Re: [Qemu-devel] [PATCH v3 1/2] qga: flush explicitly when needed

[Eric Blake]

On 11/25/2015 05:59 AM, address@hidden wrote:
> From: Marc-André Lureau <address@hidden>
> 
> According to the specification:
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.html
> 
> "the application shall ensure that output is not directly followed by
> input without an intervening call to fflush() or to a file positioning
> function (fseek(), fsetpos(), or rewind()), and input is not directly
> followed by output without an intervening call to a file positioning
> function, unless the input operation encounters end-of-file."
> 
> Without this change, a write() followed by a read() may lose the
> previously written content, as shown in the following test.
> 
> Fixes:
> https://bugzilla.redhat.com/show_bug.cgi?id=1210246
> ---
>  qga/commands-posix.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)

With Laszlo's suggested commit message improvements,
Reviewed-by: Eric Blake <address@hidden>

> 
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 0ebd473..cf1d7ec 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -216,9 +216,16 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, 
> Error **errp)
>      }
>  }
>  
> +typedef enum {
> +    RW_STATE_NEW,

Bikeshedding: NEW really only sounds right after open(), and doesn't
quite right after a flush; maybe CLEAN or WAITING would be a better name?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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