202 lines
6.2 KiB
Groff
202 lines
6.2 KiB
Groff
.\" Copyright (c) 2006 Joseph Koshy. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" This software is provided by Joseph Koshy ``as is'' and
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.\" any express or implied warranties, including, but not limited to, the
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.\" implied warranties of merchantability and fitness for a particular purpose
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.\" are disclaimed. in no event shall Joseph Koshy be liable
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.\" for any direct, indirect, incidental, special, exemplary, or consequential
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.\" damages (including, but not limited to, procurement of substitute goods
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.\" or services; loss of use, data, or profits; or business interruption)
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.\" however caused and on any theory of liability, whether in contract, strict
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.\" liability, or tort (including negligence or otherwise) arising in any way
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.\" out of the use of this software, even if advised of the possibility of
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.\" such damage.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd September 1, 2006
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.Os
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.Dt GELF 3
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.Sh NAME
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.Nm GElf
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.Nd class-independent API for ELF manipulation
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.Sh LIBRARY
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.Lb libelf
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.Sh SYNOPSIS
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.In gelf.h
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.Sh DESCRIPTION
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This manual page describes a class independent API for manipulating
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ELF objects.
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This API allows an application to operate on ELF descriptors without
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needing to the know the ELF class of the descriptor.
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.Pp
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The GElf API may be used alongside the ELF API without restriction.
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.Ss GElf Data Structures
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The GElf API defines the following class-independent data structures:
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.Bl -tag -width GElf_Sxword
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.It Vt GElf_Addr
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A representation of ELF addresses.
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.It Vt GElf_Dyn
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A class-independent representation of ELF
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.Sy .dynamic
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section entries.
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.It Vt GElf_Ehdr
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A class-independent representation of an ELF Executable Header.
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.It Vt GElf_Half
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An unsigned 16 bit quantity.
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.It Vt GElf_Off
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A class-independent representation of a ELF offset.
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.It Vt GElf_Phdr
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A class-independent representation of an ELF Program Header Table
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entry.
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.It Vt GElf_Rel
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A class-independent representation of an ELF relocation entry.
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.It Vt GElf_Rela
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A class-independent representation of an ELF relocation entry with
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addend.
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.It Vt GElf_Shdr
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A class-independent representation of an ELF Section Header Table
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entry.
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.It Vt GElf_Sword
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A signed 32 bit quantity.
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.It Vt GElf_Sxword
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A signed 64 bit quantity.
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.It Vt GElf_Sym
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A class-independent representation of an ELF symbol table entry.
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.It Vt GElf_Word
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An unsigned 32 bit quantity.
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.It Vt GElf_Xword
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An unsigned 64 bit quantity.
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.El
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.Pp
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These data structures are sized to be compatible with the
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corresponding 64 bit ELF structures, and have the same internal
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structure as their 64 bit class-dependent counterparts.
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Class-dependent ELF structures are described in
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.Xr elf 5 .
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.Ss GElf Programming Model
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GElf functions always return a
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.Em copy
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of the underlying (class-dependent) ELF data structure.
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The programming model with GElf is as follows:
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.Bl -enum
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.It
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An application will retrieve data from an ELF descriptor using a
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.Fn gelf_get_*
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function.
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This will copy out data into a private
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.Vt GElf_*
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data structure.
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.It
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The application will work with its private copy of the GElf
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structure.
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.It
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Once done, the application copies the new values back to the
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underlying ELF data structure using the
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.Fn gelf_update_*
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functions.
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.It
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The application will then use the
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.Fn elf_flag*
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APIs to indicate to the ELF library that an ELF data structure is dirty.
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.El
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.Pp
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When updating an underlying 32 bit ELF data structure, the GElf
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routines will signal an error if a GElf value is out of range
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for the underlying ELF data type.
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.Ss Namespace use
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The GElf interface uses the following symbols:
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.Bl -tag
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.It GElf_*
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Class-independent data types.
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.It gelf_*
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For functions defined in the API set.
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.El
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.Ss GElf Programming APIs
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This section provides an overview of the GElf programming APIs.
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Further information is provided in the manual page of each function
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listed here.
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.Bl -tag
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.It "Allocating ELF Data Structures"
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.Bl -tag -compact
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.It Fn gelf_newehdr
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Allocate a new ELF Executable Header.
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.It Fn gelf_newphdr
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Allocate a new ELF Program Header Table.
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.El
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.It "Data Translation"
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.Bl -tag -compact
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.It Fn gelf_xlatetof
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Translate the native representation of an ELF data structure to its
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file representation.
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.It Fn gelf_xlatetom
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Translate from the file representation of an ELF data structure to a
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native representation.
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.El
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.It "Retrieving ELF Data"
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.Bl -tag -compact
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.It Fn gelf_getdyn
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Retrieve an ELF
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.Sy .dynamic
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table entry.
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.It Fn gelf_getehdr
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Retrieve an ELF Executable Header from the underlying ELF descriptor.
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.It Fn gelf_getphdr
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Retrieve an ELF Program Header Table entry from the underlying ELF descriptor.
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.It Fn gelf_getrel
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Retrieve an ELF relocation entry.
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.It Fn gelf_getrela
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Retrieve an ELF relocation entry with addend.
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.It Fn gelf_getshdr
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Retrieve an ELF Section Header Table entry from the underlying ELF descriptor.
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.It Fn gelf_getsym
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Retrieve an ELF symbol table entry.
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.El
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.It Queries
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.Bl -tag -compact
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.It Fn gelf_checksum
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Retrieves the ELF checksum for an ELF descriptor.
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.It Fn gelf_fsize
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Retrieves the size of the file representation of an ELF type.
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.It Fn gelf_getclass
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Retrieves the ELF class of an ELF descriptor.
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.El
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.It "Updating ELF Data"
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.Bl -tag -compact -width ".Fn gelf_update_shdr"
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.It Fn gelf_update_dyn
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Copy back an ELF
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.Sy .dynamic
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Table entry.
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.It Fn gelf_update_phdr
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Copy back an ELF Program Header Table entry.
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.It Fn gelf_update_rel
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Copy back an ELF relocation entry.
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.It Fn gelf_update_rela
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Copy back an ELF relocation with addend entry.
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.It Fn gelf_update_shdr
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Copy back an ELF Section Header Table entry.
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.It Fn gelf_update_sym
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Copy back an ELF symbol table entry.
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.El
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.El
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.Sh SEE ALSO
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.Xr elf 3 ,
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.Xr elf 5
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.Sh HISTORY
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The GELF(3) API first appeared in System V Release 4.
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This implementation of the API first appeared in
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.Fx 7.0 .
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.Sh AUTHORS
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The GElf API was implemented by
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.An "Joseph Koshy"
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.Aq jkoshy@FreeBSD.org .
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