xref: /openbmc/u-boot/fs/fat/fat.c (revision 274bced8)
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 #if CONFIG_IS_ENABLED(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 offset, off8;
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 		off8 = (offset * 3) / 2;
246 		/* fatbut + off8 may be unaligned, read in byte granularity */
247 		ret = mydata->fatbuf[off8] + (mydata->fatbuf[off8 + 1] << 8);
248 
249 		if (offset & 0x1)
250 			ret >>= 4;
251 		ret &= 0xfff;
252 	}
253 	debug("FAT%d: ret: 0x%08x, entry: 0x%08x, offset: 0x%04x\n",
254 	       mydata->fatsize, ret, entry, offset);
255 
256 	return ret;
257 }
258 
259 /*
260  * Read at most 'size' bytes from the specified cluster into 'buffer'.
261  * Return 0 on success, -1 otherwise.
262  */
263 static int
264 get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
265 {
266 	__u32 idx = 0;
267 	__u32 startsect;
268 	int ret;
269 
270 	if (clustnum > 0) {
271 		startsect = mydata->data_begin +
272 				clustnum * mydata->clust_size;
273 	} else {
274 		startsect = mydata->rootdir_sect;
275 	}
276 
277 	debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect);
278 
279 	if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
280 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
281 
282 		printf("FAT: Misaligned buffer address (%p)\n", buffer);
283 
284 		while (size >= mydata->sect_size) {
285 			ret = disk_read(startsect++, 1, tmpbuf);
286 			if (ret != 1) {
287 				debug("Error reading data (got %d)\n", ret);
288 				return -1;
289 			}
290 
291 			memcpy(buffer, tmpbuf, mydata->sect_size);
292 			buffer += mydata->sect_size;
293 			size -= mydata->sect_size;
294 		}
295 	} else {
296 		idx = size / mydata->sect_size;
297 		ret = disk_read(startsect, idx, buffer);
298 		if (ret != idx) {
299 			debug("Error reading data (got %d)\n", ret);
300 			return -1;
301 		}
302 		startsect += idx;
303 		idx *= mydata->sect_size;
304 		buffer += idx;
305 		size -= idx;
306 	}
307 	if (size) {
308 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
309 
310 		ret = disk_read(startsect, 1, tmpbuf);
311 		if (ret != 1) {
312 			debug("Error reading data (got %d)\n", ret);
313 			return -1;
314 		}
315 
316 		memcpy(buffer, tmpbuf, size);
317 	}
318 
319 	return 0;
320 }
321 
322 /*
323  * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr'
324  * into 'buffer'.
325  * Update the number of bytes read in *gotsize or return -1 on fatal errors.
326  */
327 __u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
328 	__aligned(ARCH_DMA_MINALIGN);
329 
330 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
331 			__u8 *buffer, loff_t maxsize, loff_t *gotsize)
332 {
333 	loff_t filesize = FAT2CPU32(dentptr->size);
334 	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
335 	__u32 curclust = START(dentptr);
336 	__u32 endclust, newclust;
337 	loff_t actsize;
338 
339 	*gotsize = 0;
340 	debug("Filesize: %llu bytes\n", filesize);
341 
342 	if (pos >= filesize) {
343 		debug("Read position past EOF: %llu\n", pos);
344 		return 0;
345 	}
346 
347 	if (maxsize > 0 && filesize > pos + maxsize)
348 		filesize = pos + maxsize;
349 
350 	debug("%llu bytes\n", filesize);
351 
352 	actsize = bytesperclust;
353 
354 	/* go to cluster at pos */
355 	while (actsize <= pos) {
356 		curclust = get_fatent(mydata, curclust);
357 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
358 			debug("curclust: 0x%x\n", curclust);
359 			debug("Invalid FAT entry\n");
360 			return 0;
361 		}
362 		actsize += bytesperclust;
363 	}
364 
365 	/* actsize > pos */
366 	actsize -= bytesperclust;
367 	filesize -= actsize;
368 	pos -= actsize;
369 
370 	/* align to beginning of next cluster if any */
371 	if (pos) {
372 		actsize = min(filesize, (loff_t)bytesperclust);
373 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
374 				(int)actsize) != 0) {
375 			printf("Error reading cluster\n");
