* sysdeps/unix/sysv/linux/ttyname.c: Include termios.h.

	(ttyname): Use tcgetattr instead of isatty, don't set errno to ENOTTY.
	* sysdeps/unix/sysv/linux/ttyname_r.c: Include termios.h.
	(__ttyname_r): Use tcgetattr instead of isatty, don't set errno to
	ENOTTY.
	* io/Makefile: Add rules to build and run tst-ttyname_r test.
	* io/tst-ttyname_r.c: New test.

2 files changed, 12 insertions, 10 deletions

diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c
index aed0fd8e0a..1b79787515 100644
--- a/sysdeps/unix/sysv/linux/ttyname.c
+++ b/sysdeps/unix/sysv/linux/ttyname.c
@@ -22,6 +22,7 @@
 #include <dirent.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <termios.h>
 #include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
@@ -118,12 +119,12 @@ ttyname (int fd)
   int dostat = 0;
   char *name;
   int save = errno;
+  struct termios term;
 
-  if (__builtin_expect (!__isatty (fd), 0))
-    {
-      __set_errno (ENOTTY);
-      return NULL;
-    }
+  /* isatty check, tcgetattr is used because it sets the correct
+     errno (EBADF resp. ENOTTY) on error.  */
+  if (__builtin_expect (__tcgetattr (fd, &term) < 0, 0))
+    return NULL;
 
   /* We try using the /proc filesystem.  */
   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c
index bd415f167b..cef8624dc6 100644
--- a/sysdeps/unix/sysv/linux/ttyname_r.c
+++ b/sysdeps/unix/sysv/linux/ttyname_r.c
@@ -22,6 +22,7 @@
 #include <dirent.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <termios.h>
 #include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
@@ -115,11 +116,11 @@ __ttyname_r (int fd, char *buf, size_t buflen)
       return ERANGE;
     }
 
-  if (__builtin_expect (!__isatty (fd), 0))
-    {
-      __set_errno (ENOTTY);
-      return ENOTTY;
-    }
+  /* isatty check, tcgetattr is used because it sets the correct
+     errno (EBADF resp. ENOTTY) on error.  */
+  struct termios term;
+  if (__builtin_expect (__tcgetattr (fd, &term) < 0, 0))
+    return errno;
 
   /* We try using the /proc filesystem.  */
   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';