ELF_FLAGDATA(3) | Library Functions Manual | ELF_FLAGDATA(3)

# NAME

`elf_flagarhdr`, `elf_flagdata`, `elf_flagehdr`, `elf_flagelf`, `elf_flagphdr`, `elf_flagscn`, `elf_flagshdr` — manipulate flags associated with ELF data structures

# SYNOPSIS

ELF Access Library (libelf, -lelf)
`#include <libelf.h>`

unsigned int
`elf_flagarhdr`(Elf_Arhdr *arhdr, Elf_Cmd cmd, unsigned int flags);

unsigned int
`elf_flagdata`(Elf_Data *data, Elf_Cmd cmd, unsigned int flags);

unsigned int
`elf_flagehdr`(Elf *elf, Elf_Cmd cmd, unsigned int flags);

unsigned int
`elf_flagelf`(Elf *elf, Elf_Cmd cmd, unsigned int flags);

unsigned int
`elf_flagphdr`(Elf *elf, Elf_Cmd cmd, unsigned int flags);

unsigned int
`elf_flagscn`(Elf_Scn *scn, Elf_Cmd cmd, unsigned int flags);

unsigned int
`elf_flagshdr`(Elf_Scn *scn, Elf_Cmd cmd, unsigned int flags);

# DESCRIPTION

These functions are used to query, set or reset flags on data structures associated with an ELF file.

Arguments arhdr, data, elf and scn denote the data structures whose flags need to be changed. These values should have been returned by prior calls to functions in the elf(3) API set:

- Argument arhdr should have been returned by a prior call to elf_getarhdr(3).
- Argument data should have been returned by a prior call to one of elf_newdata(3), elf_getdata(3) or elf_rawdata(3).
- Argument elf should have been allocated by a prior call to one of elf_begin(3) or elf_memory(3).
- Argument scn should have been returned by a prior call to one of elf_getscn(3), elf_newscn(3) or elf_nextscn(3).

These values are allowed to be NULL to simplify error handling in application code.

Argument cmd may have the following values:

`ELF_C_CLR`
  The argument flags specifies the flags to be cleared.
`ELF_C_SET`
  The argument flags specifies the flags to be set.

The argument flags is allowed to have the following flags set:

`ELF_F_ARCHIVE`
  This flag is only valid with the `elf_flagelf`() API. It informs the library that the application desires to create an ar(1) archive. Argument elf should have been opened for writing using the `ELF_C_WRITE` command to function `elf_begin`().
`ELF_F_ARCHIVE_SYSV`
  This flag is used in conjunction with the `ELF_F_ARCHIVE` flag to indicate that library should create archives that conform to System V layout rules. The default is to create BSD style archives.
`ELF_F_DIRTY`
  Mark the associated data structure as needing to be written back to the underlying file. A subsequent call to elf_update(3) will resynchronize the library's internal data structures.
`ELF_F_LAYOUT`
  This flag is only valid with the `elf_flagelf`() API. It informs the library that the application will take responsibility for the layout of the file and that the library is not to insert any padding in between sections.

Marking a given data structure as “dirty” affects all of its contained elements. Thus marking an ELF descriptor elf with `elf_flagelf`(elf, ELF_C_SET, ELF_F_DIRTY) means that the entire contents of the descriptor are “dirty”.

Using a value of zero for argument flags will return the current set of flags for the data structure being queried.

# RETURN VALUES

These functions return the updated flags if successful, or zero if an error is detected.

# COMPATIBILITY

The `elf_flagarhdr`() function and the `ELF_F_ARCHIVE` and `ELF_F_ARCHIVE_SYSV` flags are an extension to the elf(3) API.

# ERRORS

These functions may fail with the following errors:

[`ELF_E_ARGUMENT`]
  An unsupported value was used for the cmd argument.
[`ELF_E_ARGUMENT`]
  Argument flags had unsupported flags set.
[`ELF_E_ARGUMENT`]
  The argument elf was not a descriptor for an ELF object.
[`ELF_E_MODE`]
  The `ELF_F_ARCHIVE` flag was used with an ELF descriptor that had not been opened for writing.
[`ELF_E_SEQUENCE`]
  Function `elf_flagehdr`() was called without an executable header being allocated.
[`ELF_E_SEQUENCE`]
  Function `elf_flagphdr`() was called without a program header being allocated.

# SEE ALSO

elf(3), elf32_newehdr(3), elf32_newphdr(3), elf64_newehdr(3), elf64_newphdr(3), elf_newdata(3), elf_update(3), gelf(3), gelf_newehdr(3), gelf_newphdr(3), gelf_update_dyn(3), gelf_update_move(3), gelf_update_rel(3), gelf_update_rela(3), gelf_update_sym(3), gelf_update_syminfo(3)

June 12, 2019 | Debian