Re: [PATCH 01/24] dir.c: optionally compute sha-1 of a .gitignore file

> Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:
>
>> -int add_excludes_from_file_to_list(const char *fname,
>> -                                const char *base,
>> -                                int baselen,
>> -                                struct exclude_list *el,
>> -                                int check_index)
>> +/*
>> + * Given a file with name "fname", read it (either from disk, or from
>> + * the index if "check_index" is non-zero), parse it and store the
>> + * exclude rules in "el".
>> + *
>> + * If "ss" is not NULL, compute SHA-1 of the exclude file and fill
>> + * stat data from disk (only valid if add_excludes returns zero). If
>> + * ss_valid is non-zero, "ss" must contain good value as input.
>> + */
>> +static int add_excludes(const char *fname, const char *base, int baselen,
>> +                     struct exclude_list *el, int check_index,
>> +                     struct sha1_stat *sha1_stat)
>> ...
>> @@ -571,6 +588,21 @@ int add_excludes_from_file_to_list(const char *fname,
>>               }
>>               buf[size++] = '\n';
>>               close(fd);
>> +             if (sha1_stat) {
>> +                     int pos;
>> +                     if (sha1_stat->valid &&
>> +                         !match_stat_data(&sha1_stat->stat, &st))
>> +                             ; /* no content change, ss->sha1 still good */
>> +                     else if (check_index &&
>> +                              (pos = cache_name_pos(fname, strlen(fname))) >= 0 &&
>> +                              !ce_stage(active_cache[pos]) &&
>> +                              ce_uptodate(active_cache[pos]))
>> +                             hashcpy(sha1_stat->sha1, active_cache[pos]->sha1);
>> +                     else
>> +                             hash_sha1_file(buf, size, "blob", sha1_stat->sha1);
>
> I do not think this would work well on DOS.
>
> This helper function originally is meant to work *only* on the
> checked out representation of the file and that is what is read by
> read_in_full(), and that is the reason why it handles the case where
> the contents of buf[] happens to be CRLF terminated in the function.
>
> If you want to detect the content changes across working tree, index
> and the tree objects by reusing hash_sha1_file(), however, you must
> not feed the checked out (aka "smudged") representation to it.
> You'd need to turn it into "cleaned" representation by doing the
> equivalent of calling index_path().  Some helpers in the callchain
> that originates from index_path() might directly be reusable for
> your purpose.