xref: /openbmc/u-boot/fs/fat/fat.c (revision 17fa0326)
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 static int flush_dirty_fat_buffer(fsdata *mydata);
166 #if !defined(CONFIG_FAT_WRITE)
167 /* Stub for read only operation */
168 int flush_dirty_fat_buffer(fsdata *mydata)
169 {
170 	(void)(mydata);
171 	return 0;
172 }
173 #endif
174 
175 /*
176  * Get the entry at index 'entry' in a FAT (12/16/32) table.
177  * On failure 0x00 is returned.
178  */
179 static __u32 get_fatent(fsdata *mydata, __u32 entry)
180 {
181 	__u32 bufnum;
182 	__u32 off16, offset;
183 	__u32 ret = 0x00;
184 
185 	if (CHECK_CLUST(entry, mydata->fatsize)) {
186 		printf("Error: Invalid FAT entry: 0x%08x\n", entry);
187 		return ret;
188 	}
189 
190 	switch (mydata->fatsize) {
191 	case 32:
192 		bufnum = entry / FAT32BUFSIZE;
193 		offset = entry - bufnum * FAT32BUFSIZE;
194 		break;
195 	case 16:
196 		bufnum = entry / FAT16BUFSIZE;
197 		offset = entry - bufnum * FAT16BUFSIZE;
198 		break;
199 	case 12:
200 		bufnum = entry / FAT12BUFSIZE;
201 		offset = entry - bufnum * FAT12BUFSIZE;
202 		break;
203 
204 	default:
205 		/* Unsupported FAT size */
206 		return ret;
207 	}
208 
209 	debug("FAT%d: entry: 0x%08x = %d, offset: 0x%04x = %d\n",
210 	       mydata->fatsize, entry, entry, offset, offset);
211 
212 	/* Read a new block of FAT entries into the cache. */
213 	if (bufnum != mydata->fatbufnum) {
214 		__u32 getsize = FATBUFBLOCKS;
215 		__u8 *bufptr = mydata->fatbuf;
216 		__u32 fatlength = mydata->fatlength;
217 		__u32 startblock = bufnum * FATBUFBLOCKS;
218 
219 		/* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
220 		if (startblock + getsize > fatlength)
221 			getsize = fatlength - startblock;
222 
223 		startblock += mydata->fat_sect;	/* Offset from start of disk */
224 
225 		/* Write back the fatbuf to the disk */
226 		if (flush_dirty_fat_buffer(mydata) < 0)
227 			return -1;
228 
229 		if (disk_read(startblock, getsize, bufptr) < 0) {
230 			debug("Error reading FAT blocks\n");
231 			return ret;
232 		}
233 		mydata->fatbufnum = bufnum;
234 	}
235 
236 	/* Get the actual entry from the table */
237 	switch (mydata->fatsize) {
238 	case 32:
239 		ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
240 		break;
241 	case 16:
242 		ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
243 		break;
244 	case 12:
245 		off16 = (offset * 3) / 2;
246 		ret = FAT2CPU16(*(__u16 *)(mydata->fatbuf + off16));
247 
248 		if (offset & 0x1)
249 			ret >>= 4;
250 		ret &= 0xfff;
251 	}
252 	debug("FAT%d: ret: 0x%08x, entry: 0x%08x, offset: 0x%04x\n",
253 	       mydata->fatsize, ret, entry, offset);
254 
255 	return ret;
256 }
257 
258 /*
259  * Read at most 'size' bytes from the specified cluster into 'buffer'.
260  * Return 0 on success, -1 otherwise.
261  */
262 static int
263 get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
264 {
265 	__u32 idx = 0;
266 	__u32 startsect;
267 	int ret;
268 
269 	if (clustnum > 0) {
270 		startsect = mydata->data_begin +
271 				clustnum * mydata->clust_size;
272 	} else {
273 		startsect = mydata->rootdir_sect;
274 	}
275 
276 	debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect);
277 
278 	if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
279 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
280 
281 		printf("FAT: Misaligned buffer address (%p)\n", buffer);
282 
283 		while (size >= mydata->sect_size) {
284 			ret = disk_read(startsect++, 1, tmpbuf);
285 			if (ret != 1) {
286 				debug("Error reading data (got %d)\n", ret);
287 				return -1;
288 			}
289 
290 			memcpy(buffer, tmpbuf, mydata->sect_size);
291 			buffer += mydata->sect_size;
292 			size -= mydata->sect_size;
293 		}
294 	} else {
295 		idx = size / mydata->sect_size;
296 		ret = disk_read(startsect, idx, buffer);
297 		if (ret != idx) {
298 			debug("Error reading data (got %d)\n", ret);
299 			return -1;
300 		}
301 		startsect += idx;
302 		idx *= mydata->sect_size;
303 		buffer += idx;
304 		size -= idx;
305 	}
306 	if (size) {
307 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
308 
309 		ret = disk_read(startsect, 1, tmpbuf);
310 		if (ret != 1) {
311 			debug("Error reading data (got %d)\n", ret);
312 			return -1;
313 		}
314 
315 		memcpy(buffer, tmpbuf, size);
316 	}
317 
318 	return 0;
319 }
320 
321 /*
322  * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr'
323  * into 'buffer'.
