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utf8: fix returning negative string width

The `utf8_strnwidth()` function calls `utf8_width()` in a loop and adds
its returned width to the end result. `utf8_width()` can return `-1`
though in case it reads a control character, which means that the
computed string width is going to be wrong. In the worst case where
there are more control characters than non-control characters, we may
even return a negative string width.

Fix this bug by treating control characters as having zero width.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt 2022-12-01 15:47:00 +01:00 committed by Junio C Hamano
parent 522cc87fdc
commit 17d23e8a38
2 changed files with 12 additions and 2 deletions

View File

@ -899,6 +899,12 @@ test_expect_success SIZE_T_IS_64BIT 'log --pretty with overflowing wrapping dire
test_cmp expect error
'
test_expect_success 'log --pretty with padding and preceding control chars' '
printf "\20\20 0" >expect &&
git log -1 --pretty="format:%x10%x10%>|(4)%x30" >actual &&
test_cmp expect actual
'
test_expect_success EXPENSIVE,SIZE_T_IS_64BIT 'log --pretty with huge commit message' '
# We only assert that this command does not crash. This needs to be
# executed with the address sanitizer to demonstrate failure.

8
utf8.c
View File

@ -212,11 +212,15 @@ int utf8_strnwidth(const char *string, size_t len, int skip_ansi)
const char *orig = string;
while (string && string < orig + len) {
int skip;
int glyph_width, skip;
while (skip_ansi &&
(skip = display_mode_esc_sequence_len(string)) != 0)
string += skip;
width += utf8_width(&string, NULL);
glyph_width = utf8_width(&string, NULL);
if (glyph_width > 0)
width += glyph_width;
}
return string ? width : len;
}