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/*
This file is part of ethash.
ethash is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
ethash is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ethash. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file io.c
* @author Lefteris Karapetsas <lefteris@ethdev.com>
* @date 2015
*/
#include "io.h"
#include <string.h>
#include <stdio.h>
#include <errno.h>
enum ethash_io_rc ethash_io_prepare(
char const* dirname,
ethash_h256_t const seedhash,
FILE** output_file,
uint64_t file_size,
bool force_create
)
{
char mutable_name[DAG_MUTABLE_NAME_MAX_SIZE];
enum ethash_io_rc ret = ETHASH_IO_FAIL;
// reset errno before io calls
errno = 0;
// assert directory exists
if (!ethash_mkdir(dirname)) {
ETHASH_CRITICAL("Could not create the ethash directory");
goto end;
}
ethash_io_mutable_name(ETHASH_REVISION, &seedhash, mutable_name);
char* tmpfile = ethash_io_create_filename(dirname, mutable_name, strlen(mutable_name));
if (!tmpfile) {
ETHASH_CRITICAL("Could not create the full DAG pathname");
goto end;
}
FILE *f;
if (!force_create) {
// try to open the file
f = ethash_fopen(tmpfile, "rb+");
if (f) {
size_t found_size;
if (!ethash_file_size(f, &found_size)) {
fclose(f);
ETHASH_CRITICAL("Could not query size of DAG file: \"%s\"", tmpfile);
goto free_memo;
}
if (file_size != found_size - ETHASH_DAG_MAGIC_NUM_SIZE) {
fclose(f);
ret = ETHASH_IO_MEMO_SIZE_MISMATCH;
goto free_memo;
}
// compare the magic number, no need to care about endianess since it's local
uint64_t magic_num;
if (fread(&magic_num, ETHASH_DAG_MAGIC_NUM_SIZE, 1, f) != 1) {
// I/O error
fclose(f);
ETHASH_CRITICAL("Could not read from DAG file: \"%s\"", tmpfile);
ret = ETHASH_IO_MEMO_SIZE_MISMATCH;
goto free_memo;
}
if (magic_num != ETHASH_DAG_MAGIC_NUM) {
fclose(f);
ret = ETHASH_IO_MEMO_SIZE_MISMATCH;
goto free_memo;
}
ret = ETHASH_IO_MEMO_MATCH;
goto set_file;
}
}
// file does not exist, will need to be created
f = ethash_fopen(tmpfile, "wb+");
if (!f) {
ETHASH_CRITICAL("Could not create DAG file: \"%s\"", tmpfile);
goto free_memo;
}
// make sure it's of the proper size
if (fseek(f, (long int)(file_size + ETHASH_DAG_MAGIC_NUM_SIZE - 1), SEEK_SET) != 0) {
fclose(f);
ETHASH_CRITICAL("Could not seek to the end of DAG file: \"%s\". Insufficient space?", tmpfile);
goto free_memo;
}
if (fputc('\n', f) == EOF) {
fclose(f);
ETHASH_CRITICAL("Could not write in the end of DAG file: \"%s\". Insufficient space?", tmpfile);
goto free_memo;
}
if (fflush(f) != 0) {
fclose(f);
ETHASH_CRITICAL("Could not flush at end of DAG file: \"%s\". Insufficient space?", tmpfile);
goto free_memo;
}
ret = ETHASH_IO_MEMO_MISMATCH;
goto set_file;
ret = ETHASH_IO_MEMO_MATCH;
set_file:
*output_file = f;
free_memo:
free(tmpfile);
end:
return ret;
}
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