simplify ctermid

opening /dev/tty then using ttyname_r on it does not produce a
canonical terminal name; it simply yields "/dev/tty".

it would be possible to make ctermid determine the actual controlling
terminal device via field 7 of /proc/self/stat, but doing so would
introduce a buffer overflow into applications built with L_ctermid==9,
which glibc defines, adversely affecting the quality of ABI compat.

diff --git a/src/unistd/ctermid.c b/src/unistd/ctermid.c
index 77684050e6f935c40d0b1937aa126b0aa5cb2930..1612770af158ce068e2b9a1ecc89c4d910d76edd 100644 (file)
--- a/src/unistd/ctermid.c
+++ b/src/unistd/ctermid.c
@@ -1,19 +1,7 @@
 #include <stdio.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <limits.h>
-#include "syscall.h"
+#include <string.h>
 
 char *ctermid(char *s)
 {
-       static char s2[L_ctermid];
-       int fd;
-       if (!s) s = s2;
-       *s = 0;
-       fd = open("/dev/tty", O_WRONLY | O_NOCTTY | O_CLOEXEC);
-       if (fd >= 0) {
-               ttyname_r(fd, s, L_ctermid);
-               __syscall(SYS_close, fd);
-       }
-       return s;
+       return s ? strcpy(s, "/dev/tty") : "/dev/tty";
 }