#include <libelf.h>
#include <stdlib.h>

typedef unsigned char byte;

#define SETSTRUCT(v,t,vals...) { t tmp = vals; v = tmp; }
#define DEF_FORMAT(fmt,base,htype,init...)              \
    int const fmt##_HSIZE = sizeof(htype);              \
    int const fmt##_ENTRY = sizeof(htype) + (base);     \
    int fmt##_entry() { return fmt##_ENTRY; }           \
    int fmt##_headerSize() { return fmt##_HSIZE; }      \
    byte* fmt##_headerCons(int dataSize) {              \
        htype* ret = malloc(sizeof(htype));             \
        SETSTRUCT(*ret,htype,init);                     \
        return (byte*)ret;                              \
    }

typedef struct {
    Elf64_Ehdr eh;
    Elf64_Phdr pht[1];
} elf64_Header;
DEF_FORMAT(elf64,1<<21,elf64_Header,{
    .eh = {
        .e_ident = { 
            ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
            ELFCLASS64, ELFDATA2LSB,
            EV_CURRENT,
            ELFOSABI_NONE, 0,
            0
        },
        .e_type      = ET_EXEC,
        .e_machine   = EM_X86_64,
        .e_version   = EV_CURRENT,
        .e_entry     = elf64_ENTRY,
        .e_phoff     = sizeof(Elf64_Ehdr),
        .e_shoff     = 0,
        .e_flags     = 0,
        .e_ehsize    = sizeof(Elf64_Ehdr),
        .e_phentsize = sizeof(Elf64_Phdr),
        .e_phnum     = 1,
        .e_shentsize = 0,
        .e_shnum     = 0,
        .e_shstrndx  = SHN_UNDEF
    },
    .pht = {{ 
        .p_type   = PT_LOAD,
        .p_offset = elf64_HSIZE,
        .p_vaddr  = elf64_ENTRY,
        .p_paddr  = 0,
        .p_filesz = dataSize,
        .p_memsz  = dataSize,
        .p_flags  = PF_R | PF_W | PF_X,
        .p_align  = 1<<21
    }}})

typedef struct {
    Elf32_Ehdr eh;
    Elf32_Phdr pht[1];
} elf32_Header;
DEF_FORMAT(elf32,1<<21,elf32_Header,{
    .eh = {
        .e_ident = { 
            ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
            ELFCLASS32, ELFDATA2LSB,
            EV_CURRENT,
            ELFOSABI_NONE, 0,
            0
        },
        .e_type      = ET_EXEC,
        .e_machine   = EM_386,
        .e_version   = EV_CURRENT,
        .e_entry     = elf32_ENTRY,
        .e_phoff     = sizeof(Elf32_Ehdr),
        .e_shoff     = 0,
        .e_flags     = 0,
        .e_ehsize    = sizeof(Elf32_Ehdr),
        .e_phentsize = sizeof(Elf32_Phdr),
        .e_phnum     = 1,
        .e_shentsize = 0,
        .e_shnum     = 0,
        .e_shstrndx  = SHN_UNDEF
    },
    .pht = {{ 
        .p_type   = PT_LOAD,
        .p_offset = elf32_HSIZE,
        .p_vaddr  = elf32_ENTRY,
        .p_paddr  = 0,
        .p_filesz = dataSize,
        .p_memsz  = dataSize,
        .p_flags  = PF_R | PF_W | PF_X,
        .p_align  = 1<<21
    }}})

typedef struct {
  unsigned short signature; /* == 0x5a4D */
  unsigned short bytes_in_last_block;
  unsigned short blocks_in_file;
  unsigned short num_relocs;
  unsigned short header_paragraphs;
  unsigned short min_extra_paragraphs;
  unsigned short max_extra_paragraphs;
  unsigned short ss;
  unsigned short sp;
  unsigned short checksum;
  unsigned short ip;
  unsigned short cs;
  unsigned short reloc_table_offset;
  unsigned short overlay_number;
} exe_Header;
DEF_FORMAT(exe,0x1000,exe_Header,{
    .signature = 0x5a4d,
    .bytes_in_last_block = (dataSize+exe_HSIZE)%512,
    .blocks_in_file = (dataSize+exe_HSIZE)/512,
    .num_relocs = 0,
    .header_paragraphs = 1,
    .min_extra_paragraphs = 0,
    .max_extra_paragraphs = 0,
    .ss = 0,
    .sp = 0x1000,
    .checksum = 0,
    .ip = exe_ENTRY,
    .cs = 0,
    .reloc_table_offset = 0,
    .overlay_number = 0
})

/* 
Copyright (c) 2012, Coiffier Marc <marc.coiffier@gmail.com>
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

    Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
    Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
*/