emigh@ecsvax.UUCP (Ted Emigh) (08/15/86)
The following is a pair of programs to calculate the CRC's of all the
files on a disk, and to compare this list to a previously generated list.
This allows you to keep track of files that have been added, deleted,
modified, or trashed. The programs are written to be compiled under
TURBO Pascal (ver 3.0, although I haven't tried earlier versions). See
the documentation for more information. The three files this archive
will produce are : filecrc.doc, filecrc.pas, and compare.pas.
------------------------------CUT HERE----------------------------------
#-----------------------------------------------------------
#
# filecrc.ar
# use 'sh filename.ar' to extract files from this archive
#
# Do not use csh.
#
echo "Extracting filecrc.doc <-- filecrc.ar"
cat << \===filecrc.doc=== > filecrc.doc
FILECRC
13 August 1986
Ted H. Emigh
FILECRC is a program to help detect when files have been
corrupted. FILECRC creates a list of all the files on the
default drive along with creation date, file size, and a CRC
(cyclic redundancy check) for each file. When FILECRC is run
again the new list is compared with the old list. For any file,
it is possible that:
1) The file is completely unchanged from the previous time.
The file name (and directory entry) are the same at the two
times, and it has not been modified.
2) The file has been modified in the normal manner, so that the
directory entry has a new time of creation. Files of this
sort are counted, but no special treatment is given to them.
3) The file has been deleted in the time since the first time
FILECRC was run. Files of this sort are counted, but no
special treatment is given to them.
4) A new file has appeared that was not on the disk at the time
of the previous run of FILECRC. Files of this sort are
counted, and a list is placed in the file FILES$$$.NEW.
While it is usual to find new files on the disk, this gives
an easy way to keep track of what files are new, and where
they are located. This is important when using public
domain programs to make sure they are not creating new files
without you knowing about it.
5) The directory entry for a file is the same for both of the
times the program was run, but the file was modified in some
way. This should not occur in normal practice, so the
program writes a message to the terminal, and a list of
these files is placed in the file FILES$$$.MOD. This can
occur when you use NORTON UTILITIES, or other such programs
to modify the disk directly, bypassing the normal DOS
handling of the files. It also can happen when programs
'run wild' (this is what prompted me to write this program
in the first place).
Running the program prior to each backup will assure you
that you are not backing up files that have been corrupted.
Also, in program development, running the program before and
after a test run of your program can assure you that your program
has not messed up the disk.
1
RUNNING FILECRC
There are three files associated with FILECRC:
FILECRC.COM -- The main program.
COMPARE.CHN -- The comparison program overlay.
COMPARE.COM -- A stand-alone version of the comparison program.
FILECRC is run without command line parameters (although
output redirection is permitted). It will create CHECK$$$.NEW
(or CHECK$$$.CRC if the file does not exist in the default
directory), which is a list of all the files on the default disk
in all directories. FILECRC displays the directory names as it
goes through them. FILECRC will then call COMPARE, which will
compare the files in CHECK$$$.NEW with those in CHECK$$$.CRC,
noting any differences. When COMPARE is finished, the old file
list now will be called CHECK$$$.OLD, and the newly created one
will be called CHECK$$$.CRC.
COMPARE can be run as a stand alone program by typing
COMPARE [NEWLIST.FIL [OLDLIST.FIL]]
If NEWLIST.FIL is given, this will be used instead of
CHECK$$$.NEW,and if given, OLDLIST.FIL will be used instead of
CHECK$$$.CRC. For example,
COMPARE CHECK
will check the file CHECK with CHECK$$$.CRC. If NEWLIST.FIL is
given, CHECK$$$.CRC will not be renamed.
Any files created since the previous time FILECRC was run
will be listed in the file FILES$$$.NEW, and any files that have
been modified in a "NON DOS" manner will be listed in the file
FILE$$$.MOD.
