Tribblix: manual page: elfwrap.1

ELFWRAP(1) User Commands ELFWRAP(1)

NAME

elfwrap - wrap data in an ELF file

SYNOPSIS

elfwrap [-64] [-o relobj-file] [-z target=sparc | x86]
data-file...

DESCRIPTION

The elfwrap utility creates an ELF relocatable object file from one
or more data files. The relocatable object encapsulates each data
file within an individual section, together with symbols that can be
used to reference the section. The relocatable object is appropriate
for inclusion with a subsequent link-edit. Users can reference the
encapsulated data using the associated symbols.

By default, a 32-bit ELF relocatable object is created that is
appropriate for the machine on which elfwrap is executed. The -64
option can be used to create a 64-bit ELF relocatable object. The -z
target option can be used to create a relocatable object for a
specific machine type.

Note -

Any data encapsulated with elfwrap must be in a format appropriate
for the destination target.

By default, the relocatable object a.wrap.o is created. The -o option
can be used to specify an alternative relocatable object name.

The basename(1) of each data file is used to create various pieces of
ELF information. For example, if the input data file is ISV/isv-
data, the following ELF information is created within the relocatable
object.

An ELF section named .isv-data

This section contains the entire contents of the input data file.

An ELF symbol named isv-data_start

This symbol reflects the starting address of the .isv-data
section.

An ELF symbol named isv-data_end

This symbol reflects the address of the first location after the
.isv-data section.

OPTIONS

The following options are supported:

-64

Create a 64-bit ELF relocatable object.

-o relobj-file

Produce a relocatable object that is named relobj-file.

-z target=sparc | x86

Specifies the machine type for the output relocatable object.
Supported targets are sparc and x86. The 32-bit machine type for
the specified target is used unless the -64 option is also
present, in which case the corresponding 64-bit machine type is
used. By default, the relocatable object that is generated is
32-bit for the machine one which elfwrap is executed.

EXAMPLES

The following example encapsulates the system passwd file and the
system group file within a relocatable object passgroup.o.

example% elfwrap -o passgroup.o /etc/passwd /etc/group
example% elfdump -s passgroup.o | egrep "passwd|group"
[2] 0x00000000 0x00000000 SECT LOCL D 0 .passwd
[3] 0x00000000 0x00000000 SECT LOCL D 0 .group
[7] 0x00000000 0x000002f0 OBJT GLOB D 0 .passwd passwd_start
[8] 0x000002f0 0x00000000 OBJT GLOB D 0 .passwd passwd_end
[9] 0x00000000 0x00000121 OBJT GLOB D 0 .group group_start
[10] 0x00000121 0x00000000 OBJT GLOB D 0 .group group_end
example% strings -N.passwd passgroup.o | head -1
root:x:0:0:Super-User:/:/sbin/sh
example% strings -N.group passgroup.o | head -1
root::0:

This relocatable object can be referenced from the following user
code.

example% cat main.c
#include <stdio.h>

extern char passwd_start, passwd_end;

void main()
{
char *pstart = &passwd_start, *pend = &passwd_end;
char *str, *lstr;

for (lstr = str = pstart; str < pend; str++) {
if ((*str == '\n') && (str != (pend - 1))) {
(void) printf("%.*s", (++str - lstr), lstr);
lstr = str;
}
}
}
example% cc -o main main.c passgroup.o
example% ./main
root:x:0:0:Super-User:/:/sbin/sh
....
nobody4:x:65534:65534:SunOS 4.x NFS Anonymous Access User:/:

FILES

a.wrap.o
The default relocatable object file created.

ATTRIBUTES