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llvm-mirror/include/llvm/Support/Base64.h
serge-sans-paille 0f08a282ef Syndicate, test and fix base64 implementation
llvm/Support/Base64, fix its implementation and provide a decent test suite.

Previous implementation code was using + operator instead of | to combine

results, which is a problem when shifting signed values. (0xFF << 16) is
implicitly converted to a (signed) int, and thus results in 0xffff0000,
h is
negative. Combining negative numbers with a + in that context is not what we
want to do.

This is a recommit of 5a1958f2673f8c771e406a7e309e160b432c9a79 with UB removved.

This fixes https://github.com/llvm/llvm-project/issues/149.

Differential Revision: https://reviews.llvm.org/D75057
2020-03-03 12:17:53 +01:00

57 lines
1.8 KiB
C++

//===--- Base64.h - Base64 Encoder/Decoder ----------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file provides generic base64 encoder/decoder.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_BASE64_H
#define LLVM_SUPPORT_BASE64_H
#include <string>
namespace llvm {
template <class InputBytes> std::string encodeBase64(InputBytes const &Bytes) {
static const char Table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
std::string Buffer;
Buffer.resize(((Bytes.size() + 2) / 3) * 4);
size_t i = 0, j = 0;
for (size_t n = Bytes.size() / 3 * 3; i < n; i += 3, j += 4) {
uint32_t x = ((unsigned char)Bytes[i] << 16) |
((unsigned char)Bytes[i + 1] << 8) |
(unsigned char)Bytes[i + 2];
Buffer[j + 0] = Table[(x >> 18) & 63];
Buffer[j + 1] = Table[(x >> 12) & 63];
Buffer[j + 2] = Table[(x >> 6) & 63];
Buffer[j + 3] = Table[x & 63];
}
if (i + 1 == Bytes.size()) {
uint32_t x = ((unsigned char)Bytes[i] << 16);
Buffer[j + 0] = Table[(x >> 18) & 63];
Buffer[j + 1] = Table[(x >> 12) & 63];
Buffer[j + 2] = '=';
Buffer[j + 3] = '=';
} else if (i + 2 == Bytes.size()) {
uint32_t x =
((unsigned char)Bytes[i] << 16) | ((unsigned char)Bytes[i + 1] << 8);
Buffer[j + 0] = Table[(x >> 18) & 63];
Buffer[j + 1] = Table[(x >> 12) & 63];
Buffer[j + 2] = Table[(x >> 6) & 63];
Buffer[j + 3] = '=';
}
return Buffer;
}
} // end namespace llvm
#endif