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Code Issues Releases Wiki Activity
6a7c458381
qpdf/libqpdf/QPDF_json.cc
Jay Berkenbilt 752f43d4e4 Allow empty b: binary JSON strings
2022-05-21 17:36:32 -04:00

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#include <qpdf/QPDF.hh>
#include <qpdf/FileInputSource.hh>
#include <qpdf/Pl_Base64.hh>
#include <qpdf/Pl_StdioFile.hh>
#include <qpdf/QIntC.hh>
#include <qpdf/QTC.hh>
#include <qpdf/QUtil.hh>
#include <algorithm>
#include <cstring>
// This chart shows an example of the state transitions that would
// occur in parsing a minimal file.
// | st_initial
// { | -> st_top
// "qpdf-v2": { | -> st_qpdf
// "objects": { | -> st_objects
// "obj:1 0 R": { | -> st_object_top
// "value": { | -> st_object
// "/Pages": "2 0 R", | ...
// "/Type": "/Catalog" | ...
// } | <- st_object_top
// }, | <- st_objects
// "obj:2 0 R": { | -> st_object_top
// "value": 12 | -> st_object
// } | <- st_object_top
// }, | <- st_objects
// "obj:4 0 R": { | -> st_object_top
// "stream": { | -> st_stream
// "data": "cG90YXRv", | ...
// "dict": { | -> st_object
// "/K": true | ...
// } | <- st_stream
// } | <- st_object_top
// }, | <- st_objects
// "trailer": { | -> st_trailer
// "value": { | -> st_object
// "/Root": "1 0 R", | ...
// "/Size": 7 | ...
// } | <- st_trailer
// } | <- st_objects
// } | <- st_qpdf
// } | <- st_top
// } | <- st_initial
static char const* JSON_PDF = (
// force line break
"%PDF-1.3\n"
"xref\n"
"0 1\n"
"0000000000 65535 f \n"
"trailer << /Size 1 >>\n"
"startxref\n"
"9\n"
"%%EOF\n");
// Validator methods -- these are much more performant than std::regex.
static bool
is_indirect_object(std::string const& v, int& obj, int& gen)
{
char const* p = v.c_str();
std::string o_str;
std::string g_str;
if (!QUtil::is_digit(*p)) {
return false;
}
while (QUtil::is_digit(*p)) {
o_str.append(1, *p++);
}
if (*p != ' ') {
return false;
}
while (*p == ' ') {
++p;
}
if (!QUtil::is_digit(*p)) {
return false;
}
while (QUtil::is_digit(*p)) {
g_str.append(1, *p++);
}
if (*p != ' ') {
return false;
}
while (*p == ' ') {
++p;
}
if (*p++ != 'R') {
return false;
}
if (*p) {
return false;
}
obj = QUtil::string_to_int(o_str.c_str());
gen = QUtil::string_to_int(g_str.c_str());
return true;
}
static bool
is_obj_key(std::string const& v, int& obj, int& gen)
{
if (v.substr(0, 4) != "obj:") {
return false;
}
return is_indirect_object(v.substr(4), obj, gen);
}
static bool
is_unicode_string(std::string const& v, std::string& str)
{
if (v.substr(0, 2) == "u:") {
str = v.substr(2);
return true;
}
return false;
}
static bool
is_binary_string(std::string const& v, std::string& str)
{
if (v.substr(0, 2) == "b:") {
str = v.substr(2);
int count = 0;
for (char c: str) {
if (!QUtil::is_hex_digit(c)) {
return false;
}
++count;
}
return (count % 2 == 0);
}
return false;
}
static bool
is_name(std::string const& v)
{
return ((v.length() > 1) && (v.at(0) == '/'));
}
bool
QPDF::test_json_validators()
{
bool passed = true;
auto check_fn = [&passed](char const* msg, bool expr) {
if (!expr) {
passed = false;
std::cerr << msg << std::endl;
}
};
#define check(expr) check_fn(#expr, expr)
int obj = 0;
int gen = 0;
check(!is_indirect_object("", obj, gen));
check(!is_indirect_object("12", obj, gen));
check(!is_indirect_object("x12 0 R", obj, gen));
check(!is_indirect_object("12 0 Rx", obj, gen));
