elf_cntl(3E)                                            elf_cntl(3E)


       NAME
             elf_cntl - control a file descriptor

       SYNOPSIS
             cc [flag . . . ] file . . . -lelf [library] . . .
             #include <libelf.h>
             int elf_cntl(Elf *elf, Elf_Cmd cmd);

       DESCRIPTION
             elf_cntl instructs the library to modify its behavior with
             respect to an ELF descriptor, elf.  As elf_begin(3E)
             describes, an ELF descriptor can have multiple activations,
             and multiple ELF descriptors may share a single file
             descriptor.  Generally, elf_cntl 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.

             ELF_C_FDDONE
                       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
                       elf_getdata for a section, will fail if the data is
                       not in memory already.

             ELF_C_FDREAD
                       This command is similar to ELF_C_FDDONE, 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 elf_cntl completes
                       the ELF_C_FDREAD command, future operations, such as
                       elf_getdata, will use the memory version of the file
                       without needing to use the file descriptor.





                           Copyright 1994 Novell, Inc.               Page 1

      elf_cntl(3E)                                            elf_cntl(3E)


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

      REFERENCES
            elf(3E), elf_begin(3E), elf_getdata(3E), elf_rawfile(3E)

      NOTICES
            If the program wishes to use the ``raw'' operations [see
            elf_rawdata, which elf_getdata(3E) describes, and
            elf_rawfile(3E)] after disabling the file descriptor with
            ELF_C_FDDONE or ELF_C_FDREAD, it must execute the raw
            operations explicitly beforehand.  Otherwise, the raw file
            operations will fail.  Calling elf_rawfile makes the entire
            image available, thus supporting subsequent elf_rawdata calls.


































                          Copyright 1994 Novell, Inc.               Page 2