324  * Update the number of bytes read in *gotsize or return -1 on fatal errors.
325  */
326 __u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
327 	__aligned(ARCH_DMA_MINALIGN);
328 
329 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
330 			__u8 *buffer, loff_t maxsize, loff_t *gotsize)
331 {
332 	loff_t filesize = FAT2CPU32(dentptr->size);
333 	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
334 	__u32 curclust = START(dentptr);
335 	__u32 endclust, newclust;
336 	loff_t actsize;
337 
338 	*gotsize = 0;
339 	debug("Filesize: %llu bytes\n", filesize);
340 
341 	if (pos >= filesize) {
342 		debug("Read position past EOF: %llu\n", pos);
343 		return 0;
344 	}
345 
346 	if (maxsize > 0 && filesize > pos + maxsize)
347 		filesize = pos + maxsize;
348 
349 	debug("%llu bytes\n", filesize);
350 
351 	actsize = bytesperclust;
352 
353 	/* go to cluster at pos */
354 	while (actsize <= pos) {
355 		curclust = get_fatent(mydata, curclust);
356 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
357 			debug("curclust: 0x%x\n", curclust);
358 			debug("Invalid FAT entry\n");
359 			return 0;
360 		}
361 		actsize += bytesperclust;
362 	}
363 
364 	/* actsize > pos */
365 	actsize -= bytesperclust;
366 	filesize -= actsize;
367 	pos -= actsize;
368 
369 	/* align to beginning of next cluster if any */
370 	if (pos) {
371 		actsize = min(filesize, (loff_t)bytesperclust);
372 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
373 				(int)actsize) != 0) {
374 			printf("Error reading cluster\n");
375 			return -1;
376 		}
377 		filesize -= actsize;
378 		actsize -= pos;
379 		memcpy(buffer, get_contents_vfatname_block + pos, actsize);
380 		*gotsize += actsize;
381 		if (!filesize)
382 			return 0;
383 		buffer += actsize;
384 
385 		curclust = get_fatent(mydata, curclust);
386 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
387 			debug("curclust: 0x%x\n", curclust);
388 			debug("Invalid FAT entry\n");
389 			return 0;
390 		}
391 	}
392 
393 	actsize = bytesperclust;
394 	endclust = curclust;
395 
396 	do {
397 		/* search for consecutive clusters */
398 		while (actsize < filesize) {
399 			newclust = get_fatent(mydata, endclust);
400 			if ((newclust - 1) != endclust)
401 				goto getit;
402 			if (CHECK_CLUST(newclust, mydata->fatsize)) {
403 				debug("curclust: 0x%x\n", newclust);
404 				debug("Invalid FAT entry\n");
405 				return 0;
406 			}
407 			endclust = newclust;
408 			actsize += bytesperclust;
409 		}
410 
411 		/* get remaining bytes */
412 		actsize = filesize;
413 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
414 			printf("Error reading cluster\n");
415 			return -1;
416 		}
417 		*gotsize += actsize;
418 		return 0;
419 getit:
420 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
421 			printf("Error reading cluster\n");
422 			return -1;
423 		}
424 		*gotsize += (int)actsize;
425 		filesize -= actsize;
426 		buffer += actsize;
427 
428 		curclust = get_fatent(mydata, endclust);
429 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
430 			debug("curclust: 0x%x\n", curclust);
431 			printf("Invalid FAT entry\n");
432 			return 0;
433 		}
434 		actsize = bytesperclust;
435 		endclust = curclust;
436 	} while (1);
437 }
438 
439 /*
440  * Extract the file name information from 'slotptr' into 'l_name',
441  * starting at l_name[*idx].
442  * Return 1 if terminator (zero byte) is found, 0 otherwise.
443  */
444 static int slot2str(dir_slot *slotptr, char *l_name, int *idx)
445 {
446 	int j;
447 
448 	for (j = 0; j <= 8; j += 2) {
449 		l_name[*idx] = slotptr->name0_4[j];
450 		if (l_name[*idx] == 0x00)
451 			return 1;
452 		(*idx)++;
453 	}
454 	for (j = 0; j <= 10; j += 2) {
455 		l_name[*idx] = slotptr->name5_10[j];
456 		if (l_name[*idx] == 0x00)
457 			return 1;
458 		(*idx)++;
459 	}
460 	for (j = 0; j <= 2; j += 2) {
461 		l_name[*idx] = slotptr->name11_12[j];
462 		if (l_name[*idx] == 0x00)
463 			return 1;
464 		(*idx)++;
465 	}
466 
467 	return 0;
468 }
469 
470 /*
471  * Extract the full long filename starting at 'retdent' (which is really
472  * a slot) into 'l_name'. If successful also copy the real directory entry
473  * into 'retdent'
474  * Return 0 on success, -1 otherwise.
