On 05.02.2012 00:10, Eric Sandeen wrote:
[]
Just a very quick look:
> * sparsify - utility to punch out blocks of 0s in a file
> int main(int argc, char **argv)
> {
[]
> if (optind == argc) {
> printf("Error: no filename specified\n");
> usage();
> }
>
> fname = argv[optind++];
There's no handling of the case when there are more than one file
specified on the command line.
> /*
> * Normalize to blocksize-aligned range:
> * round start down, round end up - get all blocks including the range specified
> */
>
> punch_range_start = round_down(punch_range_start, blocksize);
> punch_range_end = round_up(punch_range_end, blocksize);
> min_hole = round_up(min_hole, blocksize);
> if (!min_hole)
> min_hole = blocksize;
I think this deserves some bold warning if punch_range_start
or punch_hole_end is not a multiple of blocksize.
[]
> /*
> * Read through the file, finding block-aligned regions of 0s.
> * If the region is at least min_hole, punch it out.
> * This should be starting at a block-aligned offset
> */
>
> while ((ret = read(fd, readbuf, min_hole)) > 0) {
>
> if (!memcmp(readbuf, zerobuf, min_hole)) {
Now this is interesting. Can ret be < min_hole? Can a read
in a middle of a file be shorter than specified?
How it will work together with some other operation being done
at the same file -- ftruncate anyone?
Thanks!
/mjt
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