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mirror of https://github.com/qpdf/qpdf.git synced 2024-11-11 15:40:58 +00:00
qpdf/libqpdf/QPDFTokenizer.cc
Jay Berkenbilt 4f24617e1e Code clean up: use range-style for loops wherever possible
Where not possible, use "auto" to get the iterator type.

Editorial note: I have avoid this change for a long time because of
not wanting to make gratuitous changes to version history, which can
obscure when certain changes were made, but with having recently
touched every single file to apply automatic code formatting and with
making several broad changes to the API, I decided it was time to take
the plunge and get rid of the older (pre-C++11) verbose iterator
syntax. The new code is just easier to read and understand, and in
many cases, it will be more effecient as fewer temporary copies are
being made.

m-holger, if you're reading, you can see that I've finally come
around. :-)
2022-04-30 13:27:18 -04:00

711 lines
23 KiB
C++

#include <qpdf/QPDFTokenizer.hh>
// DO NOT USE ctype -- it is locale dependent for some things, and
// it's not worth the risk of including it in case it may accidentally
// be used.
#include <qpdf/QIntC.hh>
#include <qpdf/QPDFExc.hh>
#include <qpdf/QPDFObjectHandle.hh>
#include <qpdf/QTC.hh>
#include <qpdf/QUtil.hh>
#include <stdexcept>
#include <stdlib.h>
#include <string.h>
static bool
is_delimiter(char ch)
{
return (strchr(" \t\n\v\f\r()<>[]{}/%", ch) != 0);
}
namespace
{
class QPDFWordTokenFinder: public InputSource::Finder
{
public:
QPDFWordTokenFinder(
std::shared_ptr<InputSource> is, std::string const& str) :
is(is),
str(str)
{
}
virtual ~QPDFWordTokenFinder() = default;
virtual bool check();
private:
std::shared_ptr<InputSource> is;
std::string str;
};
} // namespace
bool
QPDFWordTokenFinder::check()
{
// Find a word token matching the given string, preceded by a
// delimiter, and followed by a delimiter or EOF.
QPDFTokenizer tokenizer;
QPDFTokenizer::Token t = tokenizer.readToken(is, "finder", true);
qpdf_offset_t pos = is->tell();
if (!(t == QPDFTokenizer::Token(QPDFTokenizer::tt_word, str))) {
QTC::TC("qpdf", "QPDFTokenizer finder found wrong word");
return false;
}
qpdf_offset_t token_start = is->getLastOffset();
char next;
bool next_okay = false;
if (is->read(&next, 1) == 0) {
QTC::TC("qpdf", "QPDFTokenizer inline image at EOF");
next_okay = true;
} else {
next_okay = is_delimiter(next);
}
is->seek(pos, SEEK_SET);
if (!next_okay) {
return false;
}
if (token_start == 0) {
// Can't actually happen...we never start the search at the
// beginning of the input.
return false;
}
return true;
}
QPDFTokenizer::Members::Members() :
allow_eof(false),
include_ignorable(false)
{
reset();
}
void
QPDFTokenizer::Members::reset()
{
state = st_top;
type = tt_bad;
val = "";
raw_val = "";
error_message = "";
unread_char = false;
char_to_unread = '\0';
inline_image_bytes = 0;
string_depth = 0;
string_ignoring_newline = false;
last_char_was_bs = false;
last_char_was_cr = false;
}
QPDFTokenizer::Token::Token(token_type_e type, std::string const& value) :
type(type),
value(value),
raw_value(value)
{
if (type == tt_string) {
raw_value = QPDFObjectHandle::newString(value).unparse();
} else if (type == tt_name) {
raw_value = QPDFObjectHandle::newName(value).unparse();
}
}
QPDFTokenizer::QPDFTokenizer() :
m(new Members())
{
}
void
QPDFTokenizer::allowEOF()
{
this->m->allow_eof = true;
}
void
QPDFTokenizer::includeIgnorable()
{
this->m->include_ignorable = true;
}
bool
QPDFTokenizer::isSpace(char ch)
{
return ((ch == '\0') || QUtil::is_space(ch));
}
bool
QPDFTokenizer::isDelimiter(char ch)
{
return is_delimiter(ch);
}
void
QPDFTokenizer::resolveLiteral()
{
if ((this->m->val.length() > 0) && (this->m->val.at(0) == '/')) {
this->m->type = tt_name;
// Deal with # in name token. Note: '/' by itself is a
// valid name, so don't strip leading /. That way we
// don't have to deal with the empty string as a name.
