man pages section 1: User Commands

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Updated: July 2014



elfwrap - wrap data in an ELF file


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


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 base name of each data file, as define by the basename(1) utility, is used to create section and symbol names that are assigned to the associated data. For example, if the input data file is ISV/isv-data, the following ELF information is associated to the data within the output relocatable object.

An ELF section named .isv-data

This section contains the entire contents of the input data file. The section is also identified with the SHF_SUNW_ELFWRAP section flag.

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.


The following options are supported:


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.


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 -c -T PROGBITS passgroup.o

Section Header[1]:  sh_name: .passwd
  sh_addr:  0      sh_flags:  [ SHF_ALLOC SHF_SUNW_ELFWRAP ]
  sh_size:  0x5a2  sh_type:   [ SHT_PROGBITS ]

Section Header[2]:  sh_name: .group
  sh_addr:  0      sh_flags:  [ SHF_ALLOC SHF_SUNW_ELFWRAP ]
  sh_size:  0x199  sh_type:   [ SHT_PROGBITS ]

example% elfdump -s passgroup.o | egrep "passwd|group"
  [2]      0     0  SECT LOCL  D  0 .passwd        
  [3]      0     0  SECT LOCL  D  0 .group         
  [7]      0 0x5a2  OBJT GLOB  D  0 .passwd  passwd_start
  [8]  0x5a2     0  OBJT GLOB  D  0 .passwd  passwd_end
  [9]      0 0x199  OBJT GLOB  D  0 .group   group_start
 [10]  0x199     0  OBJT GLOB  D  0 .group   group_end

example% strings -N.passwd passgroup.o | head -1
example% strings passgroup.o | head -1

The password data within the 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
nobody4:x:65534:65534:SunOS 4.x NFS Anonymous Access User:/:



The default relocatable object file created.


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

Interface Stability

See also

elfdump(1), ld(1), strings(1), elf(3ELF), attributes(5), ddi_modopen(9F)

Oracle Solaris 11.2 Linkers and Libraries Guide


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

The name of the input file drives the creation of the symbol names to associate with the input file data. Therefore, input files should be uniquely named to avoid the creation of symbols with the same name.