[Spice-devel] [PATCH] spice-qemu-char: buffer more data going to spice-server

[Alon Levy]

Remove the assert that forces spice-server to always consume all data. We
already had a buffer, so this just means an extra memmove when that data
is not empty and a second chunk is sent from guest to server.

This should fix BZ 672191, as long as spice chardev is used (and not
device, which is deprecated).

This fixes assert when sending data faster then server can tcp it to the
client (happens when copy pasting a screenshot or large file).

A longer term solution is to use the throttling support in virtio-serial,
to avoid adding yet another buffer.
---
 spice-qemu-char.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/spice-qemu-char.c b/spice-qemu-char.c
index 517f337..8ca4089 100644
--- a/spice-qemu-char.c
+++ b/spice-qemu-char.c
@@ -110,14 +110,16 @@ static int spice_chr_write(CharDriverState *chr, const uint8_t *buf, int len)
 
     dprintf(s, 2, "%s: %d\n", __func__, len);
     vmc_register_interface(s);
-    assert(s->datalen == 0);
-    if (s->bufsize < len) {
-        s->bufsize = len;
+    if (s->datalen > 0) {
+        memmove(s->buffer, s->datapos, s->datalen);
+    }
+    if (s->bufsize < len + s->datalen) {
+        s->bufsize = MAX(s->bufsize, MAX(len*2, len + s->datalen));
         s->buffer = qemu_realloc(s->buffer, s->bufsize);
     }
-    memcpy(s->buffer, buf, len);
+    memcpy(s->buffer + s->datalen, buf, len);
     s->datapos = s->buffer;
-    s->datalen = len;
+    s->datalen += len;
     spice_server_char_device_wakeup(&s->sin);
     return len;
 }
-- 
1.7.4.1