[Qemu-devel] [PATCH FYI 08/46] io: pull Buffer code out of VNC module

["Daniel P. Berrange" <berrange@redhat.com>]

The Buffer code in the VNC server is useful for the IO channel
code, so pull it out into a shared module, QIOBuffer.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 include/io/buffer.h | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 io/Makefile.objs    |   3 +-
 io/buffer.c         |  65 +++++++++++++++++++++++++++++
 ui/vnc-auth-sasl.c  |   4 +-
 ui/vnc-enc-tight.c  |  38 ++++++++---------
 ui/vnc-enc-zlib.c   |   6 +--
 ui/vnc-enc-zrle.c   |  18 ++++----
 ui/vnc-jobs.c       |  15 +++----
 ui/vnc-ws.c         |  36 ++++++++--------
 ui/vnc-ws.h         |   6 +--
 ui/vnc.c            |  67 ++++++-----------------------
 ui/vnc.h            |  50 ++++++++--------------
 12 files changed, 277 insertions(+), 149 deletions(-)
 create mode 100644 include/io/buffer.h
 create mode 100644 io/buffer.c

diff --git a/include/io/buffer.h b/include/io/buffer.h
new file mode 100644
index 0000000..2b1b261
--- /dev/null
+++ b/include/io/buffer.h
@@ -0,0 +1,118 @@
+/*
+ * QEMU I/O buffers
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef QIO_BUFFER_H__
+#define QIO_BUFFER_H__
+
+#include "qemu-common.h"
+
+typedef struct QIOBuffer QIOBuffer;
+
+/**
+ * QIOBuffer:
+ *
+ * The QIOBuffer object provides a simple dynamically resizing
+ * array, with separate tracking of capacity and usage. This
+ * is typically useful when buffering I/O data.
+ */
+
+struct QIOBuffer {
+    size_t capacity;
+    size_t offset;
+    uint8_t *buffer;
+};
+
+/**
+ * qio_buffer_reserve:
+ * @buffer: the buffer object
+ * @len: the minimum required free space
+ *
+ * Ensure that the buffer has space allocated for at least
+ * @len bytes. If the current buffer is too small, it will
+ * be reallocated, possibly to a larger size than requested.
+ */
+void qio_buffer_reserve(QIOBuffer *buffer, size_t len);
+
+/**
+ * qio_buffer_reset:
+ * @buffer: the buffer object
+ *
+ * Reset the length of the stored data to zero, but do
+ * not free / reallocate the memory buffer
+ */
+void qio_buffer_reset(QIOBuffer *buffer);
+
+/**
+ * qio_buffer_free:
+ * @buffer: the buffer object
+ *
+ * Reset the length of the stored data to zero and also
+ * free the internal memory buffer
+ */
+void qio_buffer_free(QIOBuffer *buffer);
+
+/**
+ * qio_buffer_append:
+ * @buffer: the buffer object
+ * @data: the data block to append
+ * @len: the length of @data in bytes
+ *
+ * Append the contents of @data to the end of the buffer.
+ * The caller must ensure that the buffer has sufficient
+ * free space for @len bytes, typically by calling the
+ * qio_buffer_reserve() method prior to appending.
+ */
+void qio_buffer_append(QIOBuffer *buffer, const void *data, size_t len);
+
+/**
+ * qio_buffer_advance:
+ * @buffer: the buffer object
+ * @len: the number of bytes to skip
+ *
+ * Remove @len bytes of data from the head of the buffer.
+ * The internal buffer will not be reallocated, so will
+ * have at least @len bytes of free space after this
+ * call completes
+ */
+void qio_buffer_advance(QIOBuffer *buffer, size_t len);
+
+/**
+ * qio_buffer_end:
+ * @buffer: the buffer object
+ *
+ * Get a pointer to the tail end of the internal buffer
+ * The returned pointer is only valid until the next
+ * call to qio_buffer_reserve().
+ *
+ * Returns: the tail of the buffer
+ */
+uint8_t *qio_buffer_end(QIOBuffer *buffer);
+
+/**
+ * qio_buffer_empty:
+ * @buffer: the buffer object
+ *
+ * Determine if the buffer contains any current data
+ *
+ * Returns: true if the buffer holds data, false otherwise
+ */
+gboolean qio_buffer_empty(QIOBuffer *buffer);
+
+#endif /* QIO_BUFFER_H__ */
diff --git a/io/Makefile.objs b/io/Makefile.objs
index b02ea90..593ed9e 100644
--- a/io/Makefile.objs
+++ b/io/Makefile.objs
@@ -1,2 +1,3 @@
-io-obj-y = channel.o
+io-obj-y = buffer.o
+io-obj-y += channel.o
 io-obj-y += channel-watch.o
diff --git a/io/buffer.c b/io/buffer.c
new file mode 100644
index 0000000..68ae68d
--- /dev/null
+++ b/io/buffer.c
@@ -0,0 +1,65 @@
+/*
+ * QEMU I/O buffers
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "io/buffer.h"
+
+void qio_buffer_reserve(QIOBuffer *buffer, size_t len)
+{
+    if ((buffer->capacity - buffer->offset) < len) {
+        buffer->capacity += (len + 1024);
+        buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
+    }
+}
+
+gboolean qio_buffer_empty(QIOBuffer *buffer)
+{
+    return buffer->offset == 0;
+}
+
+uint8_t *qio_buffer_end(QIOBuffer *buffer)
+{
+    return buffer->buffer + buffer->offset;
+}
+
+void qio_buffer_reset(QIOBuffer *buffer)
+{
+    buffer->offset = 0;
+}
+
+void qio_buffer_free(QIOBuffer *buffer)
+{
+    g_free(buffer->buffer);
+    buffer->offset = 0;
+    buffer->capacity = 0;
+    buffer->buffer = NULL;
+}
+
+void qio_buffer_append(QIOBuffer *buffer, const void *data, size_t len)
+{
+    memcpy(buffer->buffer + buffer->offset, data, len);
+    buffer->offset += len;
+}
+
+void qio_buffer_advance(QIOBuffer *buffer, size_t len)
+{
+    memmove(buffer->buffer, buffer->buffer + len,
+            (buffer->offset - len));
+    buffer->offset -= len;
+}
diff --git a/ui/vnc-auth-sasl.c b/ui/vnc-auth-sasl.c
index fc732bd..d118266 100644
--- a/ui/vnc-auth-sasl.c
+++ b/ui/vnc-auth-sasl.c
@@ -113,8 +113,8 @@ long vnc_client_read_sasl(VncState *vs)
         return vnc_client_io_error(vs, -1, -EIO);
     VNC_DEBUG("Read SASL Encoded %p size %ld Decoded %p size %d\n",
               encoded, ret, decoded, decodedLen);
-    buffer_reserve(&vs->input, decodedLen);
-    buffer_append(&vs->input, decoded, decodedLen);
+    qio_buffer_reserve(&vs->input, decodedLen);
+    qio_buffer_append(&vs->input, decoded, decodedLen);
     return decodedLen;
 }
 
