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From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Thomas Gummerer <t.gummerer@gmail.com>
Cc: git@vger.kernel.org, Duy Nguyen <pclouds@gmail.com>,
	Junio C Hamano <gitster@pobox.com>,
	Eric Sunshine <sunshine@sunshineco.com>,
	Johannes Sixt <j6t@kdbg.org>
Subject: Re: [PATCH v2 09/14] range-diff: split lines manually
Date: Fri, 5 Jul 2019 21:05:14 +0200 (CEST)	[thread overview]
Message-ID: <nycvar.QRO.7.76.6.1907052052060.44@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <20190705170630.27500-10-t.gummerer@gmail.com>

Hi Thomas,


On Fri, 5 Jul 2019, Thomas Gummerer wrote:

> Currently range-diff uses the 'strbuf_getline()' function for doing
> its line by line processing.  In a future patch we want to do parts of
> that parsing using the 'parse_git_header()' function, which does

If you like my suggestion in patch 7/14, this commit message needs to talk
about the new name, too.

> requires reading parts of the input from that function, which doesn't

s/requires/require/

> use strbufs.
>
> Switch range-diff to do our own line by line parsing, so we can re-use
> the parse_git_header function later.
>
> Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
> ---
>
> Longer term it might be better to have both range-diff and apply code
> use strbufs.  However I didn't feel it's worth making that change for
> this patch series.

Makes sense.

>  range-diff.c | 69 +++++++++++++++++++++++++++++-----------------------
>  1 file changed, 39 insertions(+), 30 deletions(-)
>
> diff --git a/range-diff.c b/range-diff.c
> index 9242b8975f..916afa44c0 100644
> --- a/range-diff.c
> +++ b/range-diff.c
> @@ -24,6 +24,17 @@ struct patch_util {
>  	struct object_id oid;
>  };
>
> +static unsigned long linelen(const char *buffer, unsigned long size)

Shouldn't this be `size_t`?

> +{
> +	unsigned long len = 0;

Likewise.

> +	while (size--) {
> +		len++;
> +		if (*buffer++ == '\n')
> +			break;
> +	}
> +	return len;

How about

	const char *eol = memchr(buffer, '\n', size);

	return !eol ? size : eol + 1 - buffer;

instead?

For an extra brownie point, you could even rename this function to
`find_end_of_line()` and replace the LF by a NUL:

	if (!eol)
		return size;

	*eol = '\0';
	return eol + 1 - buffer;

> +}
> +
>  /*
>   * Reads the patches into a string list, with the `util` field being populated
>   * as struct object_id (will need to be free()d).
> @@ -31,10 +42,12 @@ struct patch_util {
>  static int read_patches(const char *range, struct string_list *list)
>  {
>  	struct child_process cp = CHILD_PROCESS_INIT;
> -	FILE *in;
> -	struct strbuf buf = STRBUF_INIT, line = STRBUF_INIT;
> +	struct strbuf buf = STRBUF_INIT, file = STRBUF_INIT;

This puzzled me. I'd like to suggest s/file/contents/

>  	struct patch_util *util = NULL;
>  	int in_header = 1;
> +	char *line;
> +	int offset, len;
> +	size_t size;
>
>  	argv_array_pushl(&cp.args, "log", "--no-color", "-p", "--no-merges",
>  			"--reverse", "--date-order", "--decorate=no",
> @@ -54,17 +67,15 @@ static int read_patches(const char *range, struct string_list *list)
>
>  	if (start_command(&cp))
>  		return error_errno(_("could not start `log`"));
> -	in = fdopen(cp.out, "r");
> -	if (!in) {
> -		error_errno(_("could not read `log` output"));
> -		finish_command(&cp);
> -		return -1;
> -	}
> +	strbuf_read(&file, cp.out, 0);

Shouldn't we handle a negative return value here, erroring out with "could
not read `log` output" as before?

>
> -	while (strbuf_getline(&line, in) != EOF) {
> +	line = strbuf_detach(&file, &size);

I strongly suspect this to leak, given that `line` is subsequently
advanced, and there is no backup copy.

Maybe

	line = file.buf;
	size = file.len;

would make more sense here?

