Where the variable stored (data segment or heap or BSS) according to the variable's address?

Question

A little similar with Where are static variables stored (data segment or heap or BSS)?,but not the same one.

Now I get a other process's variable's address like:0x10fb90,where is this variable stored(data segment or heap or BSS), could i get the location just from the process's pid and the variable's address?

I am working on osx using obj-c and c.

score 2 · Accepted Answer · edited May 23 '17 at 12:00

2

You have 2 options.

1. Use `objdump`

Something like

objdump -x a.out | grep YOUR_VARIABLE_ADDRESS

2. Use gcc's map option to generate a map file

Compile something like this in gcc

$ gcc -o foo.exe -Wl,-Map,foo.map foo.c

and now

$ grep YOUR_VARIABLE_ADDRESS foo.map

Both these methods will show your variable's location, if at all the address you supplied exits.

PS: The link I've added for the map file shows an example map file generated by Visual Studio linkers, but the format is typically similar in most of the map file formats generated by various linkers

edited May 23 '17 at 12:00

Community

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answered Apr 16 '12 at 08:59

Pavan Manjunath

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Is there any way programming using c to achieve the target? – timestee Apr 16 '12 at 09:03
@AlanGame Try invoking `objdump` from within a C program using `system` function – Pavan Manjunath Apr 16 '12 at 09:07
I forget to specify that the target variable is belong to other process not myself. – timestee Apr 16 '12 at 09:58
@AlanGame Do you mean other program? Then just replace `a.out` with the other program's name – Pavan Manjunath Apr 16 '12 at 10:00
Did you try `objdump` by replacing a.out with the other program's name? – Pavan Manjunath Apr 16 '12 at 10:03
It is not work well,under OSX and iOS, the DATA section, stack and heap's start address may be randomized per execction. – timestee Apr 16 '12 at 10:11
What makes you search for variable addresses instead of variable names? – Pavan Manjunath Apr 16 '12 at 12:25
Because i want to change other application's variable, change other process's memory not my process's. So i do not know the variable's name. – timestee Apr 16 '12 at 15:26
@AlanGame if the variable addresses are randomized in every exxecution then your question "finding an address 0xXXXX..." itself becomes void – Pavan Manjunath Apr 17 '12 at 08:49
Actually,i have found the address by searching the process's memory space according to the changes between the variable's value. – timestee Apr 17 '12 at 09:35

Where the variable stored (data segment or heap or BSS) according to the variable's address?

1 Answers1

1. Use objdump

2. Use gcc's map option to generate a map file

1. Use `objdump`