diff --git a/ui/vnc-enc-tight.c b/ui/vnc-enc-tight.c
index 9a9ddf2..772ec79 100644
--- a/ui/vnc-enc-tight.c
+++ b/ui/vnc-enc-tight.c
@@ -856,7 +856,7 @@ static int tight_compress_data(VncState *vs, int stream_id, size_t bytes,
     }
 
     /* reserve memory in output buffer */
-    buffer_reserve(&vs->tight.zlib, bytes + 64);
+    qio_buffer_reserve(&vs->tight.zlib, bytes + 64);
 
     /* set pointers */
     zstream->next_in = vs->tight.tight.buffer;
@@ -879,7 +879,7 @@ static int tight_compress_data(VncState *vs, int stream_id, size_t bytes,
     tight_send_compact_size(vs, bytes);
     vnc_write(vs, vs->tight.zlib.buffer, bytes);
 
-    buffer_reset(&vs->tight.zlib);
+    qio_buffer_reset(&vs->tight.zlib);
 
     return bytes;
 }
@@ -1053,7 +1053,7 @@ static bool send_gradient_rect(VncState *vs, int x, int y, int w, int h)
     vnc_write_u8(vs, (stream | VNC_TIGHT_EXPLICIT_FILTER) << 4);
     vnc_write_u8(vs, VNC_TIGHT_FILTER_GRADIENT);
 
-    buffer_reserve(&vs->tight.gradient, w * 3 * sizeof (int));
+    qio_buffer_reserve(&vs->tight.gradient, w * 3 * sizeof(int));
 
     if (vs->tight.pixel24) {
         tight_filter_gradient24(vs, vs->tight.tight.buffer, w, h);
@@ -1066,7 +1066,7 @@ static bool send_gradient_rect(VncState *vs, int x, int y, int w, int h)
         bytes = 2;
     }
 
