3fe9f8e48d
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).
37 lines
1.3 KiB
C++
37 lines
1.3 KiB
C++
/*
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* Copyright (c) 2021-2022, Matthew Olsson <mattco@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibPDF/Document.h>
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#include <LibPDF/ObjectDerivatives.h>
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#include <LibPDF/Page.h>
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namespace PDF {
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PDFErrorOr<ByteBuffer> Page::page_contents(Document& document) const
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{
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// Table 3.27 Entries in a page object on Contents:
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// "If this entry is absent, the page is empty. [...]"
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if (contents.is_null())
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return ByteBuffer {};
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// "The value may be either a single stream or an array of streams. If the value
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// is an array, the effect is as if all the streams in the array were concatenated,
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// in order, to form a single stream. The division between streams may occur only at
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// the boundaries between lexical tokens"
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if (contents->is<StreamObject>())
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return TRY(ByteBuffer::copy(contents->cast<StreamObject>()->bytes()));
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// If one stream ends with (say) a `Q` and the next starts with `q`, that should be
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// two distinct tokens. Insert spaces between stream contents to ensure that.
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ByteBuffer byte_buffer;
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for (auto& ref : *contents->cast<ArrayObject>()) {
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TRY(byte_buffer.try_append(TRY(document.resolve_to<StreamObject>(ref))->bytes()));
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TRY(byte_buffer.try_append(' '));
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}
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return byte_buffer;
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}
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}
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