1.\" $NetBSD: dwarf_get_section_bytes.3,v 1.5 2022/03/14 20:50:48 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 3963 2022-03-12 16:07:32Z 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.Fa 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.Fa dwarf_section 73is currently ignored. 74.Pp 75Argument 76.Fa 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.Fa length 82should point to a location which will hold the length in bytes of the 83returned ELF section. 84.Pp 85If argument 86.Fa err 87is not 88.Dv NULL , 89it will be used to store error information in case of an error. 90.Ss Memory Management 91The memory areas used for the returned ELF section byte streams should 92be freed using the function 93.Fn dwarf_producer_finish . 94.Sh RETURN VALUES 95On success, function 96.Fn dwarf_get_section_bytes 97returns a pointer to a ELF section byte stream. 98In case of an error, function 99.Fn dwarf_get_section_bytes 100will return 101.Dv NULL 102and set the argument 103.Fa err . 104.Sh EXAMPLES 105To generate and retrieve ELF section byte streams, use: 106.Bd -literal -offset indent 107Dwarf_P_Debug dbg; 108Dwarf_Signed count, i, sec_index; 109Dwarf_Unsigned len; 110Dwarf_Ptr bytes; 111Dwarf_Error de; 112 113/* ... Assume that `dbg' refers to a DWARF producer instance, 114 * and that application code has added DWARF debugging 115 * information to the producer instance. ... 116 */ 117if ((count = dwarf_transform_to_disk_form(dbg, &de)) == 118 DW_DLV_NOCOUNT) { 119 warnx("dwarf_transform_to_disk_form failed: %s", 120 dwarf_errmsg(-1)); 121 return; 122} 123 124/* Retrieve section data. */ 125for (i = 0; i < count; i++) { 126 bytes = dwarf_get_section_bytes(dbg, i, &sec_index, &len, 127 &de); 128 if (bytes == NULL) { 129 warnx("dwarf_get_section_bytes failed: %s", 130 dwarf_errmsg(-1)); 131 continue; 132 } 133 /* ... use the returned byte stream ... */ 134} 135 136/* Release resources. */ 137dwarf_producer_finish(dbg, &de); 138.Ed 139.Sh ERRORS 140Function 141.Fn dwarf_get_section_bytes 142can fail with: 143.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY" 144.It Bq Er DW_DLE_ARGUMENT 145One of the arguments 146.Fa dbg , 147.Fa elf_section_index , 148or 149.Fa length 150was 151.Dv NULL . 152.It Bq Er DW_DLE_NO_ENTRY 153There were no more ELF sections to retrieve, or the function was 154called before a call to 155.Xr dwarf_transform_to_disk_form 3 . 156.El 157.Sh SEE ALSO 158.Xr dwarf 3 , 159.Xr dwarf_producer_finish 3 , 160.Xr dwarf_producer_init 3 , 161.Xr dwarf_producer_init_b 3 , 162.Xr dwarf_reset_section_bytes 3 , 163.Xr dwarf_transform_to_disk_form 3 164