 	ret = -1;
801 exit:
802 	free(block);
803 	return ret;
804 }
805 
806 __u8 do_fat_read_at_block[MAX_CLUSTSIZE]
807 	__aligned(ARCH_DMA_MINALIGN);
808 
809 int do_fat_read_at(const char *filename, loff_t pos, void *buffer,
810 		   loff_t maxsize, int dols, int dogetsize, loff_t *size)
811 {
812 	char fnamecopy[2048];
813 	boot_sector bs;
814 	volume_info volinfo;
815 	fsdata datablock;
816 	fsdata *mydata = &datablock;
817 	dir_entry *dentptr = NULL;
818 	__u16 prevcksum = 0xffff;
819 	char *subname = "";
820 	__u32 cursect;
821 	int idx, isdir = 0;
822 	int files = 0, dirs = 0;
823 	int ret = -1;
824 	int firsttime;
825 	__u32 root_cluster = 0;
826 	__u32 read_blk;
827 	int rootdir_size = 0;
828 	int buffer_blk_cnt;
829 	int do_read;
830 	__u8 *dir_ptr;
831 
832 	if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
833 		debug("Error: reading boot sector\n");
834 		return -1;
835 	}
836 
837 	if (mydata->fatsize == 32) {
838 		root_cluster = bs.root_cluster;
839 		mydata->fatlength = bs.fat32_length;
840 	} else {
841 		mydata->fatlength = bs.fat_length;
842 	}
843 
844 	mydata->fat_sect = bs.reserved;
845 
846 	cursect = mydata->rootdir_sect
847 		= mydata->fat_sect + mydata->fatlength * bs.fats;
848 
849 	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
850 	mydata->clust_size = bs.cluster_size;
851 	if (mydata->sect_size != cur_part_info.blksz) {
852 		printf("Error: FAT sector size mismatch (fs=%hu, dev=%lu)\n",
853 				mydata->sect_size, cur_part_info.blksz);
854 		return -1;
855 	}
856 
857 	if (mydata->fatsize == 32) {
858 		mydata->data_begin = mydata->rootdir_sect -
859 					(mydata->clust_size * 2);
860 	} else {
861 		rootdir_size = ((bs.dir_entries[1]  * (int)256 +
862 				 bs.dir_entries[0]) *
863 				 sizeof(dir_entry)) /
864 				 mydata->sect_size;
865 		mydata->data_begin = mydata->rootdir_sect +
866 					rootdir_size -
867 					(mydata->clust_size * 2);
868 	}
869 
870 	mydata->fatbufnum = -1;
871 	mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
872 	if (mydata->fatbuf == NULL) {
873 		debug("Error: allocating memory\n");
874 		return -1;
875 	}
876 
877 	if (vfat_enabled)
878 		debug("VFAT Support enabled\n");
879 
880 	debug("FAT%d, fat_sect: %d, fatlength: %d\n",
881 	       mydata->fatsize, mydata->fat_sect, mydata->fatlength);
882 	debug("Rootdir begins at cluster: %d, sector: %d, offset: %x\n"
883 	       "Data begins at: %d\n",
884 	       root_cluster,
885 	       mydata->rootdir_sect,
886 	       mydata->rootdir_sect * mydata->sect_size, mydata->data_begin);
887 	debug("Sector size: %d, cluster size: %d\n", mydata->sect_size,
888 	      mydata->clust_size);
889 
890 	/* "cwd" is always the root... */
891 	while (ISDIRDELIM(*filename))
892 		filename++;
893 
894 	/* Make a copy of the filename and convert it to lowercase */
895 	strcpy(fnamecopy, filename);
896 	downcase(fnamecopy);
897 
898 	if (*fnamecopy == '\0') {
899 		if (!dols)
900 			goto exit;
901 
902 		dols = LS_ROOT;
903 	} else if ((idx = dirdelim(fnamecopy)) >= 0) {
904 		isdir = 1;
905 		fnamecopy[idx] = '\0';
906 		subname = fnamecopy + idx + 1;
907 
908 		/* Handle multiple delimiters */
909 		while (ISDIRDELIM(*subname))
910 			subname++;
911 	} else if (dols) {
912 		isdir = 1;
913 	}
914 
915 	buffer_blk_cnt = 0;
916 	firsttime = 1;
917 	while (1) {
918 		int i;
919 
920 		if (mydata->fatsize == 32 || firsttime) {
921 			dir_ptr = do_fat_read_at_block;
922 			firsttime = 0;
923 		} else {
924 			/**
925 			 * FAT16 sector buffer modification:
926 			 * Each loop, the second buffered block is moved to
927 			 * the buffer begin, and two next sectors are read
928 			 * next to the previously moved one. So the sector
929 			 * buffer keeps always 3 sectors for fat16.
