[PULL 4/8] chardev: fix fd_chr_add_watch() when in != out

[marcandre.lureau@redhat.com]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Create child sources for the different streams, and dispatch on the
parent source with the synthesized conditions.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
---
 chardev/char-fd.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 77 insertions(+), 1 deletion(-)

diff --git a/chardev/char-fd.c b/chardev/char-fd.c
index 1cd62f2779..743d3989b4 100644
--- a/chardev/char-fd.c
+++ b/chardev/char-fd.c
@@ -28,6 +28,7 @@
 #include "qemu/sockets.h"
 #include "qapi/error.h"
 #include "chardev/char.h"
+#include "chardev/char-fe.h"
 #include "io/channel-file.h"
 
 #include "chardev/char-fd.h"
@@ -80,10 +81,85 @@ static int fd_chr_read_poll(void *opaque)
     return s->max_size;
 }
 
+typedef struct FDSource {
+    GSource parent;
+
+    GIOCondition cond;
+} FDSource;
+
+static gboolean
+fd_source_prepare(GSource *source,
+                  gint *timeout_)
+{
+    FDSource *src = (FDSource *)source;
+
+    return src->cond != 0;
+}
+
+static gboolean
+fd_source_check(GSource *source)
+{
+    FDSource *src = (FDSource *)source;
+
+    return src->cond != 0;
+}
+
+static gboolean
+fd_source_dispatch(GSource *source, GSourceFunc callback,
+                   gpointer user_data)
+{
+    FDSource *src = (FDSource *)source;
+    FEWatchFunc func = (FEWatchFunc)callback;
+    gboolean ret = G_SOURCE_CONTINUE;
+
+    if (src->cond) {
+        ret = func(NULL, src->cond, user_data);
+        src->cond = 0;
+    }
+
+    return ret;
+}
+
+static GSourceFuncs fd_source_funcs = {
+  fd_source_prepare,
+  fd_source_check,
+  fd_source_dispatch,
+  NULL, NULL, NULL
+};
+
+static GSource *fd_source_new(FDChardev *chr)
+{
+    return g_source_new(&fd_source_funcs, sizeof(FDSource));
+}
+
+static gboolean child_func(GIOChannel *source,
+                           GIOCondition condition,
+                           gpointer data)
+{
+    FDSource *parent = data;
+
+    parent->cond |= condition;
+
+    return G_SOURCE_CONTINUE;
+}
+
 static GSource *fd_chr_add_watch(Chardev *chr, GIOCondition cond)
 {
     FDChardev *s = FD_CHARDEV(chr);
-    return qio_channel_create_watch(s->ioc_out, cond);
+    g_autoptr(GSource) source = fd_source_new(s);
+
+    if (s->ioc_out) {
+        g_autoptr(GSource) child = qio_channel_create_watch(s->ioc_out, cond & ~G_IO_IN);
+        g_source_set_callback(child, (GSourceFunc)child_func, source, NULL);
+        g_source_add_child_source(source, child);
+    }
+    if (s->ioc_in) {
+        g_autoptr(GSource) child = qio_channel_create_watch(s->ioc_in, cond & ~G_IO_OUT);
+        g_source_set_callback(child, (GSourceFunc)child_func, source, NULL);
+        g_source_add_child_source(source, child);
+    }
+
+    return g_steal_pointer(&source);
 }
 
 static void fd_chr_update_read_handler(Chardev *chr)
-- 
2.32.0.264.g75ae10bc75