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Don't try to find file position beyond double indirect blocks

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This commit is contained in:
Thomas Veerman 2012-01-16 14:46:47 +00:00
parent ddbdca6cdb
commit 5691dca9f4
1 changed files with 5 additions and 4 deletions
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9
servers/mfs/read.c
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@ -313,7 +313,7 @@ off_t position; /* position in file whose blk wanted */
struct buf *bp; struct buf *bp;
zone_t z; zone_t z;
int scale, boff, index, zind, ex; int scale, boff, index, zind;
unsigned int dzones, nr_indirects; unsigned int dzones, nr_indirects;
block_t b; block_t b;
unsigned long excess, zone, block_pos; unsigned long excess, zone, block_pos;
@ -346,8 +346,10 @@ off_t position; /* position in file whose blk wanted */
excess -= nr_indirects; /* single indir doesn't count*/ excess -= nr_indirects; /* single indir doesn't count*/
b = (block_t) z << scale; b = (block_t) z << scale;
ASSERT(rip->i_dev != NO_DEV); ASSERT(rip->i_dev != NO_DEV);
bp = get_block(rip->i_dev, b, NORMAL); /* get double indirect block */
index = (int) (excess/nr_indirects); index = (int) (excess/nr_indirects);
if ((unsigned int) index > rip->i_nindirs)
return(NO_BLOCK); /* Can't go beyond double indirects */
bp = get_block(rip->i_dev, b, NORMAL); /* get double indirect block */
ASSERT(bp->b_dev != NO_DEV); ASSERT(bp->b_dev != NO_DEV);
ASSERT(bp->b_dev == rip->i_dev); ASSERT(bp->b_dev == rip->i_dev);
z = rd_indir(bp, index); /* z= zone for single*/ z = rd_indir(bp, index); /* z= zone for single*/
@ -359,8 +361,7 @@ off_t position; /* position in file whose blk wanted */
if (z == NO_ZONE) return(NO_BLOCK); if (z == NO_ZONE) return(NO_BLOCK);
b = (block_t) z << scale; /* b is blk # for single ind */ b = (block_t) z << scale; /* b is blk # for single ind */
bp = get_block(rip->i_dev, b, NORMAL); /* get single indirect block */ bp = get_block(rip->i_dev, b, NORMAL); /* get single indirect block */
ex = (int) excess; /* need an integer */ z = rd_indir(bp, (int) excess); /* get block pointed to */
z = rd_indir(bp, ex); /* get block pointed to */
put_block(bp, INDIRECT_BLOCK); /* release single indir blk */ put_block(bp, INDIRECT_BLOCK); /* release single indir blk */
if (z == NO_ZONE) return(NO_BLOCK); if (z == NO_ZONE) return(NO_BLOCK);
b = (block_t) ((z << scale) + boff); b = (block_t) ((z << scale) + boff);