From cc8a1620eb97ccddd337d157263c13c57b39ab71 Mon Sep 17 00:00:00 2001 From: Jesse Hathaway Date: Tue, 27 Mar 2018 21:17:59 +0000 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. Checked on aarch64-linux-gnu. * sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid): Return early when linux sentinel value is set. Reviewed-by: Adhemerval Zanella --- ChangeLog | 5 +++++ sysdeps/unix/sysv/linux/getlogin_r.c | 9 +++++++++ 2 files changed, 14 insertions(+) diff --git a/ChangeLog b/ChangeLog index e6fe2aa1ad..7f2044dee5 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2018-03-27 Jesse Hathaway + + * sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid): Return + early when linux sentinel value is set. + 2018-03-27 Samuel Thibault * 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;