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AK: Expose Base64 tables from Base64.h

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This change is necessary to move the forgiving base64 decoder to LibWeb
This commit is contained in:
Arda Cinar 2023-01-10 11:34:29 +03:00 committed by Linus Groh
parent 6e93d89ee3
commit 4ab2954210
Notes: sideshowbarker 2024-07-17 03:03:15 +09:00 
Author: https://github.com/kuzux
Commit: https://github.com/SerenityOS/serenity/commit/4ab2954210
Pull-request: https://github.com/SerenityOS/serenity/pull/16711
Issue: https://github.com/SerenityOS/serenity/issues/16638
Reviewed-by: https://github.com/linusg
Reviewed-by: https://github.com/nico
Reviewed-by: https://github.com/trflynn89
2 changed files with 29 additions and 27 deletions
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35
AK/Base64.cpp
View file

@ -15,29 +15,6 @@
namespace AK { namespace AK {
static constexpr Array alphabet = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/'
};
static consteval auto make_lookup_table()
{
Array<i16, 256> table;
table.fill(-1);
for (size_t i = 0; i < alphabet.size(); ++i) {
table[alphabet[i]] = static_cast<i16>(i);
}
return table;
}
static constexpr auto alphabet_lookup_table = make_lookup_table();
size_t calculate_base64_decoded_length(StringView input) size_t calculate_base64_decoded_length(StringView input)
{ {
return input.length() * 3 / 4; return input.length() * 3 / 4;
@ -50,6 +27,8 @@ size_t calculate_base64_encoded_length(ReadonlyBytes input)
ErrorOr<ByteBuffer> decode_base64(StringView input) ErrorOr<ByteBuffer> decode_base64(StringView input)
{ {
auto alphabet_lookup_table = base64_lookup_table();
auto get = [&](size_t& offset, bool* is_padding, bool& parsed_something) -> ErrorOr<u8> { auto get = [&](size_t& offset, bool* is_padding, bool& parsed_something) -> ErrorOr<u8> {
while (offset < input.length() && is_ascii_space(input[offset])) while (offset < input.length() && is_ascii_space(input[offset]))
++offset; ++offset;
@ -128,10 +107,10 @@ ErrorOr<String> encode_base64(ReadonlyBytes input)
const u8 index2 = ((in1 << 2) | (in2 >> 6)) & 0x3f; const u8 index2 = ((in1 << 2) | (in2 >> 6)) & 0x3f;
const u8 index3 = in2 & 0x3f; const u8 index3 = in2 & 0x3f;
char const out0 = alphabet[index0]; char const out0 = base64_alphabet[index0];
char const out1 = alphabet[index1]; char const out1 = base64_alphabet[index1];
char const out2 = is_16bit ? '=' : alphabet[index2]; char const out2 = is_16bit ? '=' : base64_alphabet[index2];
char const out3 = is_8bit ? '=' : alphabet[index3]; char const out3 = is_8bit ? '=' : base64_alphabet[index3];
TRY(output.try_append(out0)); TRY(output.try_append(out0));
TRY(output.try_append(out1)); TRY(output.try_append(out1));
@ -202,6 +181,8 @@ ErrorOr<ByteBuffer> decode_forgiving_base64(StringView input)
accumulated_bits = 0; accumulated_bits = 0;
}; };
auto alphabet_lookup_table = base64_lookup_table();
// 7. Let position be a position variable for data, initially pointing at the start of data. // 7. Let position be a position variable for data, initially pointing at the start of data.
// 8. While position does not point past the end of data: // 8. While position does not point past the end of data:
for (auto point : data) { for (auto point : data) {

21
AK/Base64.h
View file

@ -13,6 +13,27 @@
namespace AK { namespace AK {
constexpr Array base64_alphabet = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/'
};
consteval auto base64_lookup_table()
{
Array<i16, 256> table;
table.fill(-1);
for (size_t i = 0; i < base64_alphabet.size(); ++i) {
table[base64_alphabet[i]] = static_cast<i16>(i);
}
return table;
}
[[nodiscard]] size_t calculate_base64_decoded_length(StringView); [[nodiscard]] size_t calculate_base64_decoded_length(StringView);
[[nodiscard]] size_t calculate_base64_encoded_length(ReadonlyBytes); [[nodiscard]] size_t calculate_base64_encoded_length(ReadonlyBytes);