ELF_FLAGDATA(3ELF) ELF Library Functions ELF_FLAGDATA(3ELF)

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 0 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

Example 1: A sample display of calling the elf_flagdata() function.

The following fragment shows how one might mark the ELF header to be
written to the output file:


/* dirty ehdr ... */
ehdr = elf32_getehdr(elf);
elf_flagehdr(elf, ELF_C_SET, ELF_F_DIRTY);

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), elf32_getehdr(3ELF), elf_getdata(3ELF), elf_update(3ELF),
attributes(7)

July 11, 2001 ELF_FLAGDATA(3ELF)