Re: [PATCH] convert: legitimately disable clean/smudge filter with an empty override

> On Sun, Jan 24, 2016 at 01:22:50PM +0100, larsxschneider@gmail.com wrote:
> 
>> From: Lars Schneider <larsxschneider@gmail.com>
>> 
>> A clean/smudge filter can be disabled if set to an empty string. However,
>> Git will try to run the empty string as command which results in a error
>> message per processed file.
>> 
>> Teach Git to consider an empty clean/smudge filter as legitimately disabled
>> and do not print an error message.
> 
> That makes sense to me, as I do not think the empty filter name can
> possibly do anything useful. You omitted the real motivation here, but I
> know what it is from past discussions: you want to be able to
> temporarily disable a filter with "git -c filter.foo.clean= ...". Which
> I think makes it more immediately obvious that this is a useful thing to
> have, and not just user error.
> 
>> diff --git a/convert.c b/convert.c
>> index 814e814..58af965 100644
>> --- a/convert.c
>> +++ b/convert.c
>> @@ -786,7 +786,7 @@ int convert_to_git(const char *path, const char *src, size_t len,
>> 	struct conv_attrs ca;
>> 
>> 	convert_attrs(&ca, path);
>> -	if (ca.drv) {
>> +	if (ca.drv && ca.drv->clean && strlen(ca.drv->clean)) {
>> 		filter = ca.drv->clean;
>> 		required = ca.drv->required;
>> 	}
>> @@ -835,7 +835,7 @@ static int convert_to_working_tree_internal(const char *path, const char *src,
>> 	struct conv_attrs ca;
>> 
>> 	convert_attrs(&ca, path);
>> -	if (ca.drv) {
>> +	if (ca.drv && ca.drv->smudge && strlen(ca.drv->smudge)) {
>> 		filter = ca.drv->smudge;
>> 		required = ca.drv->required;
>> 	}
> 
> This catches two calls, but I think there are others. What about
> would_convert_to_git_filter_fd and convert_to_git_filter_fd?
> 
> Would it make more sense for apply_filter() to treat the empty string as
> a noop, just as it does for NULL?

> 
> I.e.:
> 
> 
> diff --git a/convert.c b/convert.c
> index 814e814..02d5f1e 100644
> --- a/convert.c
> +++ b/convert.c
> @@ -395,7 +395,7 @@ static int apply_filter(const char *path, const char *src, size_t len, int fd,
> 	struct async async;
> 	struct filter_params params;
> 
> -	if (!cmd)
> +	if (!cmd || !*cmd)
> 		return 0;
> 
> 	if (!dst)
> 
> which I think would cover all callers?
> 
> -Peff