xref: /freebsd/contrib/elftoolchain/libelf/elf_memory.3 (revision ae500c1ff8974130f7f2692772cf288b90349e0d)

.\" Copyright (c) 2006,2008 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_memory.3 3639 2018-10-14 14:07:02Z jkoshy $
.\"
.Dd June 28, 2006
.Dt ELF_MEMORY 3
.Os
.Sh NAME
.Nm elf_memory
.Nd process an ELF or ar(1) archive mapped into memory
.Sh LIBRARY
.Lb libelf
.Sh SYNOPSIS
.In libelf.h
.Ft "Elf *"
.Fn elf_memory "char *image" "size_t size"
.Sh DESCRIPTION
Function
.Fn elf_memory
is used to process an ELF file or
.Xr ar 1
archive whose image is present in memory.
.Pp
Argument
.Ar image
points to the start of the memory image of the file or archive.
Argument
.Ar size
contains the size in bytes of the memory image.
.Pp
The ELF descriptor is created for reading (i.e., analogous to the
use of
.Xr elf_begin 3
with a command argument value of
.Dv ELF_C_READ Ns ).
.Sh RETURN VALUES
Function
.Fn elf_memory
returns a pointer to a new ELF descriptor if successful, or NULL if an
error occurred.
.Pp
The return value may be queried for the file type using
.Xr elf_kind 3 .
.Sh EXAMPLES
To read parse an elf file, use:
.Bd -literal -offset indent
int fd;
void *p;
struct stat sb;
Elf *e;
\&...
if ((fd = open("./elf-file", O_RDONLY)) < 0 ||
    fstat(fd, &sb) < 0 ||
    (p = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t) 0)) ==
    MAP_FAILED) {
	... handle system error ...
}

if ((e = elf_memory(p, sb.st_size)) == NULL) {
	... handle elf(3) error ...
}
\&... use ELF descriptor "e" here ...
.Ed
.Sh ERRORS
Function
.Fn elf_memory
can fail with the following errors:
.Bl -tag -width "[ELF_E_RESOURCE]"
.It Bq Er ELF_E_ARGUMENT
A NULL value was used for argument
.Ar image
or the value of argument
.Ar sz
was zero.
.It Bq Er ELF_E_HEADER
The header of the ELF object contained an unsupported value in its
.Va e_ident[EI_CLASS]
field.
.It Bq Er ELF_E_HEADER
The header of the ELF object contained an unsupported value in its
.Va e_ident[EI_DATA]
field.
.It Bq Er ELF_E_RESOURCE
An out of memory condition was detected.
.It Bq Er ELF_E_SEQUENCE
Function
.Fn elf_memory
was called before a working version was set using
.Xr elf_version 3 .
.It Bq Er ELF_E_VERSION
The ELF object referenced by argument
.Ar image
was of an unsupported ELF version.
.El
.Sh SEE ALSO
.Xr elf 3 ,
.Xr elf_begin 3 ,
.Xr elf_end 3 ,
.Xr elf_errno 3 ,
.Xr elf_kind 3 ,
.Xr gelf 3