From 1ded3b11d2eda56f64ec38e09b71214b65ca371a Mon Sep 17 00:00:00 2001
From: Kim Woelders <kw@thrane.eu>
Date: Thu, 4 Oct 2018 09:23:14 +0200
Subject: [PATCH] ICS-664: Fix "cu problem"

In ttynvt_read(), the "interrupted" signal may be delivered after
installing the handler (fuse_req_interrupt_func()) but before calling
read().
If this happens the signal intended to be delivered while in the read()
function call (SIGUSR2) is handled before the read(), and we may hang
indefinitely.
---
 ttynvt.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/ttynvt.c b/ttynvt.c
index 774eb38..57e9b0b 100644
--- a/ttynvt.c
+++ b/ttynvt.c
@@ -99,9 +99,12 @@ _PRF2_ static void _log(int prio, const char *fmt, ...)
 #define DBG2(...) \
     if (ttynvt_param.debug > 1) _log(LOG_DEBUG, __VA_ARGS__)
 
+static volatile char _is_interrupted = 0;
 
 static void sig_handler(int sig)
 {
+    DBG("Interruped, signal = %d\n", sig);
+    _is_interrupted = 1;
 }
 
 static void set_signal_handler(void)
@@ -489,7 +492,9 @@ ttynvt_read(fuse_req_t req, size_t size, off_t off,
         size = TMP_BUF_SIZE;
 
     fuse_req_interrupt_func(req, ttynvt_interrupted, (void *)pthread_self());
-    res = read(tty->fds[FD_SLAVE].fd, tty->tmp_buf, size);
+    res =
+        _is_interrupted ? -2 : read(tty->fds[FD_SLAVE].fd, tty->tmp_buf, size);
+    _is_interrupted = 0;
     fuse_req_interrupt_func(req, NULL, NULL);
     if (res < 0)
     {