Using dwarf_discr_list()

Example using dwarf_discr_list, dwarf_formblock.

An example calling dwarf_get_form_class, dwarf_discr_list, and dwarf_formblock. and the dwarf_deallocs applicable.

See also

dwarf_discr_list

dwarf_get_form_class

dwarf_formblock

Parameters

dw_dbg	The applicable Dwarf_Debug
dw_die	The applicable Dwarf_Die
dw_attr	The applicable Dwarf_Attribute
dw_attrnum,The	attribute number passed in to shorten this example a bit.
dw_isunsigned,The	attribute number passed in to shorten this example a bit.
dw_theform,The	form number passed in to shorten this example a bit.
dw_error	The usual error pointer.

Returns

Returns DW_DLV_OK etc

*/
int example_discr_list(Dwarf_Debug dbg,
    Dwarf_Die die,
    Dwarf_Attribute attr,
    Dwarf_Half attrnum,
    Dwarf_Bool isunsigned,
    Dwarf_Half theform,
    Dwarf_Error *error)
{
    /*  The example here assumes that
        attribute attr is a DW_AT_discr_list.
        isunsigned should be set from the signedness
        of the parent of 'die' per DWARF rules for
        DW_AT_discr_list. */
    enum Dwarf_Form_Class fc = DW_FORM_CLASS_UNKNOWN;
    Dwarf_Half version = 0;
    Dwarf_Half offset_size = 0;
    int wres = 0;
 
    wres = dwarf_get_version_of_die(die,&version,&offset_size);
    if (wres != DW_DLV_OK) {
        /* FAIL */
        return wres;
    }
    fc = dwarf_get_form_class(version,attrnum,offset_size,theform);
    if (fc == DW_FORM_CLASS_BLOCK) {
        int fres = 0;
        Dwarf_Block *tempb = 0;
        fres = dwarf_formblock(attr, &tempb, error);
        if (fres == DW_DLV_OK) {
            Dwarf_Dsc_Head h = 0;
            Dwarf_Unsigned u = 0;
            Dwarf_Unsigned arraycount = 0;
            int sres = 0;
 
            sres = dwarf_discr_list(dbg,
                (Dwarf_Small *)tempb->bl_data,
                tempb->bl_len,
                &h,&arraycount,error);
            if (sres == DW_DLV_NO_ENTRY) {
                /* Nothing here. */
                dwarf_dealloc(dbg, tempb, DW_DLA_BLOCK);
                return sres;
            }
            if (sres == DW_DLV_ERROR) {
                /* FAIL . */
                dwarf_dealloc(dbg, tempb, DW_DLA_BLOCK);
                return sres ;
            }
            for (u = 0; u < arraycount; u++) {
                int u2res = 0;
                Dwarf_Half dtype = 0;
                Dwarf_Signed dlow = 0;
                Dwarf_Signed dhigh = 0;
                Dwarf_Unsigned ulow = 0;
                Dwarf_Unsigned uhigh = 0;
 
                if (isunsigned) {
                    u2res = dwarf_discr_entry_u(h,u,
                        &dtype,&ulow,&uhigh,error);
                } else {
                    u2res = dwarf_discr_entry_s(h,u,
                        &dtype,&dlow,&dhigh,error);
                }
                if (u2res == DW_DLV_ERROR) {
                    /* Something wrong */
                    dwarf_dealloc(dbg,h,DW_DLA_DSC_HEAD);
                    dwarf_dealloc(dbg, tempb, DW_DLA_BLOCK);
                    return u2res ;
                }
                if (u2res == DW_DLV_NO_ENTRY) {
                    /* Impossible. u < arraycount. */
                    dwarf_dealloc(dbg,h,DW_DLA_DSC_HEAD);
                    dwarf_dealloc(dbg, tempb, DW_DLA_BLOCK);
                    return u2res;
                }
                /*  Do something with dtype, and whichever
                    of ulow, uhigh,dlow,dhigh got set.
                    Probably save the values somewhere.
                    Simple casting of dlow to ulow (or vice versa)
                    will not get the right value due to the nature
                    of LEB values. Similarly for uhigh, dhigh.
                    One must use the right call.  */
            }
            dwarf_dealloc(dbg,h,DW_DLA_DSC_HEAD);
            dwarf_dealloc(dbg, tempb, DW_DLA_BLOCK);
        }
    }
    return DW_DLV_OK;
}