check(!is_indirect_object("12 0R", obj, gen));
check(is_indirect_object("52 1 R", obj, gen));
check(obj == 52);
check(gen == 1);
check(is_indirect_object("53 20 R", obj, gen));
check(obj == 53);
check(gen == 20);
check(!is_obj_key("", obj, gen));
check(!is_obj_key("obj:x", obj, gen));
check(!is_obj_key("obj:x", obj, gen));
check(is_obj_key("obj:12 13 R", obj, gen));
check(obj == 12);
check(gen == 13);
std::string str;
check(!is_unicode_string("", str));
check(!is_unicode_string("xyz", str));
check(!is_unicode_string("x:", str));
check(is_unicode_string("u:potato", str));
check(str == "potato");
check(is_unicode_string("u:", str));
check(str == "");
check(!is_binary_string("", str));
check(!is_binary_string("x:", str));
check(!is_binary_string("b:1", str));
check(!is_binary_string("b:123", str));
check(!is_binary_string("b:gh", str));
check(is_binary_string("b:", str));
check(is_binary_string("b:12", str));
check(is_binary_string("b:123aBC", str));
check(!is_name(""));
check(!is_name("/"));
check(!is_name("xyz"));
check(is_name("/Potato"));
check(is_name("/Potato Salad"));
return passed;
#undef check_arg
}
static std::function<void(Pipeline*)>
provide_data(
std::shared_ptr<InputSource> is, qpdf_offset_t start, qpdf_offset_t end)
{
return [is, start, end](Pipeline* p) {
Pl_Base64 decode("base64-decode", p, Pl_Base64::a_decode);
p = &decode;
size_t bytes = QIntC::to_size(end - start);
char buf[8192];
is->seek(start, SEEK_SET);
size_t len = 0;
while ((len = is->read(buf, std::min(bytes, sizeof(buf)))) > 0) {
p->write(buf, len);
bytes -= len;
if (bytes == 0) {
break;
}
}
decode.finish();
};
}
QPDF::JSONReactor::JSONReactor(
QPDF& pdf, std::shared_ptr<InputSource> is, bool must_be_complete) :
pdf(pdf),
is(is),
must_be_complete(must_be_complete),
errors(false),
parse_error(false),
saw_qpdf(false),
saw_objects(false),
saw_pdf_version(false),
saw_trailer(false),
state(st_initial),
next_state(st_top),
saw_value(false),
saw_stream(false),
saw_dict(false),
saw_data(false),
saw_datafile(false),
this_stream_needs_data(false)
{
state_stack.push_back(st_initial);
}
void
QPDF::JSONReactor::error(qpdf_offset_t offset, std::string const& msg)
{
this->errors = true;
std::string object = this->cur_object;
if (is->getName() != pdf.getFilename()) {
object += " from " + is->getName();
}
this->pdf.warn(qpdf_e_json, object, offset, msg);
}
bool
QPDF::JSONReactor::anyErrors() const
{
return this->errors;
}
void
QPDF::JSONReactor::containerStart()
{
state_stack.push_back(state);
state = next_state;
}
void
QPDF::JSONReactor::dictionaryStart()
{
containerStart();
}
void
QPDF::JSONReactor::arrayStart()
{
containerStart();
if (state == st_top) {
QTC::TC("qpdf", "QPDF_json top-level array");
throw std::runtime_error("QPDF JSON must be a dictionary");
}
}
void
QPDF::JSONReactor::containerEnd(JSON const& value)
{
auto from_state = state;
state = state_stack.back();
state_stack.pop_back();
if (state == st_initial) {
if (!this->saw_qpdf) {
QTC::TC("qpdf", "QPDF_json missing qpdf");
error(0, "\"qpdf\" object was not seen");
} else {
if (must_be_complete && !this->saw_pdf_version) {
QTC::TC("qpdf", "QPDF_json missing pdf version");
error(0, "\"qpdf-v2.pdfversion\" was not seen");
}
if (!this->saw_objects) {
QTC::TC("qpdf", "QPDF_json missing objects");
error(0, "\"qpdf-v2.objects\" was not seen");
} else {
if (must_be_complete && !this->saw_trailer) {
