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From: evans@ditsyda.oz (Bruce Evans)
Newsgroups: comp.os.minix
Subject: Re: CRC comparisons
Message-ID: <2557@ditsyda.oz>
Date: 7 Mar 90 20:03:46 GMT
References: <8168@sdcc6.ucsd.edu> <18091@rpp386.cactus.org> <789@ns-mx.uiowa.edu>
Reply-To: evans@ditsyda.oz (Bruce Evans)
Organization: CSIRO DIT Sydney, Australia
Lines: 157

I use the following programs (from old postings). 'checkcrc' in particular
is very useful for comparing with the official CRC lists. Unfortunately
the latter have some directory names (like include) inconsistent with the
normal layout, and must be edited a little.

The author warns that the method of 'system("crc ...")' is slow. I find it
surprisingly fast given a decent sized cache (320K). Putting the shell
and crc on a RAM disk should achieve similar benefits. It is fairly
easy to change the system() to fork() + exec() so only crc needs to be
reloaded every time, so a 50K cache might do. Or checkcrc could be merged
with crc.

51458   2385 checkcrc.c
31800    217 listcrc

#! /bin/sh
# Contents:  checkcrc.c listcrc
# Wrapped by src@besplex on Thu Mar  8 07:43:50 1990
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'checkcrc.c' -a "${1}" != "-c" ; then 
  echo shar: Will not clobber existing file \"'checkcrc.c'\"
else
echo shar: Extracting \"'checkcrc.c'\" \(2385 characters\)
sed "s/^X//" >'checkcrc.c' <<'END_OF_FILE'
X/*
X * Check_crc.c -- Check the current file system against a CRC list
X *		  Version 1.00		27 April 1989
X *
X * Usage:
X *	check_crc [directory] <script >differences
X *
X * The report lists the file name, along with the official and obtained
X * crcs and counts.  The obtained values are printed in parenthesis.
X *	file	crc 123 (44), count 33 (23)
X *
X * There are undoubtably better ways of doing this.  Perhaps using the
X * shell or AWK.  I did it this way anyway.
X *
X * This program is Public Domain.  Do what you want with it.
X *
X *		Dave Regan
X *		regan@jacobs.cs.orst.edu
X *		27 April 1989
X */
X
X/*
X * Notes:
X *
X * I tried a version of this which used "popen" instead of a temporary
X * file.  This wasn't any faster, and somewhat less portable.
X */
X
X#include <ctype.h>
X#include <stdio.h>
X#include <stdlib.h>
X#include <string.h>
X
X#define	LINESIZE	100
X
Xmain(argc, argv)
X  int			argc;
X  char			*argv[];
X    {
X    char		cmd[50];
X    long		cor_count;
X    long		cor_crc;
X    char		*cptr;
X    long		cur_count;
X    long		cur_crc;
X    FILE		*fd;
X    char		*file;
X    char		line[LINESIZE+1];
X    char		line2[LINESIZE+1];
X
X    if (argc < 1 || argc > 2)
X    	{
X    	fprintf(stderr, "Usage: check_crc [directory] <script >differences\n");
X    	exit(1);
X    	}
X    if (argc == 2)
X    	chdir(argv[1]);
X
X    while (fgets(line, LINESIZE, stdin) != NULL)
X    	{
X	if ((cptr = strchr(line, '\n')) != NULL)
X	    *cptr = '\0';
X    	if (line[0] == '\0' || line[0] == '#')
X    	    continue;
X    	for (cptr = line; isdigit(*cptr); cptr++)
X    	    ;
X    	while (isspace(*cptr))
X    	    cptr++;
X    	while (isdigit(*cptr))
X    	    cptr++;
X    	while (isspace(*cptr))
X	    cptr++;
X	file = cptr;
X
X	if (access(file, 0) < 0)
X	    {
X	    printf("%-40sDoes not exist\n", file);
X	    continue;
X	    }
X
X	sprintf(cmd, "crc %s >/tmp/crc%05d", file, getpid());
X	system(cmd);
X	sprintf(cmd, "/tmp/crc%05d", getpid());
X	if ((fd = fopen(cmd, "r")) != NULL)
X	    {
X	    fgets(line2, LINESIZE, fd);
X	    fclose(fd);
X	    if ((cptr = strchr(line2, '\n')) != NULL)
X	    	*cptr = '\0';
X	    if (strcmp(line, line2) != 0)
X	    	{
X	    	sscanf(line, "%ld %ld", &cor_crc, &cor_count);
X	    	sscanf(line2, "%ld %ld", &cur_crc, &cur_count);
X	    	printf("%-40scrc %ld (%ld), count %ld (%ld)\n",
X			file, cor_crc, cur_crc, cor_count, cur_count);
X	    	}
X	    }
X    	}
X    sprintf(cmd, "/tmp/crc%05d", getpid());
X    unlink(cmd);
X    }
END_OF_FILE
if test 2385 -ne `wc -c <'checkcrc.c'`; then
    echo shar: \"'checkcrc.c'\" unpacked with wrong size!
fi
# end of 'checkcrc.c'
fi
if test -f 'listcrc' -a "${1}" != "-c" ; then 
  echo shar: Will not clobber existing file \"'listcrc'\"
else
echo shar: Extracting \"'listcrc'\" \(217 characters\)
sed "s/^X//" >'listcrc' <<'END_OF_FILE'
X#! /bin/sh
X# a shell script to list the crcs of the files in a list of directories,
X#   recursively including all ordinary files in subdirectories
X
X(
X	for i in $*
X	do
X		find "$i" -type f -print
X	done
X) | sort | crc -
END_OF_FILE
if test 217 -ne `wc -c <'listcrc'`; then
    echo shar: \"'listcrc'\" unpacked with wrong size!
fi
chmod +x 'listcrc'
# end of 'listcrc'
fi
echo shar: End of shell archive.
exit 0
-- 
Bruce Evans		evans@ditsyda.oz.au