Re: [PATCH] src/attr_replace_test: limit size of extended attribute value

Nikolay Borisov
2019-05-20T08:27:02Z

On 20.05.19 г. 11:24 ч., Luis Henriques wrote:
> Nikolay Borisov <nborisov@suse.com> writes:
>
>> On 17.05.19 г. 15:06 ч., Luis Henriques wrote:
>>> The maximum size for extended attribute values is 65536 (XATTR_SIZE_MAX).
>>> Since there are filesystems that can set blksize to really big values
>>> (CephFS for example has a default of 4M), it's easy to have this test
>>> failing with fsetxattr returning -E2BIG.
>>>
>>> Cc: Darrick J. Wong <darrick.wong@oracle.com>
>>> Signed-off-by: Luis Henriques <lhenriques@suse.com>
>>> ---
>>> src/attr_replace_test.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/src/attr_replace_test.c b/src/attr_replace_test.c
>>> index 0720bfdc18ab..1ca9bf11ba58 100644
>>> --- a/src/attr_replace_test.c
>>> +++ b/src/attr_replace_test.c
>>> @@ -9,6 +9,7 @@
>>> #include <sys/types.h>
>>> #include <sys/xattr.h>
>>> #include <sys/stat.h>
>>> +#include <linux/limits.h>
>>>
>>> #define die() do { perror(""); \
>>> fprintf(stderr, "error at line %d\n", __LINE__); \
>>> @@ -44,6 +45,8 @@ int main(int argc, char *argv[])
>>> size = sbuf.st_blksize * 3 / 4;
>>> if (!size)
>>> fail("Invalid st_blksize(%ld)\n", sbuf.st_blksize);
>>> + if (size > XATTR_SIZE_MAX)
>>> + size = XATTR_SIZE_MAX;
>>
>> nit: size = max(size, XATTRS_SIZE_MAX);
>
> Thanks, Nikolay. But I can't find the definition of such macro or
> function. I believe it's only available in kernel, right? Also, you
> probably meant min() ;-)

Yeah, re min, but it seems there is a MIN/MAX macros provided in
<sys/param.h>. Anyway, as mentioned initially this is a minor point :) .

>
> Cheers,
>