Re: scripts/basic/fixdep: Complete error handling in print_cmdline()

From: Michal Marek <mmarek@suse.com>
To: Masahiro Yamada <yamada.masahiro@socionext.com>,
	SF Markus Elfring <elfring@users.sourceforge.net>
Cc: Jim Davis <jim.epost@gmail.com>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	kernel-janitors@vger.kernel.org
Subject: Re: scripts/basic/fixdep: Complete error handling in print_cmdline()
Date: Thu, 3 Nov 2016 16:57:44 +0100	[thread overview]
Message-ID: <9d92d3ad-d57d-d131-ebd7-2f38a423da7c@suse.com> (raw)
In-Reply-To: <CAK7LNARfBrH2ve9J8D=iq1mdk1j-G_kOXT7CL017uqBOYPRL=Q@mail.gmail.com>

Dne 2.11.2016 v 19:30 Masahiro Yamada napsal(a):
> 2016-11-03 2:38 GMT+09:00 SF Markus Elfring <elfring@users.sourceforge.net>:
>>>>> +       if (printf("cmd_%s := %s\n\n", target, cmdline) < 10) {
>>>>
>>>> Rather than scatter fragile magic numbers, like 10, throughout the
>>>> code, if you're hell-bent on checking for printf errors you could
>>>> write a little wrapper function that hid the magic number and bundled
>>>> up the errno stuff.
>>>
>>>
>>> BTW, how the magic number "10" was calculated?
>>
>> Does the passed format string indicate how many characters should be
>> printed at least?
> 
> So, the check is a bit compromised.
> The printf() should print at lease 10 characters.
> If "target" or "cmdline" is not NULL, it should print more.

printf() / fprintf() return a negative value if an error such as ENOSPC
occurs. So just check for < 0 and preferably use a wrapper.

Michal