/*

 * adler32.c (c) 2006 Bjorn Lindeijer

 * License: GPL, v2 or later

 *

 * Calculates Adler-32 checksums for all files passed as argument.

 *

 *  Usage: adler32 [file]...

 */

#include <stdlib.h>

#include <stdio.h>

#include <zlib.h>

/**

 * Calculates the Adler-32 checksum for the given file.

 */

unsigned long fadler32(FILE *file)

{

    // Obtain file size

    fseek(file, 0, SEEK_END);

    long fileSize = ftell(file);

    rewind(file);

    // Calculate Adler-32 checksum

    char *buffer = (char*) malloc(fileSize);

    fread(buffer, 1, fileSize, file);

    unsigned long adler = adler32(0L, Z_NULL, 0);

    adler = adler32(adler, (Bytef*) buffer, fileSize);

    free(buffer);

    return adler;

}

/**

 * Prints out usage and exists.

 */

void print_usage()

{

    printf("Usage: adler32 [file]...\n");

    exit(0);

}

int main(int argc, char *argv[])

{

    int i;                            /**< Loops through arguments. */

    if (argc == 1)

    {

        print_usage();

    }

    for (i = 1; i < argc; ++i)

    {

        FILE *file = fopen(argv[i], "r");

        if (!file)

        {

            printf("Error while opening '%s' for reading!\n", argv[i]);

            exit(1);

        }

        unsigned long adler = fadler32(file);

        printf("%s %lx\n", argv[i], adler);

        fclose(file);

    }

    return 0;

}