/
base64-inl.h
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/
base64-inl.h
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#ifndef SRC_BASE64_INL_H_
#define SRC_BASE64_INL_H_
#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
#include "util.h"
namespace node {
extern const int8_t unbase64_table[256];
inline static int8_t unbase64(uint8_t x) {
return unbase64_table[x];
}
inline uint32_t ReadUint32BE(const unsigned char* p) {
return static_cast<uint32_t>(p[0] << 24U) |
static_cast<uint32_t>(p[1] << 16U) |
static_cast<uint32_t>(p[2] << 8U) |
static_cast<uint32_t>(p[3]);
}
template <typename TypeName>
bool base64_decode_group_slow(char* const dst, const size_t dstlen,
const TypeName* const src, const size_t srclen,
size_t* const i, size_t* const k) {
uint8_t hi;
uint8_t lo;
#define V(expr) \
for (;;) { \
const uint8_t c = src[*i]; \
lo = unbase64(c); \
*i += 1; \
if (lo < 64) \
break; /* Legal character. */ \
if (c == '=' || *i >= srclen) \
return false; /* Stop decoding. */ \
} \
expr; \
if (*i >= srclen) \
return false; \
if (*k >= dstlen) \
return false; \
hi = lo;
V(/* Nothing. */);
V(dst[(*k)++] = ((hi & 0x3F) << 2) | ((lo & 0x30) >> 4));
V(dst[(*k)++] = ((hi & 0x0F) << 4) | ((lo & 0x3C) >> 2));
V(dst[(*k)++] = ((hi & 0x03) << 6) | ((lo & 0x3F) >> 0));
#undef V
return true; // Continue decoding.
}
template <typename TypeName>
size_t base64_decode_fast(char* const dst, const size_t dstlen,
const TypeName* const src, const size_t srclen,
const size_t decoded_size) {
const size_t available = dstlen < decoded_size ? dstlen : decoded_size;
const size_t max_k = available / 3 * 3;
size_t max_i = srclen / 4 * 4;
size_t i = 0;
size_t k = 0;
while (i < max_i && k < max_k) {
const unsigned char txt[] = {
static_cast<unsigned char>(unbase64(src[i + 0])),
static_cast<unsigned char>(unbase64(src[i + 1])),
static_cast<unsigned char>(unbase64(src[i + 2])),
static_cast<unsigned char>(unbase64(src[i + 3])),
};
const uint32_t v = ReadUint32BE(txt);
// If MSB is set, input contains whitespace or is not valid base64.
if (v & 0x80808080) {
if (!base64_decode_group_slow(dst, dstlen, src, srclen, &i, &k))
return k;
max_i = i + (srclen - i) / 4 * 4; // Align max_i again.
} else {
dst[k + 0] = ((v >> 22) & 0xFC) | ((v >> 20) & 0x03);
dst[k + 1] = ((v >> 12) & 0xF0) | ((v >> 10) & 0x0F);
dst[k + 2] = ((v >> 2) & 0xC0) | ((v >> 0) & 0x3F);
i += 4;
k += 3;
}
}
if (i < srclen && k < dstlen) {
base64_decode_group_slow(dst, dstlen, src, srclen, &i, &k);
}
return k;
}
} // namespace node
#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
#endif // SRC_BASE64_INL_H_