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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>
int
backup(const options_t *const opts, 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;
}
/* Allocate the buffers */
/* 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 ((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;
}
size_t out_buffer_index = 0;
uint64_t offset = 0;
for (;;) {
/* Read the sectors from the input file to the buffer */
const size_t in_read =
fread(res->in_buffer, 1U, opts->buffer_size, res->in_file);
if ((in_read % opts->sector_size) != 0) {
print_error(
"data read from input file is not multiple of sector size");
return 1;
} else if (ferror(res->in_file)) {
print_error("cannot read from input file: %s", strerror(errno));
return 1;
}
/* Read sectors from the reference file to the buffer */
const size_t ref_read =
fread(res->ref_buffer, 1U, opts->buffer_size, res->ref_file);
if ((ref_read % opts->sector_size) != 0) {
print_error(
"data read from reference file is not multiple of sector size");
return 1;
} else if (ferror(res->ref_file)) {
print_error("%s", strerror(errno));
return 1;
}
if (in_read != ref_read) {
print_error(
"data read from input file and reference file differ in size");
return 1;
}
/* Process sectors in the buffer */
for (size_t i = 0; i < in_read; i += opts->sector_size) {
/* Compare the sectors */
int changed = 0;
const size_t j_end = i + opts->sector_size;
for (size_t j = i; j < j_end; ++j) {
if (res->in_buffer[j] != res->ref_buffer[j]) {
changed = 1;
break;
}
}
if (changed) {
/* Write changed sector */
if (out_buffer_index >= out_buffer_size) {
/* The output buffer is full. Write it to the
* output file.
*/
const size_t x = fwrite(res->out_buffer, 1U,
out_buffer_index, res->out_file);
if (x != out_buffer_index) {
print_error("cannot write to output file: %s",
strerror(errno));
return 1;
}
out_buffer_index = 0;
}
const uint64_t o = htole64(offset);
memcpy(res->out_buffer + out_buffer_index, (void *)&o,
sizeof(o));
memcpy(res->out_buffer + out_buffer_index, &(res->in_buffer[i]),
opts->sector_size);
out_buffer_index += sizeof(o) + opts->sector_size;
}
offset += opts->sector_size;
}
if (feof(res->in_file)) {
break;
}
}
/* Write out the output buffer */
if (out_buffer_index >= 0) {
const size_t x =
fwrite(res->out_buffer, 1U, out_buffer_index, res->out_file);
if (x != out_buffer_index) {
print_error("cannot write to output file: %s", strerror(errno));
return 1;
}
}
return 0;
}
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