376 			return -1;
377 		}
378 		filesize -= actsize;
379 		actsize -= pos;
380 		memcpy(buffer, get_contents_vfatname_block + pos, actsize);
381 		*gotsize += actsize;
382 		if (!filesize)
383 			return 0;
384 		buffer += actsize;
385 
386 		curclust = get_fatent(mydata, curclust);
387 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
388 			debug("curclust: 0x%x\n", curclust);
389 			debug("Invalid FAT entry\n");
390 			return 0;
391 		}
392 	}
393 
394 	actsize = bytesperclust;
395 	endclust = curclust;
396 
397 	do {
398 		/* search for consecutive clusters */
399 		while (actsize < filesize) {
400 			newclust = get_fatent(mydata, endclust);
401 			if ((newclust - 1) != endclust)
402 				goto getit;
403 			if (CHECK_CLUST(newclust, mydata->fatsize)) {
404 				debug("curclust: 0x%x\n", newclust);
405 				debug("Invalid FAT entry\n");
406 				return 0;
407 			}
408 			endclust = newclust;
409 			actsize += bytesperclust;
410 		}
411 
412 		/* get remaining bytes */
413 		actsize = filesize;
414 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
415 			printf("Error reading cluster\n");
416 			return -1;
417 		}
418 		*gotsize += actsize;
419 		return 0;
420 getit:
421 		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
422 			printf("Error reading cluster\n");
423 			return -1;
424 		}
425 		*gotsize += (int)actsize;
426 		filesize -= actsize;
427 		buffer += actsize;
428 
429 		curclust = get_fatent(mydata, endclust);
430 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
431 			debug("curclust: 0x%x\n", curclust);
432 			printf("Invalid FAT entry\n");
433 			return 0;
434 		}
435 		actsize = bytesperclust;
436 		endclust = curclust;
437 	} while (1);
438 }
439 
440 /*
441  * Extract the file name information from 'slotptr' into 'l_name',
442  * starting at l_name[*idx].
443  * Return 1 if terminator (zero byte) is found, 0 otherwise.
444  */
445 static int slot2str(dir_slot *slotptr, char *l_name, int *idx)
446 {
447 	int j;
448 
449 	for (j = 0; j <= 8; j += 2) {
450 		l_name[*idx] = slotptr->name0_4[j];
451 		if (l_name[*idx] == 0x00)
452 			return 1;
453 		(*idx)++;
454 	}
455 	for (j = 0; j <= 10; j += 2) {
456 		l_name[*idx] = slotptr->name5_10[j];
457 		if (l_name[*idx] == 0x00)
458 			return 1;
459 		(*idx)++;
460 	}
461 	for (j = 0; j <= 2; j += 2) {
462 		l_name[*idx] = slotptr->name11_12[j];
463 		if (l_name[*idx] == 0x00)
464 			return 1;
465 		(*idx)++;
466 	}
467 
468 	return 0;
469 }
470 
471 /*
472  * Extract the full long filename starting at 'retdent' (which is really
473  * a slot) into 'l_name'. If successful also copy the real directory entry
474  * into 'retdent'
475  * Return 0 on success, -1 otherwise.
476  */
477 static int
478 get_vfatname(fsdata *mydata, int curclust, __u8 *cluster,
479 	     dir_entry *retdent, char *l_name)
480 {
481 	dir_entry *realdent;
482 	dir_slot *slotptr = (dir_slot *)retdent;
483 	__u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
484 							PREFETCH_BLOCKS :
485 							mydata->clust_size);
486 	__u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
487 	int idx = 0;
488 
489 	if (counter > VFAT_MAXSEQ) {
490 		debug("Error: VFAT name is too long\n");
491 		return -1;
492 	}
493 
494 	while ((__u8 *)slotptr < buflimit) {
495 		if (counter == 0)
496 			break;
497 		if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
498 			return -1;
499 		slotptr++;
500 		counter--;
501 	}
502 
503 	if ((__u8 *)slotptr >= buflimit) {
504 		dir_slot *slotptr2;
505 
506 		if (curclust == 0)
507 			return -1;
508 		curclust = get_fatent(mydata, curclust);
509 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
510 			debug("curclust: 0x%x\n", curclust);
511 			printf("Invalid FAT entry\n");
512 			return -1;
513 		}
514 
515 		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
516 				mydata->clust_size * mydata->sect_size) != 0) {
517 			debug("Error: reading directory block\n");
