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Editorial Team
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Asked: 2026-05-16T18:06:36+00:00

I’m using gdb and libbfd to retrieve global variables information from an elf file

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I’m using gdb and libbfd to retrieve global variables information from an elf file and show it.
I can get the following data from libbfd: Global Variable name, address and size.
I retrieve the type of the variables and its children using gdb and gdb\MI (ptype, whatis, -var-create & -var-list-children).

How can I get the address\size\offset from parent of all the children?

e.g

   type = struct {\n"
   unsigned char count;\n"
   unsigned char time;\n
   }\n

If a variable A of this type is in address 0x000100, I want to show that A.count is in 0x000100 with size 0x1 and A.time is in 0x000101 with size 0x1.

EDIT:
I’ve read that gdb can read the DWARF info, but I can’t figure out how can I get this information from gdb.

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1 Answer

  1. Editorial Team

    Here’s what I did eventually.
    To get the size, I used:

    p sizeof(A.time)

    and to get the address I used:

    p /a &A.time

    NOTE: This only applies for variable of a size bigger then 1 byte.
    To be able to get bitfields size and offset in bits, I had to recompile GDB according to the suggestion offered in nabble: Address of bitfield element bug?

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