Re: [Qemu-devel] [PATCH] trace: Fix 'char **' compilation error in simple backend

[Eric Blake]

On 10/25/2016 08:59 PM, Fam Zheng wrote:
> Currently, the generated function body will do "strlen(arg)" but the
> argument could be 'char **'. Avoid that by exclusding such cases in

s/exclusding/excluding/

> is_string check.
> 
> Reported by patchew's "make address@hidden".
> 
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>  scripts/tracetool/backend/simple.py | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/tracetool/backend/simple.py 
> b/scripts/tracetool/backend/simple.py
> index 9885e83..2538795 100644
> --- a/scripts/tracetool/backend/simple.py
> +++ b/scripts/tracetool/backend/simple.py
> @@ -21,7 +21,9 @@ PUBLIC = True
>  
>  def is_string(arg):
>      strtype = ('const char*', 'char*', 'const char *', 'char *')
> -    if arg.lstrip().startswith(strtype):
> +    non_strtype = ('const char**', 'char**', 'const char **', 'char **')
> +    arg_strip = arg.lstrip()
> +    if arg_strip.startswith(strtype) and not 
> arg_strip.startswith(non_strtype):

There may be a more compact way to write it, but I'm not enough of a
python expert to know offhand what else to suggest (it's not as simple
as string concatenation of strtype + '*', since strtype is a tuple
rather than a string).

What you have will fail to detect 'const char *const *' as a non-string
(possible if we have some argv-like function that takes a constant array
of constant strings), but I guess we can worry about that if we actually
try to trace something with that signature.  In the meantime, what you
have solves the immediate failure, so:

Reviewed-by: Eric Blake <address@hidden>

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

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