linux-kernel - Re: [PATCHv2] fat: don't use custom hex_to

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Message-ID: <CAHp75Vcdnx28i0s4sKUf+MCruMNq-zdX55f45TcTR7AcO4foSw@mail.gmail.com>
Date:	Tue, 27 Sep 2011 21:06:12 +0300
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	Denys Vlasenko <vda.linux@...glemail.com>
Subject: Re: [PATCHv2] fat: don't use custom hex_to_bin()

On Tue, Sep 27, 2011 at 8:19 PM, OGAWA Hirofumi
<hirofumi@...l.parknet.co.jp> wrote:
> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:
>
> Looks good to me.
>
> Acked-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
>
> Or if it's needed, I'll apply this to fat tree.
Please, hold on. Read my comments below.

>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>> Cc: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
>> ---
>>  fs/fat/namei_vfat.c |   30 ++++++++----------------------
>>  1 files changed, 8 insertions(+), 22 deletions(-)
>>
>> diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
>> index bb3f29c..cf0fd96 100644
>> --- a/fs/fat/namei_vfat.c
>> +++ b/fs/fat/namei_vfat.c
>> @@ -21,6 +21,8 @@
>>  #include <linux/slab.h>
>>  #include <linux/buffer_head.h>
>>  #include <linux/namei.h>
>> +#include <linux/kernel.h>
>> +
>>  #include "fat.h"
>>
>>  /*
>> @@ -505,10 +507,8 @@ xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
>>            struct nls_table *nls)
>>  {
>>       const unsigned char *ip;
>> -     unsigned char nc;
>>       unsigned char *op;
>> -     unsigned int ec;
>> -     int i, k, fill;
>> +     int i, rc, fill;
>>       int charlen;
>>
>>       if (utf8) {
>> @@ -528,26 +528,12 @@ xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
>>                               if (escape && (*ip == ':')) {
>>                                       if (i > len - 5)
>>                                               return -EINVAL;
>> -                                     ec = 0;
>> -                                     for (k = 1; k < 5; k++) {
>> -                                             nc = ip[k];
>> -                                             ec <<= 4;
>> -                                             if (nc >= '0' && nc <= '9') {
>> -                                                     ec |= nc - '0';
>> -                                                     continue;
>> -                                             }
>> -                                             if (nc >= 'a' && nc <= 'f') {
>> -                                                     ec |= nc - ('a' - 10);
>> -                                                     continue;
>> -                                             }
>> -                                             if (nc >= 'A' && nc <= 'F') {
>> -                                                     ec |= nc - ('A' - 10);
>> -                                                     continue;
>> -                                             }
>> +
>> +                                     rc = hex2bin(op, ip + 1, 2);
>> +                                     if (rc < 0)
>>                                               return -EINVAL;
>> -                                     }
>> -                                     *op++ = ec & 0xFF;
>> -                                     *op++ = ec >> 8;
Actually here we will change endianess.
So, my question is what endianess is right here? If the original code
okay, then patch should be rewritten like this:

     rc = hex2bin(op++, ip + 3, 1);
     if (rc < 0)
          return -EINVAL;

     rc = hex2bin(op++, ip + 1, 1);
     if (rc < 0)
          return -EINVAL;

>> +
>> +                                     op += 2;
>>                                       ip += 5;
>>                                       i += 5;
>>                               } else {
>
> --
> OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
> --
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-- 
With Best Regards,
Andy Shevchenko