Pl_Base64.cc
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#include <qpdf/assert_debug.h>
#include <qpdf/Pl_Base64.hh>
#include <qpdf/QIntC.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/Util.hh>
#include <cstring>
#include <stdexcept>
using namespace qpdf;
static char
to_c(unsigned int ch)
{
return static_cast<char>(ch);
}
static unsigned char
to_uc(int ch)
{
return static_cast<unsigned char>(ch);
}
static int
to_i(int i)
{
return static_cast<int>(i);
}
Pl_Base64::Pl_Base64(char const* identifier, Pipeline* next, action_e action) :
Pipeline(identifier, next),
action(action)
{
}
void
Pl_Base64::write(unsigned char const* data, size_t len)
{
in_buffer.append(reinterpret_cast<const char*>(data), len);
}
std::string
Pl_Base64::decode(std::string_view data)
{
Pl_Base64 p("base64-decode", nullptr, a_decode);
p.decode_internal(data);
return std::move(p.out_buffer);
}
std::string
Pl_Base64::encode(std::string_view data)
{
Pl_Base64 p("base64-encode", nullptr, a_encode);
p.encode_internal(data);
return std::move(p.out_buffer);
}
void
Pl_Base64::decode_internal(std::string_view data)
{
auto len = data.size();
auto res = (len / 4u + 1u) * 3u;
out_buffer.reserve(res);
unsigned char const* p = reinterpret_cast<const unsigned char*>(data.data());
while (len > 0) {
if (!util::is_space(to_c(*p))) {
buf[pos++] = *p;
if (pos == 4) {
flush_decode();
}
}
++p;
--len;
}
if (pos > 0) {
for (size_t i = pos; i < 4; ++i) {
buf[i] = '=';
}
flush_decode();
}
qpdf_assert_debug(out_buffer.size() <= res);
}
void
Pl_Base64::encode_internal(std::string_view data)
{
auto len = data.size();
static const size_t max_len = (std::string().max_size() / 4u - 1u) * 3u;
// Change to constexpr once AppImage is build with GCC >= 12
if (len > max_len) {
throw std::length_error(getIdentifier() + ": base64 decode: data exceeds maximum length");
}
auto res = (len / 3u + 1u) * 4u;
out_buffer.reserve(res);
unsigned char const* p = reinterpret_cast<const unsigned char*>(data.data());
while (len > 0) {
buf[pos++] = *p;
if (pos == 3) {
flush_encode();
}
++p;
--len;
}
if (pos > 0) {
flush_encode();
}
qpdf_assert_debug(out_buffer.size() <= res);
}
void
Pl_Base64::flush_decode()
{
if (end_of_data) {
throw std::runtime_error(getIdentifier() + ": base64 decode: data follows pad characters");
}
size_t pad = 0;
int shift = 18;
int outval = 0;
for (size_t i = 0; i < 4; ++i) {
int v = 0;
char ch = to_c(buf[i]);
if (ch >= 'A' && ch <= 'Z') {
v = ch - 'A';
} else if (ch >= 'a' && ch <= 'z') {
v = ch - 'a' + 26;
} else if (ch >= '0' && ch <= '9') {
v = ch - '0' + 52;
} else if (ch == '+' || ch == '-') {
v = 62;
} else if (ch == '/' || ch == '_') {
v = 63;
} else if (ch == '=' && (i == 3 || (i == 2 && buf[3] == '='))) {
++pad;
end_of_data = true;
v = 0;
} else {
throw std::runtime_error(getIdentifier() + ": base64 decode: invalid input");
}
outval |= v << shift;
shift -= 6;
}
unsigned char out[3] = {
to_uc(outval >> 16),
to_uc(0xff & (outval >> 8)),
to_uc(0xff & outval),
};
out_buffer.append(reinterpret_cast<const char*>(out), 3u - pad);
reset();
}
void
Pl_Base64::flush_encode()
{
int outval = ((buf[0] << 16) | (buf[1] << 8) | buf[2]);
unsigned char out[4] = {
to_uc(outval >> 18),
to_uc(0x3f & (outval >> 12)),
to_uc(0x3f & (outval >> 6)),
to_uc(0x3f & outval),
};
for (size_t i = 0; i < 4; ++i) {
int ch = to_i(out[i]);
if (ch < 26) {
ch += 'A';
} else if (ch < 52) {
ch -= 26;
ch += 'a';
} else if (ch < 62) {
ch -= 52;
ch += '0';
} else if (ch == 62) {
ch = '+';
} else if (ch == 63) {
ch = '/';
}
out[i] = to_uc(ch);
}
for (size_t i = 0; i < 3 - pos; ++i) {
out[3 - i] = '=';
}
out_buffer.append(reinterpret_cast<const char*>(out), 4);
reset();
}
void
Pl_Base64::finish()
{
if (action == a_decode) {
decode_internal(in_buffer);
} else {
encode_internal(in_buffer);
}
if (next()) {
in_buffer.clear();
in_buffer.shrink_to_fit();
next()->write(reinterpret_cast<unsigned char const*>(out_buffer.data()), out_buffer.size());
out_buffer.clear();
out_buffer.shrink_to_fit();
next()->finish();
}
}
void
Pl_Base64::reset()
{
pos = 0;
memset(buf, 0, 4);
}