-    buffer_reset(&vs->tight.gradient);
+    qio_buffer_reset(&vs->tight.gradient);
 
     bytes = w * h * bytes;
     vs->tight.tight.offset = bytes;
@@ -1149,7 +1149,7 @@ static int send_palette_rect(VncState *vs, int x, int y,
 static void jpeg_init_destination(j_compress_ptr cinfo)
 {
     VncState *vs = cinfo->client_data;
-    Buffer *buffer = &vs->tight.jpeg;
+    QIOBuffer *buffer = &vs->tight.jpeg;
 
     cinfo->dest->next_output_byte = (JOCTET *)buffer->buffer + buffer->offset;
     cinfo->dest->free_in_buffer = (size_t)(buffer->capacity - buffer->offset);
@@ -1159,10 +1159,10 @@ static void jpeg_init_destination(j_compress_ptr cinfo)
 static boolean jpeg_empty_output_buffer(j_compress_ptr cinfo)
 {
     VncState *vs = cinfo->client_data;
-    Buffer *buffer = &vs->tight.jpeg;
+    QIOBuffer *buffer = &vs->tight.jpeg;
 
     buffer->offset = buffer->capacity;
-    buffer_reserve(buffer, 2048);
+    qio_buffer_reserve(buffer, 2048);
     jpeg_init_destination(cinfo);
     return TRUE;
 }
@@ -1171,7 +1171,7 @@ static boolean jpeg_empty_output_buffer(j_compress_ptr cinfo)
 static void jpeg_term_destination(j_compress_ptr cinfo)
 {
     VncState *vs = cinfo->client_data;
-    Buffer *buffer = &vs->tight.jpeg;
+    QIOBuffer *buffer = &vs->tight.jpeg;
 
     buffer->offset = buffer->capacity - cinfo->dest->free_in_buffer;
 }
@@ -1190,7 +1190,7 @@ static int send_jpeg_rect(VncState *vs, int x, int y, int w, int h, int quality)
         return send_full_color_rect(vs, x, y, w, h);
     }
 
-    buffer_reserve(&vs->tight.jpeg, 2048);
+    qio_buffer_reserve(&vs->tight.jpeg, 2048);
 
     cinfo.err = jpeg_std_error(&jerr);
     jpeg_create_compress(&cinfo);
@@ -1227,7 +1227,7 @@ static int send_jpeg_rect(VncState *vs, int x, int y, int w, int h, int quality)
 
     tight_send_compact_size(vs, vs->tight.jpeg.offset);
     vnc_write(vs, vs->tight.jpeg.buffer, vs->tight.jpeg.offset);
-    buffer_reset(&vs->tight.jpeg);
+    qio_buffer_reset(&vs->tight.jpeg);
 
     return 1;
 }
@@ -1270,7 +1270,7 @@ static void png_write_data(png_structp png_ptr, png_bytep data,
 {
     VncState *vs = png_get_io_ptr(png_ptr);
 
-    buffer_reserve(&vs->tight.png, vs->tight.png.offset + length);
+    qio_buffer_reserve(&vs->tight.png, vs->tight.png.offset + length);
     memcpy(vs->tight.png.buffer + vs->tight.png.offset, data, length);
 
     vs->tight.png.offset += length;
@@ -1351,7 +1351,7 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
 
     png_write_info(png_ptr, info_ptr);
 
-    buffer_reserve(&vs->tight.png, 2048);
+    qio_buffer_reserve(&vs->tight.png, 2048);
     linebuf = qemu_pixman_linebuf_create(PIXMAN_BE_r8g8b8, w);
     buf = (uint8_t *)pixman_image_get_data(linebuf);
     for (dy = 0; dy < h; dy++)
@@ -1377,14 +1377,14 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
 
     tight_send_compact_size(vs, vs->tight.png.offset);
     vnc_write(vs, vs->tight.png.buffer, vs->tight.png.offset);
-    buffer_reset(&vs->tight.png);
+    qio_buffer_reset(&vs->tight.png);
     return 1;
 }
 #endif /* CONFIG_VNC_PNG */
 
 static void vnc_tight_start(VncState *vs)
 {
-    buffer_reset(&vs->tight.tight);
+    qio_buffer_reset(&vs->tight.tight);
 
