2
1
mirror of https://github.com/qpdf/qpdf.git synced 2024-11-14 00:34:03 +00:00
qpdf/libqpdf/QPDFTokenizer.cc
Jay Berkenbilt 43f91f58b8 Improve invalid name token warning message
This message used to only appear for PDF >= 1.2. The invalid name is
valid for PDF 1.0 and 1.1. However, since QPDFWriter may write a newer
version, it's better to detect and warn in all cases. Therefore make
the warning more informative.
2019-08-19 19:48:27 -04:00

879 lines
22 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/QTC.hh>
#include <qpdf/QPDFExc.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/QPDFObjectHandle.hh>
#include <qpdf/QIntC.hh>
#include <stdexcept>
#include <stdlib.h>
#include <string.h>
static bool is_delimiter(char ch)
{
return (strchr(" \t\n\v\f\r()<>[]{}/%", ch) != 0);
}
class QPDFWordTokenFinder: public InputSource::Finder
{
public:
QPDFWordTokenFinder(PointerHolder<InputSource> is,
std::string const& str) :
is(is),
str(str)
{
}
virtual ~QPDFWordTokenFinder()
{
}
virtual bool check();
private:
PointerHolder<InputSource> is;
std::string str;
};
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::Members::~Members()
{
}
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 ch = static_cast<char>(strtol(num, 0, 16));
if (ch == '\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, ch);
}
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(PointerHolder<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(PointerHolder<InputSource> input)
{
if (! input.getPointer())
{
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 (std::string::iterator iter = value.begin();
iter != value.end(); ++iter)
{
char ch = *iter;
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 (((ch < 32) && (! isSpace(ch))) || (ch > 127))
{
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(PointerHolder<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;
}