Patchwork getlogin_r: return early when linux sentinel value is set

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Submitter Jesse Hathaway
Date March 21, 2018, 9:27 p.m.
Message ID <CANSNSoV4Kf_HffDhJboyPrV15P0tL8aB+21ccBz1Anf0q1nb1w@mail.gmail.com>
Download mbox | patch
Permalink /patch/26411/
State New
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Comments

Jesse Hathaway - March 21, 2018, 9:27 p.m.
On Tue, Mar 20, 2018 at 1:30 PM, Andreas Schwab <schwab@linux-m68k.org> wrote:
> Depends on whether you want the linux __getlogin_r to fall back to the
> generic __getlogin_r.

Thanks, updated patch below:

From 04a50b5ee857aa33e1527d70f0676b6daf5a036c Mon Sep 17 00:00:00 2001
From: Jesse Hathaway <jesse@mbuki-mvuki.org>
Date: Fri, 16 Mar 2018 10:46:50 -0500
Subject: [PATCH] getlogin_r: return early when linux sentinel value is set

When there is no login uid Linux sets /proc/self/loginid to the sentinel
value of, (uid_t) - 1. If this is set we can return early and avoid
needlessly looking up the sentinel value in any configured nss
databases.
Adhemerval Zanella Netto - March 22, 2018, 6:14 a.m.
On 22/03/2018 05:27, Jesse Hathaway wrote:
> On Tue, Mar 20, 2018 at 1:30 PM, Andreas Schwab <schwab@linux-m68k.org> wrote:
>> Depends on whether you want the linux __getlogin_r to fall back to the
>> generic __getlogin_r.
> 
> Thanks, updated patch below:
> 
> From 04a50b5ee857aa33e1527d70f0676b6daf5a036c Mon Sep 17 00:00:00 2001
> From: Jesse Hathaway <jesse@mbuki-mvuki.org>
> Date: Fri, 16 Mar 2018 10:46:50 -0500
> Subject: [PATCH] getlogin_r: return early when linux sentinel value is set
> 
> When there is no login uid Linux sets /proc/self/loginid to the sentinel
> value of, (uid_t) - 1. If this is set we can return early and avoid
> needlessly looking up the sentinel value in any configured nss
> databases.

LGTM with CL bit fixed below.  Do you need someone to push it for you?

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> 
> diff --git a/ChangeLog b/ChangeLog
> index 3399e567b8..1ceff1c094 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,8 @@
> +2018-03-20  Jesse Hathaway  <jesse@mbuki-mvuki.org>  (tiny change)
> +
> + * sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid): return early
> + when linux sentinel value is set.

It should contain a tab first and respect the maximum line size of 78, as:

        * sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid): Return
        early when linux sentinel value is set.


> +
>  2018-03-20  Samuel Thibault  <samuel.thibault@ens-lyon.org>
> 
>   * manual/errno.texi (EOWNERDEAD, ENOTRECOVERABLE): Remove errno
> diff --git a/sysdeps/unix/sysv/linux/getlogin_r.c
> b/sysdeps/unix/sysv/linux/getlogin_r.c
> index 73ea14c8f9..1f90c1ca2d 100644
> --- a/sysdeps/unix/sysv/linux/getlogin_r.c
> +++ b/sysdeps/unix/sysv/linux/getlogin_r.c
> @@ -55,6 +55,15 @@ __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, (uid_t) - 1, so check if that value is set and return early to
> +     avoid making unneeded nss lookups. */
> +  if (uid == (uid_t) - 1)
> +    {
> +      __set_errno (ENXIO);
> +      return ENXIO;
> +    }
> +
>    struct passwd pwd;
>    struct passwd *tpwd;
>    int result = 0;
>
Andreas Schwab - March 22, 2018, 5:35 p.m.
On Mär 21 2018, Jesse Hathaway <jesse@mbuki-mvuki.org> wrote:

> +  /* If there is no login uid, linux sets /proc/self/loginid to the sentinel
> +     value of, (uid_t) - 1, so check if that value is set and return early to
> +     avoid making unneeded nss lookups. */
> +  if (uid == (uid_t) - 1)

No space after unary operator.

Andreas.

Patch

diff --git a/ChangeLog b/ChangeLog
index 3399e567b8..1ceff1c094 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@ 
+2018-03-20  Jesse Hathaway  <jesse@mbuki-mvuki.org>  (tiny change)
+
+ * sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid): return early
+ when linux sentinel value is set.
+
 2018-03-20  Samuel Thibault  <samuel.thibault@ens-lyon.org>

  * manual/errno.texi (EOWNERDEAD, ENOTRECOVERABLE): Remove errno
diff --git a/sysdeps/unix/sysv/linux/getlogin_r.c
b/sysdeps/unix/sysv/linux/getlogin_r.c
index 73ea14c8f9..1f90c1ca2d 100644
--- a/sysdeps/unix/sysv/linux/getlogin_r.c
+++ b/sysdeps/unix/sysv/linux/getlogin_r.c
@@ -55,6 +55,15 @@  __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, (uid_t) - 1, so check if that value is set and return early to
+     avoid making unneeded nss lookups. */
+  if (uid == (uid_t) - 1)
+    {
+      __set_errno (ENXIO);
+      return ENXIO;
+    }
+
   struct passwd pwd;
   struct passwd *tpwd;
   int result = 0;