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authorJesse Hathaway <jesse@mbuki-mvuki.org>2018-03-27 21:17:59 +0000
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2018-03-27 21:28:36 -0300
commitcc8a1620eb97ccddd337d157263c13c57b39ab71 (patch)
treec4867e4344f8d30a5163fc9b11753572b474282b
parent8bfd94d0dc9a3e0140f084ef301749846ac6d5d3 (diff)
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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 <adhemerval.zanella@linaro.org>
-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 e6fe2aa..7f2044d 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 73ea14c..1458771 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;