930 			 * And the current sector is the buffer second sector
931 			 * beside the "firsttime" read, when it is the first one.
932 			 *
933 			 * PREFETCH_BLOCKS is 2 for FAT16 == loop[0:1]
934 			 * n = computed root dir sector
935 			 * loop |  cursect-1  | cursect    | cursect+1  |
936 			 *   0  |  sector n+0 | sector n+1 | none       |
937 			 *   1  |  none       | sector n+0 | sector n+1 |
938 			 *   0  |  sector n+1 | sector n+2 | sector n+3 |
939 			 *   1  |  sector n+3 | ...
940 			*/
941 			dir_ptr = (do_fat_read_at_block + mydata->sect_size);
942 			memcpy(do_fat_read_at_block, dir_ptr, mydata->sect_size);
943 		}
944 
945 		do_read = 1;
946 
947 		if (mydata->fatsize == 32 && buffer_blk_cnt)
948 			do_read = 0;
949 
950 		if (do_read) {
951 			read_blk = (mydata->fatsize == 32) ?
952 				    mydata->clust_size : PREFETCH_BLOCKS;
953 
954 			debug("FAT read(sect=%d, cnt:%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n",
955 				cursect, read_blk, mydata->clust_size, DIRENTSPERBLOCK);
956 
957 			if (disk_read(cursect, read_blk, dir_ptr) < 0) {
958 				debug("Error: reading rootdir block\n");
959 				goto exit;
960 			}
961 
962 			dentptr = (dir_entry *)dir_ptr;
963 		}
964 
965 		for (i = 0; i < DIRENTSPERBLOCK; i++) {
966 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
967 			__u8 csum;
968 
969 			l_name[0] = '\0';
970 			if (dentptr->name[0] == DELETED_FLAG) {
971 				dentptr++;
972 				continue;
973 			}
974 
975 			if (vfat_enabled)
976 				csum = mkcksum(dentptr->name, dentptr->ext);
977 
978 			if (dentptr->attr & ATTR_VOLUME) {
979 				if (vfat_enabled &&
980 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
981 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
982 					prevcksum =
983 						((dir_slot *)dentptr)->alias_checksum;
984 
985 					get_vfatname(mydata,
986 						     root_cluster,
987 						     dir_ptr,
988 						     dentptr, l_name);
989 
990 					if (dols == LS_ROOT) {
991 						char dirc;
992 						int doit = 0;
993 						int isdir =
994 							(dentptr->attr & ATTR_DIR);
995 
996 						if (isdir) {
997 							dirs++;
998 							dirc = '/';
999 							doit = 1;
1000 						} else {
1001 							dirc = ' ';
1002 							if (l_name[0] != 0) {
1003 								files++;
1004 								doit = 1;
1005 							}
1006 						}
1007 						if (doit) {
1008 							if (dirc == ' ') {
1009 								printf(" %8u   %s%c\n",
1010 								       FAT2CPU32(dentptr->size),
1011 									l_name,
1012 									dirc);
1013 							} else {
1014 								printf("            %s%c\n",
1015 									l_name,
1016 									dirc);
1017 							}
1018 						}
1019 						dentptr++;
1020 						continue;
1021 					}
1022 					debug("Rootvfatname: |%s|\n",
1023 					       l_name);
1024 				} else {
1025 					/* Volume label or VFAT entry */
1026 					dentptr++;
1027 					continue;
1028 				}
1029 			} else if (dentptr->name[0] == 0) {
1030 				debug("RootDentname == NULL - %d\n", i);
1031 				if (dols == LS_ROOT) {
1032 					printf("\n%d file(s), %d dir(s)\n\n",
1033 						files, dirs);
1034 					ret = 0;
1035 				}
1036 				goto exit;
1037 			}
1038 			else if (vfat_enabled &&
1039 				 dols == LS_ROOT && csum == prevcksum) {
1040 				prevcksum = 0xffff;
1041 				dentptr++;
1042 				continue;
1043 			}
1044 
1045 			get_name(dentptr, s_name);
1046 
1047 			if (dols == LS_ROOT) {
1048 				int isdir = (dentptr->attr & ATTR_DIR);
