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From: Jeff King <peff@peff.net>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: Junio C Hamano <gitster@pobox.com>,
	git@vger.kernel.org, David Turner <novalis@novalis.org>
Subject: Re: [PATCH v3 20/23] try_remove_empty_parents(): don't trash argument contents
Date: Sat, 31 Dec 2016 01:40:53 -0500	[thread overview]
Message-ID: <20161231064053.prvlw6x6qprzkmw7@sigill.intra.peff.net> (raw)
In-Reply-To: <6164af2d1f9eeb5bd339b3913e8046c1ea0b02be.1483153436.git.mhagger@alum.mit.edu>

On Sat, Dec 31, 2016 at 04:13:00AM +0100, Michael Haggerty wrote:

> It's bad manners and surprising and therefore error-prone.

Agreed.

I wondered while reading your earlier patch whether the
safe_create_leading_directories() function had the same problem, but it
carefully replaces the NUL it inserts.

> -static void try_remove_empty_parents(char *refname)
> +static void try_remove_empty_parents(const char *refname)
>  {
> +	struct strbuf buf = STRBUF_INIT;
>  	char *p, *q;
>  	int i;
> -	p = refname;
> +
> +	strbuf_addstr(&buf, refname);

I see here you just make a copy. I think it would be enough to do:

> @@ -2305,10 +2306,11 @@ static void try_remove_empty_parents(char *refname)
>  			q--;
>  		if (q == p)
>  			break;
> -		*q = '\0';
> -		if (rmdir(git_path("%s", refname)))
> +		strbuf_setlen(&buf, q - buf.buf);
> +		if (rmdir(git_path("%s", buf.buf)))
>  			break;

  *q = '\0';
  r = rmdir(git_path("%s", refname));
  *q = '/';

  if (r)
          break;

or something. But I doubt the single allocation is breaking the bank,
and it has the nice side effect that callers can pass in a const string
(I didn't check yet whether that enables further cleanups).

-Peff

  reply	other threads:[~2016-12-31  6:41 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-31  3:12 [PATCH v3 00/23] Delete directories left empty after ref deletion Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 01/23] files_rename_ref(): tidy up whitespace Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 02/23] t5505: use "for-each-ref" to test for the non-existence of references Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 03/23] safe_create_leading_directories_const(): preserve errno Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 04/23] safe_create_leading_directories(): set errno on SCLD_EXISTS Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 05/23] raceproof_create_file(): new function Michael Haggerty
2016-12-31  6:11   ` Jeff King
2016-12-31  7:42     ` Michael Haggerty
2017-01-01  2:07       ` Junio C Hamano
2016-12-31  3:12 ` [PATCH v3 06/23] lock_ref_sha1_basic(): inline constant Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 07/23] lock_ref_sha1_basic(): use raceproof_create_file() Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 08/23] rename_tmp_log(): " Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 09/23] rename_tmp_log(): improve error reporting Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 10/23] log_ref_write(): inline function Michael Haggerty
2017-01-01  2:09   ` Junio C Hamano
2017-01-01  8:41     ` Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 11/23] log_ref_setup(): separate code for create vs non-create Michael Haggerty
2016-12-31  6:26   ` Jeff King
2016-12-31  7:52     ` Michael Haggerty
2017-01-01  3:28   ` Junio C Hamano
2017-01-01  8:45     ` Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 12/23] log_ref_setup(): improve robustness against races Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 13/23] log_ref_setup(): pass the open file descriptor back to the caller Michael Haggerty
2016-12-31  6:32   ` Jeff King
2016-12-31  7:58     ` Michael Haggerty
2016-12-31 17:58       ` Jeff King
2017-01-01 10:36         ` Junio C Hamano
2016-12-31  3:12 ` [PATCH v3 14/23] log_ref_write_1(): don't depend on logfile argument Michael Haggerty
2016-12-31  6:35   ` Jeff King
2016-12-31  8:01     ` Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 15/23] log_ref_setup(): manage the name of the reflog file internally Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 16/23] log_ref_write_1(): inline function Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 17/23] delete_ref_loose(): derive loose reference path from lock Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 18/23] delete_ref_loose(): inline function Michael Haggerty
2016-12-31  3:12 ` [PATCH v3 19/23] try_remove_empty_parents(): rename parameter "name" -> "refname" Michael Haggerty
2016-12-31  3:13 ` [PATCH v3 20/23] try_remove_empty_parents(): don't trash argument contents Michael Haggerty
2016-12-31  6:40   ` Jeff King [this message]
2017-01-02 16:27     ` Michael Haggerty
2017-01-02 17:10       ` Jeff King
2016-12-31  3:13 ` [PATCH v3 21/23] try_remove_empty_parents(): don't accommodate consecutive slashes Michael Haggerty
2017-01-01  2:30   ` Junio C Hamano
2017-01-01  5:59     ` Jeff King
2017-01-02 18:06       ` Michael Haggerty
2017-01-02 18:26         ` Jeff King
2016-12-31  3:13 ` [PATCH v3 22/23] try_remove_empty_parents(): teach to remove parents of reflogs, too Michael Haggerty
2016-12-31  3:13 ` [PATCH v3 23/23] files_transaction_commit(): clean up empty directories Michael Haggerty
2016-12-31  6:47 ` [PATCH v3 00/23] Delete directories left empty after ref deletion Jeff King
2017-01-01  2:32   ` Junio C Hamano
2017-01-01  9:24     ` Jacob Keller
2017-01-01  9:26       ` Jacob Keller
2017-01-01 12:43       ` Philip Oakley
2017-01-01 20:36         ` Jacob Keller
2017-01-02  4:19           ` Jeff King
2017-01-02 18:14             ` Michael Haggerty
2017-01-02 18:54               ` Jacob Keller

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