0ct0pu5/ladybird
1
0
Fork 0
mirror of https://github.com/LadybirdBrowser/ladybird.git synced 2024-12-04 05:20:30 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 7

LibPDF: Don't accidentally form new tokens on pages with contents arrays

Browse source 
A page's /Contents can be an array of streams, and the page's contents
are then as if those streams are concatenated.

Most of the time, a stream ends with whitespace. But in some cases
(e.g. 0000642.pdf from 0000.zip from the pdfa dataset), the first
stream ends with an operator (`Q`) and the next stream starts with
one (`q`), and the concatenation would form a new, unkonwn operator
(`Qq`). Separate the streams' contents with a space to prevent that.

Reduces numbers of PDF files we fail to open in the -n 500 case
from 11 to 10 (in either case, we then crash on 18 of the PDFs
that we do manage to open).
This commit is contained in:
Nico Weber 2023-10-23 09:28:41 -07:00 committed by Tim Flynn
parent f885839ba5
commit 3fe9f8e48d
Notes: sideshowbarker 2024-07-17 06:00:02 +09:00 
Author: https://github.com/nico
Commit: https://github.com/SerenityOS/serenity/commit/3fe9f8e48d
Pull-request: https://github.com/SerenityOS/serenity/pull/21561
1 changed files with 7 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
Userland/Libraries/LibPDF/Page.cpp
View file

@ -19,13 +19,18 @@ PDFErrorOr<ByteBuffer> Page::page_contents(Document& document) const
// "The value may be either a single stream or an array of streams. If the value
// is an array, the effect is as if all the streams in the array were concatenated,
// in order, to form a single stream."
// in order, to form a single stream. The division between streams may occur only at
// the boundaries between lexical tokens"
if (contents->is<StreamObject>())
return TRY(ByteBuffer::copy(contents->cast<StreamObject>()->bytes()));
// If one stream ends with (say) a `Q` and the next starts with `q`, that should be
// two distinct tokens. Insert spaces between stream contents to ensure that.
ByteBuffer byte_buffer;
for (auto& ref : *contents->cast<ArrayObject>())
for (auto& ref : *contents->cast<ArrayObject>()) {
TRY(byte_buffer.try_append(TRY(document.resolve_to<StreamObject>(ref))->bytes()));
TRY(byte_buffer.try_append(' '));
}
return byte_buffer;
}