/*
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 .
*/
/** @file io.h
* @author Lefteris Karapetsas
* @date 2015
*/
#pragma once
#include
#include
#include
#include
#ifdef __cplusplus
#define __STDC_FORMAT_MACROS 1
#endif
#include
#include "endian.h"
#include "ethash.h"
#ifdef __cplusplus
extern "C" {
#endif
// Maximum size for mutable part of DAG file name
// 6 is for "full-R", the suffix of the filename
// 10 is for maximum number of digits of a uint32_t (for REVISION)
// 1 is for - and 16 is for the first 16 hex digits for first 8 bytes of
// the seedhash and last 1 is for the null terminating character
// Reference: https://github.com/ethereum/wiki/wiki/Ethash-DAG
#define DAG_MUTABLE_NAME_MAX_SIZE (6 + 10 + 1 + 16 + 1)
/// Possible return values of @see ethash_io_prepare
enum ethash_io_rc {
ETHASH_IO_FAIL = 0, ///< There has been an IO failure
ETHASH_IO_MEMO_SIZE_MISMATCH, ///< DAG with revision/hash match, but file size was wrong.
ETHASH_IO_MEMO_MISMATCH, ///< The DAG file did not exist or there was revision/hash mismatch
ETHASH_IO_MEMO_MATCH, ///< DAG file existed and revision/hash matched. No need to do anything
};
// small hack for windows. I don't feel I should use va_args and forward just
// to have this one function properly cross-platform abstracted
#if defined(_WIN32) && !defined(__GNUC__)
#define snprintf(...) sprintf_s(__VA_ARGS__)
#endif
/**
* Prepares io for ethash
*
* Create the DAG directory and the DAG file if they don't exist.
*
* @param[in] dirname A null terminated c-string of the path of the ethash
* data directory. If it does not exist it's created.
* @param[in] seedhash The seedhash of the current block number, used in the
* naming of the file as can be seen from the spec at:
* https://github.com/ethereum/wiki/wiki/Ethash-DAG
* @param[out] output_file If there was no failure then this will point to an open
* file descriptor. User is responsible for closing it.
* In the case of memo match then the file is open on read
* mode, while on the case of mismatch a new file is created
* on write mode
* @param[in] file_size The size that the DAG file should have on disk
* @param[out] force_create If true then there is no check to see if the file
* already exists
* @return For possible return values @see enum ethash_io_rc
*/
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
);
/**
* An fopen wrapper for no-warnings crossplatform fopen.
*
* Msvc compiler considers fopen to be insecure and suggests to use their
* alternative. This is a wrapper for this alternative. Another way is to
* #define _CRT_SECURE_NO_WARNINGS, but disabling all security warnings does
* not sound like a good idea.
*
* @param file_name The path to the file to open
* @param mode Opening mode. Check fopen()
* @return The FILE* or NULL in failure
*/
FILE* ethash_fopen(char const* file_name, char const* mode);
/**
* An strncat wrapper for no-warnings crossplatform strncat.
*
* Msvc compiler considers strncat to be insecure and suggests to use their
* alternative. This is a wrapper for this alternative. Another way is to
* #define _CRT_SECURE_NO_WARNINGS, but disabling all security warnings does
* not sound like a good idea.
*
* @param des Destination buffer
* @param dest_size Maximum size of the destination buffer. This is the
* extra argument for the MSVC secure strncat
* @param src Souce buffer
* @param count Number of bytes to copy from source
* @return If all is well returns the dest buffer. If there is an
* error returns NULL
*/
char* ethash_strncat(char* dest, size_t dest_size, char const* src, size_t count);
/**
* A cross-platform mkdir wrapper to create a directory or assert it's there
*
* @param dirname The full path of the directory to create
* @return true if the directory was created or if it already
* existed
*/
bool ethash_mkdir(char const* dirname);
/**
* Get a file's size
*
* @param[in] f The open file stream whose size to get
* @param[out] size Pass a size_t by reference to contain the file size
* @return true in success and false if there was a failure
*/
bool ethash_file_size(FILE* f, size_t* ret_size);
/**
* Get a file descriptor number from a FILE stream
*
* @param f The file stream whose fd to get
* @return Platform specific fd handler
*/
int ethash_fileno(FILE* f);
/**
* Create the filename for the DAG.
*
* @param dirname The directory name in which the DAG file should reside
* If it does not end with a directory separator it is appended.
* @param filename The actual name of the file
* @param filename_length The length of the filename in bytes
* @return A char* containing the full name. User must deallocate.
*/
char* ethash_io_create_filename(
char const* dirname,
char const* filename,
size_t filename_length
);
/**
* Gets the default directory name for the DAG depending on the system
*
* The spec defining this directory is here: https://github.com/ethereum/wiki/wiki/Ethash-DAG
*
* @param[out] strbuf A string buffer of sufficient size to keep the
* null termninated string of the directory name
* @param[in] buffsize Size of @a strbuf in bytes
* @return true for success and false otherwise
*/
bool ethash_get_default_dirname(char* strbuf, size_t buffsize);
static inline bool ethash_io_mutable_name(
uint32_t revision,
ethash_h256_t const* seed_hash,
char* output
)
{
uint64_t hash = *((uint64_t*)seed_hash);
#if LITTLE_ENDIAN == BYTE_ORDER
hash = ethash_swap_u64(hash);
#endif
return snprintf(output, DAG_MUTABLE_NAME_MAX_SIZE, "full-R%u-%016" PRIx64, revision, hash) >= 0;
}
#ifdef __cplusplus
}
#endif