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Read and write syscalls may read less bytes than requested #27

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Read and write syscalls may read less bytes than requested #27

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47 changes: 31 additions & 16 deletions lfs_fuse_bd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -71,17 +71,24 @@ int lfs_fuse_bd_read(const struct lfs_config *cfg, lfs_block_t block,
assert(block < cfg->block_count);

// go to block
off_t err = lseek(fd, (off_t)block*cfg->block_size + (off_t)off, SEEK_SET);
off_t offrq = (off_t)block*cfg->block_size + (off_t)off;
off_t err = lseek(fd,offrq, SEEK_SET);
if (err < 0) {
return -errno;
} else if( err != offrq ) {
return LFS_ERR_IO;
}

// read block
ssize_t res = read(fd, buffer, (size_t)size);
if (res < 0) {
return -errno;
}

char* rdb = buffer;
do {
// read block
ssize_t res = read(fd, rdb, (size_t)size);
if (res <= 0) {
return (res==0)?(LFS_ERR_IO):(-errno);
} else {
rdb += res;
size -= res;
}
} while( size > 0 );
return 0;
}

Expand All @@ -93,16 +100,25 @@ int lfs_fuse_bd_prog(const struct lfs_config *cfg, lfs_block_t block,
assert(block < cfg->block_count);

// go to block
off_t err = lseek(fd, (off_t)block*cfg->block_size + (off_t)off, SEEK_SET);
off_t offrq = (off_t)block*cfg->block_size + (off_t)off;
off_t err = lseek(fd,offrq, SEEK_SET);
if (err < 0) {
return -errno;
} else if(err != offrq )
{
return LFS_ERR_IO;
}

// write block
ssize_t res = write(fd, buffer, (size_t)size);
if (res < 0) {
return -errno;
}
const char* wrb = buffer;
do {
// write block
ssize_t res = write(fd, wrb, (size_t)size);
if (res <= 0) {
return (res==0)?(LFS_ERR_IO):(-errno);
} else {
wrb += res;
size -= res;
}
} while(0);
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I may be missing something, but why does this do/while loop have 0 as a condition?


return 0;
}
Expand All @@ -119,7 +135,6 @@ int lfs_fuse_bd_sync(const struct lfs_config *cfg) {
if (err) {
return -errno;
}

return 0;
}