1049 				char dirc;
1050 				int doit = 0;
1051 
1052 				if (isdir) {
1053 					dirc = '/';
1054 					if (s_name[0] != 0) {
1055 						dirs++;
1056 						doit = 1;
1057 					}
1058 				} else {
1059 					dirc = ' ';
1060 					if (s_name[0] != 0) {
1061 						files++;
1062 						doit = 1;
1063 					}
1064 				}
1065 				if (doit) {
1066 					if (dirc == ' ') {
1067 						printf(" %8u   %s%c\n",
1068 						       FAT2CPU32(dentptr->size),
1069 							s_name, dirc);
1070 					} else {
1071 						printf("            %s%c\n",
1072 							s_name, dirc);
1073 					}
1074 				}
1075 				dentptr++;
1076 				continue;
1077 			}
1078 
1079 			if (strcmp(fnamecopy, s_name)
1080 			    && strcmp(fnamecopy, l_name)) {
1081 				debug("RootMismatch: |%s|%s|\n", s_name,
1082 				       l_name);
1083 				dentptr++;
1084 				continue;
1085 			}
1086 
1087 			if (isdir && !(dentptr->attr & ATTR_DIR))
1088 				goto exit;
1089 
1090 			debug("RootName: %s", s_name);
1091 			debug(", start: 0x%x", START(dentptr));
1092 			debug(", size:  0x%x %s\n",
1093 			       FAT2CPU32(dentptr->size),
1094 			       isdir ? "(DIR)" : "");
1095 
1096 			goto rootdir_done;	/* We got a match */
1097 		}
1098 		debug("END LOOP: buffer_blk_cnt=%d   clust_size=%d\n", buffer_blk_cnt,
1099 		       mydata->clust_size);
1100 
1101 		/*
1102 		 * On FAT32 we must fetch the FAT entries for the next
1103 		 * root directory clusters when a cluster has been
1104 		 * completely processed.
1105 		 */
1106 		++buffer_blk_cnt;
1107 		int rootdir_end = 0;
1108 		if (mydata->fatsize == 32) {
1109 			if (buffer_blk_cnt == mydata->clust_size) {
1110 				int nxtsect = 0;
1111 				int nxt_clust = 0;
1112 
1113 				nxt_clust = get_fatent(mydata, root_cluster);
1114 				rootdir_end = CHECK_CLUST(nxt_clust, 32);
1115 
1116 				nxtsect = mydata->data_begin +
1117 					(nxt_clust * mydata->clust_size);
1118 
1119 				root_cluster = nxt_clust;
1120 
1121 				cursect = nxtsect;
1122 				buffer_blk_cnt = 0;
1123 			}
1124 		} else {
1125 			if (buffer_blk_cnt == PREFETCH_BLOCKS)
1126 				buffer_blk_cnt = 0;
1127 
1128 			rootdir_end = (++cursect - mydata->rootdir_sect >=
1129 				       rootdir_size);
1130 		}
1131 
1132 		/* If end of rootdir reached */
1133 		if (rootdir_end) {
1134 			if (dols == LS_ROOT) {
1135 				printf("\n%d file(s), %d dir(s)\n\n",
1136 				       files, dirs);
1137 				*size = 0;
1138 			}
1139 			goto exit;
1140 		}
1141 	}
1142 rootdir_done:
1143 
1144 	firsttime = 1;
1145 
1146 	while (isdir) {
1147 		int startsect = mydata->data_begin
1148 			+ START(dentptr) * mydata->clust_size;
1149 		dir_entry dent;
1150 		char *nextname = NULL;
1151 
1152 		dent = *dentptr;
1153 		dentptr = &dent;
1154 
1155 		idx = dirdelim(subname);
1156 
1157 		if (idx >= 0) {
1158 			subname[idx] = '\0';
1159 			nextname = subname + idx + 1;
1160 			/* Handle multiple delimiters */
1161 			while (ISDIRDELIM(*nextname))
1162 				nextname++;
1163 			if (dols && *nextname == '\0')
1164 				firsttime = 0;
1165 		} else {
1166 			if (dols && firsttime) {
1167 				firsttime = 0;
1168 			} else {
1169 				isdir = 0;
1170 			}
1171 		}
1172 
1173 		if (get_dentfromdir(mydata, startsect, subname, dentptr,
1174 				     isdir ? 0 : dols) == NULL) {
1175 			if (dols && !isdir)
1176 				*size = 0;
1177 			goto exit;
1178 		}
1179 
1180 		if (isdir && !(dentptr->attr & ATTR_DIR))
1181 			goto exit;
