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#include "backup.h"
#include "file.h"
#include "print.h"
#include <errno.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
static int check_files(const options_t *const opts,
const resources_t *const res);
static int allocate_buffers(const options_t *const opts, size_t out_buffer_size,
resources_t *const res);
static int read_sector(FILE *const file, char *const buffer,
uint32_t buffer_size, uint32_t sector_size);
static int write_out_buffer(const char *const buffer, size_t size,
FILE *const file);
static int
check_files(const options_t *const opts, const resources_t *const res)
{
const long in_size = file_size(res->in_file);
if (in_size < 0) {
print_error("cannot get size of input file: %s", strerror(errno));
return 1;
}
const long ref_size = file_size(res->ref_file);
if (ref_size < 0) {
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->sector_size) != 0) {
print_error(
"size of input file and reference file is not multiple of" PRIu32,
opts->sector_size);
return 1;
}
return 0;
}
static int
allocate_buffers(const options_t *const opts, size_t out_buffer_size,
resources_t *const res)
{
if ((res->in_buffer = (char *)malloc(opts->buffer_size)) == NULL) {
print_error("cannot allocate buffer for input file data");
return 1;
} else if ((res->ref_buffer = (char *)malloc(opts->buffer_size)) == NULL) {
print_error("cannot allocate buffer for reference file data");
return 1;
} else if ((res->out_buffer = (char *)malloc(out_buffer_size)) == NULL) {
print_error("cannot allocate buffer for output file data");
return 1;
}
return 0;
}
static int
read_sector(FILE *const file, char *const buffer, uint32_t buffer_size,
uint32_t sector_size)
{
const size_t bytes_read = fread(buffer, 1U, buffer_size, file);
if (ferror(file)) {
print_error("cannot read from input file: %s", strerror(errno));
return 1;
} else if ((bytes_read % sector_size) != 0) {
print_error("data read from input file is not multiple of sector size");
return 1;
} else if (bytes_read != buffer_size) {
print_error("cannot read enough data from input file");
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 options_t *const opts, resources_t *const res)
{
if (check_files(opts, res) != 0) {
return 1;
}
/* The output buffer contains also the offsets */
const size_t out_buffer_size =
((opts->buffer_size / opts->sector_size) * sizeof(uint64_t)) +
opts->buffer_size;
if (allocate_buffers(opts, out_buffer_size, res) != 0) {
return 1;
}
size_t out_buffer_index = 0;
uint64_t input_file_offset = 0;
while (!feof(res->in_file)) {
/* Read the sectors from the input file to the buffer */
if (read_sector(res->in_file, res->in_buffer, opts->buffer_size,
opts->sector_size) != 0) {
return 1;
}
/* Read sectors from the reference file to the buffer */
if (read_sector(res->ref_file, res->ref_buffer, opts->buffer_size,
opts->sector_size) != 0) {
return 1;
}
/* Process sectors in the buffer */
for (size_t buffer_offset = 0; buffer_offset < opts->buffer_size;
buffer_offset += opts->sector_size) {
if (memcmp(res->in_buffer + buffer_offset,
res->ref_buffer + buffer_offset,
opts->sector_size) != 0) {
/* Backup the changed sector */
if (out_buffer_index >= 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) != 1) {
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->sector_size);
out_buffer_index += opts->sector_size;
}
input_file_offset += opts->sector_size;
}
}
/* Write out the output buffer */
if (out_buffer_index >= 0) {
if (write_out_buffer(res->out_buffer, out_buffer_index,
res->out_file) != 1) {
return 1;
}
}
return 0;
}
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