qemu-file: Add compression functions to QEMUFile

qemu_put_compression_data() compress the data and put it to QEMUFile.
qemu_put_qemu_file() put the data in the buffer of source QEMUFile to
destination QEMUFile.
Signed-off-by: NLiang Li <liang.z.li@intel.com>
Signed-off-by: NYang Zhang <yang.z.zhang@intel.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

include/migration/qemu-file.h

@@ -159,6 +159,9 @@ void qemu_put_be32(QEMUFile *f, unsigned int v);
 void qemu_put_be64(QEMUFile *f, uint64_t v);
 int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size, size_t offset);
 int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size);
+ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size,
+                                  int level);
+int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src);
 /*
  * Note that you can only peek continuous bytes from where the current pointer
  * is; you aren't guaranteed to be able to peak to +n bytes unless you've

migration/qemu-file.c

@@ -21,6 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+#include <zlib.h>
 #include "qemu-common.h"
 #include "qemu/iov.h"
 #include "qemu/sockets.h"
@@ -546,3 +547,41 @@ uint64_t qemu_get_be64(QEMUFile *f)
     v |= qemu_get_be32(f);
     return v;
 }
+
+/* compress size bytes of data start at p with specific compression
+ * level and store the compressed data to the buffer of f.
+ */
+
+ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size,
+                                  int level)
+{
+    ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t);
+
+    if (blen < compressBound(size)) {
+        return 0;
+    }
+    if (compress2(f->buf + f->buf_index + sizeof(int32_t), (uLongf *)&blen,
+                  (Bytef *)p, size, level) != Z_OK) {
+        error_report("Compress Failed!");
+        return 0;
+    }
+    qemu_put_be32(f, blen);
+    f->buf_index += blen;
+    return blen + sizeof(int32_t);
+}
+
+/* Put the data in the buffer of f_src to the buffer of f_des, and
+ * then reset the buf_index of f_src to 0.
+ */
+
+int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src)
+{
+    int len = 0;
+
+    if (f_src->buf_index > 0) {
+        len = f_src->buf_index;
+        qemu_put_buffer(f_des, f_src->buf, f_src->buf_index);
+        f_src->buf_index = 0;
+    }
+    return len;
+}