2
PROGRAMMING NOTES
FILECRC is written using Turbo Pascal, Version 3.0 for
MSDOS. It has been tested on an IBM PC/AT using DOS 3.10. This
program is not meant to represent the epitome of programming
skill, but it works. Any improvements and suggestions are
welcome, particularly if you can improve the speed. On my PC/AT
with some 730 files occupying 18MB the program takes about 6
minutes to complete. I am convinced that FILECRC.COM cannot be
improved significantly on speed (take that as a challenge,if you
wish), but COMPARE.CHN and COMPARE.COM are relatively inefficient
(but then of the 6 minutes, 5-1/2 minutes are spent in
FILECRC.COM). Programming notes in the programs are sparse, but
I specifically set separate routines for handling each of the the
file comparison types in COMPARE (use the procedures file_new,
file_updated, file_OK, and bad_CRC if you would like to do
something special for each file comparison type).
FILECRC will work with any number of files or directories. As
written, COMPARE has a maximum of 200 directories and 1900 files
with any number of files within any particular directory. The
maximum length of the directory name string is 64 characters. I
have used the program on subdirectories up to 10 levels deep
without any problems. These values for the number of directories
and the number of files uses up just about as much memory as
TURBO Pascal allows, so an increase in these numbers would
necessitate a redesign of the program.
Special thanks go to David Dantowitz of Digital Equipment
Corporation (Dantowitz%eagle1.dec@decwrl) for providing the CRC
routines (generate_table_256 and crc_string_256) and the routines
for getting a directory (get_DTA, set_DTA, find_first, and
find_next). Of course, he takes no responsibility for the way I
used his code.
Ted H. Emigh
Department of Genetics
North Carolina State University
Box 7614
Raleigh, NC 27695-7614
emigh@ecsvax.uucp
NEMIGH@TUCC.BITNET
3
===filecrc.doc===
# ----------
echo "Extracting filecrc.pas <-- filecrc.ar"
cat << \===filecrc.pas=== > filecrc.pas
{ PROGRAM TO CREATE OF FILE OF THE CRC'S OF THE FILES ON THE DEFAULT DISK }
{
This program was written by Ted H. Emigh, and has been placed in the public
domain, to be used at the user's discretion. The CRC routines and the
discussion of the CRC were written by David Dantowitz, Digital Equipment
Corporation, Dantowitz%eagle1.dec@decwrl.
This program calculates the CRC (cyclic redundancy check) for all the files
on the disk (with the exception of files that are hidden system files). The
CRC's are placed in a file (CHECK$$$.NEW) to be compared with the CRC's
calculated at a previous time in the file CHECK$$$.CRC. The comparison is
done with the program COMPARE.PAS. This program is set to automatically
chain to COMPARE.PAS to automate the procedure, but this can be turned off
by deleting the lines:
Assign (chain_file,'COMPARE.CHN');
Chain(chain_file);
at the end of this program.
For a good discussion of polynomial selection see "Cyclic
Codes for Error Detection", by W. W. Peterson and
D. T. Brown, Proceedings of the IEEE, volume 49, pp 228-235,
January 1961.
A reference on table driven CRC computation is "A Cyclic
Redundancy Checking (CRC) Algorithm" by A. B. Marton and
T. K. Frambs, The Honeywell Computer Journal, volume 5,
number 3, 1971.
Also used to prepare these examples was "Computer Networks",
by Andrew S. Tanenbaum, Prentice Hall, Inc. Englewood Cliffs,
New Jersey, 1981.
The following three polynomials are international standards:
CRC-12 = X^12 + X^11 + X^3 + X^2 + X^1 + 1
CRC-16 = X^16 + X^15 + X^2 + 1
CRC-CCITT = X^16 + X^12 + X^5 + 1
In Binary and hexadecimal :
Binary Hex
CRC-12 = 1111 0000 0001 $0F01
CRC-16 = 1010 0000 0000 0001 $A001
CRC-CCITT = 1000 0100 0000 1000 $8404 (Used below)
The first is used with 6-bit characters and the second two
with 8-bit characters. All of the above will detect any
odd number of errors. The second two will catch all 16-bit
bursts, a high percentage of 17-bit bursts (~99.997%) and
also a large percentage of 18-bit or larger bursts (~99.998%).
