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 24  .\" $Id$ 
 25  .\"
 26  .Dd August 9, 2006
 27  .Os
 28  .Dt ELF_CNTL 3
 29  .Sh NAME
 30  .Nm elf_cntl
 31  .Nd control an elf file descriptor
 32  .Sh LIBRARY
 33  .Lb libelf
 34  .Sh SYNOPSIS
 35  .In libelf.h
 36  .Ft int
 37  .Fn elf_cntl "Elf *elf" "Elf_Cmd cmd"
 38  .Sh DESCRIPTION
 39  Function
 40  .Fn elf_cntl
 41  controls the ELF library's subsequent use of the file descriptor
 42  used to create ELF descriptor
 43  .Ar elf .
 44  .Pp
 45  Argument
 46  .Ar cmd
 47  informs the library of the action to be taken:
 48  .Bl -tag -width "ELF_C_FDDONE"
 49  .It Dv ELF_C_FDDONE
 50  This value instructs the ELF library not to perform any further
 51  I/O on the file descriptor associated with argument
 52  .Ar elf .
 53  For ELF descriptors opened with mode
 54  .Ar ELF_C_WRITE
 55  or
 56  .Ar ELF_C_RDWR
 57  subsequent
 58  .Fn elf_update
 59  operations on the descriptor will fail.
 60  .It Dv ELF_C_FDREAD
 61  This value instructs the ELF library to read in all necessary
 62  data associated with ELF descriptor
 63  .Ar elf
 64  into memory so that the underlying file descriptor can be
 65  safely closed with command
 66  .Dv ELF_C_FDDONE .
 67  .El
 68  .Pp
 69  Argument
 70  .Ar elf
 71  must be an ELF descriptor associated with a file system object
 72  (e.g., an
 73  .Xr ar 1
 74  archive, an ELF file, or other data file).
 75  .Sh IMPLEMENTATION NOTES
 76  Due to use of
 77  .Xr mmap 2
 78  internally, this function is a no-op for ELF objects opened in
 79  .Dv ELF_C_READ
 80  mode.
 81  .Sh RETURN VALUES
 82  Function
 83  .Fn elf_cntl
 84  returns 0 on success, or -1 if an error was detected.
 85  .Sh ERRORS
 86  .Bl -tag -width "[ELF_E_RESOURCE]"
 87  .It Bq Er ELF_E_ARCHIVE
 88  Argument
 89  .Ar elf
 90  is a descriptor for an archive member.
 91  .It Bq Er ELF_E_ARGUMENT
 92  Argument
 93  .Ar elf
 94  was NULL.
 95  .It Bq Er ELF_E_ARGUMENT
 96  Argument
 97  .Ar cmd
 98  was not recognized.
 99  .It Bq Er ELF_E_MODE
100  An
101  .Dv ELF_C_FDREAD
102  operation was requested on an ELF descriptor opened
103  for writing.
104  .El
105  .Sh SEE ALSO
106  .Xr elf 3 ,
107  .Xr elf_begin 3 ,
108  .Xr elf_end 3 ,
109  .Xr elf_next 3 ,
110  .Xr elf_update 3 ,
111  .Xr gelf 3