git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: tboegi@web.de
To: git@vger.kernel.org, alexander.s.m@gmail.com
Cc: "Torsten Bögershausen" <tboegi@web.de>
Subject: [PATCH v2 1/1] diff.c: When appropriate, use utf8_strwidth()
Date: Sat, 27 Aug 2022 10:50:07 +0200	[thread overview]
Message-ID: <20220827085007.20030-1-tboegi@web.de> (raw)
In-Reply-To: <CA+VDVVVmi99i6ZY64tg8RkVXDc5gOzQP_SH12zhDKRkUnhWFgw@mail.gmail.com>

From: Torsten Bögershausen <tboegi@web.de>

When unicode filenames (encoded in UTF-8) are used, the visible width
on the screen is not the same as strlen(filename).

For example, `git log --stat` may produce an output like this:

$ git log --stat

[snip the header]

 Arger.txt  | 1 +
 Ärger.txt | 1 +
 2 files changed, 2 insertions(+)

A side note: the original report was about cyrillic filenames.
After some investigations it turned out that
a) This is not a problem with "ambiguous characters" in unicode
b) The same problem exist for all unicode code points (so we
  can use Latin based Umlauts for demonstrations below)

The 'Ä' takes the same space on the screen as the 'A'.
But needs one more byte in memory, so the the `git log --stat` output
for "Arger.txt" (!) gets mis-aligned:
The maximum length is derived from "Ärger.txt", 10 bytes in memory,
9 positions on the screen. That is why "Arger.txt" gets one extra ' '
for aligment, it needs 9 bytes in memory.
If there was a file "Ö", it would be correctly aligned by chance,
but "Öhö" would not.

The solution is of course, to use utf8_strwidth() instead of strlen()
when dealing with the width on screen.

And then there is another problem: code like this
strbuf_addf(&out, "%-*s", len, name);

(or using the underlying snprintf() function) does not align the
buffer to a minimum of len measured in screen-width, but uses the
memory count, if name is UTF-8 encoded.

We could be tempted to wish that snprintf() was UTF-8 aware.
That doesn't seem to be the case anywhere (tested on Linux and Mac),
probably snprintf() uses the "bytes in memory"/strlen() approach to be
compatible with older versions and this will never change.

The choosen solution is to split code in diff.c like this

strbuf_addf(&out, "%-*s", len, name);

into something like this:

size_t num_padding_spaces = 0;
// [snip]
if (len > utf8_strwidth(name))
    num_padding_spaces = len - utf8_strwidth(name);
strbuf_addf(&out, "%s", name);
if (num_padding_spaces)
    strbuf_addchars(&out, ' ', num_padding_spaces);

Tests:
Two things need to be tested:
- The calculation of the maximum width
- The calculation of num_padding_spaces

The name "textfile" is changed into "textfilë", both have a width of 8.
If strlen() was used, to get the maximum width, the shorter "binfile" would
have been mis-aligned:
 binfile   |  [snip]
 textfilë | [snip]

If only "binfile" would be renamed into "binfilë":
 binfilë |  [snip]
 textfile | [snip]

In order to verify that the width is calculated correctly everywhere,
"binfile" is renamed into "binfïlë", giving 2 bytes more in strlen()
"textfile" is renamed into "textfilë", 1 byte more in strlen(),
and the updated t4012-diff-binary.sh checks the correct aligment:
 binfïlë  | [snip]
 textfilë | [snip]

Reported-by: Alexander Meshcheryakov <alexander.s.m@gmail.com>
Signed-off-by: Torsten Bögershausen <tboegi@web.de>
---
 diff.c                 | 37 +++++++++++++++++++++++--------------
 t/t4012-diff-binary.sh | 14 +++++++-------
 2 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/diff.c b/diff.c
index 974626a621..cf38e1dc88 100644
--- a/diff.c
+++ b/diff.c
@@ -2591,7 +2591,7 @@ void print_stat_summary(FILE *fp, int files,
 static void show_stats(struct diffstat_t *data, struct diff_options *options)
 {
 	int i, len, add, del, adds = 0, dels = 0;
-	uintmax_t max_change = 0, max_len = 0;
+	uintmax_t max_change = 0, max_width = 0;
 	int total_files = data->nr, count;
 	int width, name_width, graph_width, number_width = 0, bin_width = 0;
 	const char *reset, *add_c, *del_c;
@@ -2620,9 +2620,9 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 			continue;
 		}
 		fill_print_name(file);
-		len = strlen(file->print_name);
-		if (max_len < len)
-			max_len = len;
+		len = utf8_strwidth(file->print_name);
+		if (max_width < len)
+			max_width = len;

 		if (file->is_unmerged) {
 			/* "Unmerged" is 8 characters */
@@ -2646,7 +2646,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)

