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/* Copyright 2021 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 "backup.h"
#include "buffered_file.h"
#include <cstring>
#include <fstream>
static void check_files(const OptionsBackup &opts);
static void
check_files(const OptionsBackup &opts)
{
size_t in_size{0};
try {
in_size = std::filesystem::file_size(opts.getInFilePath());
} catch (const std::exception &e) {
throw BackupError("cannot get size of input file: " +
std::string(e.what()));
}
size_t base_size{0};
try {
base_size = std::filesystem::file_size(opts.getBaseFilePath());
} catch (const std::exception &e) {
throw BackupError("cannot get size of base file: " +
std::string(e.what()));
}
/* Check sizes of the input file and the base file */
if (in_size != base_size) {
throw BackupError("input file and base file differ in size");
} else if ((in_size % opts.getSectorSize()) != 0) {
throw BackupError(
"size of input file and base file is not multiple of " +
std::to_string(opts.getSectorSize()));
}
}
void
backup(const OptionsBackup &opts)
{
check_files(opts);
BufferedFileReader in_file(opts.getInFilePath(), opts.getBufferSize());
BufferedFileReader base_file(opts.getBaseFilePath(), opts.getBufferSize());
BufferedFileWriter out_file(opts.getOutFilePath(), opts.getBufferSize());
std::unique_ptr<char[]> in_buffer;
try {
in_buffer = std::make_unique<char[]>(opts.getSectorSize());
} catch (const std::bad_alloc &e) {
throw BackupError("cannot allocate sector buffer for input file data");
}
std::unique_ptr<char[]> base_buffer;
try {
base_buffer = std::make_unique<char[]>(opts.getSectorSize());
} catch (const std::bad_alloc &e) {
throw BackupError("cannot allocate sector buffer for base file data");
}
uint64_t input_file_offset{0};
for (;;) {
// Read sectors
const size_t in_read_size =
in_file.read(in_buffer.get(), opts.getSectorSize());
const size_t base_read_size =
base_file.read(base_buffer.get(), opts.getSectorSize());
if (in_read_size != base_read_size) {
throw BackupError(
"cannot read equal amount of bytes from the input files");
} else if (in_read_size == 0) {
break;
} else if (in_read_size != opts.getSectorSize()) {
throw BackupError("cannot read full sectors from the input files");
}
// Check for difference
const bool differ = (memcmp(in_buffer.get(), base_buffer.get(),
opts.getSectorSize()) != 0);
if (differ) {
// Backup sector
uint64_t o = htole64(input_file_offset);
out_file.write(reinterpret_cast<char *>(&o), sizeof(o));
out_file.write(in_buffer.get(), opts.getSectorSize());
}
input_file_offset += opts.getSectorSize();
}
}
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