475  */
476 static int
477 get_vfatname(fsdata *mydata, int curclust, __u8 *cluster,
478 	     dir_entry *retdent, char *l_name)
479 {
480 	dir_entry *realdent;
481 	dir_slot *slotptr = (dir_slot *)retdent;
482 	__u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
483 							PREFETCH_BLOCKS :
484 							mydata->clust_size);
485 	__u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
486 	int idx = 0;
487 
488 	if (counter > VFAT_MAXSEQ) {
489 		debug("Error: VFAT name is too long\n");
490 		return -1;
491 	}
492 
493 	while ((__u8 *)slotptr < buflimit) {
494 		if (counter == 0)
495 			break;
496 		if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
497 			return -1;
498 		slotptr++;
499 		counter--;
500 	}
501 
502 	if ((__u8 *)slotptr >= buflimit) {
503 		dir_slot *slotptr2;
504 
505 		if (curclust == 0)
506 			return -1;
507 		curclust = get_fatent(mydata, curclust);
508 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
509 			debug("curclust: 0x%x\n", curclust);
510 			printf("Invalid FAT entry\n");
511 			return -1;
512 		}
513 
514 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
515 				mydata->clust_size * mydata->sect_size) != 0) {
516 			debug("Error: reading directory block\n");
517 			return -1;
518 		}
519 
520 		slotptr2 = (dir_slot *)get_contents_vfatname_block;
521 		while (counter > 0) {
522 			if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
523 			    & 0xff) != counter)
524 				return -1;
525 			slotptr2++;
526 			counter--;
527 		}
528 
529 		/* Save the real directory entry */
530 		realdent = (dir_entry *)slotptr2;
531 		while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
532 			slotptr2--;
533 			slot2str(slotptr2, l_name, &idx);
534 		}
535 	} else {
536 		/* Save the real directory entry */
537 		realdent = (dir_entry *)slotptr;
538 	}
539 
540 	do {
541 		slotptr--;
542 		if (slot2str(slotptr, l_name, &idx))
543 			break;
544 	} while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
545 
546 	l_name[idx] = '\0';
547 	if (*l_name == DELETED_FLAG)
548 		*l_name = '\0';
549 	else if (*l_name == aRING)
550 		*l_name = DELETED_FLAG;
551 	downcase(l_name);
552 
553 	/* Return the real directory entry */
554 	memcpy(retdent, realdent, sizeof(dir_entry));
555 
556 	return 0;
557 }
558 
559 /* Calculate short name checksum */
560 static __u8 mkcksum(const char name[8], const char ext[3])
561 {
562 	int i;
563 
564 	__u8 ret = 0;
565 
566 	for (i = 0; i < 8; i++)
567 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
568 	for (i = 0; i < 3; i++)
569 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
570 
571 	return ret;
572 }
573 
574 /*
575  * Get the directory entry associated with 'filename' from the directory
576  * starting at 'startsect'
577  */
578 __u8 get_dentfromdir_block[MAX_CLUSTSIZE]
579 	__aligned(ARCH_DMA_MINALIGN);
580 
581 static dir_entry *get_dentfromdir(fsdata *mydata, int startsect,
582 				  char *filename, dir_entry *retdent,
583 				  int dols)
584 {
585 	__u16 prevcksum = 0xffff;
586 	__u32 curclust = START(retdent);
587 	int files = 0, dirs = 0;
588 
589 	debug("get_dentfromdir: %s\n", filename);
590 
591 	while (1) {
592 		dir_entry *dentptr;
593 
594 		int i;
595 
596 		if (get_cluster(mydata, curclust, get_dentfromdir_block,
597 				mydata->clust_size * mydata->sect_size) != 0) {
598 			debug("Error: reading directory block\n");
599 			return NULL;
600 		}
601 
602 		dentptr = (dir_entry *)get_dentfromdir_block;
603 
604 		for (i = 0; i < DIRENTSPERCLUST; i++) {
605 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
606 
607 			l_name[0] = '\0';
608 			if (dentptr->name[0] == DELETED_FLAG) {
609 				dentptr++;
610 				continue;
611 			}
612 			if ((dentptr->attr & ATTR_VOLUME)) {
613 				if (vfat_enabled &&
614 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
615 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
616 					prevcksum = ((dir_slot *)dentptr)->alias_checksum;
617 					get_vfatname(mydata, curclust,
618 						     get_dentfromdir_block,
619 						     dentptr, l_name);
620 					if (dols) {
621 						int isdir;
622 						char dirc;
623 						int doit = 0;
624 