518 			return -1;
519 		}
520 
521 		slotptr2 = (dir_slot *)get_contents_vfatname_block;
522 		while (counter > 0) {
523 			if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
524 			    & 0xff) != counter)
525 				return -1;
526 			slotptr2++;
527 			counter--;
528 		}
529 
530 		/* Save the real directory entry */
531 		realdent = (dir_entry *)slotptr2;
532 		while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
533 			slotptr2--;
534 			slot2str(slotptr2, l_name, &idx);
535 		}
536 	} else {
537 		/* Save the real directory entry */
538 		realdent = (dir_entry *)slotptr;
539 	}
540 
541 	do {
542 		slotptr--;
543 		if (slot2str(slotptr, l_name, &idx))
544 			break;
545 	} while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
546 
547 	l_name[idx] = '\0';
548 	if (*l_name == DELETED_FLAG)
549 		*l_name = '\0';
550 	else if (*l_name == aRING)
551 		*l_name = DELETED_FLAG;
552 	downcase(l_name);
553 
554 	/* Return the real directory entry */
555 	memcpy(retdent, realdent, sizeof(dir_entry));
556 
557 	return 0;
558 }
559 
560 /* Calculate short name checksum */
561 static __u8 mkcksum(const char name[8], const char ext[3])
562 {
563 	int i;
564 
565 	__u8 ret = 0;
566 
567 	for (i = 0; i < 8; i++)
568 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
569 	for (i = 0; i < 3; i++)
570 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
571 
572 	return ret;
573 }
574 
575 /*
576  * Get the directory entry associated with 'filename' from the directory
577  * starting at 'startsect'
578  */
579 __u8 get_dentfromdir_block[MAX_CLUSTSIZE]
580 	__aligned(ARCH_DMA_MINALIGN);
581 
582 static dir_entry *get_dentfromdir(fsdata *mydata, int startsect,
583 				  char *filename, dir_entry *retdent,
584 				  int dols)
585 {
586 	__u16 prevcksum = 0xffff;
587 	__u32 curclust = START(retdent);
588 	int files = 0, dirs = 0;
589 
590 	debug("get_dentfromdir: %s\n", filename);
591 
592 	while (1) {
593 		dir_entry *dentptr;
594 
595 		int i;
596 
597 		if (get_cluster(mydata, curclust, get_dentfromdir_block,
598 				mydata->clust_size * mydata->sect_size) != 0) {
599 			debug("Error: reading directory block\n");
600 			return NULL;
601 		}
602 
603 		dentptr = (dir_entry *)get_dentfromdir_block;
604 
605 		for (i = 0; i < DIRENTSPERCLUST; i++) {
606 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
607 
608 			l_name[0] = '\0';
609 			if (dentptr->name[0] == DELETED_FLAG) {
610 				dentptr++;
611 				continue;
612 			}
613 			if ((dentptr->attr & ATTR_VOLUME)) {
614 				if (vfat_enabled &&
615 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
616 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
617 					prevcksum = ((dir_slot *)dentptr)->alias_checksum;
618 					get_vfatname(mydata, curclust,
619 						     get_dentfromdir_block,
620 						     dentptr, l_name);
621 					if (dols) {
622 						int isdir;
623 						char dirc;
624 						int doit = 0;
625 
626 						isdir = (dentptr->attr & ATTR_DIR);
627 
628 						if (isdir) {
629 							dirs++;
630 							dirc = '/';
631 							doit = 1;
632 						} else {
633 							dirc = ' ';
634 							if (l_name[0] != 0) {
635 								files++;
636 								doit = 1;
637 							}
638 						}
639 						if (doit) {
640 							if (dirc == ' ') {
641 								printf(" %8u   %s%c\n",
642 								       FAT2CPU32(dentptr->size),
643 									l_name,
644 									dirc);
645 							} else {
646 								printf("            %s%c\n",
647 									l_name,
648 									dirc);
649 							}
650 						}
651 						dentptr++;
652 						continue;
653 					}
654 					debug("vfatname: |%s|\n", l_name);
655 				} else {
656 					/* Volume label or VFAT entry */
657 					dentptr++;
658 					continue;
659 				}
660 			}
661 			if (dentptr->name[0] == 0) {
662 				if (dols) {
663 					printf("\n%d file(s), %d dir(s)\n\n",
664 						files, dirs);
665 				}
666 				debug("Dentname == NULL - %d\n", i);
