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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 "file.h"
#include "print.h"
#include <errno.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
typedef struct {
FILE *in_file;
FILE *ref_file;
FILE *out_file;
char *in_buffer;
char *ref_buffer;
char *out_buffer;
size_t out_buffer_size;
} resources_backup_t;
static int check_files(const OptionsBackup &opts,
const resources_backup_t *const res);
static int write_out_buffer(const char *const buffer, size_t size,
FILE *const file);
static int
resources_allocate_for_backup(const OptionsBackup &opts,
resources_backup_t *const res)
{
if ((res->in_file = fopen(opts.getInFilePath().c_str(), "r")) == NULL) {
print_error("cannot open input file: %s", strerror(errno));
return 1;
}
if ((res->ref_file = fopen(opts.getRefFilePath().c_str(), "r")) == NULL) {
print_error("cannot open reference file: %s", strerror(errno));
return 1;
}
/* When backing up, the output file is truncated to hold the
* new data
*/
if ((res->out_file = fopen(opts.getOutFilePath().c_str(), "w+")) == NULL) {
print_error("cannot open output file: %s", strerror(errno));
return 1;
}
/* The output buffer contains also the offsets */
res->out_buffer_size =
((opts.getBufferSize() / opts.getSectorSize()) * sizeof(uint64_t)) +
opts.getBufferSize();
// TODO: separate function
if ((res->in_buffer = (char *)malloc(opts.getBufferSize())) == NULL) {
print_error("cannot allocate buffer for input file data");
return 1;
} else if ((res->ref_buffer = (char *)malloc(opts.getBufferSize())) ==
NULL) {
print_error("cannot allocate buffer for reference file data");
return 1;
} else if ((res->out_buffer = (char *)malloc(res->out_buffer_size)) ==
NULL) {
print_error("cannot allocate buffer for output file data");
return 1;
}
return 0;
}
static int
check_files(const OptionsBackup &opts, const resources_backup_t *const res)
{
bool in_size_ok = false;
const size_t in_size = file_size(res->in_file, &in_size_ok);
if (!in_size_ok) {
print_error("cannot get size of input file: %s", strerror(errno));
return 1;
}
bool ref_size_ok = false;
const size_t ref_size = file_size(res->ref_file, &ref_size_ok);
if (!ref_size_ok) {
print_error("cannot get size of reference file: %s", strerror(errno));
return 1;
}
/* Check sizes of the input file and the reference file */
if (in_size != ref_size) {
print_error("input file and reference file differ in size");
return 1;
} else if ((in_size % opts.getSectorSize()) != 0) {
print_error(
"size of input file and reference file is not multiple of %" PRIu32,
opts.getSectorSize());
return 1;
}
return 0;
}
static int
write_out_buffer(const char *const buffer, size_t size, FILE *const file)
{
const size_t bytes_written = fwrite(buffer, 1U, size, file);
if (bytes_written != size) {
print_error("cannot write to output file: %s", strerror(errno));
return 1;
}
return 0;
}
int
backup(const OptionsBackup &opts)
{
resources_backup_t res;
if (resources_allocate_for_backup(opts, &res) != 0) {
return 1;
}
if (check_files(opts, &res) != 0) {
return 1;
}
size_t out_buffer_index = 0;
uint64_t input_file_offset = 0;
for (;;) {
/* Read the sectors from the input and reference files into the buffers
*/
const size_t in_sectors_read =
file_read_sectors(res.in_file, res.in_buffer, opts.getBufferSize(),
opts.getSectorSize());
const size_t ref_sectors_read =
file_read_sectors(res.ref_file, res.ref_buffer,
opts.getBufferSize(), opts.getSectorSize());
if ((in_sectors_read == 0) || (ref_sectors_read == 0)) {
break;
} else if (in_sectors_read != ref_sectors_read) {
print_error(
"cannot read equal amount of sectors from the input files");
return 1;
}
/* Process the sectors in the buffers */
for (size_t sector = 0; sector < in_sectors_read; ++sector) {
const size_t buffer_offset = sector * opts.getSectorSize();
if (memcmp(res.in_buffer + buffer_offset,
res.ref_buffer + buffer_offset,
opts.getSectorSize()) != 0) {
/* Backup the changed sector */
if (out_buffer_index >= res.out_buffer_size) {
/* The output buffer is full. Write it to the output file */
if (write_out_buffer(res.out_buffer, out_buffer_index,
res.out_file) != 0) {
return 1;
}
out_buffer_index = 0;
}
/* Write the next backup record */
const uint64_t o = htole64(input_file_offset);
memcpy(res.out_buffer + out_buffer_index, (void *)&o,
sizeof(o));
out_buffer_index += sizeof(o);
memcpy(res.out_buffer + out_buffer_index,
res.in_buffer + buffer_offset, opts.getSectorSize());
out_buffer_index += opts.getSectorSize();
}
input_file_offset += opts.getSectorSize();
}
}
/* Write out the output buffer */
if (out_buffer_index > 0) {
if (write_out_buffer(res.out_buffer, out_buffer_index, res.out_file) !=
0) {
return 1;
}
}
return 0;
}
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