 	/*
 	 * We have width = stat_width or term_columns() columns total.
-	 * We want a maximum of min(max_len, stat_name_width) for the name part.
+	 * We want a maximum of min(max_width, stat_name_width) for the name part.
 	 * We want a maximum of min(max_change, stat_graph_width) for the +- part.
 	 * We also need 1 for " " and 4 + decimal_width(max_change)
 	 * for " | NNNN " and one the empty column at the end, altogether
@@ -2701,8 +2701,8 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		graph_width = options->stat_graph_width;

 	name_width = (options->stat_name_width > 0 &&
-		      options->stat_name_width < max_len) ?
-		options->stat_name_width : max_len;
+		      options->stat_name_width < max_width) ?
+		options->stat_name_width : max_width;

 	/*
 	 * Adjust adjustable widths not to exceed maximum width
@@ -2734,6 +2734,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		char *name = file->print_name;
 		uintmax_t added = file->added;
 		uintmax_t deleted = file->deleted;
+		size_t num_padding_spaces = 0;
 		int name_len;

 		if (!file->is_interesting && (added + deleted == 0))
@@ -2743,7 +2744,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		 * "scale" the filename
 		 */
 		len = name_width;
-		name_len = strlen(name);
+		name_len = utf8_strwidth(name);
 		if (name_width < name_len) {
 			char *slash;
 			prefix = "...";
@@ -2753,10 +2754,14 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 			if (slash)
 				name = slash;
 		}
+		if (len > utf8_strwidth(name))
+			num_padding_spaces = len - utf8_strwidth(name);

 		if (file->is_binary) {
-			strbuf_addf(&out, " %s%-*s |", prefix, len, name);
-			strbuf_addf(&out, " %*s", number_width, "Bin");
+			strbuf_addf(&out, " %s%s ", prefix,  name);
+			if (num_padding_spaces)
+				strbuf_addchars(&out, ' ', num_padding_spaces);
+			strbuf_addf(&out, "| %*s", number_width, "Bin");
 			if (!added && !deleted) {
 				strbuf_addch(&out, '\n');
 				emit_diff_symbol(options, DIFF_SYMBOL_STATS_LINE,
@@ -2776,8 +2781,10 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 			continue;
 		}
 		else if (file->is_unmerged) {
-			strbuf_addf(&out, " %s%-*s |", prefix, len, name);
-			strbuf_addstr(&out, " Unmerged\n");
+			strbuf_addf(&out, " %s%s ", prefix,  name);
+			if (num_padding_spaces)
+				strbuf_addchars(&out, ' ', num_padding_spaces);
+			strbuf_addstr(&out, "| Unmerged\n");
 			emit_diff_symbol(options, DIFF_SYMBOL_STATS_LINE,
 					 out.buf, out.len, 0);
 			strbuf_reset(&out);
@@ -2803,8 +2810,10 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 				add = total - del;
 			}
 		}
-		strbuf_addf(&out, " %s%-*s |", prefix, len, name);
-		strbuf_addf(&out, " %*"PRIuMAX"%s",
+		strbuf_addf(&out, " %s%s ", prefix,  name);
+		if (num_padding_spaces)
+			strbuf_addchars(&out, ' ', num_padding_spaces);
+		strbuf_addf(&out, "| %*"PRIuMAX"%s",
 			number_width, added + deleted,
 			added + deleted ? " " : "");
 		show_graph(&out, '+', add, add_c, reset);
diff --git a/t/t4012-diff-binary.sh b/t/t4012-diff-binary.sh
index c509143c81..2d49de01c8 100755
--- a/t/t4012-diff-binary.sh
+++ b/t/t4012-diff-binary.sh
@@ -113,20 +113,20 @@ test_expect_success 'diff --no-index with binary creation' '
 '