std::string nval = "/";
size_t len = this->m->val.length();
for (size_t i = 1; i < len; ++i) {
char ch = this->m->val.at(i);
if (ch == '#') {
if ((i + 2 < len) &&
QUtil::is_hex_digit(this->m->val.at(i + 1)) &&
QUtil::is_hex_digit(this->m->val.at(i + 2))) {
char num[3];
num[0] = this->m->val.at(i + 1);
num[1] = this->m->val.at(i + 2);
num[2] = '\0';
char ch2 = static_cast<char>(strtol(num, 0, 16));
if (ch2 == '\0') {
this->m->type = tt_bad;
QTC::TC("qpdf", "QPDFTokenizer null in name");
this->m->error_message =
"null character not allowed in name token";
nval += "#00";
} else {
nval.append(1, ch2);
}
i += 2;
} else {
QTC::TC("qpdf", "QPDFTokenizer bad name");
this->m->error_message =
"name with stray # will not work with PDF >= 1.2";
// Use null to encode a bad # -- this is reversed
// in QPDF_Name::normalizeName.
nval += '\0';
}
} else {
nval.append(1, ch);
}
}
this->m->val = nval;
} else if (QUtil::is_number(this->m->val.c_str())) {
if (this->m->val.find('.') != std::string::npos) {
this->m->type = tt_real;
} else {
this->m->type = tt_integer;
}
} else if ((this->m->val == "true") || (this->m->val == "false")) {
this->m->type = tt_bool;
} else if (this->m->val == "null") {
this->m->type = tt_null;
} else {
// I don't really know what it is, so leave it as tt_word.
// Lots of cases ($, #, etc.) other than actual words fall
// into this category, but that's okay at least for now.
this->m->type = tt_word;
}
}
void
QPDFTokenizer::presentCharacter(char ch)
{
if (this->m->state == st_token_ready) {
throw std::logic_error(
"INTERNAL ERROR: QPDF tokenizer presented character "
"while token is waiting");
}
char orig_ch = ch;
// State machine is implemented such that some characters may be
// handled more than once. This happens whenever you have to use
// the character that caused a state change in the new state.
bool handled = true;
if (this->m->state == st_top) {
// Note: we specifically do not use ctype here. It is
// locale-dependent.
if (isSpace(ch)) {
if (this->m->include_ignorable) {
this->m->state = st_in_space;
this->m->val += ch;
}
} else if (ch == '%') {
this->m->state = st_in_comment;
if (this->m->include_ignorable) {
this->m->val += ch;
}
} else if (ch == '(') {
this->m->string_depth = 1;
this->m->string_ignoring_newline = false;
memset(
this->m->bs_num_register,
'\0',
sizeof(this->m->bs_num_register));
this->m->last_char_was_bs = false;
this->m->last_char_was_cr = false;
this->m->state = st_in_string;
} else if (ch == '<') {
this->m->state = st_lt;
} else if (ch == '>') {
this->m->state = st_gt;
} else {
this->m->val += ch;
if (ch == ')') {
this->m->type = tt_bad;
QTC::TC("qpdf", "QPDFTokenizer bad )");
this->m->error_message = "unexpected )";
this->m->state = st_token_ready;
} else if (ch == '[') {
this->m->type = tt_array_open;
this->m->state = st_token_ready;
} else if (ch == ']') {
this->m->type = tt_array_close;
this->m->state = st_token_ready;
} else if (ch == '{') {
this->m->type = tt_brace_open;
this->m->state = st_token_ready;
} else if (ch == '}') {
this->m->type = tt_brace_close;
this->m->state = st_token_ready;
} else {
this->m->state = st_literal;
}
}
} else if (this->m->state == st_in_space) {
// We only enter this state if include_ignorable is true.
