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.

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

See attributes(5) for descriptions of the following attributes:

See Also

elfdump(1), ld(1), strings(1), elf(3ELF), attributes(5),

Linker and Libraries Guide