elf_getphdr(3elf)

elf_getphdr: elf32_getphdr, elf32_newphdr, elf64_getphdr, elf64_newphdr -- retrieve class-dependent program header table

Synopsis

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

   Elf32_Phdr elf32_getphdr(Elf elf);
   

   Elf32_Phdr elf32_newphdr(Elf elf, size_t count);
   

   Elf64_Phdr elf64_getphdr(Elf elf);
   

   Elf64_Phdr elf64_newphdr(Elf elf, size_t count);

Description

For a 32-bit class file, elf32_getphdr returns a pointer to the program execution header table, if one is available for the ELF descriptor elf.

elf32_newphdr allocates a new table with count entries, regardless of whether one existed previously, and sets the ELF_F_DIRTY bit for the table [see elf_flag(3elf)]. Specifying a zero count deletes an existing table. Note this behavior differs from that of elf32_newehdr [see elf_getehdr(3elf)], allowing a program to replace or delete the program header table, changing its size if necessary.

If no program header table exists, the file is not a 32-bit class file, an error occurs, or elf is null, both functions return a null pointer. Additionally, elf32_newphdr returns a null pointer if count is zero.

The table is an array of Elf32_Phdr structures, each of which includes the following members.



   	Elf32_Word	p_type;
   	Elf32_Off	p_offset;
   	Elf32_Addr	p_vaddr;
   	Elf32_Addr	p_paddr;
   	Elf32_Word	p_filesz;
   	Elf32_Word	p_memsz;
   	Elf32_Word	p_flags;
   	Elf32_Word	p_align;

elf64_getphdr and elf64_newhdr provide the same functionality for 64-bit class files. The table is an array of Elf64_Phdr structures, each of which includes the following members.



           Elf64_Word      p_type;
           Elf64_Word      p_flags;
           Elf64_Off       p_offset;
           Elf64_Addr      p_vaddr;
           Elf64_Addr      p_paddr;
           Elf64_Xword      p_filesz;
           Elf64_Xword      p_memsz;
           Elf64_Xword      p_align;

The ELF header's e_phnum member tells how many entries the program header table has [see elf_getehdr(3elf)]. A program may inspect this value to determine the size of an existing table; elf32_newphdr and elf64_newphdr automatically set the member's value to count. If the program is building a new file, it is responsible for creating the file's ELF header before creating the program header table.

References

Intro(3elf), elf_begin(3elf), elf_flag(3elf), elf_getehdr(3elf)