667 				return NULL;
668 			}
669 			if (vfat_enabled) {
670 				__u8 csum = mkcksum(dentptr->name, dentptr->ext);
671 				if (dols && csum == prevcksum) {
672 					prevcksum = 0xffff;
673 					dentptr++;
674 					continue;
675 				}
676 			}
677 
678 			get_name(dentptr, s_name);
679 			if (dols) {
680 				int isdir = (dentptr->attr & ATTR_DIR);
681 				char dirc;
682 				int doit = 0;
683 
684 				if (isdir) {
685 					dirs++;
686 					dirc = '/';
687 					doit = 1;
688 				} else {
689 					dirc = ' ';
690 					if (s_name[0] != 0) {
691 						files++;
692 						doit = 1;
693 					}
694 				}
695 
696 				if (doit) {
697 					if (dirc == ' ') {
698 						printf(" %8u   %s%c\n",
699 						       FAT2CPU32(dentptr->size),
700 							s_name, dirc);
701 					} else {
702 						printf("            %s%c\n",
703 							s_name, dirc);
704 					}
705 				}
706 
707 				dentptr++;
708 				continue;
709 			}
710 
711 			if (strcmp(filename, s_name)
712 			    && strcmp(filename, l_name)) {
713 				debug("Mismatch: |%s|%s|\n", s_name, l_name);
714 				dentptr++;
715 				continue;
716 			}
717 
718 			memcpy(retdent, dentptr, sizeof(dir_entry));
719 
720 			debug("DentName: %s", s_name);
721 			debug(", start: 0x%x", START(dentptr));
722 			debug(", size:  0x%x %s\n",
723 			      FAT2CPU32(dentptr->size),
724 			      (dentptr->attr & ATTR_DIR) ? "(DIR)" : "");
725 
726 			return retdent;
727 		}
728 
729 		curclust = get_fatent(mydata, curclust);
730 		if (CHECK_CLUST(curclust, mydata->fatsize)) {
731 			debug("curclust: 0x%x\n", curclust);
732 			printf("Invalid FAT entry\n");
733 			return NULL;
734 		}
735 	}
736 
737 	return NULL;
738 }
739 
740 /*
741  * Read boot sector and volume info from a FAT filesystem
742  */
743 static int
744 read_bootsectandvi(boot_sector *bs, volume_info *volinfo, int *fatsize)
745 {
746 	__u8 *block;
747 	volume_info *vistart;
748 	int ret = 0;
749 
750 	if (cur_dev == NULL) {
751 		debug("Error: no device selected\n");
752 		return -1;
753 	}
754 
755 	block = memalign(ARCH_DMA_MINALIGN, cur_dev->blksz);
756 	if (block == NULL) {
757 		debug("Error: allocating block\n");
758 		return -1;
759 	}
760 
761 	if (disk_read(0, 1, block) < 0) {
762 		debug("Error: reading block\n");
763 		goto fail;
764 	}
765 
766 	memcpy(bs, block, sizeof(boot_sector));
767 	bs->reserved = FAT2CPU16(bs->reserved);
768 	bs->fat_length = FAT2CPU16(bs->fat_length);
769 	bs->secs_track = FAT2CPU16(bs->secs_track);
770 	bs->heads = FAT2CPU16(bs->heads);
771 	bs->total_sect = FAT2CPU32(bs->total_sect);
772 
773 	/* FAT32 entries */
774 	if (bs->fat_length == 0) {
775 		/* Assume FAT32 */
776 		bs->fat32_length = FAT2CPU32(bs->fat32_length);
777 		bs->flags = FAT2CPU16(bs->flags);
778 		bs->root_cluster = FAT2CPU32(bs->root_cluster);
779 		bs->info_sector = FAT2CPU16(bs->info_sector);
780 		bs->backup_boot = FAT2CPU16(bs->backup_boot);
781 		vistart = (volume_info *)(block + sizeof(boot_sector));
782 		*fatsize = 32;
783 	} else {
784 		vistart = (volume_info *)&(bs->fat32_length);
785 		*fatsize = 0;
786 	}
787 	memcpy(volinfo, vistart, sizeof(volume_info));
788 
789 	if (*fatsize == 32) {
790 		if (strncmp(FAT32_SIGN, vistart->fs_type, SIGNLEN) == 0)
791 			goto exit;
792 	} else {
793 		if (strncmp(FAT12_SIGN, vistart->fs_type, SIGNLEN) == 0) {
794 			*fatsize = 12;
795 			goto exit;
796 		}
797 		if (strncmp(FAT16_SIGN, vistart->fs_type, SIGNLEN) == 0) {
798 			*fatsize = 16;
799 			goto exit;
800 		}
801 	}
802 
803 	debug("Error: broken fs_type sign\n");
804 fail:
805 	ret = -1;
806 exit:
807 	free(block);
808 	return ret;
809 }
810 
811 __u8 do_fat_read_at_block[MAX_CLUSTSIZE]
812 	__aligned(ARCH_DMA_MINALIGN);
813 
814 int do_fat_read_at(const char *filename, loff_t pos, void *buffer,
815 		   loff_t maxsize, int dols, int dogetsize, loff_t *size)
816 {
817 	char fnamecopy[2048];
818 	boot_sector bs;
819 	volume_info volinfo;
