Re: [Qemu-devel] [PATCH 32/41] qemu-file: add writable socket QEMUFile

[Orit Wasserman]

On 02/15/2013 07:47 PM, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  include/migration/qemu-file.h |    2 +-
>  migration-tcp.c               |    2 +-
>  migration-unix.c              |    2 +-
>  savevm.c                      |   33 +++++++++++++++++++++++++++++++--
>  util/osdep.c                  |    6 +++++-
>  5 files changed, 39 insertions(+), 6 deletions(-)
> 
> diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
> index 987e719..25e8461 100644
> --- a/include/migration/qemu-file.h
> +++ b/include/migration/qemu-file.h
> @@ -76,7 +76,7 @@ typedef struct QEMUFileOps {
>  QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
>  QEMUFile *qemu_fopen(const char *filename, const char *mode);
>  QEMUFile *qemu_fdopen(int fd, const char *mode);
> -QEMUFile *qemu_fopen_socket(int fd);
> +QEMUFile *qemu_fopen_socket(int fd, const char *mode);
>  QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
>  int qemu_get_fd(QEMUFile *f);
>  int qemu_fclose(QEMUFile *f);
> diff --git a/migration-tcp.c b/migration-tcp.c
> index e78a296..7d975b5 100644
> --- a/migration-tcp.c
> +++ b/migration-tcp.c
> @@ -95,7 +95,7 @@ static void tcp_accept_incoming_migration(void *opaque)
>          goto out;
>      }
>  
> -    f = qemu_fopen_socket(c);
> +    f = qemu_fopen_socket(c, "rb");
>      if (f == NULL) {
>          fprintf(stderr, "could not qemu_fopen socket\n");
>          goto out;
> diff --git a/migration-unix.c b/migration-unix.c
> index 218835a..4693b43 100644
> --- a/migration-unix.c
> +++ b/migration-unix.c
> @@ -95,7 +95,7 @@ static void unix_accept_incoming_migration(void *opaque)
>          goto out;
>      }
>  
> -    f = qemu_fopen_socket(c);
> +    f = qemu_fopen_socket(c, "rb");
>      if (f == NULL) {
>          fprintf(stderr, "could not qemu_fopen socket\n");
>          goto out;
> diff --git a/savevm.c b/savevm.c
> index f593acd..b6cf415 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -198,6 +198,18 @@ static int socket_get_buffer(void *opaque, uint8_t *buf, 
> int64_t pos, int size)
>      return len;
>  }
>  
> +static int socket_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, 
> int size)
> +{
> +    QEMUFileSocket *s = opaque;
> +    ssize_t len;
> +
> +    len = qemu_send_full(s->fd, buf, size, 0);
> +    if (len == -1) {
> +        len = -socket_error();
> +    }

We won't always detect partial buffer write here
Why not check len < size? this way you won't need to change qemu_send_full
> +    return len;
> +}
> +
>  static int socket_close(void *opaque)
>  {
>      QEMUFileSocket *s = opaque;
> @@ -369,12 +381,29 @@ static const QEMUFileOps socket_read_ops = {
>      .close =      socket_close
>  };
>  
> -QEMUFile *qemu_fopen_socket(int fd)
> +static const QEMUFileOps socket_write_ops = {
> +    .get_fd =     socket_get_fd,
> +    .put_buffer = socket_put_buffer,
> +    .close =      socket_close
> +};
> +
> +QEMUFile *qemu_fopen_socket(int fd, const char *mode)
>  {
>      QEMUFileSocket *s = g_malloc0(sizeof(QEMUFileSocket));
>  
> +    if (mode == NULL ||
> +     (mode[0] != 'r' && mode[0] != 'w') ||
> +     mode[1] != 'b' || mode[2] != 0) {
> +        fprintf(stderr, "qemu_fopen: Argument validity check failed\n");
> +        return NULL;
> +    }
> +
>      s->fd = fd;
> -    s->file = qemu_fopen_ops(s, &socket_read_ops);
> +    if (mode[0] == 'w') {
> +        s->file = qemu_fopen_ops(s, &socket_write_ops);
> +    } else {
> +        s->file = qemu_fopen_ops(s, &socket_read_ops);
> +    }
>      return s->file;
>  }
>  
> diff --git a/util/osdep.c b/util/osdep.c
> index 5b51a03..be168e5 100644
> --- a/util/osdep.c
> +++ b/util/osdep.c
> @@ -243,8 +243,12 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t 
> count)
>      while (count) {
>          ret = write(fd, buf, count);
>          if (ret < 0) {
> -            if (errno == EINTR)
> +            if (errno == EINTR) {
>                  continue;
> +            }
> +            if (total == 0) {
> +                total = ret;
> +            }

I don't like it, first it only detect the first write failure (if the error 
happens when total !=0
the function won't return -1).
Secondly this behavior is different from the function documentation.

Regards,
Orit
>              break;
>          }
>  
>