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.\" $Id: elf_open.3,v 1.3 2020/05/18 06:46:23 jsg Exp $
.\"
.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