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Refactor PE parsing

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This commit is contained in:
Jeremy 2023-07-23 20:03:32 -04:00
parent 0e701903ed
commit e1c7657a3e
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GPG Key ID: 19AA8270105E8EB4
1 changed files with 28 additions and 34 deletions
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62
src/platform/pe.hpp
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@ -1,6 +1,7 @@
#ifndef PE_HPP
#define PE_HPP
#include <array>
#include <cstddef>
#include <cstdio>
#include <cstring>
@ -11,51 +12,44 @@
#if IS_WINDOWS
#include <windows.h>
static uintptr_t pe_get_module_image_base(const std::string& obj_path) {
template<typename T, typename std::enable_if<std::is_integral<T>::value, int>::type = 0>
T pe_byteswap_if_needed(T value) {
// PE header values are little endian
bool do_swap = !is_little_endian();
if(!is_little_endian()) {
return byteswap(value);
} else {
return value;
}
}
static uintptr_t pe_get_module_image_base(const std::string& obj_path) {
FILE* file = fopen(obj_path.c_str(), "rb");
char magic[2];
internal_verify(fread(magic, 1, 2, file) == 2); // file + 0x0
internal_verify(memcmp(magic, "MZ", 2) == 0);
DWORD e_lfanew;
internal_verify(fseek(file, 0x3c, SEEK_SET) == 0);
internal_verify(fread(&e_lfanew, sizeof(DWORD), 1, file) == 1); // file + 0x3c
if(do_swap) e_lfanew = byteswap(e_lfanew);
auto magic = load_bytes<std::array<char, 2>>(file, 0);
internal_verify(memcmp(magic.data(), "MZ", 2) == 0);
DWORD e_lfanew = pe_byteswap_if_needed(load_bytes<DWORD>(file, 0x3c)); // dos header + 0x3c
long nt_header_offset = e_lfanew;
char signature[4];
internal_verify(fseek(file, nt_header_offset, SEEK_SET) == 0);
internal_verify(fread(signature, 1, 4, file) == 4); // NT header + 0x0
internal_verify(memcmp(signature, "PE\0\0", 4) == 0);
//WORD machine;
//internal_verify(fseek(file, nt_header_offset + 4, SEEK_SET) == 0); // file header + 0x0
//internal_verify(fread(&machine, sizeof(WORD), 1, file) == 1);
WORD size_of_optional_header;
internal_verify(fseek(file, nt_header_offset + 4 + 0x10, SEEK_SET) == 0); // file header + 0x10
internal_verify(fread(&size_of_optional_header, sizeof(DWORD), 1, file) == 1);
if(do_swap) size_of_optional_header = byteswap(size_of_optional_header);
auto signature = load_bytes<std::array<char, 4>>(file, nt_header_offset); // nt header + 0
internal_verify(memcmp(signature.data(), "PE\0\0", 4) == 0);
WORD size_of_optional_header = pe_byteswap_if_needed(
load_bytes<WORD>(file, nt_header_offset + 4 + 0x10) // file header + 0x10
);
internal_verify(size_of_optional_header != 0);
WORD optional_header_magic;
internal_verify(fseek(file, nt_header_offset + 0x18, SEEK_SET) == 0); // optional header + 0x0
internal_verify(fread(&optional_header_magic, sizeof(DWORD), 1, file) == 1);
if(do_swap) optional_header_magic = byteswap(optional_header_magic);
WORD optional_header_magic = pe_byteswap_if_needed(
load_bytes<WORD>(file, nt_header_offset + 0x18) // optional header + 0x0
);
internal_verify(optional_header_magic == IMAGE_NT_OPTIONAL_HDR_MAGIC);
uintptr_t image_base;
if(optional_header_magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
// 32 bit
DWORD base;
internal_verify(fseek(file, nt_header_offset + 0x18 + 0x1c, SEEK_SET) == 0); // optional header + 0x1c
internal_verify(fread(&base, sizeof(DWORD), 1, file) == 1);
if(do_swap) base = byteswap(base);
image_base = base;
image_base = pe_byteswap_if_needed(
load_bytes<DWORD>(file, nt_header_offset + 0x18 + 0x1c) // optional header + 0x1c
);
} else {
// 64 bit
// I get an "error: 'QWORD' was not declared in this scope" for some reason when using QWORD
unsigned __int64 base;
internal_verify(fseek(file, nt_header_offset + 0x18 + 0x18, SEEK_SET) == 0); // optional header + 0x18
internal_verify(fread(&base, sizeof(unsigned __int64), 1, file) == 1);
if(do_swap) base = byteswap(base);
image_base = base;
image_base = pe_byteswap_if_needed(
load_bytes<unsigned __int64>(file, nt_header_offset + 0x18 + 0x18) // optional header + 0x18
);
}
fclose(file);
return image_base;