elf.h File Reference

Function for managing the Executable and Linkable Format (ELF). More...

Go to the source code of this file.

Classes
struct	elf_header
	The elf starting section. More...
struct	elf_program_header
	The elf program header, holding program layout information. More...
struct	elf_section_header
	A section header with all kinds of useful information. More...
struct	elf_symbol
	A symbol itself. More...
struct	elf_rel_t
	Holds information about relocation object (that do not need an addend). More...
struct	elf_rela_t
	Holds information about relocation object (that need an addend). More...

Macros
#define	PT_NULL   0
	Unused.
#define	PT_LOAD   1
	Specifies a loadable segment, described by p_filesz and p_memsz. The bytes from the file are mapped to the beginning of the memory segment. If the segment's memory size (p_memsz) is larger than the file size (p_filesz), the extra bytes are defined to hold the value 0 and to follow the segment's initialized area. The file size can not be larger than the memory size. Loadable segment entries in the program header table appear in ascending order, sorted on the p_vaddr member.
#define	PT_DYNAMIC   2
	Specifies dynamic linking information.
#define	PT_INTERP   3
	Specifies the location and size of a null-terminated path name to invoke as an interpreter. This segment type is mandatory for dynamic executable files and can occur in shared objects. It cannot occur more than once in a file. This type, if present, it must precede any loadable segment entry.
#define	PT_NOTE   4
	Specifies the location and size of auxiliary information.
#define	PT_SHLIB   5
	Reserved but has unspecified semantics.
#define	PT_PHDR   6
	Specifies the location and size of the program header table itself, both in the file and in the memory image of the program. This segment type cannot occur more than once in a file. Moreover, it can occur only if the program header table is part of the memory image of the program. This type, if present, must precede any loadable segment entry.
#define	PT_EH_FRAME   0x6474E550
	Section for supporting exception handling routines. More...
#define	PT_GNU_STACK   0x6474E551
	Is a program header which tells the system how to control the stack when the ELF is loaded into memory.
#define	PT_GNU_RELRO   0x6474E552
	This segment indicates the memory region which should be made Read-Only after relocation is done. This segment usually appears in a dynamic link library and it contains .ctors, .dtors, .dynamic, .got s ections. See paragraph below.
#define	PT_LOPROC   0x70000000
	TODO: Document.
#define	PT_HIPROC   0x7FFFFFFF
	TODO: Document.
#define	EI_NIDENT   16
	Elf header ident size.
#define	ELFMAG0   0x7F
	e_ident[EI_MAG0]
#define	ELFMAG1   'E'
	e_ident[EI_MAG1]
#define	ELFMAG2   'L'
	e_ident[EI_MAG2]
#define	ELFMAG3   'F'
	e_ident[EI_MAG3]
#define	ELFDATA2LSB   1
	Little Endian.
#define	ELFCLASS32   1
	32-bit Architecture
#define	EM_386   3
	x86 Machine Type.
#define	EV_CURRENT   1
	ELF Current Version.
#define	ELF32_ST_BIND(INFO)   ((INFO) >> 4)
	Provide access to teh symbol biding.
#define	ELF32_ST_TYPE(INFO)   ((INFO)&0x0F)
	Provide access to teh symbol type.

Typedefs
typedef struct elf_header	elf_header_t
	The elf starting section.
typedef struct elf_program_header	elf_program_header_t
	The elf program header, holding program layout information.
typedef struct elf_section_header	elf_section_header_t
	A section header with all kinds of useful information.
typedef struct elf_symbol	elf_symbol_t
	A symbol itself.
typedef struct elf_rel_t	elf_rel_t
	Holds information about relocation object (that do not need an addend).
typedef struct elf_rela_t	elf_rela_t
	Holds information about relocation object (that need an addend).
typedef enum Elf_Type	Elf_Type
	Type of ELF files.
typedef enum ShT_Types	ShT_Types
	Defines a number of different types of sections, which correspond to values stored in the field sh_type in the section header.

Enumerations
enum	Elf_Ident {   EI_MAG0 = 0 , EI_MAG1 = 1 , EI_MAG2 = 2 , EI_MAG3 = 3 ,   EI_CLASS = 4 , EI_DATA = 5 , EI_VERSION = 6 , EI_OSABI = 7 ,   EI_ABIVERSION = 8 , EI_PAD = 9 }
	Fields index of ELF_IDENT. More...
enum	Elf_Type { ET_NONE = 0 , ET_REL = 1 , ET_EXEC = 2 }
	Type of ELF files. More...
enum	ShT_Types {   SHT_NULL = 0 , SHT_PROGBITS = 1 , SHT_SYMTAB = 2 , SHT_STRTAB = 3 ,   SHT_RELA = 4 , SHT_NOBITS = 8 , SHT_REL = 9 }
	Defines a number of different types of sections, which correspond to values stored in the field sh_type in the section header. More...
enum	ShT_Attributes { SHF_WRITE = 0x01 , SHF_ALLOC = 0x02 }
	ShT_Attributes corresponds to the field sh_flags, but are bit flags rather than stand-alone values. More...
enum	StT_Bindings { STB_LOCAL = 0 , STB_GLOBAL = 1 , STB_WEAK = 2 }
	Provides possible symbol bindings. More...
enum	StT_Types { STT_NOTYPE = 0 , STT_OBJECT = 1 , STT_FUNC = 2 }
	Provides a number of possible symbol types. More...

