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Refactor Pl_RunLength::decode

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Buffer output locally.
Add qpdf_fuzzer test case.
This commit is contained in:
m-holger 2024-08-03 15:34:23 +01:00
parent 5edb548148
commit 3bab4cf394
5 changed files with 12 additions and 8 deletions
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1
fuzz/CMakeLists.txt
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@ -129,6 +129,7 @@ set(CORPUS_OTHER
69977b.fuzz 69977b.fuzz
69977c.fuzz 69977c.fuzz
69977d.fuzz 69977d.fuzz
69977e.fuzz
70055.fuzz 70055.fuzz
70245.fuzz 70245.fuzz
70306.fuzz 70306.fuzz

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fuzz/qpdf_extra/69977e.fuzz Normal file
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2
fuzz/qtest/fuzz.test
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@ -21,7 +21,7 @@ my @fuzzers = (
['pngpredictor' => 1], ['pngpredictor' => 1],
['runlength' => 6], ['runlength' => 6],
['tiffpredictor' => 2], ['tiffpredictor' => 2],
['qpdf' => 74], # increment when adding new files ['qpdf' => 75], # increment when adding new files
); );
my $n_tests = 0; my $n_tests = 0;

1
include/qpdf/Pl_RunLength.hh
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@ -62,6 +62,7 @@ class QPDF_DLL_CLASS Pl_RunLength: public Pipeline
state_e state; state_e state;
unsigned char buf[128]; unsigned char buf[128];
unsigned int length; unsigned int length;
std::string out;
}; };
std::shared_ptr<Members> m; std::shared_ptr<Members> m;

16
libqpdf/Pl_RunLength.cc
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@ -66,8 +66,9 @@ Pl_RunLength::encode(unsigned char const* data, size_t len)
void void
Pl_RunLength::decode(unsigned char const* data, size_t len) Pl_RunLength::decode(unsigned char const* data, size_t len)
{ {
m->out.reserve(len);
for (size_t i = 0; i < len; ++i) { for (size_t i = 0; i < len; ++i) {
unsigned char ch = data[i]; unsigned char const& ch = data[i];
switch (m->state) { switch (m->state) {
case st_top: case st_top:
if (ch < 128) { if (ch < 128) {
@ -85,16 +86,14 @@ Pl_RunLength::decode(unsigned char const* data, size_t len)
break; break;
case st_copying: case st_copying:
this->getNext()->write(&ch, 1); m->out.append(1, static_cast<char>(ch));
if (--m->length == 0) { if (--m->length == 0) {
m->state = st_top; m->state = st_top;
} }
break; break;
case st_run: case st_run:
for (unsigned int j = 0; j < m->length; ++j) { m->out.append(m->length, static_cast<char>(ch));
this->getNext()->write(&ch, 1);
}
m->state = st_top; m->state = st_top;
break; break;
} }
@ -137,10 +136,13 @@ Pl_RunLength::finish()
// When decoding, we might have read a length byte not followed by data, which means the stream // When decoding, we might have read a length byte not followed by data, which means the stream
// was terminated early, but we will just ignore this case since this is the only sensible thing // was terminated early, but we will just ignore this case since this is the only sensible thing
// to do. // to do.
auto next = getNext();
if (m->action == a_encode) { if (m->action == a_encode) {
flush_encode(); flush_encode();
unsigned char ch = 128; unsigned char ch = 128;
this->getNext()->write(&ch, 1); next->write(&ch, 1);
} else {
next->writeString(m->out);
} }
this->getNext()->finish(); next->finish();
} }