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Merge pull request #936 from m-holger/hex

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Refactor QUtil::hex_decode
This commit is contained in:
Jay Berkenbilt 2023-04-01 09:31:28 -04:00 committed by GitHub
commit ef6f5a97f4
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 39 additions and 65 deletions
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17
include/qpdf/QUtil.hh
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@ -223,6 +223,11 @@ namespace QUtil
QPDF_DLL
std::string hex_decode(std::string const&);
// Decode a single hex digit into a char in the range 0 <= char < 16. Return
// a char >= 16 if digit is not a valid hex digit.
QPDF_DLL
inline constexpr char hex_decode_char(char digit) noexcept;
// Set stdin, stdout to binary mode
QPDF_DLL
void binary_stdout();
@ -550,8 +555,7 @@ namespace QUtil
inline bool
QUtil::is_hex_digit(char ch)
{
return ('0' <= ch && ch <= '9') || ('a' <= ch && ch <= 'f') ||
('A' <= ch && ch <= 'F');
return hex_decode_char(ch) < '\20';
}
inline bool
@ -603,4 +607,13 @@ QUtil::hex_encode_char(char c)
'#', hexchars[static_cast<unsigned char>(c) >> 4], hexchars[c & 0x0f]};
}
inline constexpr char
QUtil::hex_decode_char(char digit) noexcept
{
return digit <= '9' && digit >= '0'
? char(digit - '0')
: (digit >= 'a' ? char(digit - 'a' + 10)
: (digit >= 'A' ? char(digit - 'A' + 10) : '\20'));
}
#endif // QUTIL_HH

8
libqpdf/JSON.cc
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@ -1121,12 +1121,8 @@ JSONParser::getToken()
case ls_u4:
using ui = unsigned int;
if ('0' <= *p && *p <= '9') {
u_value = 16 * u_value + (ui(*p) - ui('0'));
} else if ('a' <= *p && *p <= 'f') {
u_value = 16 * u_value + (10 + ui(*p) - ui('a'));
} else if ('A' <= *p && *p <= 'F') {
u_value = 16 * u_value + (10 + ui(*p) - ui('A'));
if (ui val = ui(QUtil::hex_decode_char(*p)); val < 16) {
u_value = 16 * u_value + val;
} else {
tokenError();
}

48
libqpdf/QPDFTokenizer.cc
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@ -449,18 +449,9 @@ QPDFTokenizer::inNameHex1(char ch)
{
this->hex_char = ch;
if ('0' <= ch && ch <= '9') {
this->char_code = 16 * (int(ch) - int('0'));
if (char hval = QUtil::hex_decode_char(ch); hval < '\20') {
this->char_code = int(hval) << 4;
this->state = st_name_hex2;
} else if ('A' <= ch && ch <= 'F') {
this->char_code = 16 * (10 + int(ch) - int('A'));
this->state = st_name_hex2;
} else if ('a' <= ch && ch <= 'f') {
this->char_code = 16 * (10 + int(ch) - int('a'));
this->state = st_name_hex2;
} else {
QTC::TC("qpdf", "QPDFTokenizer bad name 1");
this->error_message = "name with stray # will not work with PDF >= 1.2";
@ -475,15 +466,8 @@ QPDFTokenizer::inNameHex1(char ch)
void
QPDFTokenizer::inNameHex2(char ch)
{
if ('0' <= ch && ch <= '9') {
this->char_code += int(ch) - int('0');
} else if ('A' <= ch && ch <= 'F') {
this->char_code += 10 + int(ch) - int('A');
} else if ('a' <= ch && ch <= 'f') {
this->char_code += 10 + int(ch) - int('a');
if (char hval = QUtil::hex_decode_char(ch); hval < '\20') {
this->char_code |= int(hval);
} else {
QTC::TC("qpdf", "QPDFTokenizer bad name 2");
this->error_message = "name with stray # will not work with PDF >= 1.2";
@ -675,16 +659,8 @@ QPDFTokenizer::inLiteral(char ch)
void
QPDFTokenizer::inHexstring(char ch)
{
if ('0' <= ch && ch <= '9') {
this->char_code = 16 * (int(ch) - int('0'));
this->state = st_in_hexstring_2nd;
} else if ('A' <= ch && ch <= 'F') {
this->char_code = 16 * (10 + int(ch) - int('A'));
this->state = st_in_hexstring_2nd;
} else if ('a' <= ch && ch <= 'f') {
this->char_code = 16 * (10 + int(ch) - int('a'));
if (char hval = QUtil::hex_decode_char(ch); hval < '\20') {
this->char_code = int(hval) << 4;
this->state = st_in_hexstring_2nd;
} else if (ch == '>') {
@ -706,16 +682,8 @@ QPDFTokenizer::inHexstring(char ch)
void
QPDFTokenizer::inHexstring2nd(char ch)
{
if ('0' <= ch && ch <= '9') {
this->val += char(this->char_code + int(ch) - int('0'));
this->state = st_in_hexstring;
} else if ('A' <= ch && ch <= 'F') {
this->val += char(this->char_code + 10 + int(ch) - int('A'));
this->state = st_in_hexstring;
} else if ('a' <= ch && ch <= 'f') {
this->val += char(this->char_code + 10 + int(ch) - int('a'));
if (char hval = QUtil::hex_decode_char(ch); hval < '\20') {
this->val += char(this->char_code) | hval;
this->state = st_in_hexstring;
} else if (ch == '>') {

31
libqpdf/QUtil.cc
View File

@ -783,28 +783,25 @@ std::string
QUtil::hex_decode(std::string const& input)
{
std::string result;
size_t pos = 0;
// We know result.size() <= 0.5 * input.size() + 1. However, reserving
// string space for this upper bound has a negative impact.
bool first = true;
char decoded;
for (auto ch: input) {
bool skip = false;
if ((ch >= 'A') && (ch <= 'F')) {
ch = QIntC::to_char(ch - 'A' + 10);
} else if ((ch >= 'a') && (ch <= 'f')) {
ch = QIntC::to_char(ch - 'a' + 10);
} else if ((ch >= '0') && (ch <= '9')) {
ch = QIntC::to_char(ch - '0');
} else {
skip = true;
}
if (!skip) {
if (pos == 0) {
result.push_back(static_cast<char>(ch << 4));
pos = 1;
ch = hex_decode_char(ch);
if (ch < '\20') {
if (first) {
decoded = static_cast<char>(ch << 4);
first = false;
} else {
result[result.length() - 1] |= ch;
pos = 0;
result.push_back(decoded | ch);
first = true;
}
}
}
if (!first) {
result.push_back(decoded);
}
return result;
}