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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
/**
* @class vtkBase64Utilities
* @brief base64 encode and decode utilities.
*
* vtkBase64Utilities implements base64 encoding and decoding.
*/
#ifndef vtkBase64Utilities_h
#define vtkBase64Utilities_h
#include "vtkIOCoreModule.h" // For export macro
#include "vtkObject.h"
VTK_ABI_NAMESPACE_BEGIN
class VTKIOCORE_EXPORT vtkBase64Utilities : public vtkObject
{
public:
static vtkBase64Utilities* New();
vtkTypeMacro(vtkBase64Utilities, vtkObject);
void PrintSelf(ostream& os, vtkIndent indent) override;
/**
* Encode 3 bytes into 4 bytes
*/
static void EncodeTriplet(unsigned char i0, unsigned char i1, unsigned char i2, unsigned char* o0,
unsigned char* o1, unsigned char* o2, unsigned char* o3);
/**
* Encode 2 bytes into 4 bytes
*/
static void EncodePair(unsigned char i0, unsigned char i1, unsigned char* o0, unsigned char* o1,
unsigned char* o2, unsigned char* o3);
/**
* Encode 1 byte into 4 bytes
*/
static void EncodeSingle(
unsigned char i0, unsigned char* o0, unsigned char* o1, unsigned char* o2, unsigned char* o3);
/**
* Encode 'length' bytes from the input buffer and store the
* encoded stream into the output buffer. Return the length of
* the encoded stream. Note that the output buffer must be allocated
* by the caller (length * 1.5 should be a safe estimate).
* If 'mark_end' is true then an extra set of 4 bytes is added
* to the end of the stream if the input is a multiple of 3 bytes.
* These bytes are invalid chars and therefore they will stop the decoder
* thus enabling the caller to decode a stream without actually knowing
* how much data to expect (if the input is not a multiple of 3 bytes then
* the extra padding needed to complete the encode 4 bytes will stop the
* decoding anyway).
*/
static unsigned long Encode(
const unsigned char* input, unsigned long length, unsigned char* output, int mark_end = 0);
/**
* Decode 4 bytes into 3 bytes.
* Return the number of bytes actually decoded (0 to 3, inclusive).
*/
static int DecodeTriplet(unsigned char i0, unsigned char i1, unsigned char i2, unsigned char i3,
unsigned char* o0, unsigned char* o1, unsigned char* o2);
/**
* Decode 4 bytes at a time from the input buffer and store the decoded
* stream into the output buffer. The required output buffer size must be
* determined and allocated by the caller. The needed output space is
* always less than the input buffer size, so a good first order
* approximation is to allocate the same size. Base64 encoding is about
* 4/3 overhead, so a tighter bound is possible.
* Return the number of bytes atually placed into the output buffer.
*/
static size_t DecodeSafely(
const unsigned char* input, size_t inputLen, unsigned char* output, size_t outputLen);
protected:
vtkBase64Utilities() = default;
~vtkBase64Utilities() override = default;
private:
vtkBase64Utilities(const vtkBase64Utilities&) = delete;
void operator=(const vtkBase64Utilities&) = delete;
};
VTK_ABI_NAMESPACE_END
#endif
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