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From: Junio C Hamano <gitster@pobox.com>
To: Luke Shumaker <lukeshu@lukeshu.com>
Cc: git@vger.kernel.org, "Elijah Newren" <newren@gmail.com>,
	"Jeff King" <peff@peff.net>,
	"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
	"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
	"Taylor Blau" <me@ttaylorr.com>,
	"brian m . carlson" <sandals@crustytoothpaste.net>,
	"Eric Sunshine" <sunshine@sunshineco.com>,
	"Luke Shumaker" <lukeshu@datawire.io>
Subject: Re: [PATCH v4 4/5] fast-export: do not modify memory from get_commit_buffer
Date: Mon, 03 May 2021 13:41:00 +0900	[thread overview]
Message-ID: <xmqqa6pca0pv.fsf@gitster.g> (raw)
In-Reply-To: <20210430232537.1131641-5-lukeshu@lukeshu.com> (Luke Shumaker's message of "Fri, 30 Apr 2021 17:25:36 -0600")

Luke Shumaker <lukeshu@lukeshu.com> writes:

> +static char *reencode_message(const char *in_msg,
> +			      const char *in_encoding, size_t in_encoding_len)
> +{
> +	static struct strbuf in_encoding_buf = STRBUF_INIT;
> +
> +	strbuf_reset(&in_encoding_buf);
> +	strbuf_add(&in_encoding_buf, in_encoding, in_encoding_len);
> +
> +	return reencode_string(in_msg, "UTF-8", in_encoding_buf.buf);
> +}

There is only a single caller of this, so making it caller's
responsibility to do the strbuf thing would allow us to make this
thread-safe quite easily (and at that point we might not even have
this helper function).

> +	committer = strstr(commit_buffer_cursor, "\ncommitter ");
>  	if (!committer)
>  		die("could not find committer in commit %s",
>  		    oid_to_hex(&commit->object.oid));
>  	committer++;
> -	committer_end = strchrnul(committer, '\n');
> -	message = strstr(committer_end, "\n\n");
> -	encoding = find_encoding(committer_end, message);
> +	commit_buffer_cursor = committer_end = strchrnul(committer, '\n');
> +
> +	/* find_commit_header() gets a `+ 1` because
> +	 * commit_buffer_cursor points at the trailing "\n" at the end
> +	 * of the previous line, but find_commit_header() wants a
> +	 * pointer to the beginning of the next line. */
> +	encoding = find_commit_header(commit_buffer_cursor + 1, "encoding", &encoding_len);

	/*
	 * Our multi-line comments have opening and closing
	 * slash-asterisk and asterisk-slash on their own
	 * lines.
	 */

What if strchrnul() returned a pointer to the terminating NUL
instead of the LF at the end of the line?  +1 will run past the end
of the buffer.

> +	if (encoding)
> +		commit_buffer_cursor = encoding + encoding_len;
> +
> +	message = strstr(commit_buffer_cursor, "\n\n");

Good.

> @@ -685,14 +693,15 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
>  	} else if (encoding) {
>  		switch(reencode_mode) {
>  		case REENCODE_YES:
> -			reencoded = reencode_string(message, "UTF-8", encoding);
> +			reencoded = reencode_message(message, encoding, encoding_len);
>  			break;

Here is where we can do the temporary strbuf to hold encoding[0,
encoding_len] and directly call reencode_string().

Other than that, this step looks good to me.

Thanks.

  reply	other threads:[~2021-05-03  4:41 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22  0:27 [PATCH v2 0/3] fast-export, fast-import: implement signed-commits Luke Shumaker
2021-04-22  0:27 ` [PATCH v2 1/3] git-fast-import.txt: add missing LF in the BNF Luke Shumaker
2021-04-22  0:27 ` [PATCH v2 2/3] fast-export: rename --signed-tags='warn' to 'warn-verbatim' Luke Shumaker
2021-04-22  3:59   ` Eric Sunshine
2021-04-22  4:43     ` Luke Shumaker
2021-04-22  4:50       ` Luke Shumaker
2021-04-22  0:27 ` [PATCH v2 3/3] fast-export, fast-import: implement signed-commits Luke Shumaker
2021-04-23 16:41 ` [PATCH v3 0/3] " Luke Shumaker
2021-04-23 16:41   ` [PATCH v3 1/3] git-fast-import.txt: add missing LF in the BNF Luke Shumaker
2021-04-23 16:41   ` [PATCH v3 2/3] fast-export: rename --signed-tags='warn' to 'warn-verbatim' Luke Shumaker
2021-04-28  3:29     ` Junio C Hamano
2021-04-29 19:02       ` Luke Shumaker
2021-04-30  0:03         ` Junio C Hamano
2021-04-23 16:41   ` [PATCH v3 3/3] fast-export, fast-import: implement signed-commits Luke Shumaker
2021-04-28  4:02     ` Junio C Hamano
2021-04-29 20:06       ` Luke Shumaker
2021-04-29 22:38         ` Elijah Newren
2021-04-29 23:42           ` Junio C Hamano
2021-04-30  2:23             ` Elijah Newren
2021-04-30  3:20               ` Junio C Hamano
2021-04-30 17:07             ` Luke Shumaker
2021-04-30 19:34       ` Luke Shumaker
2021-04-30 19:59         ` Elijah Newren
2021-04-30 22:21           ` Luke Shumaker
2021-04-30 23:25   ` [PATCH v4 0/5] fast-export, fast-import: add support for signed-commits Luke Shumaker
2021-04-30 23:25     ` [PATCH v4 1/5] git-fast-import.txt: add missing LF in the BNF Luke Shumaker
2021-04-30 23:25     ` [PATCH v4 2/5] fast-export: rename --signed-tags='warn' to 'warn-verbatim' Luke Shumaker
2021-04-30 23:25     ` [PATCH v4 3/5] git-fast-export.txt: clarify why 'verbatim' may not be a good idea Luke Shumaker
2021-04-30 23:25     ` [PATCH v4 4/5] fast-export: do not modify memory from get_commit_buffer Luke Shumaker
2021-05-03  4:41       ` Junio C Hamano [this message]
2021-04-30 23:25     ` [PATCH v4 5/5] fast-export, fast-import: add support for signed-commits Luke Shumaker
2021-05-03  5:09       ` Junio C Hamano

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