These functions retrieve the ELF object file header from the ELF descriptor
elf and return a translated header descriptor to their callers.
Functions
elf32_getehdr() and
elf64_getehdr() return a pointer to the appropriate class-specific header descriptor if it exists in the file referenced by descriptor
elf. These functions return
NULL if an ELF header was not found in file
elf.
Function
gelf_getehdr() stores a translated copy of the header for ELF file
elf into the descriptor pointed to by argument
dst. It returns argument
dst if successful or
NULL in case of failure.