The paper mentioned above (Peterson and Brown) discusses how
to compute the statistics presented which have been quoted
from Tanenbaum.
(A burst of length N is defined a sequence of N bits, where
the first and last bits are incorrect and the bits in the
middle are any possible combination of correct and incorrect.
See the paper by Peterson and Brown for more information)
}
{$G512,P512,U+,R+ }
Program FILECRC;
Const
BufSize = 192; { Number of 128 byte sectors in the CRC buffer }
Buffer_Length = 24576; { BufSize * 128 = Length of the CRC buffer }
Version = 1.00;
Version_Date = '13 AUG 86';
POLY = $8404; { CRC Polynomial Used }
Type
Bytes = Array [1..24576] of Byte; { Length is 1..Buffer_Length }
Registers = record { Registers for 8088/8086/80286 }
ax, bx, cx, dx, bp, si, di, ds, es, flags : integer;
end;
DTA_record = record { DTA as used by MSDOS }
dos : array [1..21] of char;
attribute : byte; { Attribute byte }
time_of_day : integer; { Time of Day of File Creation }
date : integer; { Date of File Creation }
low_size, high_size : integer; { Size of the File }
filename: array [1..13] of char; { File Name }
junk : array [1..85] of byte;
end;
string255 = string[255];
Var
{ Variables used in Calculating the CRC }
str_length, RecsRead, CRC_value : integer;
table_256 : Array [0 .. 255] of Integer; {CRC Table to speed computations}
byte_string : Bytes;
{ Variables used in setting up the input and output files }
filvar : file;
chain_file : file;
outfile : TEXT[$4000];
check_crc : boolean;
{ Misc. Variables }
root : string255; { Contains the default drive and root directory }
global_reg : registers; { Registers for the DOS calls }
Procedure generate_table_256(POLY : Integer);
{
This routine computes the remainder values of 0 through 255 divided
by the polynomial represented by POLY. These values are placed in a
table and used to compute the CRC of a block of data efficiently.
More space is used, but the CRC computation will be faster.
This implementation only permits polynomials up to degree 16.
}
Var
val, i, result : Integer;
Begin
For val := 0 to 255 Do
Begin
result := val;
For i := 1 to 8 Do
Begin
If (result and 1) = 1
then result := (result shr 1) xor POLY
else result := result shr 1;
End;
table_256[val] := result;
End
End;
Function crc_string_256(Var s : Bytes; s_length, initial_crc : Integer)
: Integer;
{
This routine computes the CRC value and returns it as the function
value. The routine takes an array of Bytes, a length and an initial
value for the CRC. The routine requires that a table of 256 values
be set up by a previous call to Generate_table_256.
This routine uses table_256.
}
Begin
inline(
$c4/$7e/<s/ {les di,s[bp] (es:di points to array) }
$8b/$46/<initial_crc/ {mov ax,initial_crc[bp] (initial CRC value) }
$8b/$4e/<s_length/ {mov cx,s_length[bp] (count) }
$be/table_256/ {mov si,offset table_256 (table address) }
{ next: }
$26/$32/$05/ {xor al,es:[di] CRC = CRC XOR next byte }
$47/ {inc di (point to next byte) }
{ intermediate steps, see comments for overall effect }
$31/$db/ {xor bx,bx (bx <- 0) }
$86/$d8/ {xchg al,bl (bx <- ax and 0FF) }
$86/$e0/ {xchg al,ah (ax <- ax shr 8) }
$d1/$e3/ {shl bx,1 (bx <- bx+bx) }
$33/$00/ {xor ax,[bx+si] CRC = (CRC shr 8) XOR
table[CRC and 0FF] }
$e2/$f0/ {loop next (count <- count -1) }
$89/$46/<s+4); {mov s+4[bp],ax (crc_string_256 := CRC) }
{ basic algorithm expressed above
crc := initial_crc
For each byte Do
Begin
crc := crc XOR next_byte;
crc := (crc shr 8) XOR table_256 [crc and $FF];
End;
crc_string_256 := crc;
}
End;
Procedure set_attr (attr : byte; asciiz : string255);
{
This routine sets the file attributes. Uses Function $43 in
Interrupt $21.
