ELFFLAG(3E)                                                      ELFFLAG(3E)



NAME
     elfflagdata, elfflagehdr, elfflagelf, elfflagphdr, elfflagscn,
     elfflagshdr - manipulate flags

SYNOPSIS
     cc [flag ...] file ...  -lelf [library ...]

     #include <libelf.h>

     unsigned elfflagdata(ElfData *data, ElfCmd cmd, unsigned flags);

     unsigned elfflagehdr(Elf *elf, ElfCmd cmd, unsigned flags);

     unsigned elfflagelf(Elf *elf, ElfCmd cmd, unsigned flags);

     unsigned elfflagphdr(Elf *elf, ElfCmd cmd, unsigned flags);

     unsigned elfflagscn(ElfScn *scn, ElfCmd cmd, unsigned flags);

     unsigned elfflagshdr(ElfScn *scn, ElfCmd cmd, unsigned flags);

DESCRIPTION
     These functions manipulate the flags associated with various structures
     of an ELF file.  Given an ELF descriptor (elf), a data descriptor (data),
     or a section descriptor (scn), the functions may set or clear the
     associated status bits, returning the updated bits.  A null descriptor is
     allowed, to simplify error handling; all functions return zero for this
     degenerate case.

     cmd may have the following values.

     ELFCCLR         The functions clear the bits that are asserted in
                       flags.  Only the non-zero bits in flags are cleared;
                       zero bits do not change the status of the descriptor.

     ELFCSET         The functions set the bits that are asserted in flags.
                       Only the non-zero bits in flags are set; zero bits do
                       not change the status of the descriptor.

     Descriptions of the defined flags bits appear below.

     ELFFDIRTY       When the program intends to write an ELF file, this
                       flag asserts the associated information needs to be
                       written to the file.  Thus, for example, a program that
                       wished to update the ELF header of an existing file
                       would call elfflagehdr with this bit set in flags and
                       cmd equal to ELFCSET.  A later call to elfupdate
                       would write the marked header to the file.

     ELFFLAYOUT      Normally, the library decides how to arrange an output
                       file.  That is, it automatically decides where to place
                       sections, how to align them in the file, etc.  If this
                       bit is set for an ELF descriptor, the program assumes
                       responsibility for determining all file positions.
                       This bit is meaningful only for elfflagelf and applies



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ELFFLAG(3E)                                                      ELFFLAG(3E)



                       to the entire file associated with the descriptor.

     When a flag bit is set for an item, it affects all the subitems as well.
     Thus, for example, if the program sets the ELFFDIRTY bit with
     elfflagelf, the entire logical file is ``dirty.''

EXAMPLE
     The following fragment shows how one might mark the ELF header to be
     written to the output file.

          ehdr = elf32getehdr(elf);
          /* dirty ehdr ... */
          elfflagehdr(elf, ELFCSET, ELFFDIRTY);

SEE ALSO
     elf(3E), elfend(3E), elfgetdata(3E), elfgetehdr(3E), elfupdate(3E).







































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