1.\" $NetBSD: dwarf_get_ranges.3,v 1.6 2024/03/03 17:37:31 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 3963 2022-03-12 16:07:32Z jkoshy 28.\" 29.Dd November 9, 2011 30.Dt DWARF_GET_RANGES 3 31.Os 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.Fa dbg 72should reference a DWARF debug context allocated using 73.Xr dwarf_init 3 . 74.Pp 75Argument 76.Fa 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.Fa 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.Fa 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.Fa cnt 101should point to a location that will be set to the number of entries 102returned. 103If argument 104.Fa byte_cnt 105is not 106.Dv NULL , 107it will be set to the number of bytes occupied by the 108returned entries in the 109.Dq ".debug_ranges" 110section. 111.Pp 112If argument 113.Fa err 114is not 115.Dv NULL , 116it will be used to store error information in case of an error. 117.Pp 118.Vt Dwarf_Ranges 119descriptors are defined in the header file 120.In libdwarf.h , 121and consists of the following fields: 122.Bl -tag -width ".Va dwr_addr1" 123.It Va dwr_addr1 124The first address offset, whose meaning depends on the type of the 125entry. 126.It Va dwr_addr2 127The second address offset, whose meaning depends on the type of the 128entry. 129.It Va dwr_type 130The type of this address range entry: 131.Bl -tag -width ".Dv DW_RANGES_ENTRY" -compact 132.It Dv DW_RANGES_ENTRY 133A range list entry. 134For this type of entry, the fields 135.Va dwr_addr1 136and 137.Va dwr_addr2 138hold the beginning and ending offsets of the address range, respectively. 139.It Dv DW_RANGES_ADDRESS_SELECTION 140A base address selection entry. 141For this type of entry, the field 142.Va dwr_addr1 143is the value of the largest representable address offset, and 144.Va dwr_addr2 145is a base address for the beginning and ending address offsets of 146subsequent address range entries in the list. 147.It Dv DW_RANGES_END 148An end of list mark. 149Both 150.Va dwr_addr1 151and 152.Va dwr_addr2 153are set to 0. 154.El 155.El 156.Ss Memory Management 157The memory area used for the array of 158.Vt Dwarf_Ranges 159descriptors returned in argument 160.Fa ranges 161is owned by the 162.Lb libdwarf . 163The application should not attempt to directly free this pointer. 164Portable code should instead use 165.Fn dwarf_ranges_dealloc 166to indicate that the memory may be freed. 167.Sh RETURN VALUES 168These functions 169return 170.Dv DW_DLV_OK 171when they succeed. 172They return 173.Dv DW_DLV_NO_ENTRY 174if there is no address range list at the specified offset 175.Fa offset . 176In case of an error, they return 177.Dv DW_DLV_ERROR 178and set the argument 179.Fa err . 180.Sh EXAMPLES 181To retrieve the address range list associated with a debugging 182information entry, use: 183.Bd -literal -offset indent 184Dwarf_Debug dbg; 185Dwarf_Die die; 186Dwarf_Error de; 187Dwarf_Addr base; 188Dwarf_Attribute *attr_list; 189Dwarf_Ranges *ranges; 190Dwarf_Signed cnt; 191Dwarf_Unsigned off, attr_count, bytecnt; 192int i, j; 193 194if ((ret = dwarf_attrlist(die, &attr_list, &attr_count, &de)) != 195 DW_DLV_OK) 196 errx(EXIT_FAILURE, "dwarf_attrlist failed: %s", 197 dwarf_errmsg(de)); 198 199for (i = 0; (Dwarf_Unsigned) i < attr_count; i++) { 200 if (dwarf_whatattr(attr_list[i], &attr, &de) != DW_DLV_OK) { 201 warnx("dwarf_whatattr failed: %s", 202 dwarf_errmsg(de)); 203 continue; 204 } 205 if (attr != DW_AT_ranges) 206 continue; 207 if (dwarf_formudata(attr_list[i], &off, &de) != DW_DLV_OK) { 208 warnx("dwarf_formudata failed: %s", 209 dwarf_errmsg(de)); 210 continue; 211 } 212 if (dwarf_get_ranges(dbg, (Dwarf_Off) off, &ranges, &cnt, 213 &bytecnt, &de) != DW_DLV_OK) 214 continue; 215 for (j = 0; j < cnt; j++) { 216 if (ranges[j].dwr_type == DW_RANGES_END) 217 break; 218 else if (ranges[j].dwr_type == 219 DW_RANGES_ADDRESS_SELECTION) 220 base = ranges[j].dwr_addr2; 221 else { 222 /* 223 * DW_RANGES_ENTRY entry. 224 * .. Use dwr_addr1 and dwr_addr2 .. 225 */ 226 } 227 } 228} 229.Ed 230.Sh COMPATIBILITY 231Function 232.Fn dwarf_get_ranges_a 233is identical to 234.Fn dwarf_get_ranges , 235except that it requires one additional argument 236.Fa die 237denoting the debugging information entry associated with 238the address range list. 239In this implementation of the 240.Lb libdwarf , 241the argument 242.Fa die 243is ignored, and function 244.Fn dwarf_get_ranges_a 245is only provided for compatibility with other implementations of the 246DWARF(3) API. 247.Sh ERRORS 248These function can fail with: 249.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY" 250.It Bq Er DW_DLE_ARGUMENT 251One of the arguments 252.Fa dbg , 253.Fa ranges 254or 255.Fa cnt 256was 257.Dv NULL . 258.It Bq Er DW_DLE_NO_ENTRY 259There is no address range list at the specified offset 260.Fa offset . 261.El 262.Sh SEE ALSO 263.Xr dwarf 3 , 264.Xr dwarf_ranges_dealloc 3 265