From: Taylor Blau <me@ttaylorr.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 2/5] t/helper/test-hashmap.c: avoid using `strtok()`
Date: Tue, 18 Apr 2023 14:06:19 -0400 [thread overview]
Message-ID: <ZD7cGx2zKQ2KYnLS@nand.local> (raw)
In-Reply-To: <20230418102320.GB508219@coredump.intra.peff.net>
On Tue, Apr 18, 2023 at 06:23:20AM -0400, Jeff King wrote:
> On Thu, Apr 13, 2023 at 07:31:46PM -0400, Taylor Blau wrote:
>
> > Avoid using the non-reentrant `strtok()` to separate the parts of each
> > incoming command. Instead of replacing it with `strtok_r()`, let's
> > instead use the more friendly `string_list_split_in_place_multi()`.
>
> Junio mentioned this offhand in his response, but I wanted to highlight
> one difference in before/after behavior here.
>
> [before]
> $ printf 'add foo bar\niterate\n' | t/helper/test-tool hashmap
> foo bar
>
> [after]
> $ printf 'add foo bar\niterate\n' | t/helper/test-tool hashmap
> foo bar
>
> I think that's fine for this test script, but it may be an indication
> that we want string-list's split to support different semantics.
I agree that it's OK for the test scripts, but probably isn't the right
thing for all cases. In the reroll I'll send shortly, I reimplemented
this in a way that (a) doesn't change the behavior of
`string_list_split_in_place()`, and (b) allows us to easily change the
semantics for `string_list_split_in_place_multi()`.
> > @@ -159,21 +161,34 @@ int cmd__hashmap(int argc, const char **argv)
> >
> > /* process commands from stdin */
> > while (strbuf_getline(&line, stdin) != EOF) {
> > - char *cmd, *p1 = NULL, *p2 = NULL;
> > + char *cmd, *p1, *p2;
> > unsigned int hash = 0;
> > struct test_entry *entry;
> >
> > + /*
> > + * Because we memdup() the arguments out of the
> > + * string_list before inserting them into the hashmap,
> > + * it's OK to set its length back to zero to avoid
> > + * re-allocating the items array once per line.
> > + *
> > + * By doing so, we'll instead overwrite the existing
> > + * entries and avoid re-allocating.
> > + */
> > + parts.nr = 0;
>
> I think this is OK, but I wonder if we should wrap it in a function that
> makes sure the strings aren't owned by the strdup (and thus aren't being
> leaked). Something like:
>
> void string_list_setlen(struct string_list *sl, size_t nr)
> {
> /* alternatively, I guess we could actually free nr..sl->nr */
> if (sl->strdup_strings)
> BUG("you can't setlen on a string-list which owns its strings");
> if (nr > sl->nr)
> BUG("you can't grow a string-list with setlen");
> sl->nr = nr;
> }
>
> That is probably overkill for these two test helpers, but I wonder if
> the pattern might escape into "real" code (especially if we suggest
> using string-list instead of strtok).
I like this suggestion. I added a new patch (for which you are listed
under Co-authored-by) which adds this function as-is.
Thanks,
Taylor
next prev parent reply other threads:[~2023-04-18 18:06 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-13 23:31 [PATCH 0/5] banned: mark `strok()`, `strtok_r()` as banned Taylor Blau
2023-04-13 23:31 ` [PATCH 1/5] string-list: introduce `string_list_split_in_place_multi()` Taylor Blau
2023-04-18 10:10 ` Jeff King
2023-04-18 17:08 ` Taylor Blau
2023-04-13 23:31 ` [PATCH 2/5] t/helper/test-hashmap.c: avoid using `strtok()` Taylor Blau
2023-04-18 10:23 ` Jeff King
2023-04-18 18:06 ` Taylor Blau [this message]
2023-04-13 23:31 ` [PATCH 3/5] t/helper/test-oidmap.c: " Taylor Blau
2023-04-13 23:31 ` [PATCH 4/5] t/helper/test-json-writer.c: " Taylor Blau
2023-04-13 23:31 ` [PATCH 5/5] banned.h: mark `strtok()`, `strtok_r()` as banned Taylor Blau
2023-04-14 1:39 ` Junio C Hamano
2023-04-14 2:08 ` Chris Torek
2023-04-14 13:41 ` Taylor Blau
2023-04-18 19:18 ` [PATCH v2 0/6] banned: mark `strok()` " Taylor Blau
2023-04-18 19:18 ` [PATCH v2 1/6] string-list: introduce `string_list_split_in_place_multi()` Taylor Blau
2023-04-18 19:39 ` Junio C Hamano
2023-04-18 20:54 ` Taylor Blau
2023-04-22 11:12 ` Jeff King
2023-04-22 15:53 ` René Scharfe
2023-04-23 0:35 ` Jeff King
2023-04-24 16:24 ` Junio C Hamano
2023-04-23 2:38 ` [PATCH v2 1/6] string-list: introduce `string_list_split_in_place_multi()`t Taylor Blau
2023-04-23 2:40 ` Taylor Blau
2023-04-18 19:18 ` [PATCH v2 2/6] string-list: introduce `string_list_setlen()` Taylor Blau
2023-04-22 11:14 ` Jeff King
2023-04-18 19:18 ` [PATCH v2 3/6] t/helper/test-hashmap.c: avoid using `strtok()` Taylor Blau
2023-04-22 11:16 ` Jeff King
2023-04-24 21:19 ` Taylor Blau
2023-04-18 19:18 ` [PATCH v2 4/6] t/helper/test-oidmap.c: " Taylor Blau
2023-04-18 19:18 ` [PATCH v2 5/6] t/helper/test-json-writer.c: " Taylor Blau
2023-04-18 19:18 ` [PATCH v2 6/6] banned.h: mark `strtok()` as banned Taylor Blau
2023-04-24 22:20 ` [PATCH v3 0/6] banned: mark `strok()`, `strtok_r()` " Taylor Blau
2023-04-24 22:20 ` [PATCH v3 1/6] string-list: multi-delimiter `string_list_split_in_place()` Taylor Blau
2023-04-24 22:20 ` [PATCH v3 2/6] string-list: introduce `string_list_setlen()` Taylor Blau
2023-04-25 6:21 ` Jeff King
2023-04-25 21:00 ` Taylor Blau
2023-04-24 22:20 ` [PATCH v3 3/6] t/helper/test-hashmap.c: avoid using `strtok()` Taylor Blau
2023-04-24 22:20 ` [PATCH v3 4/6] t/helper/test-oidmap.c: " Taylor Blau
2023-04-24 22:20 ` [PATCH v3 5/6] t/helper/test-json-writer.c: " Taylor Blau
2023-04-25 13:57 ` Jeff Hostetler
2023-04-24 22:20 ` [PATCH v3 6/6] banned.h: mark `strtok()` and `strtok_r()` as banned Taylor Blau
2023-04-24 22:25 ` Chris Torek
2023-04-24 23:00 ` Taylor Blau
2023-04-25 6:26 ` Jeff King
2023-04-25 21:02 ` Taylor Blau
2023-04-25 6:27 ` [PATCH v3 0/6] banned: mark `strok()`, " Jeff King
2023-04-25 21:03 ` Taylor Blau
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