> +	for (offset = 0; size > 0; offset += len, size -= len, line += len) {
>  		const char *p;
>
> -		if (skip_prefix(line.buf, "commit ", &p)) {
> +		len = linelen(line, size);
> +		line[len - 1] = '\0';
> +		if (skip_prefix(line, "commit ", &p)) {
>  			if (util) {
>  				string_list_append(list, buf.buf)->util = util;
>  				strbuf_reset(&buf);
> @@ -75,8 +86,6 @@ static int read_patches(const char *range, struct string_list *list)
>  				free(util);
>  				string_list_clear(list, 1);
>  				strbuf_release(&buf);
> -				strbuf_release(&line);
> -				fclose(in);

We should release the file contents in `file` (or `contents`, if you like
my suggestions) here.

>  				finish_command(&cp);
>  				return -1;
>  			}
> @@ -85,26 +94,28 @@ static int read_patches(const char *range, struct string_list *list)
>  			continue;
>  		}
>
> -		if (starts_with(line.buf, "diff --git")) {
> +		if (starts_with(line, "diff --git")) {
>  			in_header = 0;
>  			strbuf_addch(&buf, '\n');
>  			if (!util->diff_offset)
>  				util->diff_offset = buf.len;
>  			strbuf_addch(&buf, ' ');
> -			strbuf_addbuf(&buf, &line);
> +			strbuf_addstr(&buf, line);
>  		} else if (in_header) {
> -			if (starts_with(line.buf, "Author: ")) {
> -				strbuf_addbuf(&buf, &line);
> +			if (starts_with(line, "Author: ")) {
> +				strbuf_addstr(&buf, line);
>  				strbuf_addstr(&buf, "\n\n");
> -			} else if (starts_with(line.buf, "    ")) {
> -				strbuf_rtrim(&line);
> -				strbuf_addbuf(&buf, &line);
> +			} else if (starts_with(line, "    ")) {
> +				p = line + len - 2;
> +				while (isspace(*p) && p >= line)
> +					p--;
> +				strbuf_add(&buf, line, p - line + 1);
>  				strbuf_addch(&buf, '\n');
>  			}
>  			continue;
> -		} else if (starts_with(line.buf, "@@ "))
> +		} else if (starts_with(line, "@@ "))
>  			strbuf_addstr(&buf, "@@");
> -		else if (!line.buf[0] || starts_with(line.buf, "index "))
> +		else if (!line[0] || starts_with(line, "index "))
>  			/*
>  			 * A completely blank (not ' \n', which is context)
>  			 * line is not valid in a diff.  We skip it
> @@ -117,25 +128,23 @@ static int read_patches(const char *range, struct string_list *list)
>  			 * we are not interested.
>  			 */
>  			continue;
> -		else if (line.buf[0] == '>') {
> +		else if (line[0] == '>') {
>  			strbuf_addch(&buf, '+');
> -			strbuf_add(&buf, line.buf + 1, line.len - 1);
> -		} else if (line.buf[0] == '<') {
> +			strbuf_addstr(&buf, line + 1);
> +		} else if (line[0] == '<') {
>  			strbuf_addch(&buf, '-');
> -			strbuf_add(&buf, line.buf + 1, line.len - 1);
> -		} else if (line.buf[0] == '#') {
> +			strbuf_addstr(&buf, line + 1);
> +		} else if (line[0] == '#') {
>  			strbuf_addch(&buf, ' ');
> -			strbuf_add(&buf, line.buf + 1, line.len - 1);
> +			strbuf_addstr(&buf, line + 1);
>  		} else {
>  			strbuf_addch(&buf, ' ');
> -			strbuf_addbuf(&buf, &line);
> +			strbuf_addstr(&buf, line);
>  		}
>
>  		strbuf_addch(&buf, '\n');
>  		util->diffsize++;
>  	}
> -	fclose(in);
> -	strbuf_release(&line);

We should release the file contents we previously read via `strbuf_read()` here.

