man pages section 3: Extended Library Functions, Volume 1

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Updated: July 2014



elf32_getehdr, elf32_newehdr, elf64_getehdr, elf64_newehdr - retrieve class-dependent object file header


cc [ flag ... ] file ... –lelf [ library ... ]
#include <libelf.h>

Elf32_Ehdr *elf32_getehdr(Elf *elf);
Elf32_Ehdr *elf32_newehdr(Elf *elf);
Elf64_Ehdr *elf64_getehdr(Elf *elf);
Elf64_Ehdr *elf64_newehdr(Elf *elf);


For a 32-bit class file, elf32_getehdr() returns a pointer to an ELF header, if one is available for the ELF descriptor elf. If no header exists for the descriptor, elf32_newehdr() allocates a clean one, but it otherwise behaves the same as elf32_getehdr(). It does not allocate a new header if one exists already. If no header exists for elf32_getehdr(), one cannot be created for elf32_newehdr(), a system error occurs, the file is not a 32-bit class file, or elf is NULL, both functions return a null pointer.

For the 64−bit class, replace 32 with 64 as appropriate.

The header includes the following members:

unsigned char	e_ident[EI_NIDENT];
Elf32_Half	e_type;
Elf32_Half	e_machine;
Elf32_Word	e_version;
Elf32_Addr	e_entry;
Elf32_Off 	e_phoff;
Elf32_Off 	e_shoff;
Elf32_Word	e_flags;
Elf32_Half	e_ehsize;
Elf32_Half	e_phentsize;
Elf32_Half	e_phnum;
Elf32_Half	e_shentsize;
Elf32_Half	e_shnum;
Elf32_Half	e_shstrndx;

The elf32_newehdr() function automatically sets the ELF_F_DIRTY bit. See elf_flagdata(3ELF).

An application can use elf_getident() to inspect the identification bytes from a file.

An application can use elf_getshnum() and elf_getshstrndx() to obtain section header information. The location of this section header information differs between standard ELF files to those that require Extended Sections.


See attributes(5) for descriptions of the following attributes:

Interface Stability

See also

elf(3ELF), elf_begin(3ELF), elf_flagdata(3ELF), elf_getident(3ELF), elf_getshnum(3ELF), elf_getshstrndx(3ELF), libelf(3LIB), attributes(5)