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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#include "vtkBase64InputStream.h"
#include "vtkBase64Utilities.h"
#include "vtkObjectFactory.h"
//------------------------------------------------------------------------------
VTK_ABI_NAMESPACE_BEGIN
vtkStandardNewMacro(vtkBase64InputStream);
//------------------------------------------------------------------------------
vtkBase64InputStream::vtkBase64InputStream()
{
this->BufferLength = 0;
}
//------------------------------------------------------------------------------
vtkBase64InputStream::~vtkBase64InputStream() = default;
//------------------------------------------------------------------------------
void vtkBase64InputStream::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os, indent);
}
//------------------------------------------------------------------------------
int vtkBase64InputStream::DecodeTriplet(unsigned char& c0, unsigned char& c1, unsigned char& c2)
{
// Read the 4 bytes encoding this triplet from the stream.
unsigned char in[4];
this->Stream->read(reinterpret_cast<char*>(in), 4);
if (this->Stream->gcount() < 4)
{
return 0;
}
return vtkBase64Utilities::DecodeTriplet(in[0], in[1], in[2], in[3], &c0, &c1, &c2);
}
//------------------------------------------------------------------------------
void vtkBase64InputStream::StartReading()
{
this->Superclass::StartReading();
this->BufferLength = 0;
}
//------------------------------------------------------------------------------
void vtkBase64InputStream::EndReading() {}
//------------------------------------------------------------------------------
int vtkBase64InputStream::Seek(vtkTypeInt64 offset)
{
vtkTypeInt64 triplet = offset / 3;
int skipLength = offset % 3;
// Seek to the beginning of the encoded triplet containing the
// offset.
std::streamoff off = static_cast<std::streamoff>(this->StreamStartPosition + (triplet * 4));
if (!this->Stream->seekg(off, std::ios::beg))
{
return 0;
}
// Decode the first triplet if it is partially skipped.
if (skipLength == 0)
{
this->BufferLength = 0;
}
else if (skipLength == 1)
{
unsigned char c;
this->BufferLength = this->DecodeTriplet(c, this->Buffer[0], this->Buffer[1]) - 1;
}
else
{
unsigned char c[2];
this->BufferLength = this->DecodeTriplet(c[0], c[1], this->Buffer[0]) - 2;
}
// A DecodeTriplet call may have failed to read the stream.
// If so, the current buffer length will be negative.
return ((this->BufferLength >= 0) ? 1 : 0);
}
//------------------------------------------------------------------------------
size_t vtkBase64InputStream::Read(void* data_in, size_t length)
{
unsigned char* data = static_cast<unsigned char*>(data_in);
unsigned char* out = data;
unsigned char* end = out + length;
// If the previous read ended before filling buffer, don't read
// more.
if (this->BufferLength < 0)
{
return 0;
}
// Use leftover characters from a previous decode.
if ((out != end) && (this->BufferLength == 2))
{
*out++ = this->Buffer[0];
this->Buffer[0] = this->Buffer[1];
this->BufferLength = 1;
}
if ((out != end) && (this->BufferLength == 1))
{
*out++ = this->Buffer[0];
this->BufferLength = 0;
}
// Decode all complete triplets.
while ((end - out) >= 3)
{
int len = this->DecodeTriplet(out[0], out[1], out[2]);
out += len;
if (len < 3)
{
this->BufferLength = len - 3;
return (out - data);
}
}
// Decode the last triplet and save leftover characters in the buffer.
if ((end - out) == 2)
{
int len = this->DecodeTriplet(out[0], out[1], this->Buffer[0]);
this->BufferLength = len - 2;
if (len > 2)
{
out += 2;
}
else
{
out += len;
}
}
else if ((end - out) == 1)
{
int len = this->DecodeTriplet(out[0], this->Buffer[0], this->Buffer[1]);
this->BufferLength = len - 1;
if (len > 1)
{
out += 1;
}
else
{
out += len;
}
}
return (out - data);
}
VTK_ABI_NAMESPACE_END
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