gelf(3) - NetBSD Manual Pages

GELF(3)                 NetBSD Library Functions Manual                GELF(3)


NAME

     gelf -- class-independent API for ELF manipulation


LIBRARY

     ELF Object Manipulation Library (libelf, -lelf)


SYNOPSIS

     #include <gelf.h>


DESCRIPTION

     This manual page describes a class independent API for manipulating ELF
     objects.  This API allows an application to operate on ELF descriptors
     without needing to the know the ELF class of the descriptor.

     The GElf API may be used alongside the ELF API without restriction.

   GElf Data Structures
     The GElf API defines the following class-independent data structures:

     GElf_Addr    A representation of ELF addresses.

     GElf_Dyn     A class-independent representation of ELF .dynamic section
                  entries.

     GElf_Ehdr    A class-independent representation of an ELF Executable
                  Header.

     GElf_Half    An unsigned 16 bit quantity.

     GElf_Off     A class-independent representation of a ELF offset.

     GElf_Phdr    A class-independent representation of an ELF Program Header
                  Table entry.

     GElf_Rel     A class-independent representation of an ELF relocation
                  entry.

     GElf_Rela    A class-independent representation of an ELF relocation
                  entry with addend.

     GElf_Shdr    A class-independent representation of an ELF Section Header
                  Table entry.

     GElf_Sword   A signed 32 bit quantity.

     GElf_Sxword  A signed 64 bit quantity.

     GElf_Sym     A class-independent representation of an ELF symbol table
                  entry.

     GElf_Word    An unsigned 32 bit quantity.

     GElf_Xword   An unsigned 64 bit quantity.

     These data structures are sized to be compatible with the corresponding
     64 bit ELF structures, and have the same internal structure as their 64
     bit class-dependent counterparts.  Class-dependent ELF structures are
     described in elf(5).

   GElf Programming Model
     GElf functions always return a copy of the underlying (class-dependent)
     ELF data structure.  The programming model with GElf is as follows:

     1.   An application will retrieve data from an ELF descriptor using a
          gelf_get_*() function.  This will copy out data into a private
          GElf_* data structure.

     2.   The application will work with its private copy of the GElf struc-
          ture.

     3.   Once done, the application copies the new values back to the under-
          lying ELF data structure using the gelf_update_*() functions.

     4.   The application will then use the elf_flag*() APIs to indicate to
          the ELF library that an ELF data structure is dirty.

     When updating an underlying 32 bit ELF data structure, the GElf routines
     will signal an error if a GElf value is out of range for the underlying
     ELF data type.

   Namespace use
     The GElf interface uses the following symbols:

     GElf_*  Class-independent data types.

     gelf_*  For functions defined in the API set.

   GElf Programming APIs
     This section provides an overview of the GElf programming APIs.  Further
     information is provided in the manual page of each function listed here.

     Allocating ELF Data Structures
             gelf_newehdr()
                     Allocate a new ELF Executable Header.
             gelf_newphdr()
                     Allocate a new ELF Program Header Table.

     Data Translation
             gelf_xlatetof()
                     Translate the native representation of an ELF data struc-
                     ture to its file representation.
             gelf_xlatetom()
                     Translate from the file representation of an ELF data
                     structure to a native representation.

     Retrieving ELF Data
             gelf_getdyn()
                     Retrieve an ELF .dynamic table entry.
             gelf_getehdr()
                     Retrieve an ELF Executable Header from the underlying ELF
                     descriptor.
             gelf_getphdr()
                     Retrieve an ELF Program Header Table entry from the
                     underlying ELF descriptor.
             gelf_getrel()
                     Retrieve an ELF relocation entry.
             gelf_getrela()
                     Retrieve an ELF relocation entry with addend.
             gelf_getshdr()
                     Retrieve an ELF Section Header Table entry from the
                     underlying ELF descriptor.
             gelf_getsym()
                     Retrieve an ELF symbol table entry.

     Queries
             gelf_checksum()
                     Retrieves the ELF checksum for an ELF descriptor.
             gelf_fsize()
                     Retrieves the size of the file representation of an ELF
                     type.
             gelf_getclass()
                     Retrieves the ELF class of an ELF descriptor.

     Updating ELF Data
             gelf_update_dyn()   Copy back an ELF .dynamic Table entry.
             gelf_update_phdr()  Copy back an ELF Program Header Table entry.
             gelf_update_rel()   Copy back an ELF relocation entry.
             gelf_update_rela()  Copy back an ELF relocation with addend
                                 entry.
             gelf_update_shdr()  Copy back an ELF Section Header Table entry.
             gelf_update_sym()   Copy back an ELF symbol table entry.


SEE ALSO

     elf(3), elf(5)


HISTORY

     The gelf API first appeared in AT&T System V.4 UNIX.  This implementation
     of the API first appeared in FreeBSD 7.0.


AUTHORS

     The GElf API was implemented by Joseph Koshy <jkoshy@FreeBSD.org>.

NetBSD 10.99                     June 12, 2019                    NetBSD 10.99