#include "elf.h"
#include "lib/string.h"
#include "usr/elf.h"
#include "io/log.h"
#include "mem/memory.h"

void*
elf_load(const void *data, size_t len)
{
    if(data == NULL) return NULL;
    if(len < 4) return NULL;

    struct ELF_header *ehdr = (struct ELF_header*)data;
    if(ehdr->e_ident[EI_MAG0] != E_IDENT_MAG0 &&
            ehdr->e_ident[EI_MAG1] != E_IDENT_MAG1 &&
            ehdr->e_ident[EI_MAG2] != E_IDENT_MAG2 &&
            ehdr->e_ident[EI_MAG3] != E_IDENT_MAG3)
        return NULL;

    if(ehdr->e_ident[EI_CLASS] != E_IDENT_CLASS64) {
        klogf("Jove does not support ELF files of class CLASS32\n");
        return NULL;
    }

    if(ehdr->e_type != ET_EXEC) {
        klogf("Jove does not support ELF files other than ET_EXEC\n");
        return NULL;
    }

    uint64_t entry = ehdr->e_entry;
    
    size_t phdrc = ehdr->e_phnum;
    struct ELF_phdr *phdrs = (struct ELF_phdr*)((uintptr_t)data + ehdr->e_phoff);
    
    for(size_t phdri = 0; phdri < phdrc; phdri++)
    {
        struct ELF_phdr *phdr = &phdrs[phdri];
        void *pdata = (void*)phdr->p_vaddr;
            
        mem_ensure_range(
                phdr->p_vaddr,
                phdr->p_vaddr + phdr->p_memsz, 
                (page_flags_t) {
                    .present = true,
                    .writeable = true,
                    .useraccess = true,
                    .executable = true
                });
        if(phdr->p_type == PT_LOAD)
        {
            memcpy(pdata, (void*)((uintptr_t)data + phdr->p_offset), phdr->p_filesz);
        }
    }
    return (void*)entry;
}