xref: /netbsd-src/external/bsd/elftoolchain/dist/libdwarf/dwarf_get_abbrev_entry.3 (revision 5ac3bc719ce6e70593039505b491894133237d12)

.\"	$NetBSD: dwarf_get_abbrev_entry.3,v 1.6 2024/03/03 17:37:31 christos Exp $
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.\" Copyright (c) 2011 Kai Wang
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.\" Id: dwarf_get_abbrev_entry.3 3962 2022-03-12 15:56:10Z jkoshy
.\"
.Dd April 02, 2011
.Dt DWARF_GET_ABBREV_ENTRY 3
.Os
.Sh NAME
.Nm dwarf_get_abbrev_entry
.Nd retrieve attribute information from an abbreviation descriptor
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_get_abbrev_entry
.Fa "Dwarf_Abbrev abbrev"
.Fa "Dwarf_Signed ndx"
.Fa "Dwarf_Half *code"
.Fa "Dwarf_Signed *form"
.Fa "Dwarf_Off *offset"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_get_abbrev_entry
retrieves attribute information from a DWARF abbreviation descriptor.
.Pp
Argument
.Fa abbrev
should be a valid abbreviation descriptor, as returned by function
.Xr dwarf_get_abbrev 3 .
.Pp
Argument
.Fa ndx
specifies the 0-based index of the attribute.
The total count of the attributes contained in the abbreviation
entry can be retrieved using the function
.Xr dwarf_get_abbrev 3 .
.Pp
Argument
.Fa code
should point to a location which will hold a returned
attribute code.
.Pp
Argument
.Fa form
should point to a location which will hold the returned
form of the attribute.
.Pp
Argument
.Fa offset
should point to a location which will hold a returned offset, relative
to the
.Dq ".debug_abbrev"
section, for the specified attribute.
.Pp
If argument
.Fa err
is not
.Dv NULL ,
it will be used to return an error descriptor in case of an error.
.Sh RETURN VALUES
Function
.Fn dwarf_get_abbrev_entry
returns
.Dv DW_DLV_OK
when it succeeds.
It returns
.Dv DW_DLV_NO_ENTRY
if the attribute index specified by argument
.Fa ndx
is out of range.
In case of an error, it returns
.Dv DW_DLV_ERROR
and sets the argument
.Fa err .
.Sh EXAMPLES
To loop through all the attribute entries contained in the
abbreviation section, use:
.Bd -literal -offset indent
Dwarf_Debug dbg;
Dwarf_Abbrev ab;
Dwarf_Off aboff, atoff;
Dwarf_Signed form;
Dwarf_Half attr;
Dwarf_Unsigned length, attr_count;
Dwarf_Error de;
int i, ret;

/* ...allocate 'dbg' using dwarf_init(3) ... */

while ((ret = dwarf_next_cu_header(dbg, NULL, NULL, &aboff,
    NULL, NULL, &de)) ==  DW_DLV_OK) {
	while ((ret = dwarf_get_abbrev(dbg, aboff, &ab, &length,
	    &attr_count, &de)) == DW_DLV_OK) {
		if (length == 1)	/* Last entry. */
			break;
		aboff += length;
		for (i = 0; (Dwarf_Unsigned) i < attr_count; i++) {
			if (dwarf_get_abbrev_entry(ab, i,
			    &attr, &form, &atoff, &de) != DW_DLV_OK) {
				warnx("dwarf_get_abbrev_entry failed:"
				    " %s", dwarf_errmsg(de));
				continue;
			}
			/* .. use the retrieved information ... */
		}
	}

	if (ret != DW_DLV_OK)
		warnx("dwarf_get_abbrev: %s", dwarf_errmsg(de));
}

if (ret == DW_DLV_ERROR)
	warnx("dwarf_next_cu_header: %s", dwarf_errmsg(de));
.Ed
.Sh ERRORS
Function
.Fn dwarf_get_abbrev_entry
can fail with:
.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY"
.It Bq Er DW_DLE_ARGUMENT
One of the arguments
.Fa abbrev ,
.Fa code ,
.Fa form
or
.Fa offset
was
.Dv NULL .
.It Bq Er DW_DLE_NO_ENTRY
The attribute index specified by argument
.Fa ndx
was out of range.
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_get_abbrev 3