Fix Linux getlogin{_r,} implementation

The old implementation uses fd 0 to determine the login TTY.  This
was needed because using /dev/tty it is not possible to deduce the
login TTY.  For some time now there is the pseudo-file
/proc/self/loginuid which directly helps us to find the user.  Prefer
using this file.  It also works if stdin is closed, redirected, or
re-opened.

1 files changed, 3 insertions, 0 deletions

diff --git a/include/unistd.h b/include/unistd.h
index ccba893abe..0ad2983280 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -176,6 +176,9 @@ extern int __have_sock_cloexec;
    unless it is really necessary.  */
 #define __have_pipe2 __have_sock_cloexec
 
+extern int __getlogin_r_loginuid (char *name, size_t namesize)
+     attribute_hidden;
+
 __END_DECLS
 
 #endif