elf_flag(S)

elf_flag: elf_flagdata, elf_flagehdr, elf_flagelf, elf_flagphdr, elf_flagscn, elf_flagshdr -- manipulate flags

Syntax

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

elf_flagdata- set or clear status bits for ELF data

elf_flagehdr- set or clear status bits for an ELF header

elf_flagelf- set or clear status bits for an ELF file

elf_flagphdr- set or clear status bits for a program header

elf_flagscn- set or clear status bits for a section

elf_flagshdr- set or clear status bits for a section header

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 needs to write an ELF file, this flag says to write the associated information to the file. For example, suppose that a program is going to update the ELF header of an existing file. The program calls elf_flagehdr(S) with this bit set in flags and with cmd equal to ELF_C_SET. A later call to elf_update(S) writes the marked header to the file.
ELF_F_LAYOUT: Normally, the library controls how to arrange an output file. That is, it automatically places sections, aligns them in the file, and so on. 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(S); it 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.''

Return values

These functions return updated descriptor status bits, or zero if given a null descriptor.

Diagnostics

Error conditions are identified through the routine elf_error(S).

Examples

The following fragment shows how you 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);

Standards conformance

elf_flagdata(S), elf_flagehdr(S), elf_flagelf(S), elf_flagphdr(S), elf_flagscn(S), and elf_flagshdr(S) are not part of any currently supported standard; they were developed by UNIX System Laboratories, Inc. and are maintained by The SCO Group.