Shell Programming and Scripting

 

help()
{
    cat <<!
SUM2

NAME
    sum2 - print checksum and block count of a file

SYNOPSIS
    sum2 [-r] files
    sum2 -h

DESCRIPTION
    Sum2 calculates and prints a 16-bit checksum for the named
    files, and also prints the number of 512 byte blocks in each
    file. It is typically used to look for bad spots, or to
    validate files communicated over some transmission line.
    The option -r causes an alternate algorithm to be used in
    computing the checksum (namely, the BSD algorithm.)

EXAMPLES
    Suppose you have files named file1 and file2, and you want to compute
    the BSD checksum. Enter this command:

        sum2 -r file1 file2

    This might produce results similar to this:

        31409     1 file1
        05017     5 file2

SEE ALSO
    sum.
!
}


# main

status=0

h=0
r=0
x=0
lines=""
files=""
fileCount=0
checksum=0
ch=0
r=0
s=0


for parameter in $*
do
        letter=`echo x$parameter | cut -c2`
        if [ "$letter" = "-" ]
        then
                parameter=`echo x$parameter | cut -c3-`
                while [ "$parameter" != "" ]
                do
                        letter=`echo "x$parameter" | cut -c2`
                        parameter=`echo "x$parameter" | cut -c3-`

                        case "$letter" in
                        h)
                                h=1
                                previous=-h
                                ;;
                        r)
                                r=1
                                if [ "$parameter" = "" ]
                                then
                                        previous=-r
                                else
                                        lines=$parameter
                                        parameter=""
                                        previous=""
                                fi
                                ;;
                        x)
                                x=1
                                previous=-x
                                ;;
                        *)
                                echo "invalid option -$letter"
                                echo
                                status=1
                                ;;
                        esac
                done
        else
                case "$previous" in
                -r)
                        files="$files $parameter"
                        fileCount=`expr $fileCount + 1`
                        previous=""
                        ;;
                esac
        fi
done

if [ "$h" -eq 1 ]
then
        help
        exit 0
fi

if [ "$r" -eq 1 -a "$files" = "" ]
then
        echo "no filess specified"
        echo
        status=1
fi



if [ "$status" -ne 0 ]
then
        help
        exit 1
fi

if [ "$x" -eq 1 ]
then
        set -x
fi

# ----------------------------------------------------------------------------
     line = $0
     while (line != "" )
            {
            byte = substr(line,1,2)
            line = substr(line,3)

            value = hex_to_decimal(byte)

            if  (algorthim ==0 )
            {
                 # The BSD Algorthim

                 checksum = int(checksum / 2) + int ((checksum % 1) * 32768)    
                 checksum = checksum + ch
                 checksum = checksum % 65535
                 printf "%05d %5s", checksum
                 printf "%s", file
            }
            else
                 #The SysV Algorthim

                 r = ( s % 65535 ) + int(( s % 4294967295 ) / 65535)
                 checksum = (r % 65535) + int(r/65535)

                 printf "%d %s", checksum
                 printf "%s", file

              }






# ------------Hex to Dec nawk script-------------------------------------------
  function decimal_to_hex(decimal)
{
        hex_value = ""

        if (decimal == 0)
        {
                hex_value = "0"
        }
        else
        {
                while (decimal != 0)
                {
                        new_decimal = int(decimal / 16)
                        digit = decimal - (new_decimal * 16)

                        if (digit == 10)
                        {
                                digit = "a"
                        }
                        if (digit == 11)
                        {
                                digit = "b"
                        }
                        if (digit == 12)
                        {
                                digit = "c"
                        }
                        if (digit == 13)
                        {
                                digit = "d"
                        }
                        if (digit == 14)
                        {
                                digit = "e"
                        }
                        if (digit == 15)
                        {
                                digit = "f"
                        }