Turbo Pascal is unable to open and read various types files
(e.g., r/o and files that are both hidden and system). This
gets around that by always setting the attribute to 0, then
reseting it to the original value.
attr is the attribute to be set on the file
asciiz is a string variable with the file name
}
begin
asciiz := asciiz + chr(0); { Make a valid DOS ASCIIZ name }
{ Set up the registers for the interrupt }
global_reg.ax := $4301;
global_reg.ds := seg(asciiz);
global_reg.dx := ofs(asciiz)+1;
global_reg.cx := attr;
intr ($21, global_reg);
end;
Procedure get_crc(this_file : string255; dta : DTA_record);
{
This procedure computes the CRC for a file. Value is returned
in the global variable CRC_value.
this_file is a string variable containing the file name
dta is a DTA_Record containing the file's DTA
}
var
length : real; { Length of the File }
begin
{ Change the Attribute byte so we can always open it }
{ To save some time, this is only done if the file }
{ Has any attribute other than ARCHIVE }
if (dta.attribute and $DF <> 0) then
set_attr ( 0, this_file);
{ Get the size of the file }
if dta.low_size < 0 then
{ Negative low_size is really number between 32768 and 65536 }
length := int(dta.high_size)*65536.0 + 32768.0
+ int(dta.low_size and $7FFF)
else
length := int(dta.high_size)*65536.0 + int(dta.low_size);
{ Open the file as untyped }
Assign (Filvar, this_file);
Reset (Filvar);
{ Calculate the CRC }
CRC_value := 0;
While length > 0.5 do
Begin
{ Read a segment of the file to process }
BlockRead(filvar,byte_string,BufSize,RecsRead);
{ Get the correct number of bytes to process }
if length >= Buffer_Length then
str_length := Buffer_Length
else
str_length := round(length);
{ Compute the CRC }
CRC_value := crc_string_256(byte_string, str_length, CRC_value);
{ Adjust the file length }
length := length - Buffer_Length;
End;
Close (Filvar);
{ Restore the correct Attribute Byte }
if (dta.attribute and $DF <> 0) then
set_attr ( dta.attribute, this_file);
end;
Procedure directory(current_directory : string255);
{
Procedure to calculate the CRC of all the files in a directory,
then all subdirectories in that directory
current_directory contains the directory name (including drive)
}
var
DTA_ofs, DTA_seg : integer; { Contains the current DTA address }
reg : Registers; { Local 8088/8086/80286 registers }
DTA : DTA_record; { Local DTA }
this_directory, this_file, asciiz : string255; { directory and file names }
function get_file : string255;
{ Get the file name from the DTA }
var
i : integer;
temp_file : string255;
begin
i := 1;
temp_file := '';
repeat
temp_file := temp_file + DTA.filename[i];
i := i+1;
until dta.filename[i] = chr(0);
get_file := temp_file;
end;
function is_directory : boolean;
{ Function to tell if the file is a directory entry }
begin
is_directory := ((dta.attribute and $10) <> 0)
and (dta.filename[1] <> '.');
end;
Procedure set_DTA(offset, segment : integer);
{ sets the disk DTA
Uses MSDOS Function $1A with interrupt $21
offset is the offset of the new DTA
segment is the segment of the new DTA
}
begin
reg.ax := $1a00;
reg.ds := segment;
reg.dx := offset;
intr($21, reg);
end;
Procedure get_DTA(var offset, segment : integer);
{ gets the disk DTA
Uses MSDOS Function $2F with Interrupt $21
offset will return with the current DTA offset
segment will return with the current DTA segment
}
begin
reg.ax := $2f00;
intr($21, reg);
offset := reg.bx;
segment := reg.es;
end;
Function find_first (attr_mask : byte) : boolean;
{
Find the first file matching the ASCIIZ string.