Ciao,
Dscho

>
>  	if (util)
>  		string_list_append(list, buf.buf)->util = util;
> --
> 2.22.0.510.g264f2c817a
>
>

  reply	other threads:[~2019-07-05 19:04 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190414210933.20875-1-t.gummerer@gmail.com/>
2019-07-05 17:06 ` [PATCH v2 00/14] output improvements for git range-diff Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 01/14] apply: replace marc.info link with public-inbox Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 02/14] apply: only pass required data to skip_tree_prefix Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 03/14] apply: only pass required data to git_header_name Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 04/14] apply: only pass required data to check_header_line Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 05/14] apply: only pass required data to find_name_* Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 06/14] apply: only pass required data to gitdiff_* functions Thomas Gummerer
2019-07-05 18:51     ` Johannes Schindelin
2019-07-05 17:06   ` [PATCH v2 07/14] apply: make parse_git_header public Thomas Gummerer
2019-07-05 18:48     ` Johannes Schindelin
2019-07-05 17:06   ` [PATCH v2 08/14] range-diff: fix function parameter indentation Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 09/14] range-diff: split lines manually Thomas Gummerer
2019-07-05 19:05     ` Johannes Schindelin [this message]
2019-07-08 11:24       ` Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 10/14] range-diff: don't remove funcname from inner diff Thomas Gummerer
2019-07-05 19:09     ` Johannes Schindelin
2019-07-05 17:06   ` [PATCH v2 11/14] range-diff: suppress line count in outer diff Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 12/14] range-diff: add section header instead of diff header Thomas Gummerer
2019-07-05 19:35     ` Johannes Schindelin
2019-07-08 11:44       ` Thomas Gummerer
2019-07-08 13:12         ` Johannes Schindelin
2019-07-05 17:06   ` [PATCH v2 13/14] range-diff: add filename to inner diff Thomas Gummerer
2019-07-05 17:06   ` [PATCH v2 14/14] range-diff: add headers to the outer hunk header Thomas Gummerer
2019-07-05 19:48   ` [PATCH v2 00/14] output improvements for git range-diff Johannes Schindelin
2019-07-08 11:45     ` Thomas Gummerer
2019-07-08 16:33   ` [PATCH v3 " Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 01/14] apply: replace marc.info link with public-inbox Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 02/14] apply: only pass required data to skip_tree_prefix Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 03/14] apply: only pass required data to git_header_name Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 04/14] apply: only pass required data to check_header_line Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 05/14] apply: only pass required data to find_name_* Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 06/14] apply: only pass required data to gitdiff_* functions Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 07/14] apply: make parse_git_header public Thomas Gummerer
2019-07-09 19:39       ` Junio C Hamano
2019-07-09 21:23         ` Thomas Gummerer
2019-07-09 23:22           ` Junio C Hamano
2019-07-10  8:48             ` Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 08/14] range-diff: fix function parameter indentation Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 09/14] range-diff: split lines manually Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 10/14] range-diff: don't remove funcname from inner diff Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 11/14] range-diff: suppress line count in outer diff Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 12/14] range-diff: add section header instead of diff header Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 13/14] range-diff: add filename to inner diff Thomas Gummerer
2019-07-08 16:33     ` [PATCH v3 14/14] range-diff: add headers to the outer hunk header Thomas Gummerer
2019-07-11 16:08     ` [PATCH v4 00/14] output improvements for git range-diff Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 01/14] apply: replace marc.info link with public-inbox Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 02/14] apply: only pass required data to skip_tree_prefix Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 03/14] apply: only pass required data to git_header_name Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 04/14] apply: only pass required data to check_header_line Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 05/14] apply: only pass required data to find_name_* Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 06/14] apply: only pass required data to gitdiff_* functions Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 07/14] apply: make parse_git_diff_header public Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 08/14] range-diff: fix function parameter indentation Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 09/14] range-diff: split lines manually Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 10/14] range-diff: don't remove funcname from inner diff Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 11/14] range-diff: suppress line count in outer diff Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 12/14] range-diff: add section header instead of diff header Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 13/14] range-diff: add filename to inner diff Thomas Gummerer
2019-07-11 16:08       ` [PATCH v4 14/14] range-diff: add headers to the outer hunk header Thomas Gummerer
2019-07-11 22:09       ` [PATCH v4 00/14] output improvements for git range-diff Ramsay Jones
2019-07-12 10:44       ` Johannes Schindelin

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