Read PE files in C - portable-executable

Question

I'm attempting to read a PE file in C.
I have code MZ and then, I don't know to code e_lfanew.
#include <stdio.h>
#include <Windows.h>
int main()
{
errno_t err;
FILE *fp = NULL;
char *buffer;
err = fopen_s(&fp, "D:\\pe.exe", "rb");
printf("----------dos header---------- \n");
buffer = new char[3]; // malloc: cap phat bo nho//
memset(buffer, 0x0, sizeof(char)* 3); // memset: gan gia tri cho buffer//
fread(buffer, 2 * sizeof(char), 1, fp);
printf("e_magic: %s \n", buffer);
}
Also, I am aware this is possible via the Win32 API; however, I want to learn from this and do it myself.

Answer 1

Typically one would define a struct called DOS_Header and read the complete struct from the file. That struct then has a field e_lfanew which can directly be accessed without pointer arithmetics etc.
e_lfanew then points to the PE signature (PE\0\0), followed by the COFF header. Then the story repeats: create a struct called COFF_Header and read the complete struct from the file...

Answer 2

As #thomas weller said you need to typecast your buffer to IMAGE_DOS_HEADER.
The last field tells you where the PE header is, then read that offset and typecast the buffer to IMAGE_NT_HEADER. The other way is to just map the file in and typecast the relevant buffers memory.

Answer 3

To get details about any header information you can directly fill it to the structure for example
IMAGE_DOS_HEADER imgDosHdr = {0};
FILE *fp = fopen("Path_to_Pe","rb");
if(fp == NULL) return;
fseek(fp,0,SEEK_SET);
fread(&imgDosHdr,1,sizeof(IMAGE_DOS_HEADER),fp);
fclose(fp);
Hence you can get all the details of PE file Header by Setting the
fseek.