1.\" $NetBSD: dwarf_get_ranges.3,v 1.2 2014/03/09 16:58:04 christos Exp $ 2.\" 3.\" Copyright (c) 2011 Kai Wang 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_get_ranges.3 2122 2011-11-09 15:35:14Z jkoshy 28.\" 29.Dd November 9, 2011 30.Os 31.Dt DWARF_GET_RANGES 3 32.Sh NAME 33.Nm dwarf_get_ranges 34.Nd retrieve non-contiguous address ranges 35.Sh LIBRARY 36.Lb libdwarf 37.Sh SYNOPSIS 38.In libdwarf.h 39.Ft int 40.Fo dwarf_get_ranges 41.Fa "Dwarf_Debug dbg" 42.Fa "Dwarf_Off offset" 43.Fa "Dwarf_Ranges **ranges" 44.Fa "Dwarf_Signed *cnt" 45.Fa "Dwarf_Unsigned *byte_cnt" 46.Fa "Dwarf_Error *err" 47.Fc 48.Ft int 49.Fo dwarf_get_ranges_a 50.Fa "Dwarf_Debug dbg" 51.Fa "Dwarf_Off offset" 52.Fa "Dwarf_Die die" 53.Fa "Dwarf_Ranges **ranges" 54.Fa "Dwarf_Signed *cnt" 55.Fa "Dwarf_Unsigned *byte_cnt" 56.Fa "Dwarf_Error *err" 57.Fc 58.Sh DESCRIPTION 59Function 60.Fn dwarf_get_ranges 61retrieves information about the non-contiguous address ranges associated 62with a DWARF debugging information entry. 63Information about address ranges is returned as an array of 64descriptors of type 65.Vt Dwarf_Ranges , 66with each 67.Vt Dwarf_Ranges 68descriptor describing one address range entry. 69.Pp 70Argument 71.Ar dbg 72should reference a DWARF debug context allocated using 73.Xr dwarf_init 3 . 74.Pp 75Argument 76.Ar offset 77is an offset, relative to the 78.Dq ".debug_ranges" 79section, to the start of the desired list of address ranges. 80The offset of an address ranges list is indicated by the 81.Dv DW_AT_ranges 82attribute of a debugging information entry. 83.Pp 84Argument 85.Ar die 86(function 87.Fn dwarf_get_ranges_a 88only) is ignored in this implementation; see the section 89.Sx "Compatibility Notes" 90below. 91.Pp 92Argument 93.Ar ranges 94should point to a location that will be set to a pointer to an array 95of 96.Vt Dwarf_Ranges 97descriptors. 98.Pp 99Argument 100.Ar cnt 101should point to a location that will be set to the number of entries 102returned. 103If argument 104.Ar byte_cnt 105is not NULL, it will be set to the number of bytes occupied by the 106returned entries in the 107.Dq ".debug_ranges" 108section. 109.Pp 110If argument 111.Ar err 112is not NULL, it will be used to store error information in case 113of an error. 114.Pp 115.Vt Dwarf_Ranges 116descriptors are defined in the header file 117.In libdwarf.h , 118and consists of the following fields: 119.Bl -tag -width ".Va dwr_addr1" 120.It Va dwr_addr1 121The first address offset, whose meaning depends on the type of the 122entry. 123.It Va dwr_addr2 124The second address offset, whose meaning depends on the type of the 125entry. 126.It Va dwr_type 127The type of this address range entry: 128.Bl -tag -width ".Dv DW_RANGES_ENTRY" -compact 129.It Dv DW_RANGES_ENTRY 130A range list entry. 131For this type of entry, the fields 132.Va dwr_addr1 133and 134.Va dwr_addr2 135hold the beginning and ending offsets of the address range, respectively. 136.It Dv DW_RANGES_ADDRESS_SELECTION 137A base address selection entry. 