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mirror of https://github.com/qpdf/qpdf.git synced 2024-09-27 20:49:06 +00:00
qpdf/libqpdf/QPDFTokenizer.cc
Jay Berkenbilt ec9e310c9e Refactor QPDFTokenizer's inline image handling
Add a version of expectInlineImage that takes an input source and
searches for EI. This is in preparation for improving the way EI is
found. This commit just refactors the code without changing the
functionality and adds tests to make sure the old and new code behave
identically.
2019-01-31 09:26:37 -05:00

821 lines
20 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 <stdexcept>
#include <string.h>
#include <cstdlib>
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)
{
/// QTC::TC("qpdf", "QPDFTokenizer finder word not followed by delimiter");
return false;
}
if (token_start == 0)
{
// Can't actually happen...we never start the search at the
// beginning of the input.
return false;
}
is->seek(token_start - 1, SEEK_SET);
char prev;
bool prev_okay = ((is->read(&prev, 1) == 1) && is_delimiter(prev));
is->seek(pos, SEEK_SET);
if (! prev_okay)
{
/// QTC::TC("qpdf", "QPDFTokenizer finder word not preceded by delimiter");
return false;
}
return true;
}
QPDFTokenizer::Members::Members() :
pound_special_in_name(true),
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::allowPoundAnywhereInName()
{
QTC::TC("qpdf", "QPDFTokenizer allow pound anywhere in name");
this->m->pound_special_in_name = false;
}
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 = "/";
char const* valstr = this->m->val.c_str() + 1;
for (char const* p = valstr; *p; ++p)
{
if ((*p == '#') && this->m->pound_special_in_name)
{
if (p[1] && p[2] &&
QUtil::is_hex_digit(p[1]) && QUtil::is_hex_digit(p[2]))
{
char num[3];
num[0] = p[1];
num[1] = p[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 += ch;
}
p += 2;
}
else
{
QTC::TC("qpdf", "QPDFTokenizer bad name");
this->m->type = tt_bad;
this->m->error_message = "invalid name token";
nval += *p;
}
}
else
{
nval += *p;
}
}
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 if ((this->m->inline_image_bytes == 0) &&
(len >= 4) &&
isDelimiter(this->m->val.at(len-4)) &&
(this->m->val.at(len-3) == 'E') &&
(this->m->val.at(len-2) == 'I') &&
isDelimiter(this->m->val.at(len-1)))
{
QTC::TC("qpdf", "QPDFTokenizer found EI the old way");
this->m->val.erase(len - 1);
this->m->type = tt_inline_image;
this->m->unread_char = true;
this->m->char_to_unread = ch;
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_inline_image)
{
size_t len = this->m->val.length();
if ((len >= 3) &&
isDelimiter(this->m->val.at(len-3)) &&
(this->m->val.at(len-2) == 'E') &&
(this->m->val.at(len-1) == 'I'))
{
QTC::TC("qpdf", "QPDFTokenizer inline image at EOF the old way");
this->m->type = tt_inline_image;
this->m->state = st_token_ready;
}
}
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()
{
expectInlineImage(PointerHolder<InputSource>());
}
void
QPDFTokenizer::expectInlineImage(PointerHolder<InputSource> input)
{
if (input.getPointer())
{
qpdf_offset_t last_offset = input->getLastOffset();
qpdf_offset_t pos = input->tell();
QPDFWordTokenFinder f(input, "EI");
if (input->findFirst("EI", pos, 0, f))
{
this->m->inline_image_bytes = input->tell() - pos;
}
input->seek(pos, SEEK_SET);
input->setLastOffset(last_offset);
}
if (this->m->state != st_top)
{
throw std::logic_error("QPDFTokenizer::expectInlineImage called"
" when tokenizer is in improper state");
}
this->m->state = st_inline_image;
}
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;
}