attr_mask is $27 for files only and $37 for directories & files
INT 21 function 4EH
Returns TRUE if found, FALSE if not found
}
begin
reg.ax := $4e00;
reg.ds := seg(asciiz);
reg.dx := ofs(asciiz)+1;
reg.cx := attr_mask;
intr($21, reg);
find_first := (lo(reg.ax) <> 18);
end;
Function find_next (attr_mask : byte) : boolean;
{
Find the next file matching the ASCIIZ string.
attr_mask is $27 for files only and $37 for directories & files
Returns TRUE if found, FALSE if not found
}
begin
reg.ax := $4f00;
reg.cx := attr_mask;
intr($21, reg);
find_next := (lo(reg.ax) <> 18);
end;
begin { directory }
get_DTA(DTA_ofs, DTA_seg); { Save the current DTA location }
set_DTA(ofs(DTA), seg(DTA)); { Set the DTA location to local area }
{
Find and print the files in the current directory
}
asciiz := current_directory + '\*.*' + CHR(0); { CHR(0) to make proper }
{ Process all the files before doing any directories }
if find_first ($27) then
repeat
if dta.filename[1] <> '.' then
begin
this_file := get_file;
get_crc(current_directory + '\' + this_file, dta);
writeln(outfile,current_directory,' ',this_file,' ',
dta. attribute,' ',dta.time_of_day,' ',dta.date,' ',
dta.low_size,' ',dta.high_size,' ',CRC_value);
end;
until not find_next ($27);
{ Now process all the directories }
if find_first ($37) then
repeat
if is_directory then
begin
this_directory := current_directory + '\' + get_file;
Writeln(this_directory);
directory(this_directory); { Now do all subdirectories }
end;
until not find_next ($37);
set_dta(DTA_ofs, DTA_seg); { restore the old DTA }
end;
Function current_drive : byte;
{
Function to return the current drive
Uses MSDOS Function $19 with Interrupt $21
current_drive is 1 if A, 2 if B, 3 if C, etc.
}
begin
global_reg.ax := $1900;
intr($21, global_reg);
current_drive := 1 + lo(global_reg.ax);
end;
BEGIN { FILECRC }
{ root will have the current drive designation }
root := chr(current_drive + ord('A') - 1) + ':';
Writeln('CRC file integrity program');
Writeln('Version ',version:5:2,', ',version_date);
Write('Written by Ted H. Emigh -- ');
Writeln('emigh@ecsvax.uucp or NEMIGH@TUCC.BITNET');
Assign (filvar,'CHECK$$$.CRC');
{$I-}
Reset (filvar); { See if CHECK$$$.CRC exists }
{$I+}
{ check_crc will be TRUE if CHECK$$$.CRC exists }
check_crc := (IOresult = 0);
if check_crc then
begin
Assign (outfile,'CHECK$$$.NEW');
Writeln ('Creating File CHECK$$$.NEW');
end
else
begin
Assign (outfile,'CHECK$$$.CRC');
Writeln ('Creating File CHECK$$$.CRC');
end;
Close (filvar);
Rewrite (outfile); { Open the output file }
Generate_table_256(POLY); { Generate the table for CRC check }
Writeln(root+'\');
directory(root); { Now, do the CRC check }
Close (outfile);
{ Now compare this with the previous CRC's }
if check_crc then
begin
Assign (chain_file,'COMPARE.CHN');
Chain(chain_file);
end;
end.