     // make the output buffer be the zlib buffer, so we can compress it later
     vs->tight.tmp = vs->output;
@@ -1686,13 +1686,13 @@ void vnc_tight_clear(VncState *vs)
         }
     }
 
-    buffer_free(&vs->tight.tight);
-    buffer_free(&vs->tight.zlib);
-    buffer_free(&vs->tight.gradient);
+    qio_buffer_free(&vs->tight.tight);
+    qio_buffer_free(&vs->tight.zlib);
+    qio_buffer_free(&vs->tight.gradient);
 #ifdef CONFIG_VNC_JPEG
-    buffer_free(&vs->tight.jpeg);
+    qio_buffer_free(&vs->tight.jpeg);
 #endif
 #ifdef CONFIG_VNC_PNG
-    buffer_free(&vs->tight.png);
+    qio_buffer_free(&vs->tight.png);
 #endif
 }
diff --git a/ui/vnc-enc-zlib.c b/ui/vnc-enc-zlib.c
index d1b97f2..47ba146 100644
--- a/ui/vnc-enc-zlib.c
+++ b/ui/vnc-enc-zlib.c
@@ -47,7 +47,7 @@ void vnc_zlib_zfree(void *x, void *addr)
 
 static void vnc_zlib_start(VncState *vs)
 {
-    buffer_reset(&vs->zlib.zlib);
+    qio_buffer_reset(&vs->zlib.zlib);
 
     // make the output buffer be the zlib buffer, so we can compress it later
     vs->zlib.tmp = vs->output;
@@ -96,7 +96,7 @@ static int vnc_zlib_stop(VncState *vs)
     }
 
     // reserve memory in output buffer
-    buffer_reserve(&vs->output, vs->zlib.zlib.offset + 64);
+    qio_buffer_reserve(&vs->output, vs->zlib.zlib.offset + 64);
 
     // set pointers
     zstream->next_in = vs->zlib.zlib.buffer;
@@ -148,5 +148,5 @@ void vnc_zlib_clear(VncState *vs)
     if (vs->zlib.stream.opaque) {
         deflateEnd(&vs->zlib.stream);
     }
-    buffer_free(&vs->zlib.zlib);
+    qio_buffer_free(&vs->zlib.zlib);
 }
diff --git a/ui/vnc-enc-zrle.c b/ui/vnc-enc-zrle.c
index ed3b484..bd1e320 100644
--- a/ui/vnc-enc-zrle.c
+++ b/ui/vnc-enc-zrle.c
@@ -36,7 +36,7 @@ static const int bits_per_packed_pixel[] = {
 
 static void vnc_zrle_start(VncState *vs)
 {
-    buffer_reset(&vs->zrle.zrle);
+    qio_buffer_reset(&vs->zrle.zrle);
 
     /* make the output buffer be the zlib buffer, so we can compress it later */
     vs->zrle.tmp = vs->output;
@@ -53,10 +53,10 @@ static void vnc_zrle_stop(VncState *vs)
 static void *zrle_convert_fb(VncState *vs, int x, int y, int w, int h,
                              int bpp)
 {
-    Buffer tmp;
+    QIOBuffer tmp;
 
-    buffer_reset(&vs->zrle.fb);
-    buffer_reserve(&vs->zrle.fb, w * h * bpp + bpp);
+    qio_buffer_reset(&vs->zrle.fb);
+    qio_buffer_reserve(&vs->zrle.fb, w * h * bpp + bpp);
 
     tmp = vs->output;
     vs->output = vs->zrle.fb;
@@ -72,7 +72,7 @@ static int zrle_compress_data(VncState *vs, int level)
 {
     z_streamp zstream = &vs->zrle.stream;
 
-    buffer_reset(&vs->zrle.zlib);
+    qio_buffer_reset(&vs->zrle.zlib);
 
     if (zstream->opaque != vs) {
         int err;
@@ -92,7 +92,7 @@ static int zrle_compress_data(VncState *vs, int level)
     }
 
     /* reserve memory in output buffer */
-    buffer_reserve(&vs->zrle.zlib, vs->zrle.zrle.offset + 64);
+    qio_buffer_reserve(&vs->zrle.zlib, vs->zrle.zrle.offset + 64);
 
