Re: [PATCH 2/2] commit: don't check for space twice when looking for header

["René Scharfe" <l.s.r@web.de>]

Am 25.02.2017 um 21:15 schrieb Jeff King:
> On Sat, Feb 25, 2017 at 08:27:40PM +0100, René Scharfe wrote:
>
>> Both standard_header_field() and excluded_header_field() check if
>> there's a space after the buffer that's handed to them.  We already
>> check in the caller if that space is present.  Don't bother calling
>> the functions if it's missing, as they are guaranteed to return 0 in
>> that case, and remove the now redundant checks from them.
>
> Makes sense, and I couldn't spot any errors in your logic or in the
> code.

Thanks for checking!

>>  static inline int standard_header_field(const char *field, size_t len)
>>  {
>> -	return ((len == 4 && !memcmp(field, "tree ", 5)) ||
>> -		(len == 6 && !memcmp(field, "parent ", 7)) ||
>> -		(len == 6 && !memcmp(field, "author ", 7)) ||
>> -		(len == 9 && !memcmp(field, "committer ", 10)) ||
>> -		(len == 8 && !memcmp(field, "encoding ", 9)));
>> +	return ((len == 4 && !memcmp(field, "tree", 4)) ||
>> +		(len == 6 && !memcmp(field, "parent", 6)) ||
>> +		(len == 6 && !memcmp(field, "author", 6)) ||
>> +		(len == 9 && !memcmp(field, "committer", 9)) ||
>> +		(len == 8 && !memcmp(field, "encoding", 8)));
>
> Unrelated, but this could probably be spelled with a macro and strlen()
> to avoid the magic numbers. It would probably be measurably slower for a
> compiler which doesn't pre-compute strlen() on a string literal, though.

sizeof(string_constant) - 1 might be a better choice here than strlen().

René