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https://github.com/qpdf/qpdf.git
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245 lines
8.7 KiB
C++
245 lines
8.7 KiB
C++
#include <qpdf/Pl_StdioFile.hh>
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#include <qpdf/QPDF.hh>
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#include <qpdf/QTC.hh>
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#include <qpdf/QUtil.hh>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <iostream>
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static char const* whoami = nullptr;
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void
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usage()
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{
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std::cerr << "Usage: " << whoami << " actual expected" << std::endl
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<< R"(Where "actual" is the actual output and "expected" is the expected)"
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<< std::endl
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<< "output of a test, compare the two PDF files. The files are considered"
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<< std::endl
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<< "to match if all their objects are identical except that, if a stream is"
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<< std::endl
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<< "compressed with FlateDecode, the uncompressed data must match." << std::endl
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<< std::endl
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<< "If the files match, the output is the expected file. Otherwise, it is"
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<< std::endl
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<< "the actual file. Read comments in the code for rationale." << std::endl;
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exit(2);
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}
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void
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cleanEncryption(QPDF& q)
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{
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auto enc = q.getTrailer().getKey("/Encrypt");
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if (!enc.isDictionary()) {
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return;
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}
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enc.removeKey("/O");
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enc.removeKey("/OE");
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enc.removeKey("/U");
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enc.removeKey("/UE");
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enc.removeKey("/Perms");
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}
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std::string
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compareObjects(std::string const& label, QPDFObjectHandle act, QPDFObjectHandle exp)
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{
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if (act.getTypeCode() != exp.getTypeCode()) {
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QTC::TC("compare", "objects with different type");
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return label + ": different types";
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}
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if (act.isStream()) {
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// Disregard stream lengths. The length of stream data is compared later, and we don't care
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// about the length of compressed data as long as the uncompressed data matches.
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auto act_dict = act.getDict();
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auto exp_dict = exp.getDict();
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act_dict.removeKey("/Length");
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exp_dict.removeKey("/Length");
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if (act_dict.unparse() != exp_dict.unparse()) {
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QTC::TC("compare", "different stream dictionaries");
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return label + ": stream dictionaries differ";
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}
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if (act_dict.getKey("/Type").isNameAndEquals("/XRef")) {
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// Cross-reference streams will generally not match, but we have numerous tests that
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// meaningfully ensure that xref streams are correct.
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QTC::TC("compare", "ignore data for xref stream");
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return "";
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}
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auto act_filters = act_dict.getKey("/Filter");
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bool uncompress = false;
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if (act_filters.isName()) {
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act_filters = act_filters.wrapInArray();
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}
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if (act_filters.isArray()) {
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for (auto& filter: act_filters.aitems()) {
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if (filter.isNameAndEquals("/FlateDecode")) {
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uncompress = true;
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break;
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}
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}
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}
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std::shared_ptr<Buffer> act_data;
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std::shared_ptr<Buffer> exp_data;
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if (uncompress) {
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QTC::TC("compare", "uncompressing");
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act_data = act.getStreamData();
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exp_data = exp.getStreamData();
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} else {
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QTC::TC("compare", "not uncompressing");
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act_data = act.getRawStreamData();
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exp_data = exp.getRawStreamData();
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}
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if (act_data->getSize() != exp_data->getSize()) {
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QTC::TC("compare", "differing data size", uncompress ? 0 : 1);
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return label + ": stream data size differs";
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}
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auto act_buf = act_data->getBuffer();
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auto exp_buf = exp_data->getBuffer();
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if (memcmp(act_buf, exp_buf, act_data->getSize()) != 0) {
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QTC::TC("compare", "different data", uncompress ? 0 : 1);
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return label + ": stream data differs";
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}
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} else if (act.unparseResolved() != exp.unparseResolved()) {
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QTC::TC("compare", "different non-stream");
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return label + ": object contents differ";
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}
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return "";
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}
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void
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cleanTrailer(QPDFObjectHandle& trailer)
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{
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// If the trailer is an object stream, it will have /Length.
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trailer.removeKey("/Length");
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// Disregard the second half of /ID. This doesn't have anything directly to do with zlib, but
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// lots of tests use --deterministic-id, and that is affected. The deterministic ID tests
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// meaningfully exercise that deterministic IDs behave as expected, so for the rest of the
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// tests, it's okay to ignore /ID[1]. If the two halves of /ID are the same, ignore both since
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// this means qpdf completely generated the /ID rather than preserving the first half.
