[Qemu-devel] [PATCH 5/5] qemu-ga: win32: add isa-serial support

[Luiz Capitulino]

It's implemented by opening the serial port in "non-blocking" mode
and using the GSourceFuncs API in the following way:

 o prepare(): issue a read request. If something has been read, it's
              stored in rs->buf and rs->pending will store the number
                          of bytes read. If there wasn't any bytes available, we
                          set the timeout to 500 ms and return

 o check():   returns true if prepare() was able to read anything,
              otherwise return false

 o finalize(): does nothing

At dispatch() time we simply copy the bytes read to the buffer passed
to ga_channel_read().

Signed-off-by: Luiz Capitulino <address@hidden>
---
 qga/channel-win32.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/qga/channel-win32.c b/qga/channel-win32.c
index c173270..887fe5f 100644
--- a/qga/channel-win32.c
+++ b/qga/channel-win32.c
@@ -179,6 +179,46 @@ static gboolean ga_channel_dispatch_ov(GSource *source, 
GSourceFunc unused,
     return success;
 }
 
+static gboolean ga_channel_prepare(GSource *source, gint *timeout_ms)
+{
+    GAWatch *watch = (GAWatch *)source;
+    GAChannel *c = (GAChannel *)watch->channel;
+    GAChannelReadState *rs = &c->rstate;
+    DWORD count_read = 0;
+    bool success;
+
+    success = ReadFile(c->handle, rs->buf, rs->buf_size, &count_read, NULL);
+    if (success) {
+        if (count_read == 0) {
+            *timeout_ms = 500;
+            return false;
+        }
+        rs->pending = count_read;
+        return true;
+    }
+
+    return false;
+}
+
+static gboolean ga_channel_check(GSource *source)
+{
+    GAWatch *watch = (GAWatch *)source;
+    GAChannel *c = (GAChannel *)watch->channel;
+    GAChannelReadState *rs = &c->rstate;
+
+    return !!rs->pending;
+}
+
+static gboolean ga_channel_dispatch(GSource *source, GSourceFunc unused,
+                                    gpointer user_data)
+{
+    GAWatch *watch = (GAWatch *)source;
+    GAChannel *c = (GAChannel *)watch->channel;
+
+    g_assert(c->cb);
+    return c->cb(0, c->user_data);
+}
+
 static void ga_channel_finalize_ov(GSource *source)
 {
     g_debug("finalize");
@@ -203,6 +243,30 @@ static GSource *ga_channel_create_watch_ov(GAChannel *c)
     return source;
 }
 
+static void ga_channel_finalize(GSource *source)
+{
+    g_debug("finalize");
+}
+
+GSourceFuncs ga_channel_watch_funcs = {
+    ga_channel_prepare,
+    ga_channel_check,
+    ga_channel_dispatch,
+    ga_channel_finalize
+};
+
+static GSource *ga_channel_create_watch(GAChannel *c)
+{
+    GSource *source = g_source_new(&ga_channel_watch_funcs, sizeof(GAWatch));
+    GAWatch *watch = (GAWatch *)source;
+
+    watch->channel = c;
+    watch->pollfd.fd = -1;
+    g_source_add_poll(source, &watch->pollfd);
+
+    return source;
+}
+
 GIOStatus ga_channel_read(GAChannel *c, char *buf, size_t size, gsize *count)
 {
     GAChannelReadState *rs = &c->rstate;
@@ -225,6 +289,12 @@ GIOStatus ga_channel_read(GAChannel *c, char *buf, size_t 
size, gsize *count)
             status = G_IO_STATUS_AGAIN;
         }
         break;
+    case GA_CHANNEL_ISA_SERIAL:
+        memcpy(buf, rs->buf, rs->pending);
+        *count = rs->pending;
+        rs->pending = 0;
+        status = G_IO_STATUS_NORMAL;
+        break;
     default:
         abort(); /* impossible */
     }
@@ -303,6 +373,7 @@ GAChannel *ga_channel_new(GAChannelMethod method, const 
gchar *path,
 {
     GAChannel *c = g_malloc0(sizeof(GAChannel));
     SECURITY_ATTRIBUTES sec_attrs;
+    COMMTIMEOUTS timeouts;
 
     switch (method) {
     case GA_CHANNEL_VIRTIO_SERIAL:
@@ -322,6 +393,22 @@ GAChannel *ga_channel_new(GAChannelMethod method, const 
gchar *path,
 
         c->source = ga_channel_create_watch_ov(c);
         break;
+    case GA_CHANNEL_ISA_SERIAL:
+        if (!ga_channel_open(c, path, 0)) {
+            g_critical("error opening channel (path: %s)", path);
+            goto out_err;
+        }
+
+        /* non-blocking I/O */
+        memset(&timeouts, 0, sizeof(timeouts));
+        timeouts.ReadIntervalTimeout = MAXDWORD;
+        if (!SetCommTimeouts(c->handle, &timeouts)) {
+            CloseHandle(c->handle);
+            goto out_err;
+        }
+
+        c->source = ga_channel_create_watch(c);
+        break;
     default:
         g_critical("unsupported communication method");
         goto out_err;
-- 
1.7.12.315.g682ce8b