     /* set pointers */
     zstream->next_in = vs->zrle.zrle.buffer;
@@ -360,7 +360,7 @@ void vnc_zrle_clear(VncState *vs)
     if (vs->zrle.stream.opaque) {
         deflateEnd(&vs->zrle.stream);
     }
-    buffer_free(&vs->zrle.zrle);
-    buffer_free(&vs->zrle.fb);
-    buffer_free(&vs->zrle.zlib);
+    qio_buffer_free(&vs->zrle.zrle);
+    qio_buffer_free(&vs->zrle.fb);
+    qio_buffer_free(&vs->zrle.zlib);
 }
diff --git a/ui/vnc-jobs.c b/ui/vnc-jobs.c
index 22c9abc..9824c34 100644
--- a/ui/vnc-jobs.c
+++ b/ui/vnc-jobs.c
@@ -54,7 +54,7 @@ struct VncJobQueue {
     QemuCond cond;
     QemuMutex mutex;
     QemuThread thread;
-    Buffer buffer;
+    QIOBuffer buffer;
     bool exit;
     QTAILQ_HEAD(, VncJob) jobs;
 };
@@ -167,7 +167,7 @@ void vnc_jobs_consume_buffer(VncState *vs)
     vnc_lock_output(vs);
     if (vs->jobs_buffer.offset) {
         vnc_write(vs, vs->jobs_buffer.buffer, vs->jobs_buffer.offset);
-        buffer_reset(&vs->jobs_buffer);
+        qio_buffer_reset(&vs->jobs_buffer);
     }
     flush = vs->csock != -1 && vs->abort != true;
     vnc_unlock_output(vs);
@@ -196,7 +196,7 @@ static void vnc_async_encoding_start(VncState *orig, VncState *local)
     local->output =  queue->buffer;
     local->csock = -1; /* Don't do any network work on this thread */
 
-    buffer_reset(&local->output);
+    qio_buffer_reset(&local->output);
 }
 
 static void vnc_async_encoding_end(VncState *orig, VncState *local)
@@ -273,10 +273,11 @@ static int vnc_worker_thread_loop(VncJobQueue *queue)
     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
 
     vnc_lock_output(job->vs);
+
     if (job->vs->csock != -1) {
-        buffer_reserve(&job->vs->jobs_buffer, vs.output.offset);
-        buffer_append(&job->vs->jobs_buffer, vs.output.buffer,
-                      vs.output.offset);
+        qio_buffer_reserve(&job->vs->jobs_buffer, vs.output.offset);
+        qio_buffer_append(&job->vs->jobs_buffer, vs.output.buffer,
+                          vs.output.offset);
         /* Copy persistent encoding data */
         vnc_async_encoding_end(job->vs, &vs);
 
@@ -310,7 +311,7 @@ static void vnc_queue_clear(VncJobQueue *q)
 {
     qemu_cond_destroy(&queue->cond);
     qemu_mutex_destroy(&queue->mutex);
-    buffer_free(&queue->buffer);
+    qio_buffer_free(&queue->buffer);
     g_free(q);
     queue = NULL; /* Unset global queue */
 }
diff --git a/ui/vnc-ws.c b/ui/vnc-ws.c
index 175ea50..2fe4476 100644
--- a/ui/vnc-ws.c
+++ b/ui/vnc-ws.c
@@ -95,8 +95,8 @@ void vncws_handshake_read(void *opaque)
     /* Typical HTTP headers from novnc are 512 bytes, so limiting
      * total header size to 4096 is easily enough. */
     size_t want = 4096 - vs->ws_input.offset;
-    buffer_reserve(&vs->ws_input, want);
-    ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), want);
+    qio_buffer_reserve(&vs->ws_input, want);
+    ret = vnc_client_read_buf(vs, qio_buffer_end(&vs->ws_input), want);
 
