io_posix.c

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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/>.
*/
#include "io.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <libgen.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pwd.h>

FILE* ethash_fopen(char const* file_name, char const* mode)
{
        return fopen(file_name, mode);
}

char* ethash_strncat(char* dest, size_t dest_size, char const* src, size_t count)
{
        return strlen(dest) + count + 1 <= dest_size ? strncat(dest, src, count) : NULL;
}

bool ethash_mkdir(char const* dirname)
{
        int rc = mkdir(dirname, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
        return rc != -1 || errno == EEXIST;
}

int ethash_fileno(FILE *f)
{
        return fileno(f);
}

char* ethash_io_create_filename(
        char const* dirname,
        char const* filename,
        size_t filename_length
)
{
        size_t dirlen = strlen(dirname);
        size_t dest_size = dirlen + filename_length + 1;
        if (dirname[dirlen] != '/') {
                dest_size += 1;
        }
        char* name = malloc(dest_size);
        if (!name) {
                return NULL;
        }

        name[0] = '\0';
        ethash_strncat(name, dest_size, dirname, dirlen);
        if (dirname[dirlen] != '/') {
                ethash_strncat(name, dest_size, "/", 1);
        }
        ethash_strncat(name, dest_size, filename, filename_length);
        return name;
}

bool ethash_file_size(FILE* f, size_t* ret_size)
{
        struct stat st;
        int fd;
        if ((fd = fileno(f)) == -1 || fstat(fd, &st) != 0) {
                return false;
        }
        *ret_size = st.st_size;
        return true;
}

bool ethash_get_default_dirname(char* strbuf, size_t buffsize)
{
        static const char dir_suffix[] = ".ethash/";
        strbuf[0] = '\0';
        char* home_dir = getenv("HOME");
        if (!home_dir || strlen(home_dir) == 0)
        {
                struct passwd* pwd = getpwuid(getuid());
                if (pwd)
                        home_dir = pwd->pw_dir;
                if (!home_dir)
                        return false;
        }
        
        size_t len = strlen(home_dir);
        if (!ethash_strncat(strbuf, buffsize, home_dir, len)) {
                return false;
        }
        if (home_dir[len] != '/') {
                if (!ethash_strncat(strbuf, buffsize, "/", 1)) {
                        return false;
                }
        }
        return ethash_strncat(strbuf, buffsize, dir_suffix, sizeof(dir_suffix));
}