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Fix wrong table padding in subsetting

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This commit is contained in:
Laurenz 2022-05-09 00:30:13 +02:00
parent 778aa4e7df
commit a247653cd0
1 changed files with 12 additions and 6 deletions
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18
src/export/subset.rs
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@ -109,7 +109,7 @@ impl<'a> Subsetter<'a> {
for (tag, data) in &mut self.tables { for (tag, data) in &mut self.tables {
if *tag == HEAD { if *tag == HEAD {
// Zero out checksum field in head table. // Zero out checksum field in head table.
data.to_mut()[8 .. 12].copy_from_slice(&[0; 4]); data.to_mut()[8 .. 12].fill(0);
checksum_adjustment_offset = Some(offset + 8); checksum_adjustment_offset = Some(offset + 8);
} }
@ -121,15 +121,20 @@ impl<'a> Subsetter<'a> {
length: len as u32, length: len as u32,
}); });
// Account for the padding to 4 bytes. // Increase offset, plus padding zeros to align to 4 bytes.
offset += len + len % 4; offset += len;
while offset % 4 != 0 {
offset += 1;
}
} }
// Write tables. // Write tables.
for (_, data) in &self.tables { for (_, data) in &self.tables {
// Write data plus padding zeros to align to 4 bytes. // Write data plus padding zeros to align to 4 bytes.
w.extend(data.as_ref()); w.extend(data.as_ref());
w.extend(iter::repeat(0).take(data.len() % 4)); while w.len() % 4 != 0 {
w.push(0);
}
} }
// Write checksumAdjustment field in head table. // Write checksumAdjustment field in head table.
@ -210,8 +215,9 @@ const LOCA: Tag = Tag::from_bytes(b"loca");
const GLYF: Tag = Tag::from_bytes(b"glyf"); const GLYF: Tag = Tag::from_bytes(b"glyf");
const CFF1: Tag = Tag::from_bytes(b"CFF "); const CFF1: Tag = Tag::from_bytes(b"CFF ");
/// Calculate a checksum over the sliced data as sum of u32's. The data length /// Calculate a checksum over the sliced data as a sum of u32s. If the data
/// must be a multiple of four. /// length is not a multiple of four, it is treated as if padded with zero to a
/// length that is a multiple of four.
fn checksum(data: &[u8]) -> u32 { fn checksum(data: &[u8]) -> u32 {
let mut sum = 0u32; let mut sum = 0u32;
for chunk in data.chunks(4) { for chunk in data.chunks(4) {