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Binary search and replace

 
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# 1  
Old 05-27-2014
Scissors Binary search and replace
Hello again. I have two problems - is it possible to solve them?
1. I want to replace a few bytes after specific hex-string.
i.e.: I want to replace two bytes after AA AB AC:
Code:
AA AB AC 00 00 AA AA AA

so the expected result should be:
Code:
AA AB AC FF FF AA AA AA

2. I want to replace three bytes before specific hex-string.
i.e.: replace two bytes before 00 00 with FF FF:
Code:
AA AB AC 00 00 AA AA AA

result:
Code:
AA FF FF 00 00 AA AA AA

Everything above is pseudo hexcode. Also I attached real binary files to this post. Since this question was posted at "newbies" section, I'm expecting all possible solutions. Thank you
binary_to_replace.pdf (8 Bytes) 
wanted_result_1.pdf (8 Bytes) 
wanted_result_2.pdf (8 Bytes) 
Last edited by useretail; 05-27-2014 at 05:01 PM..
# 2  
Old 05-27-2014
Firstly, give us a clue as to your OS, shell, terminal, etc...

Secondly this is not a binary file.
They are ASCII representations of hexadecimal pairs separated by space delimiters.

Thirdly how large will your (pseudo)-binary be?

Fourthly will there always be two "00" pairs?

Lastly in number 2 do you want three "FF" pair values or two as shown in your results?

Whichever the case then this might be of help as a starter:-

Another Building Block, Binary File Manipulation...
# 3  
Old 05-27-2014
And, to add another question,
is the data in the file formatted like your example, or are you doing something to represent the data in this manner (like an od command)?
# 4  
Old 05-27-2014
OS: POSIX-compliant
shell: sh/bash
terminal: rxvt (does it really matter?)

filesize: i don't know.. from 8 bytes to 8 terabytes

will there always be two "00" pairs: have no idea

do you want three "FF" pair values: no, its just an example

*updated 1st post
**btw, i know how to replace using sed, but i have no clue how to replace before or after some hexstring

---------- Post updated at 03:27 PM ---------- Previous update was at 03:06 PM ----------

i don't think that binary manipulations using hexdump (in this case) are wise:
Quote:
$man hexdump
The hexdump utility is a filter which displays the specified files ...
I understand that in linux everything goes, but let's face it - hexdump wasn't made for that purpose.
Last edited by useretail; 05-27-2014 at 05:16 PM..
# 5  
Old 05-27-2014
An example for the first part longhand using OSX 10.7.5, default bash terminal...

Altered the binary file to show it works...
Code:
#!/bin/bash
# bin_change.sh
# This will be SSLLOOWW with large files...
ifs_str="$IFS"
IFS=" "
> /tmp/bin
> /tmp/newbin
printf "\xBB\xCC\xAA\xAA\xAA\xAB\xAC\x00\x00\xAA\xAA\xAA" >> /tmp/bin
printf "\xBB\xCC\xAA\xAA\xAA\xAB\xAC\x00\x00\xAA\xAA\xAA" >> /tmp/bin
printf "\xBB\xCC\xAA\xAA\xAA\xAB\xAC\x00\x00\xAA\xAA\xAA" >> /tmp/bin
printf "\xBB\xCC\xAA\xAA\xAA\xAB\xAC\x00\x00\xAA\xAA\xAA" >> /tmp/bin
# Check existence of 48 bytes of example binary...
hexdump -C /tmp/bin
n=0
bin_array=(`hexdump -v -e '1/1 "%02X "' /tmp/bin`)
echo ""
# 48 is the /tmp/bin filelength.
while [ $n -lt 48 ]
do
	if [ "${bin_array[$n]}${bin_array[$((n+1))]}${bin_array[$((n+2))]}" == "AAABAC" ] && [ "${bin_array[$((n+3))]}${bin_array[$((n+4))]}" == "0000" ]
	then
		printf "\x${bin_array[$n]}\x${bin_array[$((n+1))]}\x${bin_array[$((n+2))]}\xFF\xFF" >> /tmp/newbin
		n=$((n+5))
	fi
	printf "\x${bin_array[$n]}" >> /tmp/newbin
	n=$((n+1))
done
# Now check new 48 bytes of binary...
hexdump -C /tmp/newbin
echo ""
IFS="$ifs_str"
exit 0

Results:-
Code:
Last login: Tue May 27 22:27:08 on ttys000
AMIGA:barrywalker~> ./bin_change.sh
00000000  bb cc aa aa aa ab ac 00  00 aa aa aa bb cc aa aa  |................|
00000010  aa ab ac 00 00 aa aa aa  bb cc aa aa aa ab ac 00  |................|
00000020  00 aa aa aa bb cc aa aa  aa ab ac 00 00 aa aa aa  |................|
00000030

00000000  bb cc aa aa aa ab ac ff  ff aa aa aa bb cc aa aa  |................|
00000010  aa ab ac ff ff aa aa aa  bb cc aa aa aa ab ac ff  |................|
00000020  ff aa aa aa bb cc aa aa  aa ab ac ff ff aa aa aa  |................|
00000030

AMIGA:barrywalker~> _

HTH, Good Night all...
# 6  
Old 05-27-2014
I'm confused. The title of this thread is Binary search and replace. A binary search is used to search a sorted list. I see no order in the values that you are searching?

Please explain how you are doing anything other than a linear search for five contiguous values and then replacing two of those five matched values.
# 7  
Old 05-28-2014
Hi.

I'd guess that the OP meant Byte or Binary File Search and Replace. We would not expect that everyone knows that there is an efficient procedure for searching ordered collections that goes by that name http://en.wikipedia.org/wiki/Binary_search_algorithm ... cheers, drl
Last edited by drl; 05-28-2014 at 12:52 PM..
This User Gave Thanks to drl For This Post:
Don Cragun
 
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