qemu-file: temporarily expose qemu_file_set_error and qemu_fflush

Right now, migration cannot entirely rely on QEMUFile's automatic
drop of I/O after an error, because it does its "real" I/O outside
the put_buffer callback.  To fix this until buffering is gone, expose
qemu_file_set_error which we will use in buffered_flush.

Similarly, buffered_flush is not a complete flush because some data may
still reside in the QEMUFile's own buffer.  This somewhat complicates the
process of closing the migration thread.  Again, when buffering is gone
buffered_flush will disappear and calling qemu_fflush will not be needed;
in the meanwhile, we expose the function for use in migration.c.
Reviewed-by: NOrit Wasserman <owasserm@redhat.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

include/migration/qemu-file.h

@@ -82,6 +82,7 @@ QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
 int qemu_get_fd(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
 int64_t qemu_ftell(QEMUFile *f);
+void qemu_fflush(QEMUFile *f);
 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size);
 void qemu_put_byte(QEMUFile *f, int v);
 
@@ -113,6 +114,7 @@ int qemu_file_rate_limit(QEMUFile *f);
 int64_t qemu_file_set_rate_limit(QEMUFile *f, int64_t new_rate);
 int64_t qemu_file_get_rate_limit(QEMUFile *f);
 int qemu_file_get_error(QEMUFile *f);
+void qemu_file_set_error(QEMUFile *f, int ret);
 
 static inline void qemu_put_be64s(QEMUFile *f, const uint64_t *pv)
 {

savevm.c

@@ -443,7 +443,7 @@ int qemu_file_get_error(QEMUFile *f)
     return f->last_error;
 }
 
-static void qemu_file_set_error(QEMUFile *f, int ret)
+void qemu_file_set_error(QEMUFile *f, int ret)
 {
     if (f->last_error == 0) {
         f->last_error = ret;
@@ -453,7 +453,7 @@ static void qemu_file_set_error(QEMUFile *f, int ret)
 /** Flushes QEMUFile buffer
  *
  */
-static void qemu_fflush(QEMUFile *f)
+void qemu_fflush(QEMUFile *f)
 {
     int ret = 0;