1.\" Copyright (c) 2010 Kai Wang 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $Id: dwarf_attr.3 3093 2014-09-02 22:09:40Z kaiwang27 $ 26.\" 27.Dd April 8, 2010 28.Os 29.Dt DWARF_ATTR 3 30.Sh NAME 31.Nm dwarf_attr 32.Nd retrieve an attribute descriptor associated with a DWARF debugging information entry 33.Sh LIBRARY 34.Lb libdwarf 35.Sh SYNOPSIS 36.In libdwarf.h 37.Ft int 38.Fo dwarf_attr 39.Fa "Dwarf_Die die" 40.Fa "Dwarf_Half attr" 41.Fa "Dwarf_Attribute *atp" 42.Fa "Dwarf_Error *err" 43.Fc 44.Sh DESCRIPTION 45Function 46.Fn dwarf_attr 47retrieves the attribute descriptor for an attribute associated 48with the DWARF debugging information entry descriptor in 49argument 50.Ar die . 51.Pp 52DWARF attribute descriptors are represented by value of the opaque 53type 54.Vt Dwarf_Attribute , 55see 56.Xr dwarf 3 . 57.Pp 58Argument 59.Ar attr 60names the desired DWARF attribute. 61Legal values for argument 62.Ar attr 63are those denoted by the 64.Dv DW_AT_* 65constants in the DWARF specification. 66.Pp 67Argument 68.Ar atp 69points to a location into which the returned attribute descriptor 70will be written. 71The returned descriptor may then be passed to the form query functions in the 72.Xr dwarf 3 73API set to access the data associated with the attribute. 74.Pp 75If argument 76.Ar err 77is non-NULL, it will be used to return an error descriptor in case 78of an error. 79.Sh RETURN VALUES 80Function 81.Fn dwarf_attr 82returns 83.Dv DW_DLV_OK on success. 84.Pp 85If the debugging information entry descriptor denoted by argument 86.Ar die 87does not contain the named attribute, the function returns 88.Dv DW_DLV_NO_ENTRY 89and sets argument 90.Ar err . 91For other errors, it returns 92.Dv DW_DLV_ERROR 93and sets argument 94.Ar err . 95.Sh ERRORS 96Function 97.Fn dwarf_attr 98can fail with the following errors: 99.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT" 100.It Bq Er DW_DLE_ARGUMENT 101Either of arguments 102.Ar die 103or 104.Ar atp 105was NULL. 106.It Bq Er DW_DLE_NO_ENTRY 107Argument 108.Ar die 109had no attribute corresponding to the value 110in argument 111.Ar attr . 112.El 113.Sh SEE ALSO 114.Xr dwarf 3 , 115.Xr dwarf_attrlist 3 , 116.Xr dwarf_attroffset 3 , 117.Xr dwarf_hasattr 3 , 118.Xr dwarf_hasform 3 , 119.Xr dwarf_whatattr 3 , 120.Xr dwarf_whatform 3 121