QTC::TC("qpdf", "QPDF_json missing trailer");
error(0, "\"qpdf-v2.objects.trailer\" was not seen");
}
}
}
} else if (state == st_objects) {
if (parse_error) {
QTC::TC("qpdf", "QPDF_json don't check object after parse error");
} else if (cur_object == "trailer") {
if (!saw_value) {
QTC::TC("qpdf", "QPDF_json trailer no value");
error(value.getStart(), "\"trailer\" is missing \"value\"");
}
} else if (saw_value == saw_stream) {
QTC::TC("qpdf", "QPDF_json value stream both or neither");
error(
value.getStart(),
"object must have exactly one of \"value\" or \"stream\"");
}
object_stack.clear();
this->cur_object = "";
this->saw_dict = false;
this->saw_data = false;
this->saw_datafile = false;
this->saw_value = false;
this->saw_stream = false;
} else if (state == st_object_top) {
if (saw_stream) {
if (!saw_dict) {
QTC::TC("qpdf", "QPDF_json stream no dict");
error(value.getStart(), "\"stream\" is missing \"dict\"");
}
if (saw_data == saw_datafile) {
if (this_stream_needs_data) {
QTC::TC("qpdf", "QPDF_json data datafile both or neither");
error(
value.getStart(),
"new \"stream\" must have exactly one of \"data\" or "
"\"datafile\"");
} else if (saw_datafile) {
QTC::TC("qpdf", "QPDF_json data and datafile");
error(
value.getStart(),
"existing \"stream\" may at most one of \"data\" or "
"\"datafile\"");
} else {
QTC::TC("qpdf", "QPDF_json no stream data in update mode");
}
}
}
} else if ((state == st_stream) || (state == st_object)) {
if (!parse_error) {
object_stack.pop_back();
}
} else if ((state == st_top) && (from_state == st_qpdf)) {
for (auto const& og: this->reserved) {
// Handle dangling indirect object references which the
// PDF spec says to treat as nulls. It's tempting to make
// this an error, but that would be wrong since valid
// input files may have these.
QTC::TC("qpdf", "QPDF_json non-trivial null reserved");
this->pdf.replaceObject(og, QPDFObjectHandle::newNull());
}
this->reserved.clear();
}
}
QPDFObjectHandle
QPDF::JSONReactor::reserveObject(int obj, int gen)
{
auto oh = pdf.reserveObjectIfNotExists(obj, gen);
if (oh.isReserved()) {
this->reserved.insert(QPDFObjGen(obj, gen));
}
return oh;
}
void
QPDF::JSONReactor::replaceObject(
QPDFObjectHandle to_replace,
QPDFObjectHandle replacement,
JSON const& value)
{
auto og = to_replace.getObjGen();
this->reserved.erase(og);
this->pdf.replaceObject(og, replacement);
auto oh = pdf.getObjectByObjGen(og);
setObjectDescription(oh, value);
}
void
QPDF::JSONReactor::topLevelScalar()
{
QTC::TC("qpdf", "QPDF_json top-level scalar");
throw std::runtime_error("QPDF JSON must be a dictionary");
}
void
QPDF::JSONReactor::nestedState(
std::string const& key, JSON const& value, state_e next)
{
// Use this method when the next state is for processing a nested
// dictionary.
if (value.isDictionary()) {
this->next_state = next;
} else {
error(value.getStart(), "\"" + key + "\" must be a dictionary");
this->next_state = st_ignore;
this->parse_error = true;
}
}
bool
QPDF::JSONReactor::dictionaryItem(std::string const& key, JSON const& value)
{
if (state == st_ignore) {
QTC::TC("qpdf", "QPDF_json ignoring in st_ignore");
// ignore
} else if (state == st_top) {
if (key == "qpdf-v2") {
this->saw_qpdf = true;
nestedState(key, value, st_qpdf);
} else {
// Ignore all other fields. We explicitly allow people to
// add other top-level keys for their own use.
