You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
58 lines
2.0 KiB
58 lines
2.0 KiB
From a3b69a0215fdface0fd5730872a4b3242d979dca Mon Sep 17 00:00:00 2001 |
|
From: Uli Schlachter <psychon@znc.in> |
|
Date: Tue, 9 Feb 2021 16:54:35 +0100 |
|
Subject: [PATCH] pdf font subset: Generate valid font names |
|
|
|
A hash value is encoded in base 26 with upper case letters for font |
|
names. |
|
|
|
Commit ed984146 replaced "numerator = abs (hash);" with "numerator = |
|
hash;" in this code, because hash has type uint32_t and the compiler |
|
warned about taking the absolute value of an unsigned value. However, |
|
abs() is actually defined to take an int argument. Thus, there was some |
|
implicit cast. |
|
|
|
Since numerator has type long, i.e. is signed, it is now actually |
|
possible to get an overflow in the implicit cast and then have a |
|
negative number. The following code is not prepared for this and |
|
produces non-letters when encoding the hash. |
|
|
|
This commit fixes that problem by not using ldiv() and instead using / |
|
and % to directly compute the needed values. This gets rid of the need |
|
to convert to type long. Since now everything works with uint32_t, there |
|
is no more chance for negative numbers messing things up. |
|
|
|
Fixes: https://gitlab.freedesktop.org/cairo/cairo/-/issues/449 |
|
Signed-off-by: Uli Schlachter <psychon@znc.in> |
|
--- |
|
src/cairo-pdf-surface.c | 8 ++------ |
|
1 file changed, 2 insertions(+), 6 deletions(-) |
|
|
|
diff --git a/src/cairo-pdf-surface.c b/src/cairo-pdf-surface.c |
|
index 6da460878..52c49b6d2 100644 |
|
--- a/src/cairo-pdf-surface.c |
|
+++ b/src/cairo-pdf-surface.c |
|
@@ -5310,18 +5310,14 @@ _create_font_subset_tag (cairo_scaled_font_subset_t *font_subset, |
|
{ |
|
uint32_t hash; |
|
int i; |
|
- long numerator; |
|
- ldiv_t d; |
|
|
|
hash = _hash_data ((unsigned char *) font_name, strlen(font_name), 0); |
|
hash = _hash_data ((unsigned char *) (font_subset->glyphs), |
|
font_subset->num_glyphs * sizeof(unsigned long), hash); |
|
|
|
- numerator = hash; |
|
for (i = 0; i < 6; i++) { |
|
- d = ldiv (numerator, 26); |
|
- numerator = d.quot; |
|
- tag[i] = 'A' + d.rem; |
|
+ tag[i] = 'A' + (hash % 26); |
|
+ hash /= 26; |
|
} |
|
tag[i] = 0; |
|
} |
|
-- |
|
GitLab |
|
|
|
|