1.\" $NetBSD: dwarf_formref.3,v 1.6 2024/03/03 17:37:31 christos Exp $ 2.\" 3.\" Copyright (c) 2010 Joseph Koshy 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" Id: dwarf_formref.3 3962 2022-03-12 15:56:10Z jkoshy 28.\" 29.Dd June 21, 2010 30.Dt DWARF_FORMREF 3 31.Os 32.Sh NAME 33.Nm dwarf_formref , 34.Nm dwarf_global_formref 35.Nd retrieve offsets for REFERENCE class attributes 36.Sh LIBRARY 37.Lb libdwarf 38.Sh SYNOPSIS 39.In libdwarf.h 40.Ft int 41.Fo dwarf_formref 42.Fa "Dwarf_Attribute attr" 43.Fa "Dwarf_Off *retoffset" 44.Fa "Dwarf_Error *err" 45.Fc 46.Ft int 47.Fo dwarf_global_formref 48.Fa "Dwarf_Attribute attr" 49.Fa "Dwarf_Off *retoffset" 50.Fa "Dwarf_Error *err" 51.Fc 52.Sh DESCRIPTION 53These functions return the offsets associated with a DWARF attribute 54descriptor. 55.Pp 56Function 57.Fn dwarf_formref 58returns the compilation unit relative offset of the descriptor 59referenced by argument 60.Fa attr 61in the location pointed to by argument 62.Fa retoffset . 63Argument 64.Fa attr 65must be a reference that is local to a compilation unit. 66Permitted forms for argument 67.Fa attr 68are 69.Dv DW_FORM_ref1 , 70.Dv DW_FORM_ref2 , 71.Dv DW_FORM_ref4 , 72.Dv DW_FORM_ref8 73and 74.Dv DW_FORM_ref_udata . 75.Pp 76Function 77.Fn dwarf_global_formref 78returns the section-relative offset of the descriptor referenced by 79argument 80.Fa attr 81in the location pointed to by argument 82.Fa retoffset . 83Argument 84.Fa attr 85should be a legal 86.Sy REFERENCE 87class form. 88Permitted forms for argument 89.Fa attr 90are: 91.Dv DW_FORM_ref_addr , 92.Dv DW_FORM_ref_udata , 93.Dv DW_FORM_ref1 , 94.Dv DW_FORM_ref2 , 95.Dv DW_FORM_ref4 , 96.Dv DW_FORM_ref8 97and 98.Dv DW_FORM_sec_offset . 99The returned offset is relative to the start of the 100.Dq .debug_info 101ELF section. 102.Pp 103If argument 104.Fa err 105is not 106.Dv NULL , 107it will be used to return an error descriptor in case of an error. 108.Sh RETURN VALUES 109These functions return 110.Dv DW_DLV_OK 111on success. 112In case of an error, these functions return 113.Dv DW_DLV_ERROR 114and sets argument 115.Fa err . 116.Sh ERRORS 117These functions may fail with the following errors: 118.Bl -tag -width ".Bq Er DW_DLE_ATTR_FORM_BAD" 119.It Bq Er DW_DLE_ARGUMENT 120Either of arguments 121.Fa attr 122or 123.Fa retoffset 124was 125.Dv NULL . 126.It Bq Er DW_DLE_ATTR_FORM_BAD 127The attribute referenced by argument 128.Fa attr 129was not of a permitted kind. 130.El 131.Sh SEE ALSO 132.Xr dwarf 3 , 133.Xr dwarf_attr 3 , 134.Xr dwarf_formblock 3 , 135.Xr dwarf_formflag 3 , 136.Xr dwarf_formsdata 3 , 137.Xr dwarf_formsig8 3 , 138.Xr dwarf_formstring 3 , 139.Xr dwarf_formudata 3 , 140.Xr dwarf_hasattr 3 141