                        hex_value = digit""hex_value

                        decimal = new_decimal
                }
        }
        return hex_value
}

function hex_to_decimal(hex)
{
        decimal_value = 0

        ln = length(hex)

        for (column = 1; column <= ln; column++)
        {
                hex_digit = substr(hex, column, 1)
                digit_value = 0

                if (hex_digit >= "0" && hex_digit <= "9")
                {
                        digit_value = hex_digit
                }
                else
                {
                        if (hex_digit == "a")
                        {
                                digit_value = 10
                        }
                        if (hex_digit == "b")
                        {
                                digit_value = 11
                        }
                        if (hex_digit == "c")
                        {
                                digit_value = 12
                        }
                        if (hex_digit == "d")
                        {
                                digit_value = 13
                        }
                        if (hex_digit == "e")
                        {
                                digit_value = 14
                        }
                        if (hex_digit == "f")
                        {
                                digit_value = 15
                        }
                }

                decimal_value = (decimal_value * 16) + digit_value
        }
        return decimal_value
}

function hex_and(operand1, operand2)
{
        value = 0

        len = length(operand1)
        if (len < length(operand2))
        {
                len = length(operand2)
        }

        decimal1 = hex_to_decimal(operand1)
        decimal2 = hex_to_decimal(operand2)

        factor = 1

        while (decimal1)
        {
                digit1 = decimal1 % 2
                digit2 = decimal2 % 2

                if ((digit1 == 1) && (digit2 == 1))
                {
                        digit3 = 1
                }
                else
                {
                        digit3 = 0
                }

                value = value + (digit3 * factor)

                decimal1 = int(decimal1 / 2)
                decimal2 = int(decimal2 / 2)
                factor *= 2
        }
        value = decimal_to_hex(value)
        format_string = sprintf("0x%%0%ss", len)
        value = sprintf(format_string, value) ""
        return value ""
}



# --------------------------------------------------------------------------










 -------

/* sum -- checksum and count the blocks in a file
   Copyright (C) 86, 89, 91, 1995-2002, 2004, 2005 Free Software Foundation, Inc.

   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 3 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/>.  */

/* Like BSD sum or SysV sum -r, except like SysV sum if -s option is given. */

/* Written by Kayvan Aghaiepour and David MacKenzie. */

#include <config.h>

#include <stdio.h>
#include <sys/types.h>
#include <getopt.h>
#include "system.h"
#include "error.h"
#include "human.h"
#include "safe-read.h"

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "sum"

#define AUTHORS "Kayvan Aghaiepour", "David MacKenzie"

/* The name this program was run with. */
char *program_name;

/* True if any of the files read were the standard input. */
static bool have_read_stdin;

static struct option const longopts[] =
{
  {"sysv", no_argument, NULL, 's'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
             program_name);
  else
    {
      printf (_("\
Usage: %s [OPTION]... [FILE]...\n\
"),
              program_name);
      fputs (_("\
Print checksum and block counts for each FILE.\n\
\n\
  -r              defeat -s, use BSD sum algorithm, use 1K blocks\n\
  -s, --sysv      use System V sum algorithm, use 512 bytes blocks\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      fputs (_("\
\n\
With no FILE, or when FILE is -, read standard input.\n\
"), stdout);
      emit_bug_reporting_address ();
    }
  exit (status);
}

/* Calculate and print the rotated checksum and the size in 1K blocks
   of file FILE, or of the standard input if FILE is "-".
   If PRINT_NAME is >1, print FILE next to the checksum and size.
   The checksum varies depending on sizeof (int).
   Return true if successful.  */

static bool
bsd_sum_file (const char *file, int print_name)
{
  FILE *fp;
  int checksum = 0;    /* The checksum mod 2^16. */
  uintmax_t total_bytes = 0;   /* The number of bytes. */
  int ch;              /* Each character read. */
  char hbuf[LONGEST_HUMAN_READABLE + 1];
  bool is_stdin = STREQ (file, "-");