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auto id = trailer.getKey("/ID");
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if (id.isArray() && id.getArrayNItems() == 2) {
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auto id0 = id.getArrayItem(0).unparse();
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auto id1 = id.getArrayItem(1).unparse();
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id.setArrayItem(1, "()"_qpdf);
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if (id0 == id1) {
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id.setArrayItem(0, "()"_qpdf);
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}
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}
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}
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std::string
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compare(char const* actual_filename, char const* expected_filename, char const* password)
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{
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QPDF actual;
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actual.processFile(actual_filename, password);
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QPDF expected;
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expected.processFile(expected_filename, password);
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// The motivation behind this program is to compare files in a way that allows for
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// differences in the exact bytes of zlib compression. If all zlib implementations produced
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// exactly the same output, we would just be able to use straight comparison, but since they
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// don't, we use this. As such, we are enforcing a standard of "sameness" that goes beyond
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// showing semantic equivalence. The only difference we are allowing is compressed data.
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auto act_trailer = actual.getTrailer();
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auto exp_trailer = expected.getTrailer();
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cleanTrailer(act_trailer);
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cleanTrailer(exp_trailer);
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auto trailer_diff = compareObjects("trailer", act_trailer, exp_trailer);
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if (!trailer_diff.empty()) {
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QTC::TC("compare", "different trailer");
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return trailer_diff;
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}
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cleanEncryption(actual);
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cleanEncryption(expected);
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auto actual_objects = actual.getAllObjects();
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auto expected_objects = expected.getAllObjects();
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if (actual_objects.size() != expected_objects.size()) {
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// Not exercised in the test suite since the trailers will differ in this case.
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return "different number of objects";
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}
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for (size_t i = 0; i < actual_objects.size(); ++i) {
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auto act = actual_objects[i];
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auto exp = expected_objects[i];
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auto act_og = act.getObjGen();
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auto exp_og = exp.getObjGen();
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if (act_og != exp_og) {
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// not reproduced in the test suite
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return "different object IDs";
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}
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auto ret = compareObjects(act_og.unparse(), act, exp);
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if (!ret.empty()) {
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return ret;
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}
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}
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return "";
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}
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int
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main(int argc, char* argv[])
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{
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if ((whoami = strrchr(argv[0], '/')) == nullptr) {
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whoami = argv[0];
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} else {
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++whoami;
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}
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if ((argc == 2) && (strcmp(argv[1], "--version") == 0)) {
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std::cout << whoami << " from qpdf version " << QPDF::QPDFVersion() << std::endl;
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exit(0);
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}
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if (argc < 3 || argc > 4) {
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usage();
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}
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bool show_why = QUtil::get_env("QPDF_COMPARE_WHY");
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try {
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char const* to_output;
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char const* actual = argv[1];
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char const* expected = argv[2];
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char const* password{nullptr};
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if (argc == 4) {
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password = argv[3];
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}
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auto difference = compare(actual, expected, password);
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if (difference.empty()) {
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// The files are identical; write the expected file. This way, tests can be written
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// that compare the output of this program to the expected file.
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to_output = expected;
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} else {
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if (show_why) {
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std::cerr << difference << std::endl;
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exit(2);
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}
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// The files differ; write the actual file. If it is determined that the actual file
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// is correct because of changes that result in intended differences, this enables
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// the output of this program to replace the expected file in the test suite.
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to_output = actual;
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}
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auto f = QUtil::safe_fopen(to_output, "rb");
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QUtil::FileCloser fc(f);
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QUtil::binary_stdout();
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auto out = std::make_unique<Pl_StdioFile>("stdout", stdout);
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unsigned char buf[2048];
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bool done = false;
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while (!done) {
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size_t len = fread(buf, 1, sizeof(buf), f);
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if (len <= 0) {
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done = true;
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} else {
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out->write(buf, len);
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}
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}
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if (!difference.empty()) {
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exit(2);
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}
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} catch (std::exception& e) {
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std::cerr << whoami << ": " << e.what() << std::endl;
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exit(2);
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}
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return 0;
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}
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