820 	fsdata datablock;
821 	fsdata *mydata = &datablock;
822 	dir_entry *dentptr = NULL;
823 	__u16 prevcksum = 0xffff;
824 	char *subname = "";
825 	__u32 cursect;
826 	int idx, isdir = 0;
827 	int files = 0, dirs = 0;
828 	int ret = -1;
829 	int firsttime;
830 	__u32 root_cluster = 0;
831 	__u32 read_blk;
832 	int rootdir_size = 0;
833 	int buffer_blk_cnt;
834 	int do_read;
835 	__u8 *dir_ptr;
836 
837 	if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
838 		debug("Error: reading boot sector\n");
839 		return -1;
840 	}
841 
842 	if (mydata->fatsize == 32) {
843 		root_cluster = bs.root_cluster;
844 		mydata->fatlength = bs.fat32_length;
845 	} else {
846 		mydata->fatlength = bs.fat_length;
847 	}
848 
849 	mydata->fat_sect = bs.reserved;
850 
851 	cursect = mydata->rootdir_sect
852 		= mydata->fat_sect + mydata->fatlength * bs.fats;
853 
854 	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
855 	mydata->clust_size = bs.cluster_size;
856 	if (mydata->sect_size != cur_part_info.blksz) {
857 		printf("Error: FAT sector size mismatch (fs=%hu, dev=%lu)\n",
858 				mydata->sect_size, cur_part_info.blksz);
859 		return -1;
860 	}
861 
862 	if (mydata->fatsize == 32) {
863 		mydata->data_begin = mydata->rootdir_sect -
864 					(mydata->clust_size * 2);
865 	} else {
866 		rootdir_size = ((bs.dir_entries[1]  * (int)256 +
867 				 bs.dir_entries[0]) *
868 				 sizeof(dir_entry)) /
869 				 mydata->sect_size;
870 		mydata->data_begin = mydata->rootdir_sect +
871 					rootdir_size -
872 					(mydata->clust_size * 2);
873 	}
874 
875 	mydata->fatbufnum = -1;
876 	mydata->fat_dirty = 0;
877 	mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
878 	if (mydata->fatbuf == NULL) {
879 		debug("Error: allocating memory\n");
880 		return -1;
881 	}
882 
883 	if (vfat_enabled)
884 		debug("VFAT Support enabled\n");
885 
886 	debug("FAT%d, fat_sect: %d, fatlength: %d\n",
887 	       mydata->fatsize, mydata->fat_sect, mydata->fatlength);
888 	debug("Rootdir begins at cluster: %d, sector: %d, offset: %x\n"
889 	       "Data begins at: %d\n",
890 	       root_cluster,
891 	       mydata->rootdir_sect,
892 	       mydata->rootdir_sect * mydata->sect_size, mydata->data_begin);
893 	debug("Sector size: %d, cluster size: %d\n", mydata->sect_size,
894 	      mydata->clust_size);
895 
896 	/* "cwd" is always the root... */
897 	while (ISDIRDELIM(*filename))
898 		filename++;
899 
900 	/* Make a copy of the filename and convert it to lowercase */
901 	strcpy(fnamecopy, filename);
902 	downcase(fnamecopy);
903 
904 root_reparse:
905 	if (*fnamecopy == '\0') {
906 		if (!dols)
907 			goto exit;
908 
909 		dols = LS_ROOT;
910 	} else if ((idx = dirdelim(fnamecopy)) >= 0) {
911 		isdir = 1;
912 		fnamecopy[idx] = '\0';
913 		subname = fnamecopy + idx + 1;
914 
915 		/* Handle multiple delimiters */
916 		while (ISDIRDELIM(*subname))
917 			subname++;
918 	} else if (dols) {
919 		isdir = 1;
920 	}
921 
922 	buffer_blk_cnt = 0;
923 	firsttime = 1;
924 	while (1) {
925 		int i;
926 
927 		if (mydata->fatsize == 32 || firsttime) {
928 			dir_ptr = do_fat_read_at_block;
929 			firsttime = 0;
930 		} else {
931 			/**
932 			 * FAT16 sector buffer modification:
933 			 * Each loop, the second buffered block is moved to
934 			 * the buffer begin, and two next sectors are read
935 			 * next to the previously moved one. So the sector
936 			 * buffer keeps always 3 sectors for fat16.
937 			 * And the current sector is the buffer second sector
938 			 * beside the "firsttime" read, when it is the first one.
939 			 *
940 			 * PREFETCH_BLOCKS is 2 for FAT16 == loop[0:1]
941 			 * n = computed root dir sector
942 			 * loop |  cursect-1  | cursect    | cursect+1  |
943 			 *   0  |  sector n+0 | sector n+1 | none       |
944 			 *   1  |  none       | sector n+0 | sector n+1 |
945 			 *   0  |  sector n+1 | sector n+2 | sector n+3 |
946 			 *   1  |  sector n+3 | ...
