Re: [PATCH V2] mkfs: fix mkfs.xfs -dfile,name=$NAME for new files

[Eric Sandeen <sandeen@sandeen.net>]

Alex Elder wrote:
> Eric Sandeen wrote:
>> # /sbin/mkfs.xfs -dfile,name=grrr,size=100g
>> mkfs.xfs: Use the -f option to force overwrite.
>>
>> check_overwrite is failing, because  blkid_new_probe_from_filename()
>> is failing, because the (new) image file is 0 length.
>>
>> It's easy to test for 0 length, and if found, there is
>> nothing to overwrite so return 0.
>>
>> Also, if testing itself failed for some reason, print
>> a message to that effect:
>>
>> # mkfs/mkfs.xfs -dfile,name=newfile,size=1g
>> mkfs.xfs: probe of newfile failed, cannot detect existing filesystem.
>> mkfs.xfs: Use the -f option to force overwrite.
> 
> This looks good.

except of course that st_size for devices is 0.

Oh, I suck lately :/

Ok, will send fixup patch later.  And then I'm gonna stop ;)

-Eric

>> Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
>> ---
> 
> Reviewed-by: Alex Elder <aelder@sgi.com>
> 
>> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
>> index faaafed..b6801dd 100644
>> --- a/mkfs/xfs_mkfs.c
>> +++ b/mkfs/xfs_mkfs.c
>> @@ -283,27 +283,47 @@ calc_stripe_factors(
>>  }
>>
>>  #ifdef ENABLE_BLKID
>> +/*
>> + * Check for existing filesystem or partition table on device.
>> + * Returns:
>> + *	 1 for existing fs or partition
>> + *	 0 for nothing found
>> + *	-1 for internal error
>> + */
>>  static int
>>  check_overwrite(
>>  	char		*device)
>>  {
>>  	const char	*type;
>> -	blkid_probe	pr;
>> -	int		ret = 0;
>> +	blkid_probe	pr = NULL;
>> +	int		ret;
>> +	struct stat	statbuf;
>>
>>  	if (!device || !*device)
>>  		return 0;
>>
>> +	ret = -1; /* will reset on success of all setup calls */
>> +
>> +	if (stat(device, &statbuf) < 0)
>> +		goto out;
>> +
>> +	/* nothing to overwrite on a 0-length device */
>> +	if (statbuf.st_size == 0) {
>> +		ret = 0;
>> +		goto out;
>> +	}
>> +
>>  	pr = blkid_new_probe_from_filename(device);
>>  	if (!pr)
>> -		return -1;
>> +		goto out;
>>
>>  	if (blkid_probe_enable_partitions(pr, 1))
>> -		goto out_free_probe;
>> +		goto out;
>>
>>  	if (blkid_do_fullprobe(pr))
>> -		goto out_free_probe;
>> +		goto out;
>>
>> +	ret = 0;
>>  	if (!blkid_probe_lookup_value(pr, "TYPE", &type, NULL)) {
>>  		fprintf(stderr,
>>  			_("%s: %s appears to contain an existing "
>> @@ -316,8 +336,13 @@ check_overwrite(
>>  		ret = 1;
>>  	}
>>
>> -out_free_probe:
>> -	blkid_free_probe(pr);
>> +out:
>> +	if (pr)
>> +		blkid_free_probe(pr);
>> +	if (ret == -1)
>> +		fprintf(stderr,
>> +			_("%s: probe of %s failed, cannot detect "
>> +			  "existing filesystem.\n"), progname, device);
>>  	return ret;
>>  }
>>
>>
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> 
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