From 540ddd5659c156754145419d70c094516864517c Mon Sep 17 00:00:00 2001
From: Kim Woelders <kw@thrane.eu>
Date: Mon, 15 Oct 2018 11:47:43 +0200
Subject: [PATCH] Fix polling of pty slave

---
 ttynvt.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/ttynvt.c b/ttynvt.c
index 1e51608..e4763c0 100644
--- a/ttynvt.c
+++ b/ttynvt.c
@@ -32,8 +32,8 @@
 #define TMP_BUF_SIZE 1024
 
 #define FD_NET     0
-#define FD_SLAVE   1
-#define FD_MASTER  2
+#define FD_MASTER  1
+#define FD_SLAVE   2
 
 #define _PRF_N_(no) __attribute__((__format__(__printf__, (no), (no) + 1)))
 #define _PRF2_ _PRF_N_(2)
@@ -60,6 +60,7 @@ typedef struct {
 
     struct fuse_pollhandle *ph;
 
+    volatile char   n_fds;
     struct pollfd   fds[3];
 
     char            net_buf[NET_BUF_SIZE];
@@ -178,6 +179,7 @@ static void ttynvt_release(fuse_req_t req, struct fuse_file_info *info)
 
     _log(LOG_INFO, "connection closed\n");
 
+    tty->n_fds = 0;
     close(tty->fds[FD_NET].fd);
     close(tty->fds[FD_MASTER].fd);
     close(tty->fds[FD_SLAVE].fd);
@@ -226,10 +228,13 @@ static void    *_read_net(void *arg)
     pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
     DBG2("%s: net_cnt=%d\n", __func__, tty->net_cnt);
 
-    while (1)
+    while (tty->n_fds > 0)
     {
-        res = poll(tty->fds, 3, -1);
-        DBG2("%s: res=%d events-N/M/S=%#x/%#x/%#x\n", __func__, res,
+        tty->fds[FD_NET].revents = tty->fds[FD_MASTER].revents =
+            tty->fds[FD_SLAVE].revents = 0;
+        res = poll(tty->fds, tty->n_fds, -1);
+        DBG2("%s: res=%d N=%d events-N/M/S=%#x/%#x/%#x\n", __func__,
+             res, tty->n_fds,
              tty->fds[FD_NET].revents, tty->fds[FD_MASTER].revents,
              tty->fds[FD_SLAVE].revents);
         if (res < 0)
@@ -238,6 +243,8 @@ static void    *_read_net(void *arg)
                 continue;
             break;
         }
+        if (tty->n_fds == 0)
+            break;
 
         if (tty->fds[FD_NET].revents & POLLIN)
         {
@@ -286,6 +293,7 @@ static void    *_read_net(void *arg)
         if (tty->fds[FD_SLAVE].revents & POLLIN)
         {
             tty->pollin = 1;
+            tty->n_fds = 2;     /* Disable polling of Slave */
             _notify(tty);
         }
     }
@@ -496,6 +504,8 @@ static void ttynvt_open(fuse_req_t req, struct fuse_file_info *info)
         goto open_err;
     }
 
+    tty->n_fds = 3;             /* Initially poll Net, Master, and Slave */
+
     info->fh = (uintptr_t) tty;
     info->nonseekable = 1;
     info->direct_io = 1;
@@ -552,6 +562,7 @@ ttynvt_read(fuse_req_t req, size_t size, off_t off,
     res =
         _is_interrupted ? -2 : read(tty->fds[FD_SLAVE].fd, tty->tmp_buf, size);
     _is_interrupted = 0;
+    tty->n_fds = 3;             /* Enable polling of Slave */
     fuse_req_interrupt_func(req, NULL, NULL);
     if (res < 0)
     {