===filecrc.pas===
# ----------
echo "Extracting compare.pas <-- filecrc.ar"
cat << \===compare.pas=== > compare.pas
{ PROGRAM TO COMPARE THE CRC'S OF THE FILE LISTS IN }
{ CHECK$$$.NEW AND CHECK$$$.CRC }
{$G512,P512,U+,R+ }
Program Compare;
TYPE
string255 = string[255];
string64 = string[64];
string12 = string[12];
Registers = record
ax, bx, cx, dx, bp, si, di, ds, es, flags : integer;
end;
Months = array [1..12] of string[3];
Directory_record = record
directory : string64;
FileNum : integer;
end;
File_Rec = record
name : string12;
time_of_day, date : integer;
low_size,high_size : integer;
attribute : byte;
crc : integer;
end;
CONST
month : Months = ('JAN','FEB','MAR','APR','MAY','JUN',
'JUL','AUG','SEP','OCT','NOV','DEC');
Version = 1.00;
Version_Date = '13 AUG 86';
VAR
{ File Creation time and date }
TimeOfDay, FileDate : integer;
directory_number, file_number : integer;
{ Number of files in each category }
old_file, new_file, OK_file, Update_file, Mod_file : integer;
old_filename, new_filename : string64;
infile : TEXT[$0800]; { file for reading file lists }
newfile : TEXT; { file for writing names of new files created }
modfile : TEXT; { file for writing names of modified files }
tempfile : file; { used in renaming files }
CRC_value : Integer;
filename : string12;
Name_of_File, CRC_string, instring : string255;
attribute : byte;
lowsize, highsize : integer;
new, new_dir : boolean;
number_directories, direct_count : integer;
this_directory, current_directory : string64;
directories : array [1..200] of directory_record;
fileinfo : array [1..1900] of file_rec;
function get_string : string255;
{
This function returns a string up to the first space from infile
}
var
inchar : char;
temp_string : string255;
begin
{ Ignore any leading blanks }
Repeat
read(infile, inchar);
Until inchar <> ' ';
temp_string := '';
{ Now, add on to temp_string until a blank is found }
Repeat
temp_string := temp_string + inchar;
read(infile, inchar);
Until inchar = ' ';
get_string := temp_string;
end;
procedure read_old_file;
{
Procedure to read in the old list of files and set up the list of
directories (variable directories), and the list of files along with
the various data (variable fileinfo).
On return,
old_file has the number of files in the list and
number_directories has the number of directories.
The variables directories and fileinfo have the following information:
directories directory : Name of the directory (up to 64 characters)
FileNum : Number of the name in fileinfo that contains
the information for the first file in this
directory.
fileinfo name : Name of the file
time_of_day : Time of day in DOS format
date : Date in DOS format
low_size : Low byte of the file size
high_size : High byte of the file size
attribute : Attribute of the file
crc : CRC of the file
}
begin
Reset (infile); { Set to read Old List of Files }
old_file := 0; { Number of files in the list }
number_directories := 0; { Number of directories in the list }
While not eof(infile) do
begin
old_file := old_file + 1; { Another file }
this_directory := get_string; { Get the directory name }
fileinfo[old_file].name := get_string; { Get the file name }
if this_directory <> current_directory then
begin
current_directory := this_directory;
number_directories := number_directories + 1;
directories[number_directories].directory := this_directory;
directories[number_directories].FileNum := old_file;
end;
With fileinfo[old_file] do
Readln(infile,attribute, Time_of_day, date, low_size, high_size, crc);
end;
directories[number_directories + 1].FileNum := old_file + 1;
Close (infile);
end;
function get_time(date1,date2 : integer) : string64;
{
This function returns the time and date of file creation.