625 						isdir = (dentptr->attr & ATTR_DIR);
626 
627 						if (isdir) {
628 							dirs++;
629 							dirc = '/';
630 							doit = 1;
631 						} else {
632 							dirc = ' ';
633 							if (l_name[0] != 0) {
634 								files++;
635 								doit = 1;
636 							}
637 						}
638 						if (doit) {
639 							if (dirc == ' ') {
640 								printf(" %8u   %s%c\n",
641 								       FAT2CPU32(dentptr->size),
642 									l_name,
643 									dirc);
644 							} else {
645 								printf("            %s%c\n",
646 									l_name,
647 									dirc);
648 							}
649 						}
650 						dentptr++;
651 						continue;
652 					}
653 					debug("vfatname: |%s|\n", l_name);
654 				} else {
655 					/* Volume label or VFAT entry */
656 					dentptr++;
657 					continue;
658 				}
659 			}
660 			if (dentptr->name[0] == 0) {
661 				if (dols) {
662 					printf("\n%d file(s), %d dir(s)\n\n",
663 						files, dirs);
664 				}
665 				debug("Dentname == NULL - %d\n", i);
666 				return NULL;
667 			}
668 			if (vfat_enabled) {
669 				__u8 csum = mkcksum(dentptr->name, dentptr->ext);
670 				if (dols && csum == prevcksum) {
671 					prevcksum = 0xffff;
672 					dentptr++;
673 					continue;
674 				}
675 			}
676 
677 			get_name(dentptr, s_name);
678 			if (dols) {
679 				int isdir = (dentptr->attr & ATTR_DIR);
680 				char dirc;
681 				int doit = 0;
682 
683 				if (isdir) {
684 					dirs++;
685 					dirc = '/';
686 					doit = 1;
687 				} else {
688 					dirc = ' ';
689 					if (s_name[0] != 0) {
690 						files++;
691 						doit = 1;
692 					}
693 				}
694 
695 				if (doit) {
696 					if (dirc == ' ') {
697 						printf(" %8u   %s%c\n",
698 						       FAT2CPU32(dentptr->size),
699 							s_name, dirc);
700 					} else {
701 						printf("            %s%c\n",
702 							s_name, dirc);
703 					}
704 				}
705 
706 				dentptr++;
707 				continue;
708 			}
709 
710 			if (strcmp(filename, s_name)
711 			    && strcmp(filename, l_name)) {
712 				debug("Mismatch: |%s|%s|\n", s_name, l_name);
713 				dentptr++;
714 				continue;
715 			}
716 
717 			memcpy(retdent, dentptr, sizeof(dir_entry));
718 
719 			debug("DentName: %s", s_name);
720 			debug(", start: 0x%x", START(dentptr));
721 			debug(", size:  0x%x %s\n",
722 			      FAT2CPU32(dentptr->size),
723 			      (dentptr->attr & ATTR_DIR) ? "(DIR)" : "");
724 
725 			return retdent;
726 		}
727 
728 		curclust = get_fatent(mydata, curclust);
729 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
730 			debug("curclust: 0x%x\n", curclust);
731 			printf("Invalid FAT entry\n");
732 			return NULL;
733 		}
734 	}
735 
736 	return NULL;
737 }
738 
739 /*
740  * Read boot sector and volume info from a FAT filesystem
741  */
742 static int
743 read_bootsectandvi(boot_sector *bs, volume_info *volinfo, int *fatsize)
744 {
745 	__u8 *block;
746 	volume_info *vistart;
747 	int ret = 0;
748 
749 	if (cur_dev == NULL) {
750 		debug("Error: no device selected\n");
751 		return -1;
752 	}
753 
754 	block = memalign(ARCH_DMA_MINALIGN, cur_dev->blksz);
755 	if (block == NULL) {
756 		debug("Error: allocating block\n");
757 		return -1;
758 	}
759 
760 	if (disk_read(0, 1, block) < 0) {
761 		debug("Error: reading block\n");
762 		goto fail;
763 	}
764 
765 	memcpy(bs, block, sizeof(boot_sector));
766 	bs->reserved = FAT2CPU16(bs->reserved);
767 	bs->fat_length = FAT2CPU16(bs->fat_length);
768 	bs->secs_track = FAT2CPU16(bs->secs_track);
769 	bs->heads = FAT2CPU16(bs->heads);
770 	bs->total_sect = FAT2CPU32(bs->total_sect);
771 
772 	/* FAT32 entries */
773 	if (bs->fat_length == 0) {
774 		/* Assume FAT32 */
775 		bs->fat32_length = FAT2CPU32(bs->fat32_length);
776 		bs->flags = FAT2CPU16(bs->flags);
777 		bs->root_cluster = FAT2CPU32(bs->root_cluster);
778 		bs->info_sector = FAT2CPU16(bs->info_sector);
779 		bs->backup_boot = FAT2CPU16(bs->backup_boot);
780 		vistart = (volume_info *)(block + sizeof(boot_sector));
781 		*fatsize = 32;
782 	} else {
783 		vistart = (volume_info *)&(bs->fat32_length);
784 		*fatsize = 0;
785 	}
786 	memcpy(volinfo, vistart, sizeof(volume_info));
787 
788 	if (*fatsize == 32) {