     if (!ret) {
         if (vs->csock == -1) {
@@ -111,7 +111,7 @@ void vncws_handshake_read(void *opaque)
     if (handshake_end) {
         qemu_set_fd_handler(vs->csock, vnc_client_read, NULL, vs);
         vncws_process_handshake(vs, vs->ws_input.buffer, vs->ws_input.offset);
-        buffer_advance(&vs->ws_input, handshake_end - vs->ws_input.buffer +
+        qio_buffer_advance(&vs->ws_input, handshake_end - vs->ws_input.buffer +
                 strlen(WS_HANDSHAKE_END));
     } else if (vs->ws_input.offset >= 4096) {
         VNC_DEBUG("End of headers not found in first 4096 bytes\n");
@@ -127,8 +127,8 @@ long vnc_client_read_ws(VncState *vs)
     size_t payload_size, header_size;
     VNC_DEBUG("Read websocket %p size %zd offset %zd\n", vs->ws_input.buffer,
             vs->ws_input.capacity, vs->ws_input.offset);
-    buffer_reserve(&vs->ws_input, 4096);
-    ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), 4096);
+    qio_buffer_reserve(&vs->ws_input, 4096);
+    ret = vnc_client_read_buf(vs, qio_buffer_end(&vs->ws_input), 4096);
     if (!ret) {
         return 0;
     }
@@ -146,7 +146,7 @@ long vnc_client_read_ws(VncState *vs)
                 return err;
             }
 
-            buffer_advance(&vs->ws_input, header_size);
+            qio_buffer_advance(&vs->ws_input, header_size);
         }
         if (vs->ws_payload_remain != 0) {
             err = vncws_decode_frame_payload(&vs->ws_input,
@@ -162,10 +162,10 @@ long vnc_client_read_ws(VncState *vs)
             }
             ret += err;
 
-            buffer_reserve(&vs->input, payload_size);
-            buffer_append(&vs->input, payload, payload_size);
+            qio_buffer_reserve(&vs->input, payload_size);
+            qio_buffer_append(&vs->input, payload, payload_size);
 
-            buffer_advance(&vs->ws_input, payload_size);
+            qio_buffer_advance(&vs->ws_input, payload_size);
         }
     } while (vs->ws_input.offset > 0);
 
@@ -178,13 +178,13 @@ long vnc_client_write_ws(VncState *vs)
     VNC_DEBUG("Write WS: Pending output %p size %zd offset %zd\n",
               vs->output.buffer, vs->output.capacity, vs->output.offset);
     vncws_encode_frame(&vs->ws_output, vs->output.buffer, vs->output.offset);
-    buffer_reset(&vs->output);
+    qio_buffer_reset(&vs->output);
     ret = vnc_client_write_buf(vs, vs->ws_output.buffer, vs->ws_output.offset);
     if (!ret) {
         return 0;
     }
 
-    buffer_advance(&vs->ws_output, ret);
+    qio_buffer_advance(&vs->ws_output, ret);
 
     if (vs->ws_output.offset == 0) {
         qemu_set_fd_handler(vs->csock, vnc_client_read, NULL, vs);
@@ -267,8 +267,8 @@ void vncws_process_handshake(VncState *vs, uint8_t *line, size_t size)
     g_free(key);
 }
 
-void vncws_encode_frame(Buffer *output, const void *payload,
-        const size_t payload_size)
+void vncws_encode_frame(QIOBuffer *output, const void *payload,
+                        const size_t payload_size)
 {
     size_t header_size = 0;
     unsigned char opcode = WS_OPCODE_BINARY_FRAME;
@@ -295,12 +295,12 @@ void vncws_encode_frame(Buffer *output, const void *payload,
         header_size = 10;
     }
 
-    buffer_reserve(output, header_size + payload_size);
-    buffer_append(output, header.buf, header_size);
-    buffer_append(output, payload, payload_size);
+    qio_buffer_reserve(output, header_size + payload_size);
+    qio_buffer_append(output, header.buf, header_size);
+    qio_buffer_append(output, payload, payload_size);
 }
 
-int vncws_decode_frame_header(Buffer *input,
+int vncws_decode_frame_header(QIOBuffer *input,
                               size_t *header_size,
                               size_t *payload_remain,
                               WsMask *payload_mask)
@@ -354,7 +354,7 @@ int vncws_decode_frame_header(Buffer *input,
     return 1;
 }
 
