NAME
elf_flagdata, elf_flagehdr, elf_flagelf, elf_flagphdr, elf_flagscn, elf_flagshdr — manipulate flags
SYNOPSIS
cc
[flag... ]
file...
-lelf
[library] ...
#include
<libelf.h>
unsigned elf_flagdata(Elf_Data *data, Elf_Cmd cmd, unsigned flags);
unsigned elf_flagehdr(Elf *elf, Elf_Cmd cmd, unsigned flags);
unsigned elf_flagelf(Elf *elf, Elf_Cmd cmd, unsigned flags);
unsigned elf_flagphdr(Elf *elf, Elf_Cmd cmd, unsigned flags);
unsigned elf_flagscn(Elf_Scn *scn, Elf_Cmd cmd, unsigned flags);
unsigned elf_flagshdr(Elf_Scn *scn, Elf_Cmd cmd, unsigned flags);
DESCRIPTION
These functions manipulate the flags associated with various
structures of an ELF file. Given an ELF descriptor
elf,
a data descriptor
data,
or a section descriptor
scn,
the functions may set or clear the associated status bits,
returning the updated bits. A null descriptor is allowed, to
simplify error handling; all functions return zero for this
degenerate case.
cmd
may have the following values:
- ELF_C_CLR
The functions clear the bits that are asserted in
flags.
Only the non-zero bits
in
flags
are cleared; zero bits do not change the status of the descriptor.
- ELF_C_SET
The functions set the bits that are asserted
in
flags.
Only the non-zero bits in
flags
are set; zero bits do not change the status of the descriptor.
Descriptions of the defined flags bits appear below.
- ELF_F_DIRTY
When the program intends to write an ELF
file, this flag asserts the associated
information needs to be written to the file.
Thus, for example, a program that wished to
update the ELF header of an existing file
would call
elf_flagehdr
with this bit set in
flags
and
cmd
equal to
ELF_C_SET.
A later call to
elf_update
would write the marked header to the file.
- ELF_F_LAYOUT
Normally, the library decides how to arrange
an output file. That is, it automatically
decides where to place sections, how to
align them in the file, etc. If this bit is
set for an ELF descriptor, the program
assumes responsibility for determining all
file positions. This bit is meaningful only
for
elf_flagelf
and applies to the entire
file associated with the descriptor.
When a flag bit is set for an item, it affects all the
subitems as well. Thus, for example, if the program sets the
ELF_F_DIRTY
bit with
elf_flagelf,
the entire logical file is ``dirty.''
EXAMPLES
The following fragment shows how one might mark the ELF header
to be written to the output file.
ehdr = elf32_getehdr(elf);
/* dirty ehdr . . . */
elf_flagehdr(elf, ELF_C_SET, ELF_F_DIRTY);
Printable version
