Re: [PATCH] fstests: fix blksize_t printf format warnings across architectures

[Anand Jain <anand.jain@oracle.com>]

On 21/11/24 00:28, Darrick J. Wong wrote:
> On Wed, Nov 20, 2024 at 07:40:41PM +0800, Anand Jain wrote:
>> Fix format string warnings when printing blksize_t values that vary
>> across architectures. The warning occurs because blksize_t is defined
>> differently between architectures: aarch64 architectures blksize_t is
>> int, on x86-64 it's long-int.  Cast the values to long. Fixes warnings
>> as below.
>>
>>   seek_sanity_test.c:110:45: warning: format '%ld' expects argument of type
>>   'long int', but argument 3 has type 'blksize_t' {aka 'int'}
>>
>>   attr_replace_test.c:70:22: warning: format '%ld' expects argument of type
>>   'long int', but argument 3 has type '__blksize_t' {aka 'int'}
>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> 
> I waded through a whole bunch of glibc typedef and macro crud and
> discovered that on x64 it can even be long long.  I think.  There were
> so many levels of indirection that I am not certain that my analysis was
> correct. :(
> 

Per preprocessor, it verifies blksize_t is long int and int on x86-64
and aarch64, respectively.

  gcc -E -P -dD -x c - < <(echo '#include <sys/types.h>') | grep blksize_t

  x86-64
    typedef long int __blksize_t;
    typedef __blksize_t blksize_t;

  aarch64
    typedef int __blksize_t;
    typedef __blksize_t blksize_t;


Thanks, Anand

> However, I don't see any harm in explicitly casting to long.  Nobody has
> yet come up with a 8GB fsblock filesystem, so we're ok for now. :P
> 




> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
> 
> --D
> 
>> ---
>>   src/attr_replace_test.c | 2 +-
>>   src/seek_sanity_test.c  | 2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/attr_replace_test.c b/src/attr_replace_test.c
>> index 1218e7264c8f..5d560a633361 100644
>> --- a/src/attr_replace_test.c
>> +++ b/src/attr_replace_test.c
>> @@ -67,7 +67,7 @@ int main(int argc, char *argv[])
>>   	if (ret < 0) die();
>>   	size = sbuf.st_blksize * 3 / 4;
>>   	if (!size)
>> -		fail("Invalid st_blksize(%ld)\n", sbuf.st_blksize);
>> +		fail("Invalid st_blksize(%ld)\n", (long)sbuf.st_blksize);
>>   	size = MIN(size, maxsize);
>>   	value = malloc(size);
>>   	if (!value)
>> diff --git a/src/seek_sanity_test.c b/src/seek_sanity_test.c
>> index a61ed3da9a8f..c5930357911f 100644
>> --- a/src/seek_sanity_test.c
>> +++ b/src/seek_sanity_test.c
>> @@ -107,7 +107,7 @@ static int get_io_sizes(int fd)
>>   		offset += pos ? 0 : 1;
>>   	alloc_size = offset;
>>   done:
>> -	fprintf(stdout, "Allocation size: %ld\n", alloc_size);
>> +	fprintf(stdout, "Allocation size: %ld\n", (long)alloc_size);
>>   	return 0;
>>   
>>   fail:
>> -- 
>> 2.47.0
>>
>>