On 9/3/13 8:13 AM, Wang Shilong wrote:
> Hello Eric,
> 
> Recently, i notice btrfs-progs's magic return value. For example, EACCESS 
> return 12.
> Magic return value is confusing for code reviewers. However,at least we 
> should guarantee
> all these conditions return the same value(for example 12 for this case)
> 
> Or we can change all the magic number to 1. Miao reminded me that
> there may be some applications that have catched and checked these
> magic return values…
> 
> Any ideas about this?

I think that if we want to do anything different from the standard, expected
"return 1 and set errno" then it needs to be a careful design decision, 
documented,
used consistently, and tested.

As far as I can tell, what is in btrfs-progs today is undocumented,
untested, and only occasionally/randomly used.  Therefore I don't
think it's useful as it stands today, and why I had started removing
them.

-Eric

> Thanks,
> Wang
>> From:
>> Just whitespace fixes, and magical return value removal.
>>
>> Signed-off-by: Eric Sandeen <[email protected]>
>> ---
>> cmds-subvolume.c | 18 +++++++++---------
>> 1 file changed, 9 insertions(+), 9 deletions(-)
>>
>> diff --git a/cmds-subvolume.c b/cmds-subvolume.c
>> index 01b982c..a9999ac 100644
>> --- a/cmds-subvolume.c
>> +++ b/cmds-subvolume.c
>> @@ -104,9 +104,9 @@ static int cmd_subvol_create(int argc, char **argv)
>>      dst = argv[optind];
>>
>>      res = test_isdir(dst);
>> -    if(res >= 0 ){
>> +    if (res >= 0) {
>>              fprintf(stderr, "ERROR: '%s' exists\n", dst);
>> -            return 12;
>> +            return 1;
>>      }
>>
>>      newname = strdup(dst);
>> @@ -114,24 +114,24 @@ static int cmd_subvol_create(int argc, char **argv)
>>      dstdir = strdup(dst);
>>      dstdir = dirname(dstdir);
>>
>> -    if( !strcmp(newname,".") || !strcmp(newname,"..") ||
>> +    if (!strcmp(newname, ".") || !strcmp(newname, "..") ||
>>           strchr(newname, '/') ){
>>              fprintf(stderr, "ERROR: uncorrect subvolume name ('%s')\n",
>>                      newname);
>> -            return 14;
>> +            return 1;
>>      }
>>
>>      len = strlen(newname);
>>      if (len == 0 || len >= BTRFS_VOL_NAME_MAX) {
>>              fprintf(stderr, "ERROR: subvolume name too long ('%s)\n",
>>                      newname);
>> -            return 14;
>> +            return 1;
>>      }
>>
>>      fddst = open_file_or_dir(dstdir);
>>      if (fddst < 0) {
>>              fprintf(stderr, "ERROR: can't access to '%s'\n", dstdir);
>> -            return 12;
>> +            return 1;
>>      }
>>
>>      printf("Create subvolume '%s/%s'\n", dstdir, newname);
>> @@ -159,10 +159,10 @@ static int cmd_subvol_create(int argc, char **argv)
>>      close(fddst);
>>      free(inherit);
>>
>> -    if(res < 0 ){
>> -            fprintf( stderr, "ERROR: cannot create subvolume - %s\n",
>> +    if (res < 0) {
>> +            fprintf(stderr, "ERROR: cannot create subvolume - %s\n",
>>                      strerror(e));
>> -            return 11;
>> +            return 1;
>>      }
>>
>>      return 0;
>> -- 
>> 1.7.11.7
>>
> 

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