ELF_CNTL(3ELF) ELF Library Functions ELF_CNTL(3ELF)

NAME

elf_cntl - control an elf 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(3ELF) 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 are 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.


If elf_cntl() succeeds, it returns 0. Otherwise elf was NULL or an
error occurred, and the function returns -1.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Stable |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

elf(3ELF), elf_begin(3ELF), elf_getdata(3ELF), elf_rawfile(3ELF),
libelf(3LIB), attributes(7)

NOTES

If the program wishes to use the ``raw'' operations (see
elf_rawdata(), which elf_getdata(3ELF) describes, and
elf_rawfile(3ELF)) 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.

July 11, 2001 ELF_CNTL(3ELF)