947 			*/
948 			dir_ptr = (do_fat_read_at_block + mydata->sect_size);
949 			memcpy(do_fat_read_at_block, dir_ptr, mydata->sect_size);
950 		}
951 
952 		do_read = 1;
953 
954 		if (mydata->fatsize == 32 && buffer_blk_cnt)
955 			do_read = 0;
956 
957 		if (do_read) {
958 			read_blk = (mydata->fatsize == 32) ?
959 				    mydata->clust_size : PREFETCH_BLOCKS;
960 
961 			debug("FAT read(sect=%d, cnt:%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n",
962 				cursect, read_blk, mydata->clust_size, DIRENTSPERBLOCK);
963 
964 			if (disk_read(cursect, read_blk, dir_ptr) < 0) {
965 				debug("Error: reading rootdir block\n");
966 				goto exit;
967 			}
968 
969 			dentptr = (dir_entry *)dir_ptr;
970 		}
971 
972 		for (i = 0; i < DIRENTSPERBLOCK; i++) {
973 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
974 			__u8 csum;
975 
976 			l_name[0] = '\0';
977 			if (dentptr->name[0] == DELETED_FLAG) {
978 				dentptr++;
979 				continue;
980 			}
981 
982 			if (vfat_enabled)
983 				csum = mkcksum(dentptr->name, dentptr->ext);
984 
985 			if (dentptr->attr & ATTR_VOLUME) {
986 				if (vfat_enabled &&
987 				    (dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
988 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
989 					prevcksum =
990 						((dir_slot *)dentptr)->alias_checksum;
991 
992 					get_vfatname(mydata,
993 						     root_cluster,
994 						     dir_ptr,
995 						     dentptr, l_name);
996 
997 					if (dols == LS_ROOT) {
998 						char dirc;
999 						int doit = 0;
1000 						int isdir =
1001 							(dentptr->attr & ATTR_DIR);
1002 
1003 						if (isdir) {
1004 							dirs++;
1005 							dirc = '/';
1006 							doit = 1;
1007 						} else {
1008 							dirc = ' ';
1009 							if (l_name[0] != 0) {
1010 								files++;
1011 								doit = 1;
1012 							}
1013 						}
1014 						if (doit) {
1015 							if (dirc == ' ') {
1016 								printf(" %8u   %s%c\n",
1017 								       FAT2CPU32(dentptr->size),
1018 									l_name,
1019 									dirc);
1020 							} else {
1021 								printf("            %s%c\n",
1022 									l_name,
1023 									dirc);
1024 							}
1025 						}
1026 						dentptr++;
1027 						continue;
1028 					}
1029 					debug("Rootvfatname: |%s|\n",
1030 					       l_name);
1031 				} else {
1032 					/* Volume label or VFAT entry */
1033 					dentptr++;
1034 					continue;
1035 				}
1036 			} else if (dentptr->name[0] == 0) {
1037 				debug("RootDentname == NULL - %d\n", i);
1038 				if (dols == LS_ROOT) {
1039 					printf("\n%d file(s), %d dir(s)\n\n",
1040 						files, dirs);
1041 					ret = 0;
1042 				}
1043 				goto exit;
1044 			}
1045 			else if (vfat_enabled &&
1046 				 dols == LS_ROOT && csum == prevcksum) {
1047 				prevcksum = 0xffff;
1048 				dentptr++;
1049 				continue;
1050 			}
1051 
1052 			get_name(dentptr, s_name);
1053 
1054 			if (dols == LS_ROOT) {
1055 				int isdir = (dentptr->attr & ATTR_DIR);
1056 				char dirc;
1057 				int doit = 0;
1058 
1059 				if (isdir) {
1060 					dirc = '/';
1061 					if (s_name[0] != 0) {
1062 						dirs++;
1063 						doit = 1;
1064 					}
1065 				} else {
1066 					dirc = ' ';
1067 					if (s_name[0] != 0) {
1068 						files++;
1069 						doit = 1;
1070 					}
1071 				}
1072 				if (doit) {
1073 					if (dirc == ' ') {
1074 						printf(" %8u   %s%c\n",
1075 						       FAT2CPU32(dentptr->size),
1076 							s_name, dirc);
1077 					} else {
1078 						printf("            %s%c\n",
1079 							s_name, dirc);
1080 					}
1081 				}
1082 				dentptr++;
1083 				continue;
1084 			}
1085 
1086 			if (strcmp(fnamecopy, s_name)
1087 			    && strcmp(fnamecopy, l_name)) {
1088 				debug("RootMismatch: |%s|%s|\n", s_name,
1089 				       l_name);
1090 				dentptr++;
1091 				continue;
1092 			}
1093 
1094 			if (isdir && !(dentptr->attr & ATTR_DIR))
1095 				goto exit;
1096 
1097 			debug("RootName: %s", s_name);
1098 			debug(", start: 0x%x", START(dentptr));
1099 			debug(", size:  0x%x %s\n",
1100 			       FAT2CPU32(dentptr->size),
1101 			       isdir ? "(DIR)" : "");
1102 
1103 			goto rootdir_done;	/* We got a match */
1104 		}
1105 		debug("END LOOP: buffer_blk_cnt=%d   clust_size=%d\n", buffer_blk_cnt,
1106 		       mydata->clust_size);
1107 
1108 		/*
1109 		 * On FAT32 we must fetch the FAT entries for the next
1110 		 * root directory clusters when a cluster has been
1111 		 * completely processed.
