RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-14 09:14:58 +00:00
Code Issues Activity Actions

LibPDF: An Encoding's /Differences entry is optional

Browse source 
Per "TABLE 5.11 Entries in an encoding dictionary", /Differences is
optional.

(Per "Encodings for TrueType Fonts" in 5.5.5 Character Encoding,
nonsymbolic truetype fonts are even recommended to have "no Differences
array." But in practice, most seem to have it.)

Fixes crashes on:
* 0000001.pdf
* 0000574.pdf
* 0000337.pdf

All three don't render super great, but at least they no longer crash.
This commit is contained in:
Nico Weber 2024-01-03 19:43:06 -05:00 • committed by Andreas Kling
parent e9dfa61588
commit ad5fc0eda1
1 changed files with 16 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

30
Userland/Libraries/LibPDF/Encoding.cpp
View file

@ -50,22 +50,24 @@ PDFErrorOr<NonnullRefPtr<Encoding>> Encoding::from_object(Document* document, No
encoding->m_descriptors = TRY(base_encoding->m_descriptors.clone());
encoding->m_name_mapping = TRY(base_encoding->m_name_mapping.clone());
auto differences_array = TRY(dict->get_array(document, CommonNames::Differences));
if (dict->contains(CommonNames::Differences)) {
auto differences_array = TRY(dict->get_array(document, CommonNames::Differences));
u16 current_code_point = 0;
bool first = true;
u16 current_code_point = 0;
bool first = true;
for (auto& item : *differences_array) {
if (item.has_u32()) {
current_code_point = item.to_int();
first = false;
} else {
VERIFY(item.has<NonnullRefPtr<Object>>());
VERIFY(!first);
auto& object = item.get<NonnullRefPtr<Object>>();
auto name = object->cast<NameObject>()->name();
encoding->set(current_code_point, name);
current_code_point++;
for (auto& item : *differences_array) {
if (item.has_u32()) {
current_code_point = item.to_int();
first = false;
} else {
VERIFY(item.has<NonnullRefPtr<Object>>());
VERIFY(!first);
auto& object = item.get<NonnullRefPtr<Object>>();
auto name = object->cast<NameObject>()->name();
encoding->set(current_code_point, name);
current_code_point++;
}
}
}