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python ctypes.create_string_buffer help!!!!

Answer 1

A:

sorry.. i know the value is 80 not 50

james 2010-10-29 23:58:47

You should edit your question, not "answer" with a correction :)

Mark Tolonen 2010-10-30 03:42:31

lol sorry mark im new to this site.. i hope this is the right place to post this... ok so i been doing more messing around and i found something strange.. in the python shell i type something = ctypes.create_string_buffer(4) now if i type something.raw and press enter the shell will print '\x00\x00\x00\x00'.. if i type print something.raw it prints four rectangles? why does print change the value of my something variable? using print i want the output to be '\x00\x00\x00\x00'?

james 2010-10-30 08:48:10

That's a new question, so it should be asked as one, then people can get reputation for it (don't forget to except an answer for this one as well). Anyway, to do what you want, use `print repr(s)`, which displays non-printable characters in `\x##` format.

Mark Tolonen 2010-10-30 14:22:13

k thats it then :) problem solved. thanks mark you been a great help :) i clicked the tick so you should get reputation.. anyway, thanks again

james 2010-10-30 17:11:18

Answer 2

A:

It is not returning Unicode, but four bytes as a string (probably '\x80\x00\x00\x00') Pass a pointer to an integer not a string buffer:

read_buff = ctypes.c_uint()
kernel32.ReadProcessMemory(hproc, lpbaseaddr, ctypes.byref(read_buff),
                           ctypes.sizeof(read_buff), ctypes.byref(bytread))
print read_buff.value

Mark Tolonen 2010-10-30 03:52:19

thank you so much mark it worked perfectly, thats exactly the answer i was looking for :) one last question tho, the read_buff = ctypes.c_uint() will that hold any size variable? unlike the string buffer where i had to specify 4 bytes long etc.. thanks again for the fast reply

james 2010-10-30 10:11:41

ok one last question.. say i wanted to return that byte string. eg "\x80\x00\x00\x00". what pointer would i use then?

james 2010-10-30 12:30:43

No, `c_uint` is 4 bytes in size, `ctypes.sizeof` returns the size. `print repr(read_buff.raw)` will display the string in escaped format.

Mark Tolonen 2010-10-30 14:26:16

ok so at the moment heres what ive done..

james 2010-10-30 15:23:19

read_buff = ctypes.create_string buffer

james 2010-10-30 15:23:34

sigh every time i push enter it sends... anyway.. heres my code.. read_buff = ctypes.create_string_buffer(4) print repr(read_buff.raw) this returns "\x90\x00\x00\x00" for example. then using the struct module i go struct.unpack("i", "\x90\x00\x00\x00") and it gives me the integer i want :) but now how do i get the string version? say for example at that address the value could be an int or a str of a word and i want to try both possible options to see which might contain the value im looking for... thanks

james 2010-10-30 15:27:05

If it is a string just use create_string_buffer like you were using, and `print read_buff.value`.

Mark Tolonen 2010-10-30 17:58:24

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