138For this type of entry, the field 139.Va dwr_addr1 140is the value of the largest representable address offset, and 141.Va dwr_addr2 142is a base address for the begining and ending address offsets of 143subsequent address range entries in the list. 144.It Dv DW_RANGES_END 145An end of list mark. 146Both 147.Va dwr_addr1 148and 149.Va dwr_addr2 150are set to 0. 151.El 152.El 153.Ss Memory Management 154The memory area used for the array of 155.Vt Dwarf_Ranges 156descriptors returned in argument 157.Ar ranges 158is owned by the 159.Lb libdwarf . 160The application should not attempt to directly free this pointer. 161Portable code should instead use 162.Fn dwarf_ranges_dealloc 163to indicate that the memory may be freed. 164.Sh COMPATIBILITY 165Function 166.Fn dwarf_get_ranges_a 167is identical to 168.Fn dwarf_get_ranges , 169except that it requires one additional argument 170.Ar die 171denoting the debugging information entry associated with 172the address range list. 173In this implementation of the 174.Lb libdwarf , 175the argument 176.Ar die 177is ignored, and function 178.Fn dwarf_get_ranges_a 179is only provided for compatibility with other implementations of the 180DWARF(3) API. 181.Sh RETURN VALUES 182These functions 183return 184.Dv DW_DLV_OK 185when they succeed. 186They return 187.Dv DW_DLV_NO_ENTRY 188if there is no address range list at the specified offset 189.Ar offset . 190In case of an error, they return 191.Dv DW_DLV_ERROR 192and set the argument 193.Ar err . 194.Sh ERRORS 195These function can fail with: 196.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY" 197.It Bq Er DW_DLE_ARGUMENT 198One of the arguments 199.Ar dbg , 200.Ar ranges 201or 202.Ar cnt 203was NULL. 204.It Bq Er DW_DLE_NO_ENTRY 205There is no address range list at the specified offset 206.Ar offset . 207.El 208.Sh EXAMPLE 209To retrieve the address range list associated with a debugging 210information entry, use: 211.Bd -literal -offset indent 212Dwarf_Debug dbg; 213Dwarf_Die die; 214Dwarf_Error de; 215Dwarf_Addr base; 216Dwarf_Attribute *attr_list; 217Dwarf_Ranges *ranges; 218Dwarf_Signed cnt; 219Dwarf_Unsigned off, attr_count, bytecnt; 220int i, j; 221 222if ((ret = dwarf_attrlist(die, &attr_list, &attr_count, &de)) != 223 DW_DLV_OK) 224 errx(EXIT_FAILURE, "dwarf_attrlist failed: %s", 225 dwarf_errmsg(de)); 226 227for (i = 0; (Dwarf_Unsigned) i < attr_count; i++) { 228 if (dwarf_whatattr(attr_list[i], &attr, &de) != DW_DLV_OK) { 229 warnx("dwarf_whatattr failed: %s", 230 dwarf_errmsg(de)); 231 continue; 232 } 233 if (attr != DW_AT_ranges) 234 continue; 235 if (dwarf_formudata(attr_list[i], &off, &de) != DW_DLV_OK) { 236 warnx("dwarf_formudata failed: %s", 237 dwarf_errmsg(de)); 238 continue; 239 } 240 if (dwarf_get_ranges(dbg, (Dwarf_Off) off, &ranges, &cnt, 241 &bytecnt, &de) != DW_DLV_OK) 242 continue; 243 for (j = 0; j < cnt; j++) { 244 if (ranges[j].dwr_type == DW_RANGES_END) 245 break; 246 else if (ranges[j].dwr_type == 247 DW_RANGES_ADDRESS_SELECTION) 248 base = ranges[j].dwr_addr2; 249 else { 250 /* 251 * DW_RANGES_ENTRY entry. 252 * .. Use dwr_addr1 and dwr_addr2 .. 253 */ 254 } 255 } 256} 257.Ed 258.Sh SEE ALSO 259.Xr dwarf 3 , 260.Xr dwarf_ranges_dealloc 3 261