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-rw-r--r--ChangeLog5
-rw-r--r--sysdeps/unix/sysv/linux/getlogin_r.c9
2 files changed, 14 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index e6fe2aa1ad..7f2044dee5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-03-27  Jesse Hathaway  <jesse@mbuki-mvuki.org>
+
+	* sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid): Return
+	early when linux sentinel value is set.
+
 2018-03-27  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
 	* sysdeps/mach/hurd/bits/posix_opt.h (_POSIX_MEMLOCK): Define.
diff --git a/sysdeps/unix/sysv/linux/getlogin_r.c b/sysdeps/unix/sysv/linux/getlogin_r.c
index 73ea14c8f9..14587712a7 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;