Re: [PATCH] rust: log: implement io::Write

[Zhao Liu <zhao1.liu@intel.com>]

> +/// A RAII guard for QEMU's logging infrastructure.  Creating the guard
> +/// locks the log file, and dropping it (letting it go out of scope) unlocks
> +/// the file.
> +///
> +/// As long as the guard lives, it can be written to using [`std::io::Write`].
> +///
> +/// The locking is recursive, therefore owning a guard does not prevent
> +/// using [`log_mask_ln!()`](crate::log_mask_ln).
> +pub struct LogGuard(NonNull<bindings::FILE>);

Nice! I happen to be implementing a similar RAII for FlatView:

pub struct FlatViewRefGuard(NonNull<FlatView>);

> +impl LogGuard {

...

> +    /// Writes a formatted string into the log, returning any error encountered.
> +    ///
> +    /// This method is primarily used by the [`log_mask_ln!()`](crate::log_mask_ln)
> +    /// macro, and it is rare for it to be called explicitly.
> +    pub fn log_fmt(args: std::fmt::Arguments) -> io::Result<()> {
> +        if let Some(mut log) = Self::new() {
> +            use io::Write;

I think it's better to place this "use" at the beginning of the file.

> +            log.write_fmt(args)?;
> +        }
> +        Ok(())
> +    }
> +}

Overall, LGTM,

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>