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Old 12-09-2022, 10:31 AM   #1
Racho
LQ Newbie
 
Registered: Oct 2021
Posts: 26

Rep: Reputation: Disabled
How can i get the .data, .text and .bss segment addresses in C?


Hi there!
I've made this program to show the memory map of a program in linux:

Code:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
int una_funcion()
{
        return 0;
}
int global_uninitialized;
int global_initialized=1;

int main()
{
        char *mem;
        register void *stack1 asm("ebp");
        int i=100;
        int j;
        static int static_var=10;
        static int static_var2;
        mem = malloc(100);
        if (mem == NULL)
                return -1;
        printf("64 bit memory addresses are:\n");
        printf("        +-----------------------------------------------+  0xffff ffff ffff ffff\n");
        printf("        |                                               |\n");
        printf("        |               kernel segment                  |       kernel space\n");
        printf("        |                                               |\n");
        printf("        +-----------------------------------------------+  0xffff 8000 0000 0000\n");
        printf("        |                                               |\n");
        printf("        |             Non-canonical space               |       unused\n");
        printf("        |                                               |\n");
        printf("        +-------------------+--+-------------------+----+  0x0000 7fff ffff ffff\n");
        printf("        | stack 1           |  | stack 2           | ....\n");
        printf("        | ...               |  | ...               |\n");
        printf("        | library mapping1  |  | library mapping2  |\n");
        printf("        | ...               |  | ...               |\n");
        printf("        | Heap1             |  | Heap2             |            User space\n");
        printf("        | bss segment1      |  | bss segment2      |\n");
        printf("        | data segment1     |  | data segment2     |\n");
        printf("        | text1             |  | text2             |\n");
        printf("        +-------------------+  +-------------------+       0x0000 0000 0000 0000\n");
        printf("\n");

        printf("Stack begins at: ebp:\t\t\t%p\n", stack1);
        printf("In the stack, local variable:\t\t%p\n", &j);
        printf("In the stack, local variable:\t\t%p\n", &i);
        printf("In library mappings: printf:\t\t%p\n", printf);
        printf("In library mappings: fork:\t\t%p\n", fork);
        printf("In heap segment: reserva con malloc:\t%p\n", mem);
        printf("In .bss uninitialized global var:\t%p\n", &global_uninitialized);
        printf("In .data initialized gloval var:\t%p\n", &global_initialized);
        printf("In .data local static inizialized:\t%p\n", &static_var);
        printf("In .data local static uninizialized:\t%p\n", &static_var2);
        printf("In .text segment: main():\t\t%p\n", main);
        printf("In .text segment: funcion:\t\t%p\n", una_funcion);
        free(mem);

        return 0;
}
I would like to add the start address of .text, .data and .bss segments. And it would be great to add the ending addresses too!
Can anyone help me?
 
Old 12-09-2022, 10:40 AM   #2
pan64
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Registered: Mar 2012
Location: Hungary
Distribution: debian/ubuntu/suse ...
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I'm afraid they do not exist. They are only used when compiling and building the executable, but you won't need them in the end.
 
1 members found this post helpful.
Old 12-09-2022, 11:03 AM   #3
NevemTeve
Senior Member
 
Registered: Oct 2011
Location: Budapest
Distribution: Debian/GNU/Linux, AIX
Posts: 4,428
Blog Entries: 1

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Might be useful: https://linux.die.net/man/3/etext
 
2 members found this post helpful.
Old 12-09-2022, 11:08 AM   #4
Racho
LQ Newbie
 
Registered: Oct 2021
Posts: 26

Original Poster
Rep: Reputation: Disabled
Ohhh... too bad!

Thanks anyway!
 
Old 12-09-2022, 11:25 AM   #5
Racho
LQ Newbie
 
Registered: Oct 2021
Posts: 26

Original Poster
Rep: Reputation: Disabled
Thanks a lot NevemTeve!

I've added that addresses to my little program
 
  


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