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#include "elf_load.hpp"
#include "elf_format.hpp"
#include <algorithm>
#include <cstring>
//constexpr unsigned int ELF_LOAD_ADDR = 0x10000000;
static const unsigned char elf_header[] = { '\177', 'E', 'L', 'F' };
template<typename T>
constexpr static auto ptr_from_offset(void *base, uint32_t offset)
{
return reinterpret_cast<T>(reinterpret_cast<uint8_t *>(base) + offset);
}
//static Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name);
namespace elf {
entry_t load(void *elf_data)
{
// Check the ELF's header signature
auto ehdr = reinterpret_cast<Elf32_Ehdr *>(elf_data);
if (!std::equal(ehdr->e_ident, ehdr->e_ident + 4, elf_header))
return nullptr;
// Iterate through program header LOAD sections
bool loaded = false;
auto phdr = ptr_from_offset<Elf32_Phdr *>(elf_data, ehdr->e_phoff);
for (Elf32_Half i = 0; i < ehdr->e_phnum; i++) {
if (phdr->p_type == PT_LOAD) {
if (phdr->p_filesz == 0) {
std::memset(reinterpret_cast<void *>(phdr->p_vaddr),
0,
phdr->p_memsz);
} else {
std::memcpy(reinterpret_cast<void *>(phdr->p_vaddr),
ptr_from_offset<void *>(elf_data, phdr->p_offset),
phdr->p_filesz);
if (!loaded)
loaded = true;
}
}
phdr = ptr_from_offset<Elf32_Phdr *>(phdr, ehdr->e_phentsize);
}
return loaded ? reinterpret_cast<entry_t>(ehdr->e_entry) : nullptr;
}
} // namespace elf
//Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name)
//{
// auto shdr = ptr_from_offset<Elf32_Shdr *>(ehdr, ehdr->e_shoff);
// auto shdr_str = ptr_from_offset<Elf32_Shdr *>(ehdr,
// ehdr->e_shoff + ehdr->e_shstrndx * ehdr->e_shentsize);
//
// for (Elf32_Half i = 0; i < ehdr->e_shnum; i++) {
// char *section = ptr_from_offset<char *>(ehdr, shdr_str->sh_offset) + shdr->sh_name;
// if (!strcmp(section, name))
// return shdr;
//
// shdr = ptr_from_offset<Elf32_Shdr *>(shdr, ehdr->e_shentsize);
// }
//
// return 0;
//}
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