QTC::TC("qpdf", "QPDF_json ignoring unknown top-level key");
next_state = st_ignore;
}
} else if (state == st_qpdf) {
if (key == "pdfversion") {
this->saw_pdf_version = true;
bool version_okay = false;
std::string v;
if (value.getString(v)) {
std::string version;
char const* p = v.c_str();
if (QPDF::validatePDFVersion(p, version) && (*p == '\0')) {
version_okay = true;
this->pdf.m->pdf_version = version;
}
}
if (!version_okay) {
QTC::TC("qpdf", "QPDF_json bad pdf version");
error(value.getStart(), "invalid PDF version (must be x.y)");
}
} else if (key == "objects") {
this->saw_objects = true;
nestedState(key, value, st_objects);
} else {
// ignore unknown keys for forward compatibility and to
// skip keys we don't care about like "maxobjectid".
QTC::TC("qpdf", "QPDF_json ignore second-level key");
next_state = st_ignore;
}
} else if (state == st_objects) {
int obj = 0;
int gen = 0;
if (key == "trailer") {
this->saw_trailer = true;
nestedState(key, value, st_trailer);
this->cur_object = "trailer";
} else if (is_obj_key(key, obj, gen)) {
this->cur_object = key;
auto oh = reserveObject(obj, gen);
object_stack.push_back(oh);
nestedState(key, value, st_object_top);
} else {
QTC::TC("qpdf", "QPDF_json bad object key");
error(
value.getStart(),
"object key should be \"trailer\" or \"obj:n n R\"");
next_state = st_ignore;
parse_error = true;
}
} else if (state == st_object_top) {
if (object_stack.size() == 0) {
throw std::logic_error("no object on stack in st_object_top");
}
auto tos = object_stack.back();
QPDFObjectHandle replacement;
if (key == "value") {
// Don't use nestedState since this can have any type.
this->saw_value = true;
next_state = st_object;
replacement = makeObject(value);
replaceObject(tos, replacement, value);
} else if (key == "stream") {
this->saw_stream = true;
nestedState(key, value, st_stream);
this->this_stream_needs_data = false;
if (tos.isStream()) {
QTC::TC("qpdf", "QPDF_json updating existing stream");
} else {
this->this_stream_needs_data = true;
replacement =
pdf.reserveStream(tos.getObjectID(), tos.getGeneration());
replaceObject(tos, replacement, value);
}
} else {
// Ignore unknown keys for forward compatibility
QTC::TC("qpdf", "QPDF_json ignore unknown key in object_top");
next_state = st_ignore;
}
if (replacement.isInitialized()) {
object_stack.pop_back();
object_stack.push_back(replacement);
}
} else if (state == st_trailer) {
if (key == "value") {
this->saw_value = true;
// The trailer must be a dictionary, so we can use nestedState.
nestedState("trailer.value", value, st_object);
this->pdf.m->trailer = makeObject(value);
setObjectDescription(this->pdf.m->trailer, value);
} else if (key == "stream") {
// Don't need to set saw_stream here since there's already
// an error.
QTC::TC("qpdf", "QPDF_json trailer stream");
error(value.getStart(), "the trailer may not be a stream");
next_state = st_ignore;
parse_error = true;
} else {
// Ignore unknown keys for forward compatibility
QTC::TC("qpdf", "QPDF_json ignore unknown key in trailer");
next_state = st_ignore;
}
} else if (state == st_stream) {
if (object_stack.size() == 0) {
throw std::logic_error("no object on stack in st_stream");
}
auto tos = object_stack.back();
if (!tos.isStream()) {
throw std::logic_error("top of stack is not stream in st_stream");
}
auto uninitialized = QPDFObjectHandle();
if (key == "dict") {
this->saw_dict = true;
// Since a stream dictionary must be a dictionary, we can
// use nestedState to transition to st_value.
