93 lines
		
	
	
		
			2.3 KiB
		
	
	
	
		
			C
		
	
	
	
			
		
		
	
	
			93 lines
		
	
	
		
			2.3 KiB
		
	
	
	
		
			C
		
	
	
	
// SPDX-License-Identifier: GPL-2.0
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/*
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 * 2017 by Marek Behun <marek.behun@nic.cz>
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 *
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 * Derived from code in ext4/dev.c, which was based on reiserfs/dev.c
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 */
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#include <common.h>
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#include <compiler.h>
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#include <part.h>
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#include <memalign.h>
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int fs_devread(struct blk_desc *blk, disk_partition_t *partition,
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	       lbaint_t sector, int byte_offset, int byte_len, char *buf)
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{
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	unsigned block_len;
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	int log2blksz;
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	ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, (blk ? blk->blksz : 0));
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	if (blk == NULL) {
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		printf("** Invalid Block Device Descriptor (NULL)\n");
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		return 0;
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	}
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	log2blksz = blk->log2blksz;
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	/* Check partition boundaries */
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	if ((sector + ((byte_offset + byte_len - 1) >> log2blksz))
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	    >= partition->size) {
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		printf("%s read outside partition " LBAFU "\n", __func__,
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		       sector);
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		return 0;
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	}
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	/* Get the read to the beginning of a partition */
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	sector += byte_offset >> log2blksz;
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	byte_offset &= blk->blksz - 1;
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	debug(" <" LBAFU ", %d, %d>\n", sector, byte_offset, byte_len);
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	if (byte_offset != 0) {
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		int readlen;
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		/* read first part which isn't aligned with start of sector */
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		if (blk_dread(blk, partition->start + sector, 1,
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			      (void *)sec_buf) != 1) {
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			printf(" ** %s read error **\n", __func__);
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			return 0;
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		}
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		readlen = min((int)blk->blksz - byte_offset,
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			      byte_len);
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		memcpy(buf, sec_buf + byte_offset, readlen);
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		buf += readlen;
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		byte_len -= readlen;
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		sector++;
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	}
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	if (byte_len == 0)
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		return 1;
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	/* read sector aligned part */
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	block_len = byte_len & ~(blk->blksz - 1);
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	if (block_len == 0) {
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		ALLOC_CACHE_ALIGN_BUFFER(u8, p, blk->blksz);
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		block_len = blk->blksz;
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		blk_dread(blk, partition->start + sector, 1,
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			  (void *)p);
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		memcpy(buf, p, byte_len);
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		return 1;
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	}
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	if (blk_dread(blk, partition->start + sector,
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		      block_len >> log2blksz, (void *)buf) !=
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			block_len >> log2blksz) {
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		printf(" ** %s read error - block\n", __func__);
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		return 0;
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	}
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	block_len = byte_len & ~(blk->blksz - 1);
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	buf += block_len;
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	byte_len -= block_len;
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	sector += block_len / blk->blksz;
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	if (byte_len != 0) {
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		/* read rest of data which are not in whole sector */
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		if (blk_dread(blk, partition->start + sector, 1,
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			      (void *)sec_buf) != 1) {
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			printf("* %s read error - last part\n", __func__);
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			return 0;
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		}
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		memcpy(buf, sec_buf, byte_len);
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	}
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	return 1;
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}
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