1.\" $NetBSD: dwarf_get_section_bytes.3,v 1.4 2020/11/26 22:51:35 jkoshy 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_section_bytes.3 3644 2018-10-15 19:55:01Z jkoshy 28.\" 29.Dd August 26, 2011 30.Dt DWARF_GET_SECTION_BYTES 3 31.Os 32.Sh NAME 33.Nm dwarf_get_section_bytes 34.Nd retrieve ELF section byte streams 35.Sh LIBRARY 36.Lb libdwarf 37.Sh SYNOPSIS 38.In libdwarf.h 39.Ft Dwarf_Ptr 40.Fo dwarf_get_section_bytes 41.Fa "Dwarf_P_Debug dbg" 42.Fa "Dwarf_Signed dwarf_section" 43.Fa "Dwarf_Signed *elf_section_index" 44.Fa "Dwarf_Unsigned *length" 45.Fa "Dwarf_Error *err" 46.Fc 47.Sh DESCRIPTION 48Function 49.Fn dwarf_get_section_bytes 50returns the ELF section byte streams generated by a prior call 51to function 52.Xr dwarf_transform_to_disk_form 3 . 53.Pp 54Each call to function 55.Fn dwarf_get_section_bytes 56will return the byte stream for one ELF section. 57The first call to this function will always return the first ELF 58section, and the subsequent calls will return the rest of sections 59in the order when they were generated, until the last one. 60The total number of sections generated is returned by the function 61.Xr dwarf_transform_to_disk_form 3 . 62.Pp 63Argument 64.Ar dbg 65should reference a DWARF producer instance allocated using the 66functions 67.Xr dwarf_producer_init 3 68or 69.Xr dwarf_producer_init_b 3 . 70.Pp 71Argument 72.Ar dwarf_section 73is currently ignored. 74.Pp 75Argument 76.Ar elf_section_index 77should point to a location which will be set to the section index value 78of the returned ELF section. 79.Pp 80Argument 81.Ar length 82should point to a location which will hold the length in bytes of the 83returned ELF section. 84.Pp 85If argument 86.Ar err 87is not NULL, it will be used to store error information in case of an 88error. 89.Ss Memory Management 90The memory areas used for the returned ELF section byte streams should 91be freed using the function 92.Fn dwarf_producer_finish . 93.Sh RETURN VALUES 94On success, function 95.Fn dwarf_get_section_bytes 96returns a pointer to a ELF section byte stream. 97In case of an error, function 98.Fn dwarf_get_section_bytes 99will return NULL and set the argument 100.Ar err . 101.Sh EXAMPLES 102To generate and retrieve ELF section byte streams, use: 103.Bd -literal -offset indent 104Dwarf_P_Debug dbg; 105Dwarf_Signed count, i, sec_index; 106Dwarf_Unsigned len; 107Dwarf_Ptr bytes; 108Dwarf_Error de; 109 110/* ... Assume that `dbg' refers to a DWARF producer instance, 111 * and that application code has added DWARF debugging 112 * information to the producer instance. ... 113 */ 114if ((count = dwarf_transform_to_disk_form(dbg, &de)) == 115 DW_DLV_NOCOUNT) { 116 warnx("dwarf_transform_to_disk_form failed: %s", 117 dwarf_errmsg(-1)); 118 return; 119} 120 121/* Retrieve section data. */ 122for (i = 0; i < count; i++) { 123 bytes = dwarf_get_section_bytes(dbg, i, &sec_index, &len, 124 &de); 125 if (bytes == NULL) { 126 warnx("dwarf_get_section_bytes failed: %s", 127 dwarf_errmsg(-1)); 128 continue; 129 } 130 /* ... use the returned byte stream ... */ 131} 132 133/* Release resources. */ 134dwarf_producer_finish(dbg, &de); 135.Ed 136.Sh ERRORS 137Function 138.Fn dwarf_get_section_bytes 139can fail with: 140.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY" 141.It Bq Er DW_DLE_ARGUMENT 142One of the arguments 143.Ar dbg , 144.Ar elf_section_index , 145or 146.Ar length 147was NULL. 148.It Bq Er DW_DLE_NO_ENTRY 149There were no more ELF sections to retrieve, or the function was 150called before a call to 151.Xr dwarf_transform_to_disk_form 3 . 152.El 153.Sh SEE ALSO 154.Xr dwarf 3 , 155.Xr dwarf_producer_finish 3 , 156.Xr dwarf_producer_init 3 , 157.Xr dwarf_producer_init_b 3 , 158.Xr dwarf_reset_section_bytes 3 , 159.Xr dwarf_transform_to_disk_form 3 160