#ifndef ELF_H
#define ELF_H

#include <stdint.h>
#include <stddef.h>

#define EI_NIDENT 16

typedef struct {
    unsigned char e_ident[EI_NIDENT];
    uint16_t e_type;
    uint16_t e_machine;
    uint32_t e_version;
    uint32_t e_entry;
    uint32_t e_phoff;
    uint32_t e_shoff;
    uint32_t e_flags;
    uint16_t e_ehsize;
    uint16_t e_phentsize;
    uint16_t e_phnum;
    uint16_t e_shentsize;
    uint16_t e_shnum;
    uint16_t e_shstrndx;
} elf32_ehdr_t;

typedef struct {
    uint32_t p_type;
    uint32_t p_offset;
    uint32_t p_vaddr;
    uint32_t p_paddr;
    uint32_t p_filesz;
    uint32_t p_memsz;
    uint32_t p_flags;
    uint32_t p_align;
} elf32_phdr_t;

#define ELF_MAGIC0 0x7F
#define ELF_MAGIC1 'E'
#define ELF_MAGIC2 'L'
#define ELF_MAGIC3 'F'

#define ELFCLASS32 1
#define ELFDATA2LSB 1

#define ET_EXEC 2
#define EM_386 3

#define PT_NULL    0
#define PT_LOAD    1
#define PT_DYNAMIC 2
#define PT_INTERP  3
#define PT_NOTE    4
#define PT_PHDR    6

#define ET_DYN  3

#define PF_X 0x1
#define PF_W 0x2
#define PF_R 0x4

/* Dynamic section entry */
typedef struct {
    int32_t  d_tag;
    uint32_t d_val;
} elf32_dyn_t;

#define DT_NULL    0
#define DT_NEEDED  1
#define DT_HASH    4
#define DT_STRTAB  5
#define DT_SYMTAB  6
#define DT_RELA    7
#define DT_RELASZ  8
#define DT_RELAENT 9
#define DT_STRSZ   10
#define DT_SYMENT  11
#define DT_REL     17
#define DT_RELSZ   18
#define DT_RELENT  19
#define DT_PLTGOT  3
#define DT_JMPREL  23
#define DT_PLTRELSZ 2
#define DT_PLTREL  20

/* Relocation entry (without addend) */
typedef struct {
    uint32_t r_offset;
    uint32_t r_info;
} elf32_rel_t;

#define ELF32_R_SYM(i)   ((i) >> 8)
#define ELF32_R_TYPE(i)  ((unsigned char)(i))

#define R_386_NONE      0
#define R_386_32        1
#define R_386_PC32      2
#define R_386_GLOB_DAT  6
#define R_386_JMP_SLOT  7
#define R_386_RELATIVE  8

/* Symbol table entry */
typedef struct {
    uint32_t st_name;
    uint32_t st_value;
    uint32_t st_size;
    uint8_t  st_info;
    uint8_t  st_other;
    uint16_t st_shndx;
} elf32_sym_t;

/* Auxiliary vector (passed on user stack after envp) */
typedef struct {
    uint32_t a_type;
    uint32_t a_val;
} elf32_auxv_t;

#define AT_NULL   0
#define AT_PHDR   3
#define AT_PHENT  4
#define AT_PHNUM  5
#define AT_PAGESZ 6
#define AT_BASE   7   /* Interpreter base address */
#define AT_ENTRY  9   /* Program entry point */

int elf32_load_user_from_initrd(const char* filename, uintptr_t* entry_out, uintptr_t* user_stack_top_out, uintptr_t* addr_space_out, uintptr_t* heap_break_out);

/* Retrieve and consume pending auxv entries (set by elf32_load_user_from_initrd
 * when an interpreter is present).  Returns number of entries copied, 0 if none. */
int elf32_pop_pending_auxv(elf32_auxv_t* out, int max);

#endif