nestedState("stream.dict", value, st_object);
auto dict = makeObject(value);
if (dict.isDictionary()) {
tos.replaceDict(dict);
} else {
// An error had already been given by nestedState
QTC::TC("qpdf", "QPDF_json stream dict not dict");
parse_error = true;
}
} else if (key == "data") {
this->saw_data = true;
std::string v;
if (!value.getString(v)) {
error(value.getStart(), "\"stream.data\" must be a string");
} else {
// The range includes the quotes.
auto start = value.getStart() + 1;
auto end = value.getEnd() - 1;
if (end < start) {
throw std::logic_error("QPDF_json: JSON string length < 0");
}
tos.replaceStreamData(
provide_data(is, start, end), uninitialized, uninitialized);
}
} else if (key == "datafile") {
this->saw_datafile = true;
std::string filename;
if (value.getString(filename)) {
tos.replaceStreamData(
QUtil::file_provider(filename),
uninitialized,
uninitialized);
} else {
error(
value.getStart(),
"\"stream.datafile\" must be a string containing a file "
"name");
}
} else {
// Ignore unknown keys for forward compatibility.
QTC::TC("qpdf", "QPDF_json ignore unknown key in stream");
next_state = st_ignore;
}
} else if (state == st_object) {
if (!parse_error) {
auto dict = object_stack.back();
if (dict.isStream()) {
dict = dict.getDict();
}
dict.replaceKey(key, makeObject(value));
}
} else {
throw std::logic_error(
"QPDF_json: unknown state " + QUtil::int_to_string(state));
}
return true;
}
bool
QPDF::JSONReactor::arrayItem(JSON const& value)
{
if (state == st_object) {
if (!parse_error) {
auto tos = object_stack.back();
tos.appendItem(makeObject(value));
}
}
return true;
}
void
QPDF::JSONReactor::setObjectDescription(QPDFObjectHandle& oh, JSON const& value)
{
std::string description = this->is->getName();
if (!this->cur_object.empty()) {
description += ", " + this->cur_object;
}
description += " at offset " + QUtil::int_to_string(value.getStart());
oh.setObjectDescription(&this->pdf, description);
}
QPDFObjectHandle
QPDF::JSONReactor::makeObject(JSON const& value)
{
QPDFObjectHandle result;
std::string str_v;
bool bool_v = false;
if (value.isDictionary()) {
result = QPDFObjectHandle::newDictionary();
object_stack.push_back(result);
} else if (value.isArray()) {
result = QPDFObjectHandle::newArray();
object_stack.push_back(result);
} else if (value.isNull()) {
result = QPDFObjectHandle::newNull();
} else if (value.getBool(bool_v)) {
result = QPDFObjectHandle::newBool(bool_v);
} else if (value.getNumber(str_v)) {
if (QUtil::is_long_long(str_v.c_str())) {
result = QPDFObjectHandle::newInteger(
QUtil::string_to_ll(str_v.c_str()));
} else {
result = QPDFObjectHandle::newReal(str_v);
}
} else if (value.getString(str_v)) {
int obj = 0;
int gen = 0;
std::string str;
if (is_indirect_object(str_v, obj, gen)) {
result = reserveObject(obj, gen);
} else if (is_unicode_string(str_v, str)) {
result = QPDFObjectHandle::newUnicodeString(str);
} else if (is_binary_string(str_v, str)) {
result = QPDFObjectHandle::newString(QUtil::hex_decode(str));
} else if (is_name(str_v)) {
result = QPDFObjectHandle::newName(str_v);
} else {
QTC::TC("qpdf", "QPDF_json unrecognized string value");
error(value.getStart(), "unrecognized string value");
result = QPDFObjectHandle::newNull();
}
}
if (!result.isInitialized()) {
throw std::logic_error(
"JSONReactor::makeObject didn't initialize the object");
}
if (!result.hasObjectDescription()) {
setObjectDescription(result, value);
}
return result;
}
void
QPDF::createFromJSON(std::string const& json_file)