date1 is the time of day in DOS format
date2 is the date of creation in DOS format
get_time is a string with the time and date (e.g., 14:31:42 8 AUG 1986)
}
var
hour, minute, second : integer;
temp, time : string64;
year, n_month, day : integer;
begin
hour := date1 shr 11;
minute := (date1 shr 5) - (hour shl 6);
second := (date1 - (minute shl 5) - (hour shl 11))*2;
year := date2 shr 9;
n_month := (date2 shr 5) - (year shl 4);
day := date2 - (n_month shl 5) - (year shl 9);
Str(hour:2,temp);
time := temp + ':';
Str(minute:2,temp);
time := time + temp + ':';
Str(second:2,temp);
time := time + temp + ' ';
Str(day:2,temp);
time := time + temp + ' ' + month[n_month] + ' ';
Str(year + 1980:4,temp);
get_time := time + temp;
end;
procedure write_old_file ( file_number : integer);
{
Procedure to write the attribute, size and CRC for a file from
the old list
file_number is the number of the file name
}
var
filesize : real;
begin
with fileinfo[file_number] do
begin
if low_size < 0 then
filesize := int(high_size)*65536.0 + 32768.0 + int(low_size and $7FFF)
else
filesize := int(high_size)*65536.0 + int(low_size);
Write ('Attribute = ',attribute:3,', Size = ',filesize:10:0);
Writeln(', CRC = ',CRC);
end;
end;
procedure write_new_file;
{
Procedure to write the attribute, size and CRC for a file from
the new list
}
var
filesize : real;
begin
if lowsize < 0 then
filesize := int(highsize)*65536.0 + 32768.0 + int(lowsize and $7FFF)
else
filesize := int(highsize)*65536.0 + int(lowsize);
Write ('Attribute = ',attribute:3,', Size = ',filesize:10:0);
Writeln(', CRC = ', CRC_value)
end;
procedure find_directory( var number : integer; var newdir : boolean);
{
Procedure to the the directory from the old list that matches the
directory name from the new list
If the directory name is the same as the current directory, then
number and newdir are unchanged.
If the directory name is not the same, and it exists on the old list,
number will be the number of the old directory, and newdir is FALSE.
The current directory will be updated.
If the directory name is not the same, and it does not exist on the
old list, newdir is FALSE. Number is number of directories + 1, but
is never used.
}
begin
{ If the directory is the same, then the status of number and newdir }
{ will not change }
if this_directory <> current_directory then
begin { search from the beginning -- nothing fancy }
number := 0;
Repeat
number := number + 1;
Until (number > number_directories) or
(this_directory = directories[number].directory);
newdir := (number > number_directories);
current_directory := this_directory;
end;
end;
procedure find_file( var number : integer; var new : boolean;
number_begin, number_end : integer);
{
Procedure to find the file name. The directory name has been
found prior to this time, so the starting point in the search
has been found. The search will continue until the first file
name in the next directory.
}
begin
number := number_begin -1;
Repeat
number := number + 1;
Until (number = number_end) or (filename = fileinfo[number].name);
new := (filename <> fileinfo[number].name);
end;
procedure file_new;
{
This procedure processes the new files. new_file is the counter
for the number of new files. The file name and information is
written to the file assigned to newfile.
}
var
filesize : real;
begin
new_file := new_file + 1;
Write (newfile,this_directory+filename);
Writeln (newfile,' Date: ',get_time(TimeOfDay, FileDate));
if lowsize < 0 then
filesize := int(highsize)*65536.0 + 32768.0 + int(lowsize and $7FFF)
else
filesize := int(highsize)*65536.0 + int(lowsize);
Writeln (newfile,'Attribute = ',attribute:3,
', Size = ',filesize:10:0,', CRC = ', CRC_value);
end;
procedure file_updated;
{
This procedure processes the updated files. Update_file is the counter
for the number of updated files.
}
begin
Update_file := Update_file + 1;
end;
procedure file_OK;
{
This procedure processes the files that have not been changed, modified
or deleted. OK_file is the counter for the number of such files.
}
begin
OK_file := OK_file + 1;
end;
procedure bad_CRC;
{
This procedure processes the files that have been modified without
changing the directory entry date or time. Mod_file is the counter for
the number of such files. In normal operations, this should not happen,
so for such files, the name and date information is shown on the console
and sent to the file assigned to modfile.
}
begin
Mod_file := Mod_file + 1;
Writeln ('CRC''s do not match! File: ',this_directory+filename);
Writeln ('Date: ',get_time(TimeOfDay, FileDate));
Write ('Old file: ');
write_old_file(file_number);
Write ('New file: ');
write_new_file;
Write (modfile, this_directory + filename);
Writeln (modfile,' Date: ', get_time(TimeOfDay, FileDate));
end;
procedure read_new_file;
{
Procedure to read the list of new files, and compare them to the
old files. The various comparison types are processed according to
the preceeding routines.
