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: gelf_newehdr.3 3500 2016-12-04 11:08:44Z jkoshy $ 25.\" 26.Dd October 22, 2007 27.Os 28.Dt GELF_NEWEHDR 3 29.Sh NAME 30.Nm elf32_newehdr , 31.Nm elf64_newehdr , 32.Nm gelf_newehdr 33.Nd retrieve or allocate the object file header 34.Sh LIBRARY 35.Lb libelf 36.Sh SYNOPSIS 37.In libelf.h 38.Ft "Elf32_Ehdr *" 39.Fn elf32_newehdr "Elf *elf" 40.Ft "Elf64_Ehdr *" 41.Fn elf64_newehdr "Elf *elf" 42.In gelf.h 43.Ft "void *" 44.Fn gelf_newehdr "Elf *elf" "int elfclass" 45.Sh DESCRIPTION 46These functions retrieve the ELF header from the ELF descriptor 47.Ar elf , 48allocating a new header if needed. 49File data structures are translated to their in-memory representations 50as described in 51.Xr elf 3 . 52.Pp 53Function 54.Fn elf32_newehdr 55returns a pointer to a 32 bit 56.Vt Elf32_Ehdr 57structure. 58Function 59.Fn elf64_newehdr 60returns a pointer to a 64 bit 61.Vt Elf64_Ehdr structure. 62.Pp 63When argument 64.Ar elfclass 65has value 66.Dv ELFCLASS32 , 67function 68.Fn gelf_newehdr 69returns the value returned by 70.Fn elf32_newehdr "elf" . 71When argument 72.Ar elfclass 73has value 74.Dv ELFCLASS64 75it returns the value returned by 76.Fn elf64_newehdr "elf" . 77.Pp 78If a fresh header structure is allocated, the members of the 79structure are initialized as follows: 80.Bl -tag -width indent 81.It Va "e_ident[EI_MAG0..EI_MAG3]" 82Identification bytes at offsets 83.Dv EI_MAG0 , 84.Dv EI_MAG1 , 85.Dv EI_MAG2 86and 87.Dv EI_MAG3 88are set to the ELF signature. 89.It Va "e_ident[EI_CLASS]" 90The identification byte at offset 91.Dv EI_CLASS 92is set to the ELF class associated with the function being called 93or to argument 94.Ar elfclass 95for function 96.Fn gelf_newehdr . 97.It Va "e_ident[EI_DATA]" 98The identification byte at offset 99.Dv EI_DATA 100is set to 101.Dv ELFDATANONE . 102.It Va "e_ident[EI_VERSION]" 103The identification byte at offset 104.Dv EI_VERSION 105is set to the ELF library's operating version set by a prior call to 106.Xr elf_version 3 . 107.It Va e_machine 108is set to 109.Dv EM_NONE . 110.It Va e_type 111is set to 112.Dv ELF_K_NONE . 113.It Va e_version 114is set to the ELF library's operating version set by a prior call to 115.Xr elf_version 3 . 116.El 117.Pp 118Other members of the header are set to zero. 119The application is responsible for changing these values 120as needed before calling 121.Fn elf_update . 122.Pp 123If successful, these three functions set the 124.Dv ELF_F_DIRTY 125flag on ELF descriptor 126.Ar elf . 127.Sh RETURN VALUES 128These functions return a pointer to a translated header descriptor 129if successful, or NULL on failure. 130.Sh COMPATIBILITY 131The 132.Fn gelf_newehdr 133function uses a type of 134.Ft "void *" 135for its returned value. 136This differs from some other implementations of the ELF(3) API, which use an 137.Ft "unsigned long" 138return type. 139.Sh ERRORS 140These functions can fail with the following errors: 141.Bl -tag -width "[ELF_E_RESOURCE]" 142.It Bq Er ELF_E_ARGUMENT 143The argument 144.Ar elf 145was null. 146.It Bq Er ELF_E_ARGUMENT 147Argument 148.Ar elf 149was not a descriptor for an ELF object. 150.It Bq Er ELF_E_ARGUMENT 151Argument 152.Ar elfclass 153had an unsupported value. 154.It Bq Er ELF_E_ARGUMENT 155The class of the ELF descriptor 156.Ar elf 157did not match that of the requested operation. 158.It Bq Er ELF_E_ARGUMENT 159For function 160.Fn gelf_newehdr , 161the class of argument 162.Ar elf 163was not 164.Dv ELFCLASSNONE 165and did not match the argument 166.Ar elfclass . 167.It Bq Er ELF_E_CLASS 168The ELF class of descriptor 169.Ar elf 170did not match that of the API function being called. 171.It Bq Er ELF_E_HEADER 172A malformed ELF header was detected. 173.It Bq Er ELF_E_RESOURCE 174An out of memory condition was detected during execution. 175.It Bq Er ELF_E_SECTION 176The ELF descriptor in argument 177.Ar elf 178did not adhere to the conventions used for extended numbering. 179.It Bq Er ELF_E_VERSION 180The ELF descriptor 181.Ar elf 182had an unsupported ELF version number. 183.El 184.Sh SEE ALSO 185.Xr elf 3 , 186.Xr elf32_getehdr 3 , 187.Xr elf64_getehdr 3 , 188.Xr elf_flagdata 3 , 189.Xr elf_getident 3 , 190.Xr elf_update 3 , 191.Xr elf_version 3 , 192.Xr gelf 3 , 193.Xr gelf_getehdr 3 , 194.Xr elf 5 195