1112 		 */
1113 		++buffer_blk_cnt;
1114 		int rootdir_end = 0;
1115 		if (mydata->fatsize == 32) {
1116 			if (buffer_blk_cnt == mydata->clust_size) {
1117 				int nxtsect = 0;
1118 				int nxt_clust = 0;
1119 
1120 				nxt_clust = get_fatent(mydata, root_cluster);
1121 				rootdir_end = CHECK_CLUST(nxt_clust, 32);
1122 
1123 				nxtsect = mydata->data_begin +
1124 					(nxt_clust * mydata->clust_size);
1125 
1126 				root_cluster = nxt_clust;
1127 
1128 				cursect = nxtsect;
1129 				buffer_blk_cnt = 0;
1130 			}
1131 		} else {
1132 			if (buffer_blk_cnt == PREFETCH_BLOCKS)
1133 				buffer_blk_cnt = 0;
1134 
1135 			rootdir_end = (++cursect - mydata->rootdir_sect >=
1136 				       rootdir_size);
1137 		}
1138 
1139 		/* If end of rootdir reached */
1140 		if (rootdir_end) {
1141 			if (dols == LS_ROOT) {
1142 				printf("\n%d file(s), %d dir(s)\n\n",
1143 				       files, dirs);
1144 				*size = 0;
1145 			}
1146 			goto exit;
1147 		}
1148 	}
1149 rootdir_done:
1150 
1151 	firsttime = 1;
1152 
1153 	while (isdir) {
1154 		int startsect = mydata->data_begin
1155 			+ START(dentptr) * mydata->clust_size;
1156 		dir_entry dent;
1157 		char *nextname = NULL;
1158 
1159 		dent = *dentptr;
1160 		dentptr = &dent;
1161 
1162 		idx = dirdelim(subname);
1163 
1164 		if (idx >= 0) {
1165 			subname[idx] = '\0';
1166 			nextname = subname + idx + 1;
1167 			/* Handle multiple delimiters */
1168 			while (ISDIRDELIM(*nextname))
1169 				nextname++;
1170 			if (dols && *nextname == '\0')
1171 				firsttime = 0;
1172 		} else {
1173 			if (dols && firsttime) {
1174 				firsttime = 0;
1175 			} else {
1176 				isdir = 0;
1177 			}
1178 		}
1179 
1180 		if (get_dentfromdir(mydata, startsect, subname, dentptr,
1181 				     isdir ? 0 : dols) == NULL) {
1182 			if (dols && !isdir)
1183 				*size = 0;
1184 			goto exit;
1185 		}
1186 
1187 		if (isdir && !(dentptr->attr & ATTR_DIR))
1188 			goto exit;
1189 
1190 		/*
1191 		 * If we are looking for a directory, and found a directory
1192 		 * type entry, and the entry is for the root directory (as
1193 		 * denoted by a cluster number of 0), jump back to the start
1194 		 * of the function, since at least on FAT12/16, the root dir
1195 		 * lives in a hard-coded location and needs special handling
1196 		 * to parse, rather than simply following the cluster linked
1197 		 * list in the FAT, like other directories.
1198 		 */
1199 		if (isdir && (dentptr->attr & ATTR_DIR) && !START(dentptr)) {
1200 			/*
1201 			 * Modify the filename to remove the prefix that gets
1202 			 * back to the root directory, so the initial root dir
1203 			 * parsing code can continue from where we are without
1204 			 * confusion.
1205 			 */
1206 			strcpy(fnamecopy, nextname ?: "");
1207 			/*
1208 			 * Set up state the same way as the function does when
1209 			 * first started. This is required for the root dir
1210 			 * parsing code operates in its expected environment.
