src/module/elf.hpp

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/* include file for src/module/elf.cpp */

#ifndef _CORE_MODULE_ELF_HPP
#define _CORE_MODULE_ELF_HPP

/* necessary includes */
// #include "LINKER/blist.hpp"
// #include "modules.hpp"

/*================================ELF FORMAT CONSTANTS=====================================*/

/*the elf ident header size*/
const uint32 DEF_EI_NIDENT = 16;
/*elf header specs*/
const uint32 EI_CLASS   = 4;    /*32bit/64bit*/
const uint32 EI_DATA    = 5;    /*big/little-endian*/
const uint32 EI_VERSION = 6;    /*version*/
const uint32 ELFCLASSNONE = 0;  /*invalid class type*/
const uint32 ELFCLASS32 = 1;    /*32bit architecture*/
const uint32 ELFCLASS64 = 2;    /*64bit architecture*/
const uint32 ELFDATANONE        = 0;    /*invalid endianness*/
const uint32 ELFDATA2LSB        = 1;    /*little-endian*/
const uint32 ELFDATA2MSB        = 2;    /*big-endian*/
const uint32 EV_NONE = 0;               /*invalid version*/
const uint32 EV_CURRENT = 1;    /*current version*/
const uint32 ET_NONE    = 0;    /*invalid module type*/
const uint32 ET_REL             = 1;    /*relocatable file*/
const uint32 ET_EXEC    = 2;    /*executable file*/
const uint32 ET_DYN             = 3;    /*shared object file*/
const uint32 ET_CORE    = 4;    /*core file*/
const uint32 ET_LOPROC  = 0xff00;       /*processor-specific*/
const uint32 ET_HIPROC  = 0xffff;       /*processor-specific*/
const uint32 EM_NONE    = 0;    /*invalid machine*/
const uint32 EM_M32             = 1;    /*AT&T WE 32100*/
const uint32 EM_SPARC   = 2;    /*SPARC*/
const uint32 EM_386             = 3;    /*Intel Architecture*/
const uint32 EM_68K             = 4;    /*Motorola 68000*/
const uint32 EM_88K             = 5;    /*Motorola 88000*/
const uint32 EM_860             = 7;    /*Intel 80860*/
const uint32 EM_MIPS    = 8;    /*MIPS RS3000 Big-Endian*/
const uint32 EM_MIPS_RS4_BE = 10;       /*MIPS RS4000 Big-Endian*/

/*section header types*/
const uint32 SHT_NULL           = 0;
const uint32 SHT_PROGBITS       = 1;
const uint32 SHT_SYMTAB         = 2;
const uint32 SHT_STRTAB         = 3;
const uint32 SHT_RELA           = 4;
const uint32 SHT_HASH           = 5;
const uint32 SHT_DYNAMIC        = 6;
const uint32 SHT_NOTE           = 7;
const uint32 SHT_NOBITS         = 8;
const uint32 SHT_REL            = 9;
const uint32 SHT_SHLIB          = 10;
const uint32 SHT_DYNSYM         = 11;
const uint32 SHT_LOPROC         = 0x70000000;
const uint32 SHT_HIPROC         = 0x7fffffff;
const uint32 SHT_LOUSER         = 0x80000000;
const uint32 SHT_HIUSER         = 0x8fffffff;

/*program header types*/
const uint32 PT_NULL            = 0;
const uint32 PT_LOAD            = 1;
const uint32 PT_DYNAMIC         = 2;
const uint32 PT_INTERP          = 3;
const uint32 PT_NOTE            = 4;
const uint32 PT_SHLIB           = 5;
const uint32 PT_PHDR            = 6;
const uint32 PT_LOPROC          = 0x70000000;
const uint32 PT_HIPROC          = 0x7fffffff;

/*symbol info*/
const uint32 STB_LOCAL          = 0x0;
const uint32 STB_GLOBAL         = 0x1;
const uint32 STB_WEAK           = 0x2;
const uint32 STB_LOPROC         = 13;
const uint32 STB_HIPROC         = 15;

/*symbol type*/
const uint32 STT_NOTYPE         = 0;
const uint32 STT_OBJECT         = 1;
const uint32 STT_FUNC           = 2;
const uint32 STT_SECTION        = 3;
const uint32 STT_FILE           = 4;
const uint32 STT_LOPROC         = 13;
const uint32 STT_HIPROC         = 15;

/*section header index values*/
const uint32 SHN_UNDEF          = 0;
const uint32 SHN_LORESERVE      = 0xff00;
const uint32 SHN_LOPROC         = 0xff00;
const uint32 SHN_HIPROC         = 0xff1f;
const uint32 SHN_ABS            = 0xfff1;
const uint32 SHN_COMMON         = 0xfff2;
const uint32 SHN_HIRESERVE      = 0xffff;