789 		if (strncmp(FAT32_SIGN, vistart->fs_type, SIGNLEN) == 0)
790 			goto exit;
791 	} else {
792 		if (strncmp(FAT12_SIGN, vistart->fs_type, SIGNLEN) == 0) {
793 			*fatsize = 12;
794 			goto exit;
795 		}
796 		if (strncmp(FAT16_SIGN, vistart->fs_type, SIGNLEN) == 0) {
797 			*fatsize = 16;
798 			goto exit;
799 		}
800 	}
801 
802 	debug("Error: broken fs_type sign\n");
803 fail:
804 	ret = -1;
805 exit:
806 	free(block);
807 	return ret;
808 }
809 
810 __u8 do_fat_read_at_block[MAX_CLUSTSIZE]
811 	__aligned(ARCH_DMA_MINALIGN);
812 
813 int do_fat_read_at(const char *filename, loff_t pos, void *buffer,
814 		   loff_t maxsize, int dols, int dogetsize, loff_t *size)
815 {
816 	char fnamecopy[2048];
817 	boot_sector bs;
818 	volume_info volinfo;
819 	fsdata datablock;
820 	fsdata *mydata = &datablock;
821 	dir_entry *dentptr = NULL;
822 	__u16 prevcksum = 0xffff;
823 	char *subname = "";
824 	__u32 cursect;
825 	int idx, isdir = 0;
826 	int files = 0, dirs = 0;
827 	int ret = -1;
828 	int firsttime;
829 	__u32 root_cluster = 0;
830 	__u32 read_blk;
831 	int rootdir_size = 0;
832 	int buffer_blk_cnt;
833 	int do_read;
834 	__u8 *dir_ptr;
835 
836 	if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
837 		debug("Error: reading boot sector\n");
838 		return -1;
839 	}
840 
841 	if (mydata->fatsize == 32) {
842 		root_cluster = bs.root_cluster;
843 		mydata->fatlength = bs.fat32_length;
844 	} else {
845 		mydata->fatlength = bs.fat_length;
846 	}
847 
848 	mydata->fat_sect = bs.reserved;
849 
850 	cursect = mydata->rootdir_sect
851 		= mydata->fat_sect + mydata->fatlength * bs.fats;
852 
853 	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
854 	mydata->clust_size = bs.cluster_size;
855 	if (mydata->sect_size != cur_part_info.blksz) {
856 		printf("Error: FAT sector size mismatch (fs=%hu, dev=%lu)\n",
857 				mydata->sect_size, cur_part_info.blksz);
858 		return -1;
859 	}
860 
861 	if (mydata->fatsize == 32) {
862 		mydata->data_begin = mydata->rootdir_sect -
863 					(mydata->clust_size * 2);
864 	} else {
865 		rootdir_size = ((bs.dir_entries[1]  * (int)256 +
866 				 bs.dir_entries[0]) *
867 				 sizeof(dir_entry)) /
868 				 mydata->sect_size;
869 		mydata->data_begin = mydata->rootdir_sect +
870 					rootdir_size -
871 					(mydata->clust_size * 2);
872 	}
873 
874 	mydata->fatbufnum = -1;
875 	mydata->fat_dirty = 0;
876 	mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
877 	if (mydata->fatbuf == NULL) {
878 		debug("Error: allocating memory\n");
879 		return -1;
880 	}
881 
882 	if (vfat_enabled)
883 		debug("VFAT Support enabled\n");
884 
885 	debug("FAT%d, fat_sect: %d, fatlength: %d\n",
886 	       mydata->fatsize, mydata->fat_sect, mydata->fatlength);
887 	debug("Rootdir begins at cluster: %d, sector: %d, offset: %x\n"
888 	       "Data begins at: %d\n",
889 	       root_cluster,
890 	       mydata->rootdir_sect,
891 	       mydata->rootdir_sect * mydata->sect_size, mydata->data_begin);
892 	debug("Sector size: %d, cluster size: %d\n", mydata->sect_size,
893 	      mydata->clust_size);
894 
895 	/* "cwd" is always the root... */
896 	while (ISDIRDELIM(*filename))
897 		filename++;
898 
899 	/* Make a copy of the filename and convert it to lowercase */
900 	strcpy(fnamecopy, filename);
901 	downcase(fnamecopy);
902 
903 root_reparse:
904 	if (*fnamecopy == '\0') {
905 		if (!dols)
906 			goto exit;
907 
908 		dols = LS_ROOT;
909 	} else if ((idx = dirdelim(fnamecopy)) >= 0) {
910 		isdir = 1;
911 		fnamecopy[idx] = '\0';
912 		subname = fnamecopy + idx + 1;
913 
914 		/* Handle multiple delimiters */
915 		while (ISDIRDELIM(*subname))
916 			subname++;
917 	} else if (dols) {
918 		isdir = 1;
919 	}
920 
921 	buffer_blk_cnt = 0;
922 	firsttime = 1;
923 	while (1) {
924 		int i;
925 
926 		if (mydata->fatsize == 32 || firsttime) {
927 			dir_ptr = do_fat_read_at_block;
928 			firsttime = 0;
929 		} else {
930 			/**
931 			 * FAT16 sector buffer modification:
932 			 * Each loop, the second buffered block is moved to
933 			 * the buffer begin, and two next sectors are read
934 			 * next to the previously moved one. So the sector
935 			 * buffer keeps always 3 sectors for fat16.