{
createFromJSON(std::make_shared<FileInputSource>(json_file.c_str()));
}
void
QPDF::createFromJSON(std::shared_ptr<InputSource> is)
{
processMemoryFile(is->getName().c_str(), JSON_PDF, strlen(JSON_PDF));
importJSON(is, true);
}
void
QPDF::updateFromJSON(std::string const& json_file)
{
updateFromJSON(std::make_shared<FileInputSource>(json_file.c_str()));
}
void
QPDF::updateFromJSON(std::shared_ptr<InputSource> is)
{
importJSON(is, false);
}
void
QPDF::importJSON(std::shared_ptr<InputSource> is, bool must_be_complete)
{
JSONReactor reactor(*this, is, must_be_complete);
try {
JSON::parse(*is, &reactor);
} catch (std::runtime_error& e) {
throw std::runtime_error(is->getName() + ": " + e.what());
}
if (reactor.anyErrors()) {
throw std::runtime_error(is->getName() + ": errors found in JSON");
}
}
void
QPDF::writeJSONStream(
int version,
Pipeline* p,
bool& first,
std::string const& key,
QPDFObjectHandle& obj,
qpdf_stream_decode_level_e decode_level,
qpdf_json_stream_data_e json_stream_data,
std::string const& file_prefix)
{
Pipeline* stream_p = nullptr;
FILE* f = nullptr;
std::shared_ptr<Pl_StdioFile> f_pl;
std::string filename;
if (json_stream_data == qpdf_sj_file) {
filename = file_prefix + "-" + QUtil::int_to_string(obj.getObjectID());
f = QUtil::safe_fopen(filename.c_str(), "wb");
f_pl = std::make_shared<Pl_StdioFile>("stream data", f);
stream_p = f_pl.get();
}
auto j = JSON::makeDictionary();
j.addDictionaryMember(
"stream",
obj.getStreamJSON(
version, json_stream_data, decode_level, stream_p, filename));
JSON::writeDictionaryItem(p, first, key, j, 2);
if (f) {
f_pl->finish();
f_pl = nullptr;
fclose(f);
}
}
void
QPDF::writeJSONObject(
int version,
Pipeline* p,
bool& first,
std::string const& key,
QPDFObjectHandle& obj)
{
auto j = JSON::makeDictionary();
j.addDictionaryMember("value", obj.getJSON(version, true));
JSON::writeDictionaryItem(p, first, key, j, 2);
}
void
QPDF::writeJSON(
int version,
Pipeline* p,
qpdf_stream_decode_level_e decode_level,
qpdf_json_stream_data_e json_stream_data,
std::string const& file_prefix,
std::set<std::string> wanted_objects)
{
if (version != 2) {
throw std::runtime_error(
"QPDF::writeJSON: only version 2 is supported");
}
bool first = true;
JSON::writeDictionaryOpen(p, first, 0);
JSON::writeDictionaryKey(p, first, "qpdf-v2", 0);
bool first_qpdf = true;
JSON::writeDictionaryOpen(p, first_qpdf, 1);
JSON::writeDictionaryItem(
p, first_qpdf, "pdfversion", JSON::makeString(getPDFVersion()), 1);
JSON::writeDictionaryItem(
p,
first_qpdf,
"maxobjectid",
JSON::makeInt(QIntC::to_longlong(getObjectCount())),
1);
JSON::writeDictionaryKey(p, first_qpdf, "objects", 1);
bool first_object = true;
JSON::writeDictionaryOpen(p, first_object, 2);
bool all_objects = wanted_objects.empty();
std::vector<QPDFObjectHandle> objects = getAllObjects();
for (auto& obj: objects) {
std::string key = "obj:" + obj.unparse();
if (all_objects || wanted_objects.count(key)) {
if (obj.isStream()) {
writeJSONStream(
version,
p,
first_object,
key,
obj,
decode_level,
json_stream_data,
file_prefix);
} else {
writeJSONObject(version, p, first_object, key, obj);
}
}
}
if (all_objects || wanted_objects.count("trailer")) {
auto trailer = getTrailer();
writeJSONObject(version, p, first_object, "trailer", trailer);
}
JSON::writeDictionaryClose(p, first_object, 2);
JSON::writeDictionaryClose(p, first_qpdf, 1);
JSON::writeDictionaryClose(p, first, 0);
*p << "\n";
}
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