1182 
1183 		if (idx >= 0)
1184 			subname = nextname;
1185 	}
1186 
1187 	if (dogetsize) {
1188 		*size = FAT2CPU32(dentptr->size);
1189 		ret = 0;
1190 	} else {
1191 		ret = get_contents(mydata, dentptr, pos, buffer, maxsize, size);
1192 	}
1193 	debug("Size: %u, got: %llu\n", FAT2CPU32(dentptr->size), *size);
1194 
1195 exit:
1196 	free(mydata->fatbuf);
1197 	return ret;
1198 }
1199 
1200 int do_fat_read(const char *filename, void *buffer, loff_t maxsize, int dols,
1201 		loff_t *actread)
1202 {
1203 	return do_fat_read_at(filename, 0, buffer, maxsize, dols, 0, actread);
1204 }
1205 
1206 int file_fat_detectfs(void)
1207 {
1208 	boot_sector bs;
1209 	volume_info volinfo;
1210 	int fatsize;
1211 	char vol_label[12];
1212 
1213 	if (cur_dev == NULL) {
1214 		printf("No current device\n");
1215 		return 1;
1216 	}
1217 
1218 #if defined(CONFIG_CMD_IDE) || \
1219     defined(CONFIG_CMD_SATA) || \
1220     defined(CONFIG_CMD_SCSI) || \
1221     defined(CONFIG_CMD_USB) || \
1222     defined(CONFIG_MMC)
1223 	printf("Interface:  ");
1224 	switch (cur_dev->if_type) {
1225 	case IF_TYPE_IDE:
1226 		printf("IDE");
1227 		break;
1228 	case IF_TYPE_SATA:
1229 		printf("SATA");
1230 		break;
1231 	case IF_TYPE_SCSI:
1232 		printf("SCSI");
1233 		break;
1234 	case IF_TYPE_ATAPI:
1235 		printf("ATAPI");
1236 		break;
1237 	case IF_TYPE_USB:
1238 		printf("USB");
1239 		break;
1240 	case IF_TYPE_DOC:
1241 		printf("DOC");
1242 		break;
1243 	case IF_TYPE_MMC:
1244 		printf("MMC");
1245 		break;
1246 	default:
1247 		printf("Unknown");
1248 	}
1249 
1250 	printf("\n  Device %d: ", cur_dev->dev);
1251 	dev_print(cur_dev);
1252 #endif
1253 
1254 	if (read_bootsectandvi(&bs, &volinfo, &fatsize)) {
1255 		printf("\nNo valid FAT fs found\n");
1256 		return 1;
1257 	}
1258 
1259 	memcpy(vol_label, volinfo.volume_label, 11);
1260 	vol_label[11] = '\0';
1261 	volinfo.fs_type[5] = '\0';
1262 
1263 	printf("Filesystem: %s \"%s\"\n", volinfo.fs_type, vol_label);
1264 
1265 	return 0;
1266 }
1267 
1268 int file_fat_ls(const char *dir)
1269 {
1270 	loff_t size;
1271 
1272 	return do_fat_read(dir, NULL, 0, LS_YES, &size);
1273 }
1274 
1275 int fat_exists(const char *filename)
1276 {
1277 	int ret;
1278 	loff_t size;
1279 
1280 	ret = do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, &size);
1281 	return ret == 0;
1282 }
1283 
1284 int fat_size(const char *filename, loff_t *size)
1285 {
1286 	return do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, size);
1287 }
1288 
1289 int file_fat_read_at(const char *filename, loff_t pos, void *buffer,
1290 		     loff_t maxsize, loff_t *actread)
1291 {
1292 	printf("reading %s\n", filename);
1293 	return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO, 0,
1294 			      actread);
1295 }
1296 
1297 int file_fat_read(const char *filename, void *buffer, int maxsize)
1298 {
1299 	loff_t actread;
1300 	int ret;
1301 
1302 	ret =  file_fat_read_at(filename, 0, buffer, maxsize, &actread);
1303 	if (ret)
1304 		return ret;
1305 	else
1306 		return actread;
1307 }
1308 
1309 int fat_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
1310 		  loff_t *actread)
1311 {
1312 	int ret;
1313 
1314 	ret = file_fat_read_at(filename, offset, buf, len, actread);
1315 	if (ret)
1316 		printf("** Unable to read file %s **\n", filename);
1317 
1318 	return ret;
1319 }
1320 
1321 void fat_close(void)
1322 {
1323 }
1324