936 			 * And the current sector is the buffer second sector
937 			 * beside the "firsttime" read, when it is the first one.
938 			 *
939 			 * PREFETCH_BLOCKS is 2 for FAT16 == loop[0:1]
940 			 * n = computed root dir sector
941 			 * loop |  cursect-1  | cursect    | cursect+1  |
942 			 *   0  |  sector n+0 | sector n+1 | none       |
943 			 *   1  |  none       | sector n+0 | sector n+1 |
944 			 *   0  |  sector n+1 | sector n+2 | sector n+3 |
945 			 *   1  |  sector n+3 | ...
946 			*/
947 			dir_ptr = (do_fat_read_at_block + mydata->sect_size);
948 			memcpy(do_fat_read_at_block, dir_ptr, mydata->sect_size);
949 		}
950 
951 		do_read = 1;
952 
953 		if (mydata->fatsize == 32 && buffer_blk_cnt)
954 			do_read = 0;
955 
956 		if (do_read) {
957 			read_blk = (mydata->fatsize == 32) ?
958 				    mydata->clust_size : PREFETCH_BLOCKS;
959 
960 			debug("FAT read(sect=%d, cnt:%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n",
961 				cursect, read_blk, mydata->clust_size, DIRENTSPERBLOCK);
962 
963 			if (disk_read(cursect, read_blk, dir_ptr) < 0) {
964 				debug("Error: reading rootdir block\n");
965 				goto exit;
966 			}
967 
968 			dentptr = (dir_entry *)dir_ptr;
969 		}
970 
971 		for (i = 0; i < DIRENTSPERBLOCK; i++) {
972 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
973 			__u8 csum;
974 
975 			l_name[0] = '\0';
976 			if (dentptr->name[0] == DELETED_FLAG) {
977 				dentptr++;
978 				continue;
979 			}
980 
981 			if (vfat_enabled)
982 				csum = mkcksum(dentptr->name, dentptr->ext);
983 
984 			if (dentptr->attr & ATTR_VOLUME) {
985 				if (vfat_enabled &&
986 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
987 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
988 					prevcksum =
989 						((dir_slot *)dentptr)->alias_checksum;
990 
991 					get_vfatname(mydata,
992 						     root_cluster,
993 						     dir_ptr,
994 						     dentptr, l_name);
995 
996 					if (dols == LS_ROOT) {
997 						char dirc;
998 						int doit = 0;
999 						int isdir =
1000 							(dentptr->attr & ATTR_DIR);
1001 
1002 						if (isdir) {
1003 							dirs++;
1004 							dirc = '/';
1005 							doit = 1;
1006 						} else {
1007 							dirc = ' ';
1008 							if (l_name[0] != 0) {
1009 								files++;
1010 								doit = 1;
1011 							}
1012 						}
1013 						if (doit) {
1014 							if (dirc == ' ') {
1015 								printf(" %8u   %s%c\n",
1016 								       FAT2CPU32(dentptr->size),
1017 									l_name,
1018 									dirc);
1019 							} else {
1020 								printf("            %s%c\n",
1021 									l_name,
1022 									dirc);
1023 							}
1024 						}
1025 						dentptr++;
1026 						continue;
1027 					}
1028 					debug("Rootvfatname: |%s|\n",
1029 					       l_name);
1030 				} else {
1031 					/* Volume label or VFAT entry */
1032 					dentptr++;
1033 					continue;
1034 				}
1035 			} else if (dentptr->name[0] == 0) {
1036 				debug("RootDentname == NULL - %d\n", i);
1037 				if (dols == LS_ROOT) {
1038 					printf("\n%d file(s), %d dir(s)\n\n",
1039 						files, dirs);
1040 					ret = 0;
1041 				}
1042 				goto exit;
1043 			}
1044 			else if (vfat_enabled &&
1045 				 dols == LS_ROOT && csum == prevcksum) {
1046 				prevcksum = 0xffff;
1047 				dentptr++;
1048 				continue;
1049 			}
1050 
1051 			get_name(dentptr, s_name);
1052 
1053 			if (dols == LS_ROOT) {
1054 				int isdir = (dentptr->attr & ATTR_DIR);
1055 				char dirc;
1056 				int doit = 0;
1057 
1058 				if (isdir) {
1059 					dirc = '/';
1060 					if (s_name[0] != 0) {
1061 						dirs++;
1062 						doit = 1;
1063 					}
1064 				} else {
1065 					dirc = ' ';
1066 					if (s_name[0] != 0) {
1067 						files++;
1068 						doit = 1;
1069 					}
1070 				}
1071 				if (doit) {
1072 					if (dirc == ' ') {
