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Editing Binary File

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# 1  
Old 07-17-2011
Editing Binary File
Dear Experts,

I have one binary file which contains multiple 31k (31744) records.
Each record begins with "a6 82".

So the pattern is:
Code:
  a6 82 (+31742 bytes)
  a6 82 (+31742 bytes)
  a6 82 (+31742 bytes)
  a6 82 (+31742 bytes)

There are some corrupted files where record does not begin with
a6 82, before them there are some fillers (00)
Code:
  a6 82 (+31742 bytes)
  00 00 00 a6 82 (+31742 bytes)
  00 00 a6 82 (+31742 bytes)
  00 00 00 00 00 00 a6 82 (+31742 bytes)

The number of 00 fillers is not constant.

Is there someway to edit this file via some script & change to following
pattern:
Code:
  a6 82 (+31742 bytes)
  a6 82 (+31742 bytes)
  a6 82 (+31742 bytes)
  a6 82 (+31742 bytes)


Note: the count of number of records in file is variable

Thanks,
Dhiraj
Last edited by Franklin52; 07-17-2011 at 03:24 PM.. Reason: Please use code tags for data and code samples, thank you
# 2  
Old 07-17-2011
Code:
sed 's/00 //g' file

# 3  
Old 07-17-2011
Hi Franklin52,

The file I am working with is binary file.
Not sure if sed would work on it?

Also this pattern of 00 can occur anywhere in valid data record.
I do not want it to be deleted if it is in "a6 82 (+31742 bytes)" chunk.
For example:

a6 82 00 00 00 11 22 33 00 00 00 00 (+31732 bytes)

Thanks,
Dhiraj
# 4  
Old 07-17-2011
I don't know perl and haven't used awk for binary before.. Do you have GNU gawk available? Can you show output of:

Code:
gawk 'BEGIN{FS="";RS="\xa6\x82";}{print length($0)}' binary

I got an idea...
# 5  
Old 07-18-2011
I'm no master of perl but this should do what you want:

Code:
#!/usr/bin/perl
open INFILE, "<", "binary" or die $!;
open OUTFILE, ">", "bin_fixed" or die $!;
binmode INFILE;
binmode OUTFILE;
my $data=chr(0);
while(1) {
    while(ord($data) == 0x00 && read(INFILE , $data, 1) == 1) { }
    last if ord($data) != 0xA6;
    read(INFILE , $data, 1);
    last if ord($data) != 0x82;
    last if read(INFILE , $data, 31742) != 31742;
    printf(OUTFILE  "%c%c", 0xA6, 0x82);
    print OUTFILE  $data;
    $data=chr(0);
}
close INFILE;
close OUTFILE;

This User Gave Thanks to Chubler_XL For This Post:
dhiraj4mann
# 6  
Old 07-18-2011
Code:
od -An -v -tu1 binfile | tr -cs '[:digit:]' '[\n*]' | > binfile.fixed awk '
        NR >= r {
                if (int($0) == 0)
                        next
                r = NR + 31744
        }
        { printf("%c", $0) }'

Regards,
Alister
This User Gave Thanks to alister For This Post:
dhiraj4mann
# 7  
Old 07-18-2011
Thanks
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