if (!isSpace(ch)) {
this->m->type = tt_space;
this->m->unread_char = true;
this->m->char_to_unread = ch;
this->m->state = st_token_ready;
} else {
this->m->val += ch;
}
} else if (this->m->state == st_in_comment) {
if ((ch == '\r') || (ch == '\n')) {
if (this->m->include_ignorable) {
this->m->type = tt_comment;
this->m->unread_char = true;
this->m->char_to_unread = ch;
this->m->state = st_token_ready;
} else {
this->m->state = st_top;
}
} else if (this->m->include_ignorable) {
this->m->val += ch;
}
} else if (this->m->state == st_lt) {
if (ch == '<') {
this->m->val = "<<";
this->m->type = tt_dict_open;
this->m->state = st_token_ready;
} else {
handled = false;
this->m->state = st_in_hexstring;
}
} else if (this->m->state == st_gt) {
if (ch == '>') {
this->m->val = ">>";
this->m->type = tt_dict_close;
this->m->state = st_token_ready;
} else {
this->m->val = ">";
this->m->type = tt_bad;
QTC::TC("qpdf", "QPDFTokenizer bad >");
this->m->error_message = "unexpected >";
this->m->unread_char = true;
this->m->char_to_unread = ch;
this->m->state = st_token_ready;
}
} else if (this->m->state == st_in_string) {
if (this->m->string_ignoring_newline && (ch != '\n')) {
this->m->string_ignoring_newline = false;
}
size_t bs_num_count = strlen(this->m->bs_num_register);
bool ch_is_octal = ((ch >= '0') && (ch <= '7'));
if ((bs_num_count == 3) || ((bs_num_count > 0) && (!ch_is_octal))) {
// We've accumulated \ddd. PDF Spec says to ignore
// high-order overflow.
this->m->val +=
static_cast<char>(strtol(this->m->bs_num_register, 0, 8));
memset(
this->m->bs_num_register,
'\0',
sizeof(this->m->bs_num_register));
bs_num_count = 0;
}
if (this->m->string_ignoring_newline && (ch == '\n')) {
// ignore
this->m->string_ignoring_newline = false;
} else if (
ch_is_octal && (this->m->last_char_was_bs || (bs_num_count > 0))) {
this->m->bs_num_register[bs_num_count++] = ch;
} else if (this->m->last_char_was_bs) {
switch (ch) {
case 'n':
this->m->val += '\n';
break;
case 'r':
this->m->val += '\r';
break;
case 't':
this->m->val += '\t';
break;
case 'b':
this->m->val += '\b';
break;
case 'f':
this->m->val += '\f';
break;
case '\n':
break;
case '\r':
this->m->string_ignoring_newline = true;
break;
default:
// PDF spec says backslash is ignored before anything else
this->m->val += ch;
break;
}
} else if (ch == '\\') {
// last_char_was_bs is set/cleared below as appropriate
if (bs_num_count) {
throw std::logic_error(
"INTERNAL ERROR: QPDFTokenizer: bs_num_count != 0 "
"when ch == '\\'");
}
} else if (ch == '(') {
this->m->val += ch;
++this->m->string_depth;
} else if ((ch == ')') && (--this->m->string_depth == 0)) {
this->m->type = tt_string;
this->m->state = st_token_ready;
} else if (ch == '\r') {
// CR by itself is converted to LF
this->m->val += '\n';
} else if (ch == '\n') {
// CR LF is converted to LF
if (!this->m->last_char_was_cr) {
this->m->val += ch;
}
} else {
this->m->val += ch;
}
this->m->last_char_was_cr =
((!this->m->string_ignoring_newline) && (ch == '\r'));
this->m->last_char_was_bs =
((!this->m->last_char_was_bs) && (ch == '\\'));
} else if (this->m->state == st_literal) {
if (isDelimiter(ch)) {
// A C-locale whitespace character or delimiter terminates
// token. It is important to unread the whitespace
// character even though it is ignored since it may be the
// newline after a stream keyword. Removing it here could
// make the stream-reading code break on some files,
// though not on any files in the test suite as of this
// writing.