1073 						printf(" %8u   %s%c\n",
1074 						       FAT2CPU32(dentptr->size),
1075 							s_name, dirc);
1076 					} else {
1077 						printf("            %s%c\n",
1078 							s_name, dirc);
1079 					}
1080 				}
1081 				dentptr++;
1082 				continue;
1083 			}
1084 
1085 			if (strcmp(fnamecopy, s_name)
1086 			    && strcmp(fnamecopy, l_name)) {
1087 				debug("RootMismatch: |%s|%s|\n", s_name,
1088 				       l_name);
1089 				dentptr++;
1090 				continue;
1091 			}
1092 
1093 			if (isdir && !(dentptr->attr & ATTR_DIR))
1094 				goto exit;
1095 
1096 			debug("RootName: %s", s_name);
1097 			debug(", start: 0x%x", START(dentptr));
1098 			debug(", size:  0x%x %s\n",
1099 			       FAT2CPU32(dentptr->size),
1100 			       isdir ? "(DIR)" : "");
1101 
1102 			goto rootdir_done;	/* We got a match */
1103 		}
1104 		debug("END LOOP: buffer_blk_cnt=%d   clust_size=%d\n", buffer_blk_cnt,
1105 		       mydata->clust_size);
1106 
1107 		/*
1108 		 * On FAT32 we must fetch the FAT entries for the next
1109 		 * root directory clusters when a cluster has been
1110 		 * completely processed.
1111 		 */
1112 		++buffer_blk_cnt;
1113 		int rootdir_end = 0;
1114 		if (mydata->fatsize == 32) {
1115 			if (buffer_blk_cnt == mydata->clust_size) {
1116 				int nxtsect = 0;
1117 				int nxt_clust = 0;
1118 
1119 				nxt_clust = get_fatent(mydata, root_cluster);
1120 				rootdir_end = CHECK_CLUST(nxt_clust, 32);
1121 
1122 				nxtsect = mydata->data_begin +
1123 					(nxt_clust * mydata->clust_size);
1124 
1125 				root_cluster = nxt_clust;
1126 
1127 				cursect = nxtsect;
1128 				buffer_blk_cnt = 0;
1129 			}
1130 		} else {
1131 			if (buffer_blk_cnt == PREFETCH_BLOCKS)
1132 				buffer_blk_cnt = 0;
1133 
1134 			rootdir_end = (++cursect - mydata->rootdir_sect >=
1135 				       rootdir_size);
1136 		}
1137 
1138 		/* If end of rootdir reached */
1139 		if (rootdir_end) {
1140 			if (dols == LS_ROOT) {
1141 				printf("\n%d file(s), %d dir(s)\n\n",
1142 				       files, dirs);
1143 				*size = 0;
1144 			}
1145 			goto exit;
1146 		}
1147 	}
1148 rootdir_done:
1149 
1150 	firsttime = 1;
1151 
1152 	while (isdir) {
1153 		int startsect = mydata->data_begin
1154 			+ START(dentptr) * mydata->clust_size;
1155 		dir_entry dent;
1156 		char *nextname = NULL;
1157 
1158 		dent = *dentptr;
1159 		dentptr = &dent;
1160 
1161 		idx = dirdelim(subname);
1162 
1163 		if (idx >= 0) {
1164 			subname[idx] = '\0';
1165 			nextname = subname + idx + 1;
1166 			/* Handle multiple delimiters */
1167 			while (ISDIRDELIM(*nextname))
1168 				nextname++;
1169 			if (dols && *nextname == '\0')
1170 				firsttime = 0;
1171 		} else {
1172 			if (dols && firsttime) {
1173 				firsttime = 0;
1174 			} else {
1175 				isdir = 0;
1176 			}
1177 		}
1178 
1179 		if (get_dentfromdir(mydata, startsect, subname, dentptr,
1180 				     isdir ? 0 : dols) == NULL) {
1181 			if (dols && !isdir)
1182 				*size = 0;
1183 			goto exit;
1184 		}
1185 
1186 		if (isdir && !(dentptr->attr & ATTR_DIR))
1187 			goto exit;
1188 
1189 		/*
1190 		 * If we are looking for a directory, and found a directory
1191 		 * type entry, and the entry is for the root directory (as
1192 		 * denoted by a cluster number of 0), jump back to the start
1193 		 * of the function, since at least on FAT12/16, the root dir
1194 		 * lives in a hard-coded location and needs special handling
1195 		 * to parse, rather than simply following the cluster linked
1196 		 * list in the FAT, like other directories.
1197 		 */
1198 		if (isdir && (dentptr->attr & ATTR_DIR) && !START(dentptr)) {
1199 			/*
1200 			 * Modify the filename to remove the prefix that gets
1201 			 * back to the root directory, so the initial root dir
1202 			 * parsing code can continue from where we are without
1203 			 * confusion.
