<elf.h>

The parts of the ELF32 format the loader reads.

#include <elf.h>

Constants

Name	Value	Description
ELF_MAGIC	"\x7f" \ "ELF"	The first four bytes of every ELF file.
ELF_CLASS_32	1	e_ident[4]: 32-bit objects.
ELF_DATA_LITTLE	1	e_ident[5]: little-endian.
ELF_MACHINE_ARM	40	e_machine: ARM.
ET_EXEC	2	e_type: executable.
PT_LOAD	1	p_type: loadable segment.
PF_X	0x1	p_flags: executable.
PF_W	0x2	p_flags: writable.
PF_R	0x4	p_flags: readable.

Structures

Elf32_Ehdr

ELF32 file header.

Field	Type	Description
e_ident	uint8_t	ELF identification.
e_type	uint16_t	Object file type.
e_machine	uint16_t	Machine type.
e_version	uint32_t	Object file version.
e_entry	uint32_t	Entry point address.
e_phoff	uint32_t	Program header offset.
e_shoff	uint32_t	Section header offset.
e_flags	uint32_t	Processor-specific flags.
e_ehsize	uint16_t	ELF header size.
e_phentsize	uint16_t	Size of program header entry.
e_phnum	uint16_t	Number of program header entries.
e_shentsize	uint16_t	Size of section header entry.
e_shnum	uint16_t	Number of section header entries.
e_shstrndx	uint16_t	Section name string table index.

Elf32_Phdr

ELF32 program header.

Field	Type	Description
p_type	uint32_t	Type of segment.
p_offset	uint32_t	Offset in file.
p_vaddr	uint32_t	Virtual address in memory.
p_paddr	uint32_t	Physical address.
p_filesz	uint32_t	Size of segment in file.
p_memsz	uint32_t	Size of segment in memory.
p_flags	uint32_t	Segment attributes.
p_align	uint32_t	Alignment of segment.

Functions

ElfValidate

uint32_t ElfValidate(const void *data, size_t size);

Checks that data is a 32-bit little-endian ARM executable whose program headers fit.

Parameter	Direction	Description
data	in	Pointer to the ELF file data in memory.
size	in	Size of the ELF file data in bytes.

Returns: The entry point, or 0 if the file is not acceptable.

ElfPhdrCount

int ElfPhdrCount(const void *data);

Returns the number of program headers in the ELF file.

Parameter	Direction	Description
data	in	A file that passed ElfValidate().

Returns: Number of program headers.

ElfPhdrGet

const Elf32_Phdr * ElfPhdrGet(const void *data, int index);

Returns a pointer to the program header at the specified index.

Parameter	Direction	Description
data	in	A file that passed ElfValidate().
index	in	Index of the program header, below ElfPhdrCount(); not checked.

Returns: Pointer to the program header, inside data.