Subject: Re: [PATCH] lsprop: Fixes to work correctly when built little endian

From: Nathan Fontenot <[email-masked]>
Date: Mon, 07 Jan 2013 21:55:09 -0600

On 01/07/2013 08:12 PM, Benjamin Herrenschmidt wrote:
> On Mon, 2013-01-07 at 15:23 +1100, Michael Ellerman wrote:
>> Add and use dt_swap_int() to byte swap on little endian.
>>
>> Also declare buf as unsigned char, so that we don't sign extend when
>> printing values from it.
>>
>> Signed-off-by: Michael Ellerman <[email-masked]>
>> ---
>>
>> Ben, based on your patch, can you add your s-o-b? :
>>   https://lists.ozlabs.org/pipermail/linuxppc-dev/2008-May/056088.html
> 
> I didn't know powerpc-utils required sob's :-)

Not technically, it's more a CYA thing. It (hopefully) keeps big blue legal
happy, which keeps me happy.

-Nathan

> 
> Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
> 
>> ---
>>  src/lsprop.c |   17 ++++++++++++++---
>>  1 file changed, 14 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/lsprop.c b/src/lsprop.c
>> index 5969a97..38a8fa5 100644
>> --- a/src/lsprop.c
>> +++ b/src/lsprop.c
>> @@ -13,11 +13,22 @@
>>  #include <sys/stat.h>
>>  #include <sys/types.h>
>>  #include <dirent.h>
>> +#include <endian.h>
>> +#include <byteswap.h>
>> +
>> +static inline unsigned int dt_swap_int(unsigned int data)
>> +{
>> +#if __BYTE_ORDER == __LITTLE_ENDIAN
>> +	return bswap_32(data);
>> +#else
>> +	return data;
>> +#endif
>> +}
>>  
>>  int recurse;
>>  int maxbytes = 128;
>>  int words_per_line = 0;
>> -char *buf;
>> +unsigned char *buf;
>>  
>>  void lsprop(FILE *f, char *name);
>>  void lsdir(char *name);
>> @@ -183,7 +194,7 @@ void lsprop(FILE *f, char *name)
>>      } else if ((n & 3) == 0) {
>>  	nw = n >> 2;
>>  	if (nw == 1) {
>> -	    i = *(int *)buf;
>> +	    i = dt_swap_int(*(int *)buf);
>>  	    printf(" %.8x", i);
>>  	    if (i > -0x10000 && !(i >= 0 && i <= 9))
>>  		printf(" (%d)", i);
>> @@ -201,7 +212,7 @@ void lsprop(FILE *f, char *name)
>>  		if (i != 0)
>>  		    printf("\n\t\t");
>>  		for (j = 0; j < npl && i + j < nw; ++j)
>> -		    printf(" %.8x", ((unsigned int *)buf)[i+j]);
>> +		    printf(" %.8x", dt_swap_int(((unsigned int *)buf)[i+j]));
>>  	    }
>>  	}
>>      } else {
> 
> 

-- 
-Nathan