lint: replace ctermid() with ctermid_r()

configure.ac

@@ -417,6 +417,17 @@ fi
 # features that Autoconf doesn't tell us about
 #
 
+dnl AC_CHECK_FUNCS uses C linkage, but sometimes (Solaris!) the behaviour is
+dnl different with C++.
+AC_MSG_CHECKING([if ctermid_r() available])
+AC_TRY_LINK( [ #include <stdio.h> ],
+             [ char buf[L_ctermid]; char *foo = ctermid_r(buf); ],
+             [ AC_MSG_RESULT(yes)
+               AC_DEFINE(HAVE_CTERMID_R, 1, Define to 1 if you have the `ctermid_r' function.)
+             ],
+             [AC_MSG_RESULT(no)],
+             )
+
 #
 # Check if struct winsize and TIOCGWINSZ exist
 #

src/reader.cpp

@@ -1520,7 +1520,12 @@ static bool check_for_orphaned_process(unsigned long loop_count, pid_t shell_pgi
     if (!we_think_we_are_orphaned && loop_count % 128 == 0) {
         // Try reading from the tty; if we get EIO we are orphaned. This is sort of bad because it
         // may block.
+#ifdef HAVE_CTERMID_R
+        char buf[L_ctermid];
+        char *tty = ctermid_r(buf);
+#else
         char *tty = ctermid(NULL);
+#endif
         if (!tty) {
             wperror(L"ctermid");
             exit_without_destructors(1);