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Re: [PATCH] getlogin_r: return early when linux sentinel value is set
- From: Andreas Schwab <schwab at suse dot de>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- Cc: libc-alpha at sourceware dot org
- Date: Tue, 20 Mar 2018 10:05:22 +0100
- Subject: Re: [PATCH] getlogin_r: return early when linux sentinel value is set
- References: <CANSNSoWLXfsYq6kP0niyP8r25S=S1uTKN=+46xnC_SPLBmKXhQ@mail.gmail.com> <73b04097-ef36-b597-4f7c-2e73c6eb9fa3@linaro.org>
On Mär 20 2018, Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:
> On 17/03/2018 00:18, Jesse Hathaway wrote:
>> When there is no login uid Linux sets /proc/self/loginid to the sentinel
>> value of 4294967295. If this is set we can return early and avoid
>> needlessly looking up the sentinel value in any configured nss
>> databases.
>
> The change is short enough so I think it won't require a copyright
> assignment. However it does require a ChangeLog entry, could you please
> resend the patch with a proper one?
>
>>
>> diff --git a/sysdeps/unix/sysv/linux/getlogin_r.c
>> b/sysdeps/unix/sysv/linux/getlogin_r.c
>> index 73ea14c8f9..43f55a2188 100644
>> --- a/sysdeps/unix/sysv/linux/getlogin_r.c
>> +++ b/sysdeps/unix/sysv/linux/getlogin_r.c
>> @@ -55,6 +55,12 @@ __getlogin_r_loginuid (char *name, size_t namesize)
>> endp == uidbuf || *endp != '\0'))
>> return -1;
>>
>> + /* If there is no login uid, linux sets /proc/self/loginid to the sentinel
>> + value of 4294967295, so check if the value is set and return early to
>> + avoid making unneeded nss lookups. */
>> + if (uid == 4294967295)
>> + return ENXIO;
>
> I prefer to just use either (int)-1 or just 0xffffffff.
That should be (uid_t) -1.
Andreas.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
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