1.\"	$NetBSD: dwarf_formref.3,v 1.2 2014/03/09 16:58:03 christos Exp $
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3.\" Copyright (c) 2010 Joseph Koshy
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27.\" Id: dwarf_formref.3 2073 2011-10-27 03:30:47Z jkoshy
28.\"
29.Dd June 21, 2010
30.Os
31.Dt DWARF_FORMREF 3
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.Ar attr
61in the location pointed to by argument
62.Ar retoffset .
63Argument
64.Ar attr
65must be a reference that is local to a compilation unit.
66Permitted forms for argument
67.Ar 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.Ar attr
81in the location pointed to by argument
82.Ar retoffset .
83Argument
84.Ar attr
85should be a legal
86.Sy REFERENCE
87class form.
88Permitted forms for argument
89.Ar 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.Ar err
105is not NULL, it will be used to return an error descriptor in case
106of an error.
107.Sh RETURN VALUES
108These functions return
109.Dv DW_DLV_OK
110on success.
111In case of an error, these functions return
112.Dv DW_DLV_ERROR
113and sets argument
114.Ar err .
115.Sh ERRORS
116These functions may fail with the following errors:
117.Bl -tag -width ".Bq Er DW_DLE_ATTR_FORM_BAD"
118.It Bq Er DW_DLE_ARGUMENT
119Either of arguments
120.Ar attr
121or
122.Ar retoffset
123was NULL.
124.It Bq Er DW_DLE_ATTR_FORM_BAD
125The attribute referenced by argument
126.Ar attr
127was not of a permitted kind.
128.El
129.Sh SEE ALSO
130.Xr dwarf 3 ,
131.Xr dwarf_attr 3 ,
132.Xr dwarf_formblock 3 ,
133.Xr dwarf_formflag 3 ,
134.Xr dwarf_formsdata 3 ,
135.Xr dwarf_formsig8 3 ,
136.Xr dwarf_formstring 3 ,
137.Xr dwarf_formudata 3 ,
138.Xr dwarf_hasattr 3
139