.\" Copyright (c) 2006 Joseph Koshy.  All rights reserved.
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.\" $FreeBSD$
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.Dd November 5, 2006
.Os
.Dt ELF 3
.Sh NAME
.Nm gelf_getsymshndx ,
.Nm gelf_update_symshndx
.Nd read and update symbol information using extended section indices
.Sh LIBRARY
.Lb libelf
.Sh SYNOPSIS
.In gelf.h
.Ft "GElf_Sym *"
.Fo gelf_getsyminfo
.Fa "Elf_Data *symdata"
.Fa "Elf_Data *xndxdata"
.Fa "int ndx"
.Fa "GElf_Sym *sym"
.Fa "Elf32_Word *xndxptr"
.Fc
.Ft int
.Fo gelf_update_syminfo
.Fa "Elf_Data *symdata"
.Fa "Elf_Data *xndxdata"
.Fa "int ndx"
.Fa "GElf_Sym *sym"
.Fa "Elf32_Word xndx"
.Fc
.Sh DESCRIPTION
These functions are analogous to
.Fn gelf_getsym
and
.Fn gelf_update_sym
respectively, but are capable of handling symbol tables using extended
section numbering.
.Pp
Argument
.Ar symdata
is an
.Vt Elf_Data
descriptor associated with a section of type
.Dv SHT_SYMTAB .
Argument
.Ar xndxdata
is an
.Vt Elf_Data
descriptor associated with a section of type
.Dv SHT_SYMTAB_SHNDX .
Argument
.Ar ndx
is the index of the symbol table entry being retrieved or updated.
Argument
.Ar sym
is a pointer to a class-independent
.Vt GElf_Sym
structure.
.Vt GElf_Sym
structures are described in detail in
.Xr gelf 3 .
.Pp
Function
.Fn gelf_getsymshndx
retrieves symbol information at index
.Ar ndx
from the data descriptor specified by argument
.Ar symdata
and stores in class-independent form in argument
.Ar sym .
In addition it retrieves the extended section index for the
symbol from data buffer
.Ar xndxdata
and stores it into the location pointed to by argument
.Ar xndxptr .
.Pp
Function
.Fn gelf_update_symshndx
updates the underlying symbol table entry in data
descriptor
.Ar symdata
with the information in argument
.Ar sym .
In addition it sets the extended section index in
data buffer
.Ar xndxdata
to the value of argument
.Ar xndx .
.Sh RETURN VALUES
Function
.Fn gelf_getsymshndx
returns the value of argument
.Ar sym
if successful, or NULL in case of an error.
.Pp
Function
.Fn gelf_update_symshndx
returns a non-zero value if successful, or zero in case of an error.
.Sh ERRORS
These functions may fail with the following errors:
.Bl -tag -width "[ELF_E_RESOURCE]"
.It Bq Er ELF_E_ARGUMENT
Arguments
.Ar symdata ,
.Ar xndxdata ,
.Ar xndxptr
or
.Ar sym
were NULL.
.It Bq Er ELF_E_ARGUMENT
Argument
.Ar ndx
was less than zero, or too large for either of descriptors
.Ar symdata
or
.Ar xndxdata .
.It Bq Er ELF_E_ARGUMENT
Data descriptor
.Ar symdata
was not associated with a section of type
.Dv SHT_SYMTAB .
.It Bq Er ELF_E_ARGUMENT
Data descriptor
.Ar xndxdata
was not associated with a section of type
.Dv SHT_SYMTAB_SHNDX .
.It Bq Er ELF_E_ARGUMENT
Data descriptor
.Ar symdata
and
.Ar xndxdata
were associated with different ELF objects.
.El
.Sh SEE ALSO
.Xr elf 3 ,
.Xr elf_getdata 3 ,
.Xr elf_getscn 3 ,
.Xr gelf 3 ,
.Xr gelf_getsym 3 ,
.Xr gelf_update_sym 3