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[cairo] Guard hb_cairo_glyphs_from_buffer() against bad UTF-8

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Previously it was assuming valid UTF-8.
This commit is contained in:
Behdad Esfahbod 2024-11-10 22:43:28 -07:00
parent 6898a6048c
commit 1767f99e2e
2 changed files with 6 additions and 2 deletions
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2
src/hb-cairo.cc
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@ -1000,6 +1000,7 @@ hb_cairo_glyphs_from_buffer (hb_buffer_t *buffer,
end = start + hb_glyph[i].cluster - hb_glyph[i+1].cluster;
else
end = (const char *) hb_utf_offset_to_pointer<hb_utf8_t> ((const uint8_t *) start,
(const uint8_t *) utf8, utf8_len,
(signed) (hb_glyph[i].cluster - hb_glyph[i+1].cluster));
(*clusters)[cluster].num_bytes = end - start;
start = end;
@ -1020,6 +1021,7 @@ hb_cairo_glyphs_from_buffer (hb_buffer_t *buffer,
end = start + hb_glyph[i].cluster - hb_glyph[i-1].cluster;
else
end = (const char *) hb_utf_offset_to_pointer<hb_utf8_t> ((const uint8_t *) start,
(const uint8_t *) utf8, utf8_len,
(signed) (hb_glyph[i].cluster - hb_glyph[i-1].cluster));
(*clusters)[cluster].num_bytes = end - start;
start = end;

6
src/hb-utf.hh
View file

@ -458,19 +458,21 @@ struct hb_ascii_t
template <typename utf_t>
static inline const typename utf_t::codepoint_t *
hb_utf_offset_to_pointer (const typename utf_t::codepoint_t *start,
const typename utf_t::codepoint_t *text,
unsigned text_len,
signed offset)
{
hb_codepoint_t unicode;
while (offset-- > 0)
start = utf_t::next (start,
start + utf_t::max_len,
text + text_len,
&unicode,
HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT);
while (offset++ < 0)
start = utf_t::prev (start,
start - utf_t::max_len,
text,
&unicode,
HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT);