Hello Python world,
I am on Linux and Python 2.7 , I need some help to figure out what is
going wrong in the below piece of code
I am trying to replace seven bytes in the hexdumfile at a given offset
Program 1 works fine
#!/usr/bin/python
from qa.utils.easy_popen import run
import pdb
def replace_hex(fname, offset, newdata):
#pdb.set_trace()
with open(fname, 'r+b') as f:
#Show current contents
f.seek(offset)
stringdata = f.read(len(newdata))
print 'Current data:'
print '%08X: %s\n' % (offset, stringdata.encode('hex'))
#Replace data at offset with newdata
f.seek(offset)
f.write(newdata)
f.close()
#print the data
cmd = 'hexdump -C %s' % (fname)
print cmd
out, err, ret = run(cmd)
print "Hexdump file data for corrupting"
print out, err, ret
return fname
fname = '/tmp/2017-02-20_08-42-22/file1.raw'
offset = 0x1
newdata = '64000101057804'.decode('hex')
replace_hex(fname, offset, newdata)
-200-1# python file_2.py
Current data:
00000001: 6400010105789a
hexdump -C /tmp/2017-02-20_08-42-22/file1.raw
Hexdump file data for corrupting
00000000 06 64 00 01 01 05 78 04 73 1c ab 58 08 f9 8b 3b
|.d....x.s..X...;| ==> Replaced
00000010 1e 00 a1 00 01 00 00 00 64 00 01 01 05 78 02 00
|........d....x..|
Program 2 ( Doesn't work , some junk character got replaced )
g-200-1# vi file_2.py
#!/usr/bin/python
from qa.utils.easy_popen import run
import pdb
def replace_hex(fname, offset, newdata):
#pdb.set_trace()
with open(fname, 'r+b') as f:
#Show current contents
f.seek(offset)
stringdata = f.read(len(newdata))
print 'Current data:'
print '%08X: %s\n' % (offset, stringdata.encode('hex'))
#Replace data at offset with newdata
f.seek(offset)
f.write(newdata)
f.close()
#print the data
cmd = 'hexdump -C %s' % (fname)
print cmd
out, err, ret = run(cmd)
print "Hexdump file data for corrupting"
print out, err, ret
return fname
fname = '/tmp/2017-02-20_08-42-22/file1.raw'
offset = 0x10
newdata = ""
newdata = '64000101057804'
newdata.decode('hex')
replace_hex(fname, offset, newdata)
g-200-1# python file_2.py
Current data:
00000010: 1e00a10001000000640001010578
hexdump -C /tmp/2017-02-20_08-42-22/MOB_file1.raw
Hexdump file data for corrupting
00000000 06 64 00 01 01 05 78 04 73 1c ab 58 08 f9 8b 3b
|.d....x.s..X...;|
00000010 36 34 30 30 30 31 30 31 30 35 37 38 30 34 02 00
|64000101057804..|===> Some junk values got writen ???
00000020 e0 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00
|................|
00000030 00 03 10 21 bf cd 05 80 00 00 00 00 00 00 00 00
|...!............|
00000040 58 02 00 00 00 00 00 00 00 20 00 00 00 00 00 00 |X........
......|
00000050 01 00 00 00 00 00 00 00 03 00 00 00 00 00 00 00
|................|
00000060 00 00 00 00 00 00 00 00 74 1c ab 58 a0 84 2b 00
|........t..X..+.|
00000070 74 1c ab 58 a0 84 2b 00 fd ff fd ff 00 00 00 00
|t..X..+.........|
00000080 02 04 25 40 04 00 01 64 00 01 01 05 78 04 31 30
|..%@...d....x.10|
00000090 35 37 38 00 02 84 02 64 00 01 01 05 78 30 30 30
|578....d....x000|
000000a0 31 30 30 30 32 00 0f fe 94 ba 15 00 00 00 00 00
|10002...........|
000000b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
000001d0 00 00 00 00 00 22 ff ff ff ff 20 03 00 00 00 00 |....."....
.....|
000001e0 00 00 00 0b 04 00 0b 01 00 02 01 0a 00 01 00 64
|...............d|
000001f0 06 00 00 01 00 02 97 0a 33 9b 3f 32 f3 62 b1 15
|........3.?2.b..|
Questions:
1. The only difference between both the programs the difference are just
the below lines.
newdata = '64000101057804'.decode('hex')
and
newdata = ""
newdata = '64000101057804'
newdata.decode('hex')
What is happening here and how do I fix this in program 2 ? for my eyes
there doesn't look any difference .
question 2:
I am using the variable newdata because I can't hardcore the value , I
have to keep changing this every time the function is called, will return
it as a string help me slove this problem
def get_data() :
return str(data)
new_data =get_data(input)
Regards,
Ganesh
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