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

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Message-ID: <1317301641.2676.120.camel@smile>
Date:	Thu, 29 Sep 2011 16:07:21 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Andy Shevchenko <andy.shevchenko@...il.com>,
	linux-kernel@...r.kernel.org,
	Denys Vlasenko <vda.linux@...glemail.com>
Subject: Re: [PATCHv2] fat: don't use custom hex_to_bin()

On Wed, 2011-09-28 at 08:15 +0900, OGAWA Hirofumi wrote: 
> Andy Shevchenko <andy.shevchenko@...il.com> writes:
> 
> > 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;
> 
> Original code may work only for little endian. Well, anyway, the output
> should be wchar_t (u16) of native endian.

> So, I think it should be something like
> 
> 	u8 uc[2];
> 	if (hex2bin(uc, ip + 1, 2) < 0)
>         	return -EINVAL;
> 	*(wchar_t *)op = uc[0] << 8 | uc[1];
> This should be readable more.
It might be so, but it's not okay to do such constructions in C

fs/fat/namei_vfat.c:535:1: warning: ISO C90 forbids mixed declarations
and code [-Wdeclaration-after-statement]

So, I will resend patch as I proposed with additional comments.


-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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