Functions
int	elf_load_file (task_struct *task, vfs_file_t *file, uint32_t *entry)
	Loads an ELF file into the memory of task. More...
int	elf_check_file_type (vfs_file_t *file, Elf_Type type)
	Checks if the file is a valid ELF. More...
int	elf_check_file_header (elf_header_t *hdr)
	Checks the correctness of the ELF header. More...
int	elf_check_magic_number (elf_header_t *hdr)
	Checks the correctness of the ELF header magic number. More...
const char *	elf_type_to_string (int type)
	Transforms the passed ELF type to string. More...
const char *	elf_section_header_type_to_string (int type)
	Transforms the passed ELF section header type to string. More...
const char *	elf_symbol_type_to_string (int type)
	Transforms the passed ELF symbol type to string. More...
const char *	elf_symbol_bind_to_string (int bind)
	Transforms the passed ELF symbol bind to string. More...

Detailed Description

Function for managing the Executable and Linkable Format (ELF).

Copyright

(c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Enumeration Type Documentation

Elf_Ident

enum Elf_Ident

Fields index of ELF_IDENT.

Enumerator
EI_MAG0	0x7F
EI_MAG1	'E'
EI_MAG2	'L'
EI_MAG3	'F'
EI_CLASS	Architecture (32/64)
EI_DATA	Set to either 1 or 2 to signify little or big endianness.
EI_VERSION	ELF Version.
EI_OSABI	OS Specific.
EI_ABIVERSION	OS Specific.
EI_PAD	Padding.

Elf_Type

enum Elf_Type

Type of ELF files.

Enumerator
ET_NONE	Unkown Type.
ET_REL	Relocatable File.
ET_EXEC	Executable File.

ShT_Attributes

enum ShT_Attributes

ShT_Attributes corresponds to the field sh_flags, but are bit flags rather than stand-alone values.

Enumerator
SHF_WRITE	Writable section.
SHF_ALLOC	Exists in memory.

ShT_Types

enum ShT_Types

Defines a number of different types of sections, which correspond to values stored in the field sh_type in the section header.

Enumerator
SHT_NULL	Null section.
SHT_PROGBITS	Program information.
SHT_SYMTAB	Symbol table.
SHT_STRTAB	String table.
SHT_RELA	Relocation (w/ addend)
SHT_NOBITS	Not present in file.
SHT_REL	Relocation (no addend)

StT_Bindings

enum StT_Bindings

Provides possible symbol bindings.

Enumerator
STB_LOCAL	Local scope.
STB_GLOBAL	Global scope.
STB_WEAK	Weak, (ie. attribute((weak)))

StT_Types

enum StT_Types

Provides a number of possible symbol types.

Enumerator
STT_NOTYPE	No type.
STT_OBJECT	Variables, arrays, etc.
STT_FUNC	Methods or functions.

Function Documentation

elf_check_file_header()

int elf_check_file_header

(

elf_header_t *

hdr

)

Checks the correctness of the ELF header.

Parameters

hdr	The header to check.

Returns

0 if fails, 1 if succeed.

elf_check_file_type()

int elf_check_file_type	(	vfs_file_t *	file,
		Elf_Type	type
	)

Checks if the file is a valid ELF.

Parameters

file	The file to check.
type	The type of ELF file we expect.

Returns

0 if fails, 1 if succeed.

elf_check_magic_number()

int elf_check_magic_number

(

elf_header_t *

hdr

)

Checks the correctness of the ELF header magic number.

Parameters

hdr	The header to check.

Returns

0 if fails, 1 if succeed.

elf_load_file()

int elf_load_file	(	task_struct *	task,
		vfs_file_t *	file,
		uint32_t *	entry
	)

Loads an ELF file into the memory of task.

Parameters

task	The task for which we load the ELF.
file	The ELF file.
entry	The ELF binary entry.

Returns

0 if fails, 1 if succeed.

elf_section_header_type_to_string()

const char* elf_section_header_type_to_string

(

int

type

)

Transforms the passed ELF section header type to string.

Parameters

type	The integer representing the ELF section header type.

Returns

The string representing the ELF section header type.

elf_symbol_bind_to_string()

const char* elf_symbol_bind_to_string

(

int

bind

)

Transforms the passed ELF symbol bind to string.

Parameters

bind	The integer representing the ELF symbol bind.

Returns

The string representing the ELF symbol bind.

elf_symbol_type_to_string()

const char* elf_symbol_type_to_string

(

int

type

)

Transforms the passed ELF symbol type to string.

Parameters

type	The integer representing the ELF symbol type.

Returns

The string representing the ELF symbol type.

elf_type_to_string()

const char* elf_type_to_string

(

int

type

)

Transforms the passed ELF type to string.

Parameters

type	The integer representing the ELF type.

Returns

The string representing the ELF type.