2 files changed, 50 insertions, 33 deletions

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index e60aea85b6..36bf8593f8 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -260,25 +260,35 @@ void qemu_set_block(int fd)
     assert(f != -1);
 }
 
-void qemu_set_nonblock(int fd)
+int qemu_try_set_nonblock(int fd)
 {
     int f;
     f = fcntl(fd, F_GETFL);
-    assert(f != -1);
-    f = fcntl(fd, F_SETFL, f | O_NONBLOCK);
-#ifdef __OpenBSD__
     if (f == -1) {
+        return -errno;
+    }
+    if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) {
+#ifdef __OpenBSD__
         /*
          * Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on
          * memory devices and sets errno to ENODEV.
          * It's OK if we fail to set O_NONBLOCK on devices like /dev/null,
          * because they will never block anyway.
          */
-        assert(errno == ENODEV);
-    }
-#else
-    assert(f != -1);
+        if (errno == ENODEV) {
+            return 0;
+        }
 #endif
+        return -errno;
+    }
+    return 0;
+}
+
+void qemu_set_nonblock(int fd)
+{
+    int f;
+    f = qemu_try_set_nonblock(fd);
+    assert(f == 0);
 }
 
 int socket_set_fast_reuse(int fd)
diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index 3b49d27297..7eedbe5859 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -132,31 +132,6 @@ struct tm *localtime_r(const time_t *timep, struct tm *result)
 }
 #endif /* CONFIG_LOCALTIME_R */
 
-void qemu_set_block(int fd)
-{
-    unsigned long opt = 0;
-    WSAEventSelect(fd, NULL, 0);
-    ioctlsocket(fd, FIONBIO, &opt);
-}
-
-void qemu_set_nonblock(int fd)
-{
-    unsigned long opt = 1;
-    ioctlsocket(fd, FIONBIO, &opt);
-    qemu_fd_register(fd);
-}
-
-int socket_set_fast_reuse(int fd)
-{
-    /* Enabling the reuse of an endpoint that was used by a socket still in
-     * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows
-     * fast reuse is the default and SO_REUSEADDR does strange things. So we
-     * don't have to do anything here. More info can be found at:
-     * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */
-    return 0;
-}
-
-
 static int socket_error(void)
 {
     switch (WSAGetLastError()) {
@@ -233,6 +208,38 @@ static int socket_error(void)
     }
 }
 
+void qemu_set_block(int fd)
+{
+    unsigned long opt = 0;
+    WSAEventSelect(fd, NULL, 0);
+    ioctlsocket(fd, FIONBIO, &opt);
+}
+
+int qemu_try_set_nonblock(int fd)
+{
+    unsigned long opt = 1;
+    if (ioctlsocket(fd, FIONBIO, &opt) != NO_ERROR) {
+        return -socket_error();
+    }
+    qemu_fd_register(fd);
+    return 0;
+}
+
+void qemu_set_nonblock(int fd)
+{
+    (void)qemu_try_set_nonblock(fd);
+}
+
+int socket_set_fast_reuse(int fd)
+{
+    /* Enabling the reuse of an endpoint that was used by a socket still in
+     * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows
+     * fast reuse is the default and SO_REUSEADDR does strange things. So we
+     * don't have to do anything here. More info can be found at:
+     * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */
+    return 0;
+}
+
 int inet_aton(const char *cp, struct in_addr *ia)
 {
     uint32_t addr = inet_addr(cp);