-int vncws_decode_frame_payload(Buffer *input,
+int vncws_decode_frame_payload(QIOBuffer *input,
                                size_t *payload_remain, WsMask *payload_mask,
                                uint8_t **payload, size_t *payload_size)
 {
diff --git a/ui/vnc-ws.h b/ui/vnc-ws.h
index 4ab0a8c..2a222a8 100644
--- a/ui/vnc-ws.h
+++ b/ui/vnc-ws.h
@@ -77,13 +77,13 @@ void vncws_handshake_read(void *opaque);
 long vnc_client_write_ws(VncState *vs);
 long vnc_client_read_ws(VncState *vs);
 void vncws_process_handshake(VncState *vs, uint8_t *line, size_t size);
-void vncws_encode_frame(Buffer *output, const void *payload,
+void vncws_encode_frame(QIOBuffer *output, const void *payload,
             const size_t payload_size);
-int vncws_decode_frame_header(Buffer *input,
+int vncws_decode_frame_header(QIOBuffer *input,
                               size_t *header_size,
                               size_t *payload_remain,
                               WsMask *payload_mask);
-int vncws_decode_frame_payload(Buffer *input,
+int vncws_decode_frame_payload(QIOBuffer *input,
                                size_t *payload_remain, WsMask *payload_mask,
                                uint8_t **payload, size_t *payload_size);
 
diff --git a/ui/vnc.c b/ui/vnc.c
index d73966a..3303987 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -647,49 +647,6 @@ void vnc_framebuffer_update(VncState *vs, int x, int y, int w, int h,
     vnc_write_s32(vs, encoding);
 }
 
-void buffer_reserve(Buffer *buffer, size_t len)
-{
-    if ((buffer->capacity - buffer->offset) < len) {
-        buffer->capacity += (len + 1024);
-        buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
-    }
-}
-
-static int buffer_empty(Buffer *buffer)
-{
-    return buffer->offset == 0;
-}
-
-uint8_t *buffer_end(Buffer *buffer)
-{
-    return buffer->buffer + buffer->offset;
-}
-
-void buffer_reset(Buffer *buffer)
-{
-        buffer->offset = 0;
-}
-
-void buffer_free(Buffer *buffer)
-{
-    g_free(buffer->buffer);
-    buffer->offset = 0;
-    buffer->capacity = 0;
-    buffer->buffer = NULL;
-}
-
-void buffer_append(Buffer *buffer, const void *data, size_t len)
-{
-    memcpy(buffer->buffer + buffer->offset, data, len);
-    buffer->offset += len;
-}
-
-void buffer_advance(Buffer *buf, size_t len)
-{
-    memmove(buf->buffer, buf->buffer + len,
-            (buf->offset - len));
-    buf->offset -= len;
-}
 
 static void vnc_desktop_resize(VncState *vs)
 {
@@ -1220,10 +1177,10 @@ void vnc_disconnect_finish(VncState *vs)
     vnc_lock_output(vs);
     vnc_qmp_event(vs, QAPI_EVENT_VNC_DISCONNECTED);
 
-    buffer_free(&vs->input);
-    buffer_free(&vs->output);
-    buffer_free(&vs->ws_input);
-    buffer_free(&vs->ws_output);
+    qio_buffer_free(&vs->input);
+    qio_buffer_free(&vs->output);
+    qio_buffer_free(&vs->ws_input);
+    qio_buffer_free(&vs->ws_output);
 
     qapi_free_VncClientInfo(vs->info);
 
@@ -1251,7 +1208,7 @@ void vnc_disconnect_finish(VncState *vs)
     if (vs->bh != NULL) {
         qemu_bh_delete(vs->bh);
     }
-    buffer_free(&vs->jobs_buffer);
+    qio_buffer_free(&vs->jobs_buffer);
 
     for (i = 0; i < VNC_STAT_ROWS; ++i) {
         g_free(vs->lossy_rect[i]);
@@ -1393,7 +1350,7 @@ static ssize_t vnc_client_write_plain(VncState *vs)
     if (!ret)
         return 0;
 
-    buffer_advance(&vs->output, ret);
+    qio_buffer_advance(&vs->output, ret);
 
     if (vs->output.offset == 0) {
         qemu_set_fd_handler(vs->csock, vnc_client_read, NULL, vs);
@@ -1496,8 +1453,8 @@ static ssize_t vnc_client_read_plain(VncState *vs)
     ssize_t ret;
     VNC_DEBUG("Read plain %p size %zd offset %zd\n",
               vs->input.buffer, vs->input.capacity, vs->input.offset);
-    buffer_reserve(&vs->input, 4096);
-    ret = vnc_client_read_buf(vs, buffer_end(&vs->input), 4096);
+    qio_buffer_reserve(&vs->input, 4096);
+    ret = vnc_client_read_buf(vs, qio_buffer_end(&vs->input), 4096);
     if (!ret)
         return 0;
     vs->input.offset += ret;
@@ -1555,7 +1512,7 @@ void vnc_client_read(void *opaque)
         }
 
         if (!ret) {
-            buffer_advance(&vs->input, len);
+            qio_buffer_advance(&vs->input, len);
         } else {
             vs->read_handler_expect = ret;
         }
@@ -1564,13 +1521,13 @@ void vnc_client_read(void *opaque)
 
 void vnc_write(VncState *vs, const void *data, size_t len)
 {
-    buffer_reserve(&vs->output, len);
+    qio_buffer_reserve(&vs->output, len);
 
