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Test for direct, rather than resolved nulls in parser 

Just because we know an indirect reference is null, doesn't mean we
shouldn't keep it indirect.
This commit is contained in:
Jay Berkenbilt 2019-08-22 17:53:20 -04:00
parent 3f3dbe22ea
commit 4b2e72c4cd
8 changed files with 259 additions and 10 deletions
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4
ChangeLog
View File

@ -1,5 +1,9 @@
2019-08-22 Jay Berkenbilt <ejb@ql.org>
* Add QPDFObjectHandle::isDirectNull() -- a const method that
allows determining whether an object is a literal null without
attempting to resolve it.
* Stop replacing indirect references to null with literal null in
arrays when writing output with QPDFWriter.

11
include/qpdf/QPDFObjectHandle.hh
View File

@ -281,13 +281,12 @@ class QPDFObjectHandle
QPDF_DLL
bool isReserved();
// True for objects that are direct nulls or have previously been
// resolved to be nulls. Does not attempt to resolve objects. This
// is intended for internal use, but it can be used as an
// efficient way to check for nulls if you don't mind unresolved
// indirect nulls being false negatives.
// True for objects that are direct nulls. Does not attempt to
// resolve objects. This is intended for internal use, but it can
// be used as an efficient way to check for nulls that are not
// indirect objects.
QPDF_DLL
bool isResolvedNull() const;
bool isDirectNull() const;
// This returns true in addition to the query for the specific
// type for indirect objects.

5
libqpdf/QPDFObjectHandle.cc
View File

@ -263,9 +263,10 @@ QPDFObjectHandle::isBool()
}
bool
QPDFObjectHandle::isResolvedNull() const
QPDFObjectHandle::isDirectNull() const
{
return QPDFObjectTypeAccessor<QPDF_Null>::check(m->obj.getPointer());
return (this->m->initialized && (this->m->objid == 0) &&
QPDFObjectTypeAccessor<QPDF_Null>::check(m->obj.getPointer()));
}
bool

4
libqpdf/SparseOHArray.cc
View File

@ -15,7 +15,7 @@ SparseOHArray::size() const
void
SparseOHArray::append(QPDFObjectHandle oh)
{
if (! oh.isResolvedNull())
if (! oh.isDirectNull())
{
this->elements[this->n_elements] = oh;
}
@ -73,7 +73,7 @@ SparseOHArray::setAt(size_t idx, QPDFObjectHandle oh)
{
throw std::logic_error("bounds error setting item in SparseOHArray");
}
if (oh.isResolvedNull())
if (oh.isDirectNull())
{
this->elements.erase(idx);
}

1
qpdf/qtest/qpdf.test
View File

@ -2456,6 +2456,7 @@ my @goodfiles = ("implicit null", # 1
"hybrid xref old mode", # 18
"xref with prev", # 19
"lots of compressible objects", # 20
"array with indirect nulls", # 21
);
$n_tests += (3 * @goodfiles) + 6;

11
qpdf/qtest/qpdf/good21.out Normal file
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@ -0,0 +1,11 @@
/QTest is indirect and has type array (8)
/QTest is an array with 6 items
item 0 is direct
item 1 is direct
item 2 is direct
item 3 is indirect
item 4 is direct
item 5 is indirect
unparse: 9 0 R
unparseResolved: [ /literal null /indirect 8 0 R /undefined 10 0 R ]
test 1 done

106
qpdf/qtest/qpdf/good21.pdf Normal file
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@ -0,0 +1,106 @@
%PDF-1.3
%¿÷¢þ
%QDF-1.0
1 0 obj
<<
/Pages 2 0 R
/Type /Catalog
>>
endobj
2 0 obj
<<
/Count 1
/Kids [
3 0 R
]
/Type /Pages
>>
endobj
%% Page 1
3 0 obj
<<
/Contents 4 0 R
/MediaBox [
0
0
612
792
]
/Parent 2 0 R
/Resources <<
/Font <<
/F1 6 0 R
>>
/ProcSet 7 0 R
>>
/Type /Page
>>
endobj
%% Contents for page 1
4 0 obj
<<
/Length 5 0 R
>>
stream
BT
/F1 24 Tf
72 720 Td
(Potato) Tj
ET
endstream
endobj
5 0 obj
44
endobj
6 0 obj
<<
/BaseFont /Helvetica
/Encoding /WinAnsiEncoding
/Name /F1
/Subtype /Type1
/Type /Font
>>
endobj
7 0 obj
[
/PDF
/Text
]
endobj
8 0 obj
null
endobj
9 0 obj
[ /literal null /indirect 8 0 R /undefined 10 0 R ]
endobj
xref
0 10
0000000000 65535 f
0000000025 00000 n
0000000079 00000 n
0000000161 00000 n
0000000376 00000 n
0000000475 00000 n
0000000494 00000 n
0000000612 00000 n
0000000647 00000 n
0000000668 00000 n
trailer <<
/Root 1 0 R
/Size 10
/QTest 9 0 R
/ID [<06c2c8fc54c5f9cc9246898e1e1a7146><06c2c8fc54c5f9cc9246898e1e1a7146>]
>>
startxref
736
%%EOF

127
qpdf/qtest/qpdf/good21.qdf Normal file
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@ -0,0 +1,127 @@
%PDF-1.3
%¿÷¢þ
%QDF-1.0
%% Original object ID: 1 0
1 0 obj
<<
/Pages 3 0 R
/Type /Catalog
>>
endobj
%% Original object ID: 9 0
2 0 obj
[
/literal
null
/indirect
4 0 R
/undefined
5 0 R
]
endobj
%% Original object ID: 2 0
3 0 obj
<<
/Count 1
/Kids [
6 0 R
]
/Type /Pages
>>
endobj
%% Original object ID: 8 0
4 0 obj
null
endobj
%% Original object ID: 10 0
5 0 obj
null
endobj
%% Page 1
%% Original object ID: 3 0
6 0 obj
<<
/Contents 7 0 R
/MediaBox [
0
0
612
792
]
/Parent 3 0 R
/Resources <<
/Font <<
/F1 9 0 R
>>
/ProcSet 10 0 R
>>
/Type /Page
>>
endobj
%% Contents for page 1
%% Original object ID: 4 0
7 0 obj
<<
/Length 8 0 R
>>
stream
BT
/F1 24 Tf
72 720 Td
(Potato) Tj
ET
endstream
endobj
8 0 obj
44
endobj
%% Original object ID: 6 0
9 0 obj
<<
/BaseFont /Helvetica
/Encoding /WinAnsiEncoding
/Name /F1
/Subtype /Type1
/Type /Font
>>
endobj
%% Original object ID: 7 0
10 0 obj
[
/PDF
/Text
]
endobj
xref
0 11
0000000000 65535 f
0000000052 00000 n
0000000133 00000 n
0000000239 00000 n
0000000338 00000 n
0000000387 00000 n
0000000445 00000 n
0000000688 00000 n
0000000787 00000 n
0000000833 00000 n
0000000978 00000 n
trailer <<
/QTest 2 0 R
/Root 1 0 R
/Size 11
/ID [<06c2c8fc54c5f9cc9246898e1e1a7146><31415926535897932384626433832795>]
>>
startxref
1014
%%EOF