  if (is_stdin)
    {
      fp = stdin;
      have_read_stdin = true;
      if (O_BINARY && ! isatty (STDIN_FILENO))
        freopen (NULL, "rb", stdin);
    }
  else
    {
      fp = fopen (file, (O_BINARY ? "rb" : "r"));
      if (fp == NULL)
        {
          error (0, errno, "%s", file);
          return false;
        }
    }

  while ((ch = getc (fp)) != EOF)
    {
      total_bytes++;
      checksum = (checksum >> 1) + ((checksum & 1) << 15);
      checksum += ch;
      checksum &= 0xffff;      /* Keep it within bounds. */
    }

  if (ferror (fp))
    {
      error (0, errno, "%s", file);
      if (!is_stdin)
        fclose (fp);
      return false;
    }

  if (!is_stdin && fclose (fp) != 0)
    {
      error (0, errno, "%s", file);
      return false;
    }

  printf ("%05d %5s", checksum,
          human_readable (total_bytes, hbuf, human_ceiling, 1, 1024));
  if (print_name > 1)
    printf (" %s", file);
  putchar ('\n');

  return true;
}

/* Calculate and print the checksum and the size in 512-byte blocks
   of file FILE, or of the standard input if FILE is "-".
   If PRINT_NAME is >0, print FILE next to the checksum and size.
   Return true if successful.  */

static bool
sysv_sum_file (const char *file, int print_name)
{
  int fd;
  unsigned char buf[8192];
  uintmax_t total_bytes = 0;
  char hbuf[LONGEST_HUMAN_READABLE + 1];
  int r;
  int checksum;

  /* The sum of all the input bytes, modulo (UINT_MAX + 1).  */
  unsigned int s = 0;

  bool is_stdin = STREQ (file, "-");

  if (is_stdin)
    {
      fd = STDIN_FILENO;
      have_read_stdin = true;
      if (O_BINARY && ! isatty (STDIN_FILENO))
        freopen (NULL, "rb", stdin);
    }
  else
    {
      fd = open (file, O_RDONLY | O_BINARY);
      if (fd == -1)
        {
          error (0, errno, "%s", file);
          return false;
        }
    }

  while (1)
    {
      size_t i;
      size_t bytes_read = safe_read (fd, buf, sizeof buf);

      if (bytes_read == 0)
        break;

      if (bytes_read == SAFE_READ_ERROR)
        {
          error (0, errno, "%s", file);
          if (!is_stdin)
            close (fd);
          return false;
        }

      for (i = 0; i < bytes_read; i++)
        s += buf[i];
      total_bytes += bytes_read;
    }

  if (!is_stdin && close (fd) != 0)
    {
      error (0, errno, "%s", file);
      return false;
    }

  r = (s & 0xffff) + ((s & 0xffffffff) >> 16);
  checksum = (r & 0xffff) + (r >> 16);

  printf ("%d %s", checksum,
          human_readable (total_bytes, hbuf, human_ceiling, 1, 512));
  if (print_name)
    printf (" %s", file);
  putchar ('\n');

  return true;
}

int
main (int argc, char **argv)
{
  bool ok;
  int optc;
  int files_given;
  bool (*sum_func) (const char *, int) = bsd_sum_file;

  initialize_main (&argc, &argv);
  program_name = argv[0];
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  have_read_stdin = false;

  while ((optc = getopt_long (argc, argv, "rs", longopts, NULL)) != -1)
    {
      switch (optc)
        {
        case 'r':              /* For SysV compatibility. */
          sum_func = bsd_sum_file;
          break;

        case 's':
          sum_func = sysv_sum_file;
          break;

        case_GETOPT_HELP_CHAR;

        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);

        default:
          usage (EXIT_FAILURE);
        }
    }

  files_given = argc - optind;
  if (files_given <= 0)
    ok = sum_func ("-", files_given);
  else
    for (ok = true; optind < argc; optind++)
      ok &= sum_func (argv[optind], files_given);

  if (have_read_stdin && fclose (stdin) == EOF)
    error (EXIT_FAILURE, errno, "-");
  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}
------