Johannes Schindelin <Johannes.Schindelin@xxxxxx> writes:
> Hi Michał,
>
> On Mon, 12 Oct 2020, Michał Kępień wrote:
>
>> @@ -5203,6 +5207,22 @@ static int diff_opt_patience(const struct option *opt,
>> return 0;
>> }
>>
>> +static int diff_opt_ignore_regex(const struct option *opt,
>> + const char *arg, int unset)
>> +{
>> + struct diff_options *options = opt->value;
>> + regex_t *regex;
>> +
>> + BUG_ON_OPT_NEG(unset);
>> + regex = xcalloc(1, sizeof(*regex));
>> + if (regcomp(regex, arg, REG_EXTENDED | REG_NEWLINE))
>> + die("invalid regex: %s", arg);
>> + ALLOC_GROW(options->ignore_regex, options->ignore_regex_nr + 1,
>> + options->ignore_regex_alloc);
>> + options->ignore_regex[options->ignore_regex_nr++] = regex;
>
> A slightly more elegant way would be to have `ignore_regex` have the type
> `regex_t *` and use `ALLOC_GROW_BY()` (which zeroes the newly-added
> elements automagically).
It may be "elegant", but we we know if it is "correct" on
everybody's implementation of regex_t?
A struct like
struct foo {
char *str;
char in_place_buffer[10];
};
where str points at in_place_buffer[] only when it needs to point at
a very short string, and points at an allocated memory on heap, can
not be safely copied and used, and an array of such a struct breaks
when ALLOC_GROW_BY() needs to call realloc(). Keeping an array of
pointers to regex_t and growing it would not break even for such a
structure type.
Since we cannot rely on the implementation detail of regex_t on a
single platform, I'd rather not to see anybody suggest such an
"elegant" approach.
Thanks.
