From d4e7fe55c76b9b3544e25b065d702835502d8234 Mon Sep 17 00:00:00 2001
From: Tiago Medicci Serrano <tiago.medicci@gmail.com>
Date: Thu, 27 Apr 2023 16:25:06 -0300
Subject: [PATCH] drivers/pipe: fix blocking file_pipe

Similar to the fix introduced by
4d6a8663fa0932a8c1b40639464f68af670f0808, it's necessary to set
one end of the file_pipe as non-blocking temporarily while opening
the other end to avoid it blocking unexpectedily.
---
 drivers/pipes/pipe.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/pipes/pipe.c b/drivers/pipes/pipe.c
index 5f62473bca..5ff22b044b 100644
--- a/drivers/pipes/pipe.c
+++ b/drivers/pipes/pipe.c
@@ -192,6 +192,7 @@ int file_pipe(FAR struct file *filep[2], size_t bufsize, int flags)
 {
   char devname[32];
   int ret;
+  bool blocking;
 
   /* Register a new pipe device */
 
@@ -201,14 +202,29 @@ int file_pipe(FAR struct file *filep[2], size_t bufsize, int flags)
       return ret;
     }
 
+  /* Check for the O_NONBLOCK bit on flags */
+
+  blocking = (flags & O_NONBLOCK) == 0;
+
   /* Get a write file descriptor */
 
-  ret = file_open(filep[1], devname, O_WRONLY | flags);
+  ret = file_open(filep[1], devname, O_WRONLY | O_NONBLOCK | flags);
   if (ret < 0)
     {
       goto errout_with_driver;
     }
 
+  /* Clear O_NONBLOCK if it was set previously */
+
+  if (blocking)
+    {
+      ret = file_fcntl(filep[1], F_SETFL, flags & (~O_NONBLOCK));
+      if (ret < 0)
+        {
+          goto errout_with_driver;
+        }
+    }
+
   /* Get a read file descriptor */
 
   ret = file_open(filep[0], devname, O_RDONLY | flags);