NAME

       elf_flagelf,  elf_flagdata, elf_flagehdr, elf_flagphdr, elf_flagscn, elf_flagshdr - set or clear flags on
       ELF descriptors and components

SYNOPSIS

       #include <libelf.h>

       unsigned int elf_flagelf(Elf * elf, Elf_Cmd cmd, unsigned int flags);
       unsigned int elf_flagehdr(Elf * elf, Elf_Cmd cmd, unsigned int flags);
       unsigned int elf_flagphdr(Elf * elf, Elf_Cmd cmd, unsigned int flags);
       unsigned int elf_flagscn(Elf_Scn * scn, Elf_Cmd cmd, unsigned int flags);
       unsigned int elf_flagshdr(Elf_Scn * scn, Elf_Cmd cmd, unsigned int flags);
       unsigned int elf_flagdata(Elf_Data * data, Elf_Cmd cmd, unsigned int flags);

DESCRIPTION

       These functions allow the caller to set or clear flags on various ELF  components  managed  by  libelf  .
       They  are  typically  used  to  indicate that a component has been modified (dirty), or to control layout
       behavior during output.

       elf_flagelf() modifies flags on the top-level Elf descriptor.

       elf_flagdata() modifies flags on an Elf_Data descriptor,  typically  retrieved  using  elf_getdata(3)  or
       created with elf_newdata(3).

       elf_flagehdr()   modifies   flags  on  the  ELF  header  for  a  ELF  descriptor  (e.g.,  the  result  of
       gelf_getehdr(3)).

       elf_flagphdr() modifies flags on the program header table of an ELF descriptor.

       elf_flagscn() modifies flags on an Elf_Scn (section) descriptor.

       elf_flagshdr() modifies flags on the section header of a given Elf_Scn .

       The cmd argument determines whether the given flags should be set ( ELF_C_SET ) or cleared ( ELF_C_CLR ).

       The following flag values may be passed via the flags parameter:

       ELF_F_DIRTY
              Marks the object as modified. This  ensures  changes  to  the  component  is  written  out  during
              elf_update(3).

       ELF_F_LAYOUT
              Indicates  that  the  layout  of  the ELF component is managed manually. Offsets and sizes will be
              preserved as provided.  This flag is only used with elf_flagelf() and is ignored  when  used  with
              other functions.  If this flag is set the user must set Ehdr e_phoff, e_shoff, as well as Elf_Data
              d_off  and Shdr sh_offset.  If not set, then these offsets will be recalculated when elf_update is
              called.  If ELF_F_LAYOUT is set  then  changes  to  phdr  offsets  will  prevent  elf_update  from
              automatically adjusting shdr offsets.

       ELF_F_PERMISSIVE
              Enables  relaxed  validation  of  object  structure. This flag permits nonstandard layouts without
              strict checks.  Specifically this removes a check in elf_update() that the section  sh_size  is  a
              multiple  of  the section sh_entsize (if not zero).  This flag is only used with elf_flagelf() and
              is ignored when used with other functions.  ELF_F_PERMISSIVE is an elfutils libelf  extention  and
              may not be available in other libelf implementations.

PARAMETERS

       obj    The  object  to  be  modified:  For  elf_flagelf,  elf_flagehdr,  elf_flagphdr,  this  is an Elf *
              descriptor.  For elf_flagscn and elf_flagshdr , this is an Elf_Scn * descriptor.  For elf_flagdata
              , an Elf_Data * buffer.

       cmd    Must be either: ELF_C_SET to set the given flags, or ELF_C_CLR to clear them.

       flags  Bitmask of flags to modify. May include any  combination  of  ELF_F_DIRTY  ,  ELF_F_LAYOUT  ,  and
              ELF_F_PERMISSIVE .

              Note  that  ELF_F_LAYOUT and ELF_F_PERMISSIVE are only used with elf_flagelf() and are ignored for
              other functions.

RETURN VALUE

       Returns the new value of the flags after the set/clear operation.

       Returns 0 on error, and sets an error code retrievable via elf_errmsg(3).  If the first argument is  NULL
       then 0 is return and no error code is set.

       If  the  last  flag is cleared, 0 will be returned as the new flag value.  In this case 0 is not an error
       indicator and no error code is set.

SEE ALSO

       elf_errmsg(3), elf_update(3), libelf(3), elf(5)

ATTRIBUTES

       ┌──────────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │ Interface                                                                                    │ Attribute     │ Value          │
       ├──────────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │ elf_flagelf(), elf_flagehdr(), elf_flagphdr(), elf_flagscn(), elf_flagshdr(), elf_flagdata() │ Thread safety │ MT-Unsafe race │
       └──────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴────────────────┘

REPORTING BUGS

       Report bugs to <elfutils-devel@sourceware.org> or https://sourceware.org/bugzilla/.

Libelf                                             2025-06-23                                     ELF_FLAGELF(3)