.\" Copyright (c) 2012 Joseph Koshy.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" This software is provided by Joseph Koshy ``as is'' and
.\" any express or implied warranties, including, but not limited to, the
.\" implied warranties of merchantability and fitness for a particular purpose
.\" are disclaimed.  in no event shall Joseph Koshy be liable
.\" for any direct, indirect, incidental, special, exemplary, or consequential
.\" damages (including, but not limited to, procurement of substitute goods
.\" or services; loss of use, data, or profits; or business interruption)
.\" however caused and on any theory of liability, whether in contract, strict
.\" liability, or tort (including negligence or otherwise) arising in any way
.\" out of the use of this software, even if advised of the possibility of
.\" such damage.
.\"
.\" $Id: elf_open.3 3743 2019-06-12 19:36:30Z jkoshy $
.\"
.Dd June 12, 2019
.Dt ELF_OPEN 3
.Os
.Sh NAME
.Nm elf_open
.Nd open ELF objects and ar(1) archives
.Sh LIBRARY
.Lb libelf
.Sh SYNOPSIS
.In libelf.h
.Ft "Elf *"
.Fn elf_open "int fd"
.Ft "Elf *"
.Fn elf_openmemory "char *image" "size_t sz"
.Sh DESCRIPTION
.Em Important :
The functions
.Fn elf_open
and
.Fn elf_openmemory
are extensions to the
.Xr elf 3
API, for the internal use of the
Elftoolchain project.
Portable applications should not use these functions.
.Pp
The function
.Fn elf_open
returns an Elf descriptor opened with mode
.Dv ELF_C_READ
for the ELF object or
.Xr ar 1
archive referenced by the file descriptor in argument
.Ar fd .
.Pp
The function
.Fn elf_openmemory
returns an ELF descriptor opened with mode
.Dv ELF_C_READ
for the ELF object or
.Xr ar 1
archive contained in the memory area pointed to by the argument
.Ar image .
The argument
.Ar sz
specifies the size of the memory area in bytes.
.Sh RETURN VALUES
The function returns a pointer to a ELF descriptor if successful, or
NULL if an error occurred.
.Sh COMPATIBILITY
These functions are non-standard extensions to the
.Xr elf 3
API set.
.Pp
The behavior of these functions differs from their counterparts
.Xr elf_begin 3
and
.Xr elf_memory 3
in that these functions will successfully open malformed ELF objects
and
.Xr ar 1
archives, returning an Elf descriptor of type
.Dv ELF_K_NONE .
.Sh ERRORS
These functions can fail with the following errors:
.Bl -tag -width "[ELF_E_RESOURCE]"
.It Bq Er ELF_E_ARGUMENT
The argument
.Ar fd
was of an unsupported file type.
.It Bq Er ELF_E_ARGUMENT
The argument
.Ar sz
was zero, or the argument
.Ar image
was NULL.
.It Bq Er ELF_E_IO
The file descriptor in argument
.Ar fd
was invalid.
.It Bq Er ELF_E_IO
The file descriptor in argument
.Ar fd
could not be read.
.It Bq Er ELF_E_RESOURCE
An out of memory condition was encountered.
.It Bq Er ELF_E_SEQUENCE
Functions
.Fn elf_open
or
.Fn elf_openmemory
was called before a working version was established with
.Xr elf_version 3 .
.El
.Sh SEE ALSO
.Xr elf 3 ,
.Xr elf_begin 3 ,
.Xr elf_errno 3 ,
.Xr elf_memory 3 ,
.Xr gelf 3