freebsd-dev/lib/libelf/elf_memory.3

.\" Copyright (c) 2006 Joseph Koshy.  All rights reserved.
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.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 argument
.Ar image
corresponds to an ELF file with an unsupported 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