-    if (vs->csock != -1 && buffer_empty(&vs->output)) {
+    if (vs->csock != -1 && qio_buffer_empty(&vs->output)) {
         qemu_set_fd_handler(vs->csock, vnc_client_read, vnc_client_write, vs);
     }
 
-    buffer_append(&vs->output, data, len);
+    qio_buffer_append(&vs->output, data, len);
 }
 
 void vnc_write_s32(VncState *vs, int32_t value)
diff --git a/ui/vnc.h b/ui/vnc.h
index 4dd769c..339a1bf 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -34,6 +34,7 @@
 #include "audio/audio.h"
 #include "qemu/bitmap.h"
 #include "crypto/tlssession.h"
+#include "io/buffer.h"
 #include <zlib.h>
 #include <stdbool.h>
 
@@ -56,13 +57,6 @@
  *
  *****************************************************************************/
 
-typedef struct Buffer
-{
-    size_t capacity;
-    size_t offset;
-    uint8_t *buffer;
-} Buffer;
-
 typedef struct VncState VncState;
 typedef struct VncJob VncJob;
 typedef struct VncRect VncRect;
@@ -191,15 +185,15 @@ typedef struct VncTight {
     uint8_t quality;
     uint8_t compression;
     uint8_t pixel24;
-    Buffer tight;
-    Buffer tmp;
-    Buffer zlib;
-    Buffer gradient;
+    QIOBuffer tight;
+    QIOBuffer tmp;
+    QIOBuffer zlib;
+    QIOBuffer gradient;
 #ifdef CONFIG_VNC_JPEG
-    Buffer jpeg;
+    QIOBuffer jpeg;
 #endif
 #ifdef CONFIG_VNC_PNG
-    Buffer png;
+    QIOBuffer png;
 #endif
     int levels[4];
     z_stream stream[4];
@@ -210,18 +204,18 @@ typedef struct VncHextile {
 } VncHextile;
 
 typedef struct VncZlib {
-    Buffer zlib;
-    Buffer tmp;
+    QIOBuffer zlib;
+    QIOBuffer tmp;
     z_stream stream;
     int level;
 } VncZlib;
 
 typedef struct VncZrle {
     int type;
-    Buffer fb;
-    Buffer zrle;
-    Buffer tmp;
-    Buffer zlib;
+    QIOBuffer fb;
+    QIOBuffer zrle;
+    QIOBuffer tmp;
+    QIOBuffer zlib;
     z_stream stream;
     VncPalette palette;
 } VncZrle;
@@ -290,10 +284,10 @@ struct VncState
 
     VncClientInfo *info;
 
-    Buffer output;
-    Buffer input;
-    Buffer ws_input;
-    Buffer ws_output;
+    QIOBuffer output;
+    QIOBuffer input;
+    QIOBuffer ws_input;
+    QIOBuffer ws_output;
     size_t ws_payload_remain;
     WsMask ws_payload_mask;
     /* current output mode information */
@@ -315,7 +309,7 @@ struct VncState
     bool initialized;
     QemuMutex output_mutex;
     QEMUBH *bh;
-    Buffer jobs_buffer;
+    QIOBuffer jobs_buffer;
 
     /* Encoding specific, if you add something here, don't forget to
      *  update vnc_async_encoding_start()
@@ -535,14 +529,6 @@ ssize_t vnc_client_io_error(VncState *vs, ssize_t ret, int last_errno);
 void start_client_init(VncState *vs);
 void start_auth_vnc(VncState *vs);
 
-/* Buffer management */
-void buffer_reserve(Buffer *buffer, size_t len);
-void buffer_reset(Buffer *buffer);
-void buffer_free(Buffer *buffer);
-void buffer_append(Buffer *buffer, const void *data, size_t len);
-void buffer_advance(Buffer *buf, size_t len);
-uint8_t *buffer_end(Buffer *buffer);
-
 
 /* Misc helpers */
 
-- 
2.4.3