using dwarf_validate_die_sibling

Example of a DIE tree validation.

Here we show how one uses dwarf_validate_die_sibling(). Dwarfdump uses this function as a part of its validation of DIE trees.

It is not something you need to use. But one must use it in a specific pattern for it to work properly.

dwarf_validate_die_sibling() depends on data set by dwarf_child() preceeding dwarf_siblingof_b() . dwarf_child() records a little bit of information invisibly in the Dwarf_Debug data.

*/
 
int example_sibvalid(Dwarf_Debug dbg,
    Dwarf_Die in_die,
    Dwarf_Error*error)
{
    int        cres = DW_DLV_OK;
    int        sibres = DW_DLV_OK;
    Dwarf_Die  die = 0;
    Dwarf_Die  sibdie = 0;
    Dwarf_Die  child = 0;
    Dwarf_Bool is_info = dwarf_get_die_infotypes_flag(die);
 
    die = in_die;
    for ( ; die ; die = sibdie) {
        int vres = 0;
        Dwarf_Unsigned offset = 0;
 
        /* Maybe print something you extract from the DIE */
        cres = dwarf_child(die,&child,error);
        if (cres == DW_DLV_ERROR) {
            if (die != in_die) {
                dwarf_dealloc_die(die);
            }
            printf("dwarf_child ERROR\n");
            return DW_DLV_ERROR;
        }
        if (cres == DW_DLV_OK) {
            int lres = 0;
 
            child = 0;
            lres = example_sibvalid(dbg,child,error);
            if (lres == DW_DLV_ERROR) {
                if (die != in_die) {
                    dwarf_dealloc_die(die);
                }
                dwarf_dealloc_die(child);
                printf("example_sibvalid ERROR\n");
                return lres;
            }
        }
        sibdie = 0;
        sibres = dwarf_siblingof_b(dbg,die,is_info,
            &sibdie,error);
        if (sibres == DW_DLV_ERROR) {
            if (die != in_die) {
                dwarf_dealloc_die(die);
            }
            if (child) {
                dwarf_dealloc_die(child);
            }
            printf("dwarf_siblingof_b ERROR\n");
            return DW_DLV_ERROR;
        }
        if (sibres == DW_DLV_NO_ENTRY) {
            if (die != in_die) {
                dwarf_dealloc_die(die);
            }
            if (child) {
                dwarf_dealloc_die(child);
            }
            return DW_DLV_OK;
        }
        vres = dwarf_validate_die_sibling(sibdie,&offset);
        if (vres == DW_DLV_ERROR) {
            if (die != in_die) {
                dwarf_dealloc_die(die);
            }
            if (child) {
                dwarf_dealloc_die(child);
            }
            dwarf_dealloc_die(sibdie);
            printf("Invalid sibling DIE\n");
            return DW_DLV_ERROR;
        }
        /*  loop again */
        if (die != in_die) {
            dwarf_dealloc_die(die);
        }
        die = 0;
    }
    return DW_DLV_OK;
}