[v1,05/22] migration: introduce set_blocking function in QEMUFileOps

Remove the assumption that every QEMUFile implementation has
a file descriptor available by introducing a new function
in QEMUFileOps to change the blocking state of a QEMUFile.

If not set, it will fallback to the original code using
the get_fd method.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 include/migration/qemu-file.h |  5 +++++
 migration/migration.c         |  4 +---
 migration/qemu-file.c         | 10 +++++++---
 3 files changed, 13 insertions(+), 6 deletions(-)

* Daniel P. Berrange (berrange@redhat.com) wrote:
> Remove the assumption that every QEMUFile implementation has
> a file descriptor available by introducing a new function
> in QEMUFileOps to change the blocking state of a QEMUFile.
> 
> If not set, it will fallback to the original code using
> the get_fd method.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  include/migration/qemu-file.h |  5 +++++
>  migration/migration.c         |  4 +---
>  migration/qemu-file.c         | 10 +++++++---
>  3 files changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
> index ddffc6a..072bb38 100644
> --- a/include/migration/qemu-file.h
> +++ b/include/migration/qemu-file.h
> @@ -55,6 +55,10 @@ typedef int (QEMUFileCloseFunc)(void *opaque);
>   */
>  typedef int (QEMUFileGetFD)(void *opaque);
>  
> +/* Called to change the blocking mode of the file
> + */
> +typedef int (QEMUFileSetBlocking)(void *opaque, bool enabled);
> +
>  /*
>   * This function writes an iovec to file. The handler must write all
>   * of the data or return a negative errno value.
> @@ -108,6 +112,7 @@ typedef struct QEMUFileOps {
>      QEMUFileGetBufferFunc *get_buffer;
>      QEMUFileCloseFunc *close;
>      QEMUFileGetFD *get_fd;
> +    QEMUFileSetBlocking *set_blocking;
>      QEMUFileWritevBufferFunc *writev_buffer;
>      QEMURetPathFunc *get_return_path;
>      QEMUFileShutdownFunc *shut_down;
> diff --git a/migration/migration.c b/migration/migration.c
> index c842499..c964a8d 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -408,11 +408,9 @@ static void process_incoming_migration_co(void *opaque)
>  void process_incoming_migration(QEMUFile *f)
>  {
>      Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
> -    int fd = qemu_get_fd(f);
>  
> -    assert(fd != -1);
>      migrate_decompress_threads_create();
> -    qemu_set_nonblock(fd);
> +    qemu_file_set_blocking(f, false);
>      qemu_coroutine_enter(co, f);
>  }
>  
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index 337cb4c..fc5977e 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -683,9 +683,13 @@ size_t qemu_get_counted_string(QEMUFile *f, char buf[256])
>   */
>  void qemu_file_set_blocking(QEMUFile *f, bool block)
>  {
> -    if (block) {
> -        qemu_set_block(qemu_get_fd(f));
> +    if (f->ops->set_blocking) {
> +        f->ops->set_blocking(f->opaque, block);
>      } else {
> -        qemu_set_nonblock(qemu_get_fd(f));
> +        if (block) {
> +            qemu_set_block(qemu_get_fd(f));
> +        } else {
> +            qemu_set_nonblock(qemu_get_fd(f));
> +        }
>      }
>  }
> -- 
> 2.5.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK