1.\" Copyright (c) 2006-2008 Joseph Koshy. All rights reserved. 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 12.\" This software is provided by Joseph Koshy ``as is'' and 13.\" any express or implied warranties, including, but not limited to, the 14.\" implied warranties of merchantability and fitness for a particular purpose 15.\" are disclaimed. in no event shall Joseph Koshy be liable 16.\" for any direct, indirect, incidental, special, exemplary, or consequential 17.\" damages (including, but not limited to, procurement of substitute goods 18.\" or services; loss of use, data, or profits; or business interruption) 19.\" however caused and on any theory of liability, whether in contract, strict 20.\" liability, or tort (including negligence or otherwise) arising in any way 21.\" out of the use of this software, even if advised of the possibility of 22.\" such damage. 23.\" 24.\" $Id: elf_getscn.3 189 2008-07-20 10:38:08Z jkoshy $ 25.\" 26.Dd October 22, 2007 27.Os 28.Dt ELF_GETSCN 3 29.Sh NAME 30.Nm elf_getscn , 31.Nm elf_ndxscn , 32.Nm elf_newscn , 33.Nm elf_nextscn 34.Nd get/allocate section information for an ELF object 35.Sh LIBRARY 36.Lb libelf 37.Sh SYNOPSIS 38.In libelf.h 39.Ft "Elf_Scn *" 40.Fn elf_getscn "Elf *elf" "size_t index" 41.Ft size_t 42.Fn elf_ndxscn "Elf_Scn *scn" 43.Ft "Elf_Scn *" 44.Fn elf_newscn "Elf *elf" 45.Ft "Elf_Scn *" 46.Fn elf_nextscn "Elf *elf" "Elf_Scn *scn" 47.Sh DESCRIPTION 48These functions are used to iterate through the sections associated 49with an ELF descriptor. 50.Pp 51Function 52.Fn elf_getscn 53will return a section descriptor for the section at index 54.Ar index 55in the object denoted by ELF descriptor 56.Ar elf . 57An error will be signalled if the specified section does not 58exist. 59.Pp 60Function 61.Fn elf_ndxscn 62returns the section table index associated with section descriptor 63.Ar scn . 64.Pp 65Function 66.Fn elf_newscn 67creates a new section and appends it to the list of sections 68associated with descriptor 69.Ar elf . 70The library will automatically increment the 71.Va e_shnum 72field of the ELF header associated with descriptor 73.Ar elf , 74and will set the 75.Dv ELF_F_DIRTY 76flag on the returned section descriptor. 77For ELF descriptors opened for writing, the ELF library will 78automatically create an empty section at index zero 79.Dv ( SHN_UNDEF ) 80on the first call to 81.Fn elf_newscn . 82.Pp 83Function 84.Fn elf_nextscn 85takes a section descriptor 86.Ar scn 87and returns a pointer to the section descriptor at the next higher 88index. 89Argument 90.Ar scn 91is allowed to be NULL, in which case this function will return a 92pointer to the section descriptor at index 1. 93If no further sections are present, function 94.Fn elf_nextscn 95will return a NULL pointer. 96.Sh RETURN VALUES 97Functions 98.Fn elf_getscn , 99.Fn elf_newscn 100and 101.Fn elf_nextscn 102return a valid pointer to a section descriptor if successful, or 103NULL if an error occurs. 104.Pp 105Function 106.Fn elf_ndxscn 107returns a valid section table index if successful, or 108.Dv SHN_UNDEF 109if an error occurs. 110.Sh ERRORS 111These functions may fail with the following errors: 112.Bl -tag -width "[ELF_E_RESOURCE]" 113.It Bq Er ELF_E_ARGUMENT 114Arguments 115.Ar elf 116or 117.Ar scn 118were NULL. 119.It Bq Er ELF_E_ARGUMENT 120Argument 121.Ar index 122exceeded the current number of sections in the ELF object. 123.It Bq Er ELF_E_ARGUMENT 124Argument 125.Ar elf 126was not a descriptor for an ELF file. 127.It Bq Er ELF_E_ARGUMENT 128Section descriptor 129.Ar scn 130was not associated with ELF descriptor 131.Ar elf . 132.It Bq Er ELF_E_CLASS 133Descriptor 134.Ar elf 135was of an unknown ELF class. 136.It Bq Er ELF_E_SECTION 137Argument 138.Ar elf 139specified extended section numbering in the ELF header with the section header at 140index 141.Dv SHN_UNDEF 142not being of type 143.Dv SHT_NULL . 144.El 145.Sh SEE ALSO 146.Xr elf 3 , 147.Xr elf_flagdata 3 , 148.Xr elf_flagscn 3 , 149.Xr elf_getdata 3 , 150.Xr elf_getshdr 3 , 151.Xr gelf 3 152