 cat >expect <<EOF
- binfile  |   Bin 0 -> 1026 bytes
- textfile | 10000 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ binfïlë  |   Bin 0 -> 1026 bytes
+ textfilë | 10000 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 EOF

 test_expect_success 'diff --stat with binary files and big change count' '
-	printf "\01\00%1024d" 1 >binfile &&
-	git add binfile &&
+	printf "\01\00%1024d" 1 >binfïlë &&
+	git add binfïlë &&
 	i=0 &&
 	while test $i -lt 10000; do
 		echo $i &&
 		i=$(($i + 1)) || return 1
-	done >textfile &&
-	git add textfile &&
-	git diff --cached --stat binfile textfile >output &&
+	done >textfilë &&
+	git add textfilë &&
+	git -c core.quotepath=false diff --cached --stat binfïlë textfilë >output &&
 	grep " | " output >actual &&
 	test_cmp expect actual
 '
--
2.34.0


  parent reply	other threads:[~2022-08-27  8:50 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-09 13:11 [BUG] Unicode filenames handling in `git log --stat` Alexander Meshcheryakov
2022-08-09 18:20 ` Calvin Wan
2022-08-09 19:03   ` Alexander Meshcheryakov
2022-08-09 21:36     ` Calvin Wan
2022-08-10  5:55   ` Junio C Hamano
2022-08-10  8:40     ` Torsten Bögershausen
2022-08-10  8:56       ` Alexander Meshcheryakov
2022-08-10  9:51         ` Torsten Bögershausen
2022-08-10 11:41           ` Torsten Bögershausen
2022-08-10 15:53       ` Junio C Hamano
2022-08-10 17:35         ` Torsten Bögershausen
2022-08-14 13:35 ` [PATCH/RFC 1/1] diff.c: When appropriate, use utf8_strwidth() tboegi
2022-08-14 23:12   ` Junio C Hamano
2022-08-15  6:34     ` Torsten Bögershausen
2022-08-18 21:00       ` Junio C Hamano
2022-08-27  8:50 ` tboegi [this message]
2022-08-27  8:54   ` [PATCH v2 " Torsten Bögershausen
2022-08-27  9:50     ` Eric Sunshine
2022-08-29 12:04   ` Johannes Schindelin
2022-08-29 17:54     ` Torsten Bögershausen
2022-08-29 18:37       ` Junio C Hamano
2022-09-02  9:47       ` Johannes Schindelin
2022-09-02  4:21 ` [PATCH v3 1/2] diff.c: When appropriate, use utf8_strwidth(), part1 tboegi
2022-09-02  9:39   ` Johannes Schindelin
2022-09-02  4:21 ` [PATCH v3 2/2] diff.c: More changes and tests around utf8_strwidth() tboegi
2022-09-02 10:12   ` Johannes Schindelin
2022-09-03  5:39 ` [PATCH v4 1/2] diff.c: When appropriate, use utf8_strwidth(), part1 tboegi
2022-09-05 20:46   ` Junio C Hamano
2022-09-07  4:30     ` Torsten Bögershausen
2022-09-07 18:31       ` Junio C Hamano
2022-09-03  5:39 ` [PATCH v4 2/2] diff.c: More changes and tests around utf8_strwidth() tboegi
2022-09-05 10:13   ` Johannes Schindelin
2022-09-14 15:13 ` [PATCH v5 1/1] diff.c: When appropriate, use utf8_strwidth() tboegi
2022-09-14 16:40   ` Junio C Hamano
2022-09-26 18:43     ` Torsten Bögershausen
2022-10-10 21:58       ` Junio C Hamano
2022-10-20 15:46         ` Torsten Bögershausen
2022-10-20 17:43           ` Junio C Hamano
2022-10-21 15:19             ` Torsten Bögershausen
2022-10-21 21:59               ` Junio C Hamano
2022-10-23 20:02                 ` Torsten Bögershausen
2022-09-15  2:57   ` Junio C Hamano

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220827085007.20030-1-tboegi@web.de \
    --to=tboegi@web.de \
    --cc=alexander.s.m@gmail.com \
    --cc=git@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).