From f8418d68a6263df7ddf6a10b92752b7dfa0e1f37 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 9 Jul 2019 18:47:21 +0530
Subject: [PATCH] Fully drain the wakeupfd

---
 glfw/backend_utils.c  | 10 +++++++++-
 kitty/child-monitor.c |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/glfw/backend_utils.c b/glfw/backend_utils.c
index 59b84c86b..f1ba80612 100644
--- a/glfw/backend_utils.c
+++ b/glfw/backend_utils.c
@@ -224,7 +224,15 @@ dispatchTimers(EventLoopData *eld) {
 static void
 drain_wakeup_fd(int fd, int events UNUSED, void* data UNUSED) {
     static char drain_buf[64];
-    while(read(fd, drain_buf, sizeof(drain_buf)) < 0 && errno == EINTR);
+    while(true) {
+        ssize_t ret = read(fd, drain_buf, sizeof(drain_buf));
+        if (ret < 0) {
+            if (errno == EINTR) continue;
+            break;
+        }
+        if (ret > 0) continue;
+        break;
+    }
 }
 
 bool
diff --git a/kitty/child-monitor.c b/kitty/child-monitor.c
index abccfe7f9..f4f7ef91b 100644
--- a/kitty/child-monitor.c
+++ b/kitty/child-monitor.c
@@ -1057,9 +1057,9 @@ drain_fd(int fd) {
         ssize_t len = read(fd, drain_buf, sizeof(drain_buf));
         if (len < 0) {
             if (errno == EINTR) continue;
-            if (errno != EIO) perror("Call to read() from drain fd failed");
             break;
         }
+        if (len > 0) continue;
         break;
     }
 }