Structure
- Programme header
- Section
- Symbol table
Programme header
- An executable or shared object file's program header table is an array of structures.
- each describing a segment or other information the system needs to prepare the program for execution.
- An object file segment contains one or more sections.
- Program headers are meaningful only for executable and shared object files.
- A file specifies its own program header size with the ELF header's e_phentsize and e_phnum members.
- typedef struct {
- Elf32_Word p_type;//tells what kind of segment this array element describes or how to interpret the array element's information.
- Elf32_Off p_offset;//gives the offset from the beginning of the file at which the first byte of the segment resides.
- Elf32_Addr p_vaddr;//gives the virtual address at which the first byte of the segment resides in memory.
- Elf32_Addr p_paddr; //On systems for which physical addressing is relevant, this member is reserved for the segment's physical address.
- Elf32_Word p_filesz; //This member gives the number of bytes in the file image of the segment; it may be zero.
- Elf32_Word p_memsz; //This member gives the number of bytes in the memory image of the segment; it may be zero.
- Elf32_Word p_flags; //This member gives flags relevant to the segment.
- Elf32_Word p_align; //This member gives the value to which the segments are aligned in memory and in the file.
- } Elf32_Phdr;
- p_type
-
- Name Value meaning
- PT_NULL 0 The array element is unused
- PT_LOAD 1 The array element specifies a loadable segment
- PT_DYNAMIC 2 The array element specifies dynamic linking information
- PT_INTERP 3 The array element specifies the location and size of a null- terminated path name to invoke as an interpreter
- PT_NOTE 4 The array element specifies the location and size of auxiliary information
- PT_SHLIB 5 This segment type is reserved, has unspecified semantics
- PT_PHDR 6 specifies the location and size of the program header table itself
- PT_LOPROC 0x70000000 reserved for processor-specific semantics
- PT_HIPROC 0x7fffffff
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