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#include "restore.h"
#include "file.h"
#include "print.h"
#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static bool
is_reference_file_valid(resources_t *const res, uint32_t sector_size)
{
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 false;
} else if (ref_size == 0) {
print_error("reference file is empty");
return false;
} else if ((ref_size % (sizeof(uint64_t) + sector_size)) != 0) {
/* The reference file must hold equally sized sectors and the
* offset of each of them
*/
print_error(
"reference file has size that cannot contain valid diff data");
return false;
}
const long out_size = file_size(res->out_file);
if (out_size < 0) {
print_error("cannot get size of output file: %s", strerror(errno));
return 1;
}
uint64_t ref_offset = 0;
uint64_t prev_out_offset;
/* Scan the reference file and check */
for (;;) {
uint64_t out_offset;
/* Read the next offset */
const size_t ref_read =
fread(&out_offset, sizeof(out_offset), 1U, res->ref_file);
out_offset = le64toh(out_offset);
if (feof(res->ref_file)) {
break;
} else if ((ref_read != 1U) || ferror(res->ref_file)) {
print_error("cannot read from reference file: %s", strerror(errno));
return false;
} else if (((ref_offset != 0) && (out_offset <= prev_out_offset)) ||
((out_offset + sector_size) > out_size)) {
/* The offset must be higher than the previous one and it
* must point into the file
*/
print_error("reference file is not valid");
return false;
} else if (fseek(res->ref_file, sector_size, SEEK_CUR) != 0) {
print_error("cannot seek in reference file: %s", strerror(errno));
return false;
}
prev_out_offset = out_offset;
}
if (ftell(res->ref_file) != ref_size) {
/* The reference file must be read completely */
print_error("reference file is not valid");
return false;
} else if (fseek(res->ref_file, 0L, SEEK_SET) != 0) {
/* The file must be prepared for the restoring */
print_error("cannot seek in reference file: %s", strerror(errno));
return false;
}
return true;
}
int
restore(const options_t *const opts, resources_t *const res)
{
/* Check validity of the reference file */
if (!is_reference_file_valid(res, opts->sector_size)) {
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;
}
/* Allocate the buffer for data from the reference file */
/* The reference buffer contains also the offsets */
const size_t ref_buffer_size =
((opts->buffer_size / opts->sector_size) * sizeof(uint64_t)) +
opts->buffer_size;
if ((res->ref_buffer = (char *)malloc(ref_buffer_size)) == NULL) {
print_error("cannot allocate buffer for reference file data");
return 1;
}
/* Restore data from the differential image */
uint64_t out_offset;
for (;;) {
/* Read data of the offset and the next sector */
const size_t ref_read =
fread(res->ref_buffer, ref_buffer_size, 1U, res->ref_file);
if (feof(res->ref_file)) {
break;
} else if ((ref_read != 1U) || ferror(res->ref_file)) {
print_error("cannot read from reference file: %s", strerror(errno));
return 1;
}
/* Get offset */
out_offset = le64toh(*((uint64_t *)res->ref_buffer));
if (fseek(res->out_file, out_offset, SEEK_SET) != 0) {
print_error("cannot seek in output file: %s", strerror(errno));
return 1;
}
/* Write the sector data to the output file */
const size_t out_written = fwrite(res->ref_buffer + sizeof(out_offset),
opts->sector_size, 1U, res->out_file);
if (out_written != 1U) {
print_error("cannot write to output file: %s", strerror(errno));
return 1;
}
}
/* The reference file must be read completely */
if (ftell(res->ref_file) != ref_size) {
print_error("reference file is not valid");
return 1;
}
return 0;
}
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