elf_cntl(3E)      MISC. REFERENCE MANUAL PAGES       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 opera-
               tions, 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).





                    Last change: ELF Library                    1

elf_cntl(3E)      MISC. REFERENCE MANUAL PAGES       elf_cntl(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 opera-
     tions explicitly beforehand.  Otherwise, the raw file opera-
     tions will fail.  Calling elfrawfile makes the entire image
     available, thus supporting subsequent elfrawdata calls.















































                    Last change: ELF Library                    2