/* -*- tab-width:4;c-file-style:"cc-mode"; -*- */
/*
 * oshash.c -- generate oshash for provided files 
 * Copyright (C) 2011-2012 Jan Gerber <j@mailb.org>
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 This program.  If not, see <http://www.gnu.org/licenses/>.
 */

#if !defined(_GNU_SOURCE)
#define _GNU_SOURCE
#endif
#if !defined(_LARGEFILE_SOURCE)
#define _LARGEFILE_SOURCE
#endif
#if !defined(_LARGEFILE64_SOURCE)
#define _LARGEFILE64_SOURCE
#endif
#if !defined(_FILE_OFFSET_BITS)
#define _FILE_OFFSET_BITS 64
#endif

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <getopt.h>
#include <math.h>
#include <errno.h>
#include <sys/stat.h>

#ifndef WIN32
#if !defined(off64_t)
#define off64_t off_t
#endif
#endif

#ifdef WIN32
#define fseeko fseeko64
#define ftello ftello64
#endif

#ifdef _BIG_ENDIAN
#define htonll(x) \
((((x) & 0xff00000000000000LL) >> 56) | \
(((x) & 0x00ff000000000000LL) >> 40) | \
(((x) & 0x0000ff0000000000LL) >> 24) | \
(((x) & 0x000000ff00000000LL) >> 8) | \
(((x) & 0x00000000ff000000LL) << 8) | \
(((x) & 0x0000000000ff0000LL) << 24) | \
(((x) & 0x000000000000ff00LL) << 40) | \
(((x) & 0x00000000000000ffLL) << 56))
#else
#define htonll(x) x
#endif

/* 
 * os hash
 * based on public domain example from
 * http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes   
 * 
 * plus modification for files < 64k, buffer is filled with file data and padded with 0
 */

unsigned long long gen_oshash(char const *filename) {
    FILE *file;
    int i;
    unsigned long long t1=0;
    unsigned long long buffer1[8192*2];
    int used = 8192*2;
    file = fopen(filename, "rb");
    if (file) {
        //add filesize
        fseeko(file, 0, SEEK_END);
        t1 = ftello(file);
        fseeko(file, 0, SEEK_SET);

        if(t1 < 65536) {
            used = t1/8;
            fread(buffer1, used, 8, file);
        } else {
            fread(buffer1, 8192, 8, file);
            fseeko(file, -65536, SEEK_END);
            fread(&buffer1[8192], 8192, 8, file); 
        }
        for (i=0; i < used; i++)
            t1+=htonll(buffer1[i]);
        fclose(file);
    }
    return t1;
}

int print_oshash(FILE *output, char const *filename) {
    char hash[32];
#ifdef WIN32
    sprintf(hash, "%016I64x", gen_oshash(filename));
#elif defined (__SVR4) && defined (__sun)
    sprintf(hash,"%016llx", gen_oshash(filename));
#else
    sprintf(hash, "%016qx", gen_oshash(filename));
#endif
    if (strcmp(hash,"0000000000000000") > 0) {
        fprintf(output, "%s  %s\n", hash, filename);
        return 0;
    } else {
        fprintf(stderr,"%s: No such file or permission denied\n",filename);
        return 1;
    }
}

int main(int argc, char **argv) {
    int i,r=0;
    FILE* output = stdout;
    
    if(argc == 1) {
        fprintf(stderr, "usage: %s [filename]\n", argv[0]);
        exit(1);
    }
    for(i=1;i<argc;i++)
        r+=print_oshash(output, argv[i]);
    return r>0?1:0;
}