/*relocation type*/
const uint32 R_386_NONE         = 0;
const uint32 R_386_32           = 1;    /*S (symbol value) + A (addend)*/
const uint32 R_386_PC32         = 2;    /*S (symbol value) + A (addend) - P (the relocated address)*/

/*defines to use with Elf32_sym*/
#define ELF32_ST_BIND(i)        ((i)>>4)                                /*st_bind from st_info*/
#define ELF32_ST_TYPE(i)        ((i)&0xf)                               /*st_type from st_info*/
#define ELF32_ST_INFO(b,t)      (((b)<<4)+((t)&0xf))    /*st_info from st_bind and st_type*/

/*the struct of an elf header*/
struct Elf32_ehdr
 {
        unsigned char   e_ident [DEF_EI_NIDENT];
        uint16  e_type;
        uint16  e_machine;
        uint32  e_version;
        uint32  e_entry;
        uint32  e_phoff;
        uint32  e_shoff;
        uint32  e_flags;
        uint16  e_ehsize;
        uint16  e_phentsize;
        uint16  e_phnum;
        uint16  e_shentsize;
        uint16  e_shnum;
        uint16  e_shstrndx;
 }  __attribute__ ((packed));

/*the elf section header*/
struct Elf32_shdr
 {
        uint32  sh_name;
        uint32  sh_type;
        uint32  sh_flags;
        uint32  sh_addr;
        uint32  sh_offset;
        uint32  sh_size;
        uint32  sh_link;
        uint32  sh_info;
        uint32  sh_addralign;
        uint32  sh_entsize;
 };

/*the program header*/
struct Elf32_phdr
 {
        uint32 p_type;
        uint32 p_offset;
        uint32 p_vaddr;
        uint32 p_paddr;
        uint32 p_filesz;
        uint32 p_memsz;
        uint32 p_flags;
        uint32 p_align;
 } __attribute__ ((packed));

//symbol type entry
struct Elf32_sym
 {
        uint32 st_name;
        uint32 st_value;
        uint32 st_size;
        uint8  st_info;
        uint8  st_other;
        uint16 st_shndx;
 }  __attribute__ ((packed));

//relocation type entry
struct Elf32_reloc
 {
        uint32 r_addr;
        uint8  r_type;
        uint32 r_symtabndx :24;
        uint32 r_addend;
 } __attribute__ ((packed));

/*========================================IMPLEMENTATION====================================*/

/*the class*/
class elf_t
 {
public:
        char *image;
        Elf32_ehdr *ehdr;       /*the elf header*/
        uint32 size;    /*data size*/
        char valid;             /*check if module valid*/

//      elf_t();                        /*init*/
//      elf_t(char *ptr, uint32 sze);   /*init and set ptr to data*/
        void init(char *ptr, uint32 sze);       /*init and set ptr to data*/
        void set_ehdr(Elf32_ehdr *_ehdr, uint32 sze);   /*set with custom ehdr. sets image to NULL*/
//      ~elf_t();       /*done.*/
        void done();    /*done.*/

        char ident();   /*check elf validity*/

        Elf32_shdr *section(uint32 n);  /*returns pointer to a section header, if exists*/
        void *sect_addr(uint32 n);      /*returns pointer to a section, if exists*/
        Elf32_phdr *segment(uint32 n);  /*returns pointer to a program header, if exists*/
        void *segm_addr(uint32 n);      /*returns pointer to a segment, if exists*/

        Elf32_sym *symbol(uint32 sect, uint32 n);       /*returns pointer to a symtab entry #n in section sect*/
        char *str(uint32 sect, uint32 off);             /*returns a pointer to a strtab entry with offset off in section sect*/

        Elf32_reloc *reloc(uint32 sect, uint32 n);      /*returns a pointer to a rel/rela section entry #n in section sect*/
//      void relocate(); /*perform relocations indicitated by rel/rela sections*/
//      void relocate(Elf32_sym *sym); /*perform relocations indicitated by rel/rela sections for symtab entry sym*/
//      void un_reloc(Elf32_sym *sym); /*perform relocations indicitated by rel/rela sections for symtab entry sym*/
        
//      void do_elf_reloc(Elf32_reloc *reloc, Elf32_shdr *sect);        /*perform single relocation*/
//      void undo_elf_reloc(Elf32_reloc *reloc, Elf32_shdr *sect);      /*delete old relocation*/


//      uint32 save_syms(blist_t *list, uint32 sym_bind, uint32 defined, struct mod_t *mod);    /*saves all defined/undefined (defined == [0;1]) symbols with bind_type == sym_bind from this elf to list*/
 };

/*consts for the save_syms proc*/
const uint32 DEFINED = 1;
const uint32 UNDEFINED = 0;

int create_ehdr(Elf32_ehdr *elf_hdr, uint32 shnum, Elf32_shdr *shaddr,
        uint32 shentsize, uint32 shstrndx, uint32 e_type);              /*create a header*/

#endif

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