1204 			 */
1205 			strcpy(fnamecopy, nextname ?: "");
1206 			/*
1207 			 * Set up state the same way as the function does when
1208 			 * first started. This is required for the root dir
1209 			 * parsing code operates in its expected environment.
1210 			 */
1211 			subname = "";
1212 			cursect = mydata->rootdir_sect;
1213 			isdir = 0;
1214 			goto root_reparse;
1215 		}
1216 
1217 		if (idx >= 0)
1218 			subname = nextname;
1219 	}
1220 
1221 	if (dogetsize) {
1222 		*size = FAT2CPU32(dentptr->size);
1223 		ret = 0;
1224 	} else {
1225 		ret = get_contents(mydata, dentptr, pos, buffer, maxsize, size);
1226 	}
1227 	debug("Size: %u, got: %llu\n", FAT2CPU32(dentptr->size), *size);
1228 
1229 exit:
1230 	free(mydata->fatbuf);
1231 	return ret;
1232 }
1233 
1234 int do_fat_read(const char *filename, void *buffer, loff_t maxsize, int dols,
1235 		loff_t *actread)
1236 {
1237 	return do_fat_read_at(filename, 0, buffer, maxsize, dols, 0, actread);
1238 }
1239 
1240 int file_fat_detectfs(void)
1241 {
1242 	boot_sector bs;
1243 	volume_info volinfo;
1244 	int fatsize;
1245 	char vol_label[12];
1246 
1247 	if (cur_dev == NULL) {
1248 		printf("No current device\n");
1249 		return 1;
1250 	}
1251 
1252 #if defined(CONFIG_CMD_IDE) || \
1253     defined(CONFIG_CMD_SATA) || \
1254     defined(CONFIG_SCSI) || \
1255     defined(CONFIG_CMD_USB) || \
1256     defined(CONFIG_MMC)
1257 	printf("Interface:  ");
1258 	switch (cur_dev->if_type) {
1259 	case IF_TYPE_IDE:
1260 		printf("IDE");
1261 		break;
1262 	case IF_TYPE_SATA:
1263 		printf("SATA");
1264 		break;
1265 	case IF_TYPE_SCSI:
1266 		printf("SCSI");
1267 		break;
1268 	case IF_TYPE_ATAPI:
1269 		printf("ATAPI");
1270 		break;
1271 	case IF_TYPE_USB:
1272 		printf("USB");
1273 		break;
1274 	case IF_TYPE_DOC:
1275 		printf("DOC");
1276 		break;
1277 	case IF_TYPE_MMC:
1278 		printf("MMC");
1279 		break;
1280 	default:
1281 		printf("Unknown");
1282 	}
1283 
1284 	printf("\n  Device %d: ", cur_dev->devnum);
1285 	dev_print(cur_dev);
1286 #endif
1287 
1288 	if (read_bootsectandvi(&bs, &volinfo, &fatsize)) {
1289 		printf("\nNo valid FAT fs found\n");
1290 		return 1;
1291 	}
1292 
1293 	memcpy(vol_label, volinfo.volume_label, 11);
1294 	vol_label[11] = '\0';
1295 	volinfo.fs_type[5] = '\0';
1296 
1297 	printf("Filesystem: %s \"%s\"\n", volinfo.fs_type, vol_label);
1298 
1299 	return 0;
1300 }
1301 
1302 int file_fat_ls(const char *dir)
1303 {
1304 	loff_t size;
1305 
1306 	return do_fat_read(dir, NULL, 0, LS_YES, &size);
1307 }
1308 
1309 int fat_exists(const char *filename)
1310 {
1311 	int ret;
1312 	loff_t size;
1313 
1314 	ret = do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, &size);
1315 	return ret == 0;
1316 }
1317 
1318 int fat_size(const char *filename, loff_t *size)
1319 {
1320 	return do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, size);
1321 }
1322 
1323 int file_fat_read_at(const char *filename, loff_t pos, void *buffer,
1324 		     loff_t maxsize, loff_t *actread)
1325 {
1326 	printf("reading %s\n", filename);
1327 	return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO, 0,
1328 			      actread);
1329 }
1330 
1331 int file_fat_read(const char *filename, void *buffer, int maxsize)
1332 {
1333 	loff_t actread;
1334 	int ret;
1335 
1336 	ret =  file_fat_read_at(filename, 0, buffer, maxsize, &actread);
1337 	if (ret)
1338 		return ret;
1339 	else
1340 		return actread;
1341 }
1342 
1343 int fat_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
1344 		  loff_t *actread)
1345 {
1346 	int ret;
1347 
1348 	ret = file_fat_read_at(filename, offset, buf, len, actread);
1349 	if (ret)
1350 		printf("** Unable to read file %s **\n", filename);
1351 
1352 	return ret;
1353 }
1354 
1355 void fat_close(void)
1356 {
1357 }
1358