cttyhack: don't do anything if ctty is already available

function                                             old     new   delta
cttyhack_main                                        244     269     +25

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 26 insertions, 17 deletions

diff --git a/shell/cttyhack.c b/shell/cttyhack.c
index 572a3af03..bde2acdc9 100644
--- a/shell/cttyhack.c
+++ b/shell/cttyhack.c
@@ -53,23 +53,32 @@ int cttyhack_main(int argc UNUSED_PARAM, char **argv)
         }
 
         strcpy(console, "/dev/tty");
-        if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
-                /* this is a serial console */
-                sprintf(console + 8, "S%d", u.sr.line);
-        } else if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
-                /* this is linux virtual tty */
-                sprintf(console + 8, "S%d" + 1, u.vt.v_active);
-        }
-
-        if (console[8]) {
-                fd = xopen(console, O_RDWR);
-                //bb_error_msg("switching to '%s'", console);
-                dup2(fd, 0);
-                dup2(fd, 1);
-                dup2(fd, 2);
-                while (fd > 2) close(fd--);
-                /* Some other session may have it as ctty. Steal it from them */
-                ioctl(0, TIOCSCTTY, 1);
+        fd = open(console, O_RDWR);
+        if (fd >= 0) {
+                /* We already have ctty, nothing to do */
+                close(fd);
+        } else {
+                /* We don't have ctty (or don't have "/dev/tty" node...) */
+                if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
+                        /* this is a serial console */
+                        sprintf(console + 8, "S%d", u.sr.line);
+                } else if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
+                        /* this is linux virtual tty */
+                        sprintf(console + 8, "S%d" + 1, u.vt.v_active);
+                }
+                if (console[8]) {
+                        fd = xopen(console, O_RDWR);
+                        //bb_error_msg("switching to '%s'", console);
+                        dup2(fd, 0);
+                        dup2(fd, 1);
+                        dup2(fd, 2);
+                        while (fd > 2)
+                                close(fd--);
+                        /* Some other session may have it as ctty,
+                         * steal it from them:
+                         */
+                        ioctl(0, TIOCSCTTY, 1);
+                }
         }
 
         BB_EXECVP(argv[0], argv);