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