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/* Copyright 2024 Ján Sučan <jan@jansucan.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "buffered_file.h"
#include "exception.h"
#include <algorithm>
#include <cassert>
#include <cstring>
#include <filesystem>
#include <fstream>
BufferedFileReader::BufferedFileReader(std::istream &istream,
size_t buffer_capacity)
: m_istream(istream), m_buffer_offset(0), m_buffer_size(0),
m_buffer_capacity(buffer_capacity)
{
try {
m_buffer = std::make_unique<char[]>(m_buffer_capacity);
} catch (const std::bad_alloc &e) {
throw BufferedFileError("cannot allocate buffer for input file data");
}
};
size_t
BufferedFileReader::read(char *data, size_t data_size)
{
size_t retry_count{0};
size_t offset{0};
while ((data_size > 0) && (retry_count < 2)) {
char *d;
const size_t r{tryRead(data_size, &d)};
if (r == 0) {
++retry_count;
continue;
}
memcpy(data + offset, d, r);
offset += r;
data_size -= r;
}
return offset;
}
size_t
BufferedFileReader::tryRead(size_t data_size, char **return_data)
{
const size_t size_left{m_buffer_size - m_buffer_offset};
if (size_left == 0) {
refill_buffer();
if (m_buffer_size == 0) {
return 0;
}
}
// There is at least one byte in the buffer
const size_t size_read{read_buffer(data_size, return_data)};
assert(size_read > 0);
return size_read;
};
size_t
BufferedFileReader::read_buffer(size_t data_size, char **return_data)
{
*return_data = static_cast<char *>(m_buffer.get()) + m_buffer_offset;
const size_t size_left{m_buffer_size - m_buffer_offset};
const size_t size_read{std::min(data_size, size_left)};
m_buffer_offset += size_read;
return size_read;
};
void
BufferedFileReader::refill_buffer()
{
m_buffer_size = read_file(m_buffer.get(), m_buffer_capacity);
m_buffer_offset = 0;
};
size_t
BufferedFileReader::read_file(char *data, size_t data_size)
{
m_istream.read(data, data_size);
if (!m_istream.good() && !m_istream.eof()) {
throw BufferedFileError("cannot read from file");
}
return m_istream.gcount();
};
BufferedFileWriter::BufferedFileWriter(std::ostream &ostream,
size_t buffer_capacity)
: m_ostream(ostream), m_buffer_size(0), m_buffer_capacity(buffer_capacity)
{
try {
m_buffer = std::make_unique<char[]>(m_buffer_capacity);
} catch (const std::bad_alloc &e) {
throw BufferedFileError("cannot allocate buffer for output file data");
}
};
BufferedFileWriter::~BufferedFileWriter() { flush_buffer(); };
void
BufferedFileWriter::write(const char *data, size_t data_size)
{
size_t free{m_buffer_capacity - m_buffer_size};
if (data_size <= free) {
// There is free space in the buffer
write_buffer(data, data_size);
} else {
// No free space
flush_buffer();
if (data_size <= m_buffer_capacity) {
// Data fits into the buffer
write_buffer(data, data_size);
} else {
// Doesn't fit
write_file(data, data_size);
}
}
};
void
BufferedFileWriter::write_buffer(const char *data, size_t data_size)
{
memcpy(reinterpret_cast<char *>(m_buffer.get()) + m_buffer_size, data,
data_size);
m_buffer_size += data_size;
};
void
BufferedFileWriter::flush_buffer()
{
write_file(m_buffer.get(), m_buffer_size);
m_buffer_size = 0;
};
void
BufferedFileWriter::write_file(const char *data, size_t data_size)
{
m_ostream.write(data, data_size);
if (!m_ostream) {
throw BufferedFileError("cannot write to output file");
}
};
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