1211 			 */
1212 			subname = "";
1213 			cursect = mydata->rootdir_sect;
1214 			isdir = 0;
1215 			goto root_reparse;
1216 		}
1217 
1218 		if (idx >= 0)
1219 			subname = nextname;
1220 	}
1221 
1222 	if (dogetsize) {
1223 		*size = FAT2CPU32(dentptr->size);
1224 		ret = 0;
1225 	} else {
1226 		ret = get_contents(mydata, dentptr, pos, buffer, maxsize, size);
1227 	}
1228 	debug("Size: %u, got: %llu\n", FAT2CPU32(dentptr->size), *size);
1229 
1230 exit:
1231 	free(mydata->fatbuf);
1232 	return ret;
1233 }
1234 
1235 int do_fat_read(const char *filename, void *buffer, loff_t maxsize, int dols,
1236 		loff_t *actread)
1237 {
1238 	return do_fat_read_at(filename, 0, buffer, maxsize, dols, 0, actread);
1239 }
1240 
1241 int file_fat_detectfs(void)
1242 {
1243 	boot_sector bs;
1244 	volume_info volinfo;
1245 	int fatsize;
1246 	char vol_label[12];
1247 
1248 	if (cur_dev == NULL) {
1249 		printf("No current device\n");
1250 		return 1;
1251 	}
1252 
1253 #if defined(CONFIG_CMD_IDE) || \
1254     defined(CONFIG_CMD_SATA) || \
1255     defined(CONFIG_SCSI) || \
1256     defined(CONFIG_CMD_USB) || \
1257     defined(CONFIG_MMC)
1258 	printf("Interface:  ");
1259 	switch (cur_dev->if_type) {
1260 	case IF_TYPE_IDE:
1261 		printf("IDE");
1262 		break;
1263 	case IF_TYPE_SATA:
1264 		printf("SATA");
1265 		break;
1266 	case IF_TYPE_SCSI:
1267 		printf("SCSI");
1268 		break;
1269 	case IF_TYPE_ATAPI:
1270 		printf("ATAPI");
1271 		break;
1272 	case IF_TYPE_USB:
1273 		printf("USB");
1274 		break;
1275 	case IF_TYPE_DOC:
1276 		printf("DOC");
1277 		break;
1278 	case IF_TYPE_MMC:
1279 		printf("MMC");
1280 		break;
1281 	default:
1282 		printf("Unknown");
1283 	}
1284 
1285 	printf("\n  Device %d: ", cur_dev->devnum);
1286 	dev_print(cur_dev);
1287 #endif
1288 
1289 	if (read_bootsectandvi(&bs, &volinfo, &fatsize)) {
1290 		printf("\nNo valid FAT fs found\n");
1291 		return 1;
1292 	}
1293 
1294 	memcpy(vol_label, volinfo.volume_label, 11);
1295 	vol_label[11] = '\0';
1296 	volinfo.fs_type[5] = '\0';
1297 
1298 	printf("Filesystem: %s \"%s\"\n", volinfo.fs_type, vol_label);
1299 
1300 	return 0;
1301 }
1302 
1303 int file_fat_ls(const char *dir)
1304 {
1305 	loff_t size;
1306 
1307 	return do_fat_read(dir, NULL, 0, LS_YES, &size);
1308 }
1309 
1310 int fat_exists(const char *filename)
1311 {
1312 	int ret;
1313 	loff_t size;
1314 
1315 	ret = do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, &size);
1316 	return ret == 0;
1317 }
1318 
1319 int fat_size(const char *filename, loff_t *size)
1320 {
1321 	return do_fat_read_at(filename, 0, NULL, 0, LS_NO, 1, size);
1322 }
1323 
1324 int file_fat_read_at(const char *filename, loff_t pos, void *buffer,
1325 		     loff_t maxsize, loff_t *actread)
1326 {
1327 	printf("reading %s\n", filename);
1328 	return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO, 0,
1329 			      actread);
1330 }
1331 
1332 int file_fat_read(const char *filename, void *buffer, int maxsize)
1333 {
1334 	loff_t actread;
1335 	int ret;
1336 
1337 	ret =  file_fat_read_at(filename, 0, buffer, maxsize, &actread);
1338 	if (ret)
1339 		return ret;
1340 	else
1341 		return actread;
1342 }
1343 
1344 int fat_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
1345 		  loff_t *actread)
1346 {
1347 	int ret;
1348 
1349 	ret = file_fat_read_at(filename, offset, buf, len, actread);
1350 	if (ret)
1351 		printf("** Unable to read file %s **\n", filename);
1352 
1353 	return ret;
1354 }
1355 
1356 void fat_close(void)
1357 {
1358 }
1359