Re: [XEN PATCH v2 3/3] libxl: Update the documentation of libxl_xen_console_read_line()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 23/08/2024 6:05 pm, Javi Merino wrote:
> diff --git a/tools/libs/light/libxl_console.c 
> b/tools/libs/light/libxl_console.c
> index f42f6a51ee6f..652897e4ef6d 100644
> --- a/tools/libs/light/libxl_console.c
> +++ b/tools/libs/light/libxl_console.c
> @@ -789,17 +789,19 @@ libxl_xen_console_reader *
>      return cr;
>  }
>  
> -/* return values:                                          *line_r
> - *   1          success, whole line obtained from buffer    non-0
> - *   0          no more lines available right now           0
> - *   negative   error code ERROR_*                          0
> - * On success *line_r is updated to point to a nul-terminated
> +/* Copy part of the console ring into a buffer
> + *
> + * Return values:
> + *   1: Success, the buffer obtained from the console ring an
> + *   0: No more lines available right now
> + *   -ERROR_* on error
> + *
> + * On success, *line_r is updated to point to a nul-terminated

*buff.

Also this really wants to say somewhere "despite the function name,
there can be multiple lines in the returned buffer" or something to this
effect.

>   * string which is valid until the next call on the same console
> - * reader.  The libxl caller may overwrite parts of the string
> - * if it wishes. */
> + * reader. */

While I don't want to derail this patch further, what happens if there
happens to be an embedded \0 in Xen's console?  The hypercall is works
by a count of chars, and AFACIT, in this function we're assuming that
there's no \0 earlier in the string.

~Andrew