}
begin
current_directory := '';
new_dir := FALSE;
Assign (infile, new_filename);
Reset (infile);
While not eof(infile) do
begin
this_directory := get_string; { First is the directory name }
filename := get_string; { Next is the file name }
Readln(infile, attribute, TimeOfDay, FileDate, lowsize,
highsize, crc_value); { Then the file parameters }
{ Find the entry in the list of old files with the same name }
find_directory(directory_number,new_dir);
if not new_dir then
find_file(file_number,new,
directories[directory_number].FileNum,
directories[directory_number + 1].FileNum-1);
if (new_dir or new) then { New directory means new file }
file_new
else { Existing file, compare the two }
if (fileinfo[file_number].Time_of_day <> TimeOfDay)
or (fileinfo[file_number].date <> FileDate) then
file_updated
else
if (fileinfo[file_number].crc <> CRC_value) then bad_CRC
else
file_OK;
end;
Close (infile);
end;
BEGIN { Compare }
Writeln('CRC file integrity comparison program');
Writeln('Version ',version:5:2,', ',version_date);
Write('Written by Ted H. Emigh -- ');
Writeln('emigh@ecsvax.uucp or NEMIGH@TUCC.BITNET');
number_directories := 1;
current_directory := '';
directories[1].directory := current_directory;
directories[1].FileNum := 1;
{ Reset the counters for the various comparisons }
New_file := 0;
OK_file := 0;
Update_file := 0;
Mod_file := 0;
{ Set up the input and output files }
Case ParamCount of
0 : begin { No command line parameters, use default names }
old_filename := 'CHECK$$$.CRC';
new_filename := 'CHECK$$$.NEW';
end;
1 : begin { File name with listing of new files has been given }
old_filename := 'CHECK$$$.CRC';
new_filename := ParamStr(1);
end;
else
begin { Both file names have been given }
old_filename := ParamStr(2);
new_filename := ParamStr(1);
end;
end;
{ Set up the various input and output files }
Assign (infile,old_filename);
Assign(newfile,'FILES$$$.NEW');
Rewrite (newfile);
Writeln (newfile,'New files created on this disk');
Assign(modfile,'FILES$$$.MOD');
Rewrite (modfile);
Writeln (modfile,'Files that were modified without updating the directory');
Writeln ('Reading old CRC list, please wait ...');
read_old_file;
Writeln ('Reading new CRC list and checking, please wait ...');
read_new_file;
{ Print the summary numbers for this check }
Writeln ('Number of Files in the last CRC check: ',old_file);
Writeln ('Number of Files that are the same as last time: ',OK_file);
Writeln ('Number of New Files: ',new_file);
Writeln ('Number of Deleted Files: ',
old_file - update_file - OK_file - Mod_file);
Writeln ('Number of Updated Files: ',update_file);
Writeln ('Number of Invalidly Modified Files: ',Mod_file);
Writeln;
Writeln;
{ Erase the output files if they are empty }
Close (newfile);
if new_file = 0 then Erase (newfile);
Close (modfile);
if Mod_file = 0 then Erase (modfile);
{ No command line parameters -- Rename the files with the file lists }
if ParamCount = 0 then
begin
Assign (tempfile, 'CHECK$$$.OLD');
{$I-}
Reset (tempfile); { See if the file already exists }
{$I+}
if IOresult =0 then
Erase (tempfile); { Yes, it exists -- delete it }
Close (tempfile);
Assign (tempfile, 'CHECK$$$.CRC');
Rename (tempfile, 'CHECK$$$.OLD');
Assign (tempfile, 'CHECK$$$.NEW');
Rename (tempfile, 'CHECK$$$.CRC');
Writeln ('Old CRC file is now CHECK$$$.OLD');
Writeln ('New CRC file is now CHECK$$$.CRC');
Writeln;
end;
end.
===compare.pas===
# ----------
--
Ted H. Emigh Genetics and Statistics, North Carolina State U, Raleigh NC
USENET: {akgua decvax duke ihnp4 unc}!mcnc!ecsvax!emigh
ARPA: decvax!mcnc!ecsvax!emigh@BERKELEY
BITNET: NEMIGH@TUCC