this->m->type = tt_word;
this->m->unread_char = true;
this->m->char_to_unread = ch;
this->m->state = st_token_ready;
} else {
this->m->val += ch;
}
} else if (this->m->state == st_inline_image) {
this->m->val += ch;
size_t len = this->m->val.length();
if (len == this->m->inline_image_bytes) {
QTC::TC("qpdf", "QPDFTokenizer found EI by byte count");
this->m->type = tt_inline_image;
this->m->inline_image_bytes = 0;
this->m->state = st_token_ready;
}
} else {
handled = false;
}
if (handled) {
// okay
} else if (this->m->state == st_in_hexstring) {
if (ch == '>') {
this->m->type = tt_string;
this->m->state = st_token_ready;
if (this->m->val.length() % 2) {
// PDF spec says odd hexstrings have implicit
// trailing 0.
this->m->val += '0';
}
char num[3];
num[2] = '\0';
std::string nval;
for (unsigned int i = 0; i < this->m->val.length(); i += 2) {
num[0] = this->m->val.at(i);
num[1] = this->m->val.at(i + 1);
char nch = static_cast<char>(strtol(num, 0, 16));
nval += nch;
}
this->m->val = nval;
} else if (QUtil::is_hex_digit(ch)) {
this->m->val += ch;
} else if (isSpace(ch)) {
// ignore
} else {
this->m->type = tt_bad;
QTC::TC("qpdf", "QPDFTokenizer bad hexstring character");
this->m->error_message =
std::string("invalid character (") + ch + ") in hexstring";
this->m->state = st_token_ready;
}
} else {
throw std::logic_error(
"INTERNAL ERROR: invalid state while reading token");
}
if ((this->m->state == st_token_ready) && (this->m->type == tt_word)) {
resolveLiteral();
}
if (!(betweenTokens() ||
((this->m->state == st_token_ready) && this->m->unread_char))) {
this->m->raw_val += orig_ch;
}
}
void
QPDFTokenizer::presentEOF()
{
if (this->m->state == st_literal) {
QTC::TC("qpdf", "QPDFTokenizer EOF reading appendable token");
resolveLiteral();
} else if (
(this->m->include_ignorable) && (this->m->state == st_in_space)) {
this->m->type = tt_space;
} else if (
(this->m->include_ignorable) && (this->m->state == st_in_comment)) {
this->m->type = tt_comment;
} else if (betweenTokens()) {
this->m->type = tt_eof;
} else if (this->m->state != st_token_ready) {
QTC::TC("qpdf", "QPDFTokenizer EOF reading token");
this->m->type = tt_bad;
this->m->error_message = "EOF while reading token";
}
this->m->state = st_token_ready;
}
void
QPDFTokenizer::expectInlineImage(std::shared_ptr<InputSource> input)
{
if (this->m->state != st_top) {
throw std::logic_error("QPDFTokenizer::expectInlineImage called"
" when tokenizer is in improper state");
}
findEI(input);
this->m->state = st_inline_image;
}
void
QPDFTokenizer::findEI(std::shared_ptr<InputSource> input)
{
if (!input.get()) {
return;
}
qpdf_offset_t last_offset = input->getLastOffset();
qpdf_offset_t pos = input->tell();
// Use QPDFWordTokenFinder to find EI surrounded by delimiters.
// Then read the next several tokens or up to EOF. If we find any
// suspicious-looking or tokens, this is probably still part of
// the image data, so keep looking for EI. Stop at the first EI
// that passes. If we get to the end without finding one, return
// the last EI we found. Store the number of bytes expected in the
// inline image including the EI and use that to break out of
// inline image, falling back to the old method if needed.
bool okay = false;
bool first_try = true;
while (!okay) {
QPDFWordTokenFinder f(input, "EI");
if (!input->findFirst("EI", input->tell(), 0, f)) {
break;
}
this->m->inline_image_bytes = QIntC::to_size(input->tell() - pos - 2);
QPDFTokenizer check;
bool found_bad = false;
// Look at the next 10 tokens or up to EOF. The next inline
// image's image data would look like bad tokens, but there
// will always be at least 10 tokens between one inline
// image's EI and the next valid one's ID since width, height,
// bits per pixel, and color space are all required as well as
// a BI and ID. If we get 10 good tokens in a row or hit EOF,
// we can be pretty sure we've found the actual EI.
