elf_cntl(3E)                      SDK R4.11                     elf_cntl(3E)


NAME
       elfcntl - control a file descriptor

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

       #include <libelf.h>
       int elfcntl(Elf *elf, ElfCmd cmd);

DESCRIPTION
       elfcntl instructs the library to modify its behavior with respect to
       an  ELF  descriptor,  elf.   As  elfbegin(3E)  describes,   an   ELF
       descriptor   can   have   multiple   activations,  and  multiple  ELF
       descriptors may share a single file descriptor.  Generally,  elfcntl
       commands  apply  to  all  activations  of  elf.  Moreover, if the ELF
       descriptor is  associated  with  an  archive  file,  descriptors  for
       members  within the archive will also be affected as described below.
       Unless stated otherwise, operations on archive members do not  affect
       the descriptor for the containing archive.

       The  cmd  argument  tells  what  actions  to  take  and  may have the
       following values.

       ELFCFDDONE  This value tells  the  library  not  to  use  the  file
                     descriptor  associated  with elf.  A program should use
                     this command when it has requested all the  information
                     it  cares  to  use  and wishes to avoid the overhead of
                     reading the rest of  the  file.   The  memory  for  all
                     completed  operations  remains  valid,  but  later file
                     operations, such  as  the  initial  elfgetdata  for  a
                     section,  will  fail  if  the  data  are  not in memory
                     already.

       ELFCFDREAD  This command is  similar  to  ELFCFDDONE,  except  it
                     forces  the  library  to  read the rest of the file.  A
                     program should use this command when it must close  the
                     file  descriptor  but  has  not  yet read everything it
                     needs from the  file.   After  elfcntl  completes  the
                     ELFCFDREAD   command,   future  operations,  such  as
                     elfgetdata, will use the memory version  of  the  file
                     without needing to use the file descriptor.

       If  elfcntl succeeds, it returns zero.  Otherwise elf was null or an
       error occurred, and the function returns -1.

SEE ALSO
       elf(3E), elfbegin(3E), elfgetdata(3E), elfrawfile(3E).

NOTE
       If the program wishes to use the ``raw'' operations [see elfrawdata,
       which elfgetdata(3E) describes, and elfrawfile(3E)] after disabling
       the file descriptor with ELFCFDDONE or ELFCFDREAD, it must
       execute the raw operations explicitly beforehand.  Otherwise, the raw
       file operations will fail.  Calling elfrawfile makes the entire
       image available, thus supporting subsequent elfrawdata calls.


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