Re: [Qemu-devel] [PATCH] simpletrace: correctly detect pointers to strings

[Fam Zheng <famz@redhat.com>]

On Mon, 10/31 14:25, Paolo Bonzini wrote:
> The visit_type_str tracepoint takes a char**, and the simpletrace backend
> incorrectly treats that as a string.  The resulting compiler warning breaks
> --enable-trace-backend=simple builds (including the mingw docker target).
> Fix it by rejecting pointers to pointers to char; rewrite the detection
> as a regular expression for simplicity.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  scripts/tracetool/backend/simple.py | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/scripts/tracetool/backend/simple.py b/scripts/tracetool/backend/simple.py
> index 9885e83..9dae646 100644
> --- a/scripts/tracetool/backend/simple.py
> +++ b/scripts/tracetool/backend/simple.py
> @@ -14,17 +14,15 @@ __email__      = "stefanha@linux.vnet.ibm.com"
>  
>  
>  from tracetool import out
> +import re
>  
>  
>  PUBLIC = True
> +STRTYPE_RE = re.compile(r'\s*(?:const )?char\s*\*(?!\s*\*)')
>  
>  
>  def is_string(arg):
> -    strtype = ('const char*', 'char*', 'const char *', 'char *')
> -    if arg.lstrip().startswith(strtype):
> -        return True
> -    else:
> -        return False
> +    return not (STRTYPE_RE.match(arg) is None)
>  
>  
>  def generate_h_begin(events, group):
> -- 
> 1.8.3.1
> 
> 

There is already:

commit db4df20de86c6e8ecd6c9f042c029ffb9f9cddac
Author: Fam Zheng <famz@redhat.com>
Date:   Wed Oct 26 11:50:06 2016 +0800

    trace: Fix 'char **' compilation error in simple backend

    Currently, the generated function body will do "strlen(arg)" but the
    argument could be 'char **' or 'char * const *'. Avoid that by excluding
    such cases in is_string check.

    Reported by patchew's "make docker-test-mingw@fedora".

    Suggested-by: Eric Blake <eblake@redhat.com>
    Signed-off-by: Fam Zheng <famz@redhat.com>
    Reviewed-by: Eric Blake <eblake@redhat.com>
    Message-id: 1477453806-21097-1-git-send-email-famz@redhat.com
    Signed-off-by: Peter Maydell <peter.maydell@linaro.org>