for (int i = 0; i < 10; ++i) {
QPDFTokenizer::Token t = check.readToken(input, "checker", true);
token_type_e type = t.getType();
if (type == tt_eof) {
okay = true;
} else if (type == tt_bad) {
found_bad = true;
} else if (type == tt_word) {
// The qpdf tokenizer lumps alphabetic and otherwise
// uncategorized characters into "words". We recognize
// strings of alphabetic characters as potential valid
// operators for purposes of telling whether we're in
// valid content or not. It's not perfect, but it
// should work more reliably than what we used to do,
// which was already good enough for the vast majority
// of files.
bool found_alpha = false;
bool found_non_printable = false;
bool found_other = false;
std::string value = t.getValue();
for (char ch: value) {
if (((ch >= 'a') && (ch <= 'z')) ||
((ch >= 'A') && (ch <= 'Z')) || (ch == '*')) {
// Treat '*' as alpha since there are valid
// PDF operators that contain * along with
// alphabetic characters.
found_alpha = true;
} else if (
(static_cast<signed char>(ch) < 32) && (!isSpace(ch))) {
// Compare ch as a signed char so characters
// outside of 7-bit will be < 0.
found_non_printable = true;
break;
} else {
found_other = true;
}
}
if (found_non_printable || (found_alpha && found_other)) {
found_bad = true;
}
}
if (okay || found_bad) {
break;
}
}
if (!found_bad) {
okay = true;
}
if (!okay) {
first_try = false;
}
}
if (okay && (!first_try)) {
QTC::TC("qpdf", "QPDFTokenizer found EI after more than one try");
}
input->seek(pos, SEEK_SET);
input->setLastOffset(last_offset);
}
bool
QPDFTokenizer::getToken(Token& token, bool& unread_char, char& ch)
{
bool ready = (this->m->state == st_token_ready);
unread_char = this->m->unread_char;
ch = this->m->char_to_unread;
if (ready) {
if (this->m->type == tt_bad) {
this->m->val = this->m->raw_val;
}
token = Token(
this->m->type,
this->m->val,
this->m->raw_val,
this->m->error_message);
this->m->reset();
}
return ready;
}
bool
QPDFTokenizer::betweenTokens()
{
return (
(this->m->state == st_top) ||
((!this->m->include_ignorable) &&
((this->m->state == st_in_comment) ||
(this->m->state == st_in_space))));
}
QPDFTokenizer::Token
QPDFTokenizer::readToken(
std::shared_ptr<InputSource> input,
std::string const& context,
bool allow_bad,
size_t max_len)
{
qpdf_offset_t offset = input->tell();
Token token;
bool unread_char;
char char_to_unread;
bool presented_eof = false;
while (!getToken(token, unread_char, char_to_unread)) {
char ch;
if (input->read(&ch, 1) == 0) {
if (!presented_eof) {
presentEOF();
presented_eof = true;
if ((this->m->type == tt_eof) && (!this->m->allow_eof)) {
// Nothing in the qpdf library calls readToken
// without allowEOF anymore, so this case is not
// exercised.
this->m->type = tt_bad;
this->m->error_message = "unexpected EOF";
offset = input->getLastOffset();
}
} else {
throw std::logic_error(
"getToken returned false after presenting EOF");
}
} else {
presentCharacter(ch);
if (betweenTokens() && (input->getLastOffset() == offset)) {
++offset;
}
if (max_len && (this->m->raw_val.length() >= max_len) &&
(this->m->state != st_token_ready)) {
// terminate this token now
QTC::TC("qpdf", "QPDFTokenizer block long token");
this->m->type = tt_bad;
this->m->state = st_token_ready;
this->m->error_message =
"exceeded allowable length while reading token";
}
}
}
if (unread_char) {
input->unreadCh(char_to_unread);
}
if (token.getType() != tt_eof) {
input->setLastOffset(offset);
}
if (token.getType() == tt_bad) {
if (allow_bad) {
QTC::TC("qpdf", "QPDFTokenizer allowing bad token");
} else {
throw QPDFExc(
qpdf_e_damaged_pdf,
input->getName(),
context,
offset,
token.getErrorMessage());
}
}
return token;
}