PE import start (fixed header size -> sections work)

src/backend/container/elf.rs

@@ -1,6 +1,7 @@
-use crate::backend::{Addr, LinkedProgram, container::as_u8_slice};
+use crate::backend::{LinkedProgram, container::encode::ByteEncoder};
 
 #[repr(C)]
+#[derive(Default)]
 pub struct ELF64Header {
     magic: u32,
     class: u8,
@@ -25,6 +26,7 @@ pub struct ELF64Header {
 }
 
 #[repr(C)]
+#[derive(Default)]
 pub struct ProgramHeader {
     ty: u32,
     flags: u32,
@@ -80,19 +82,17 @@ pub fn create(program: &[u8], start_offset: u64) -> Vec<u8> {
     let page_size = 0x1000;
     // I don't know if I have to add addr_start here, idk how it maps the memory
     let program_size = std::mem::size_of_val(program) as u64;
-    let program_header = ProgramHeader {
-        ty: 0x1,      // LOAD
-        flags: 0b101, // executable, readable
-        offset: 0x0,
-        vaddr: addr_start,
-        paddr: 0x0,
-        filesz: program_size,
-        memsz: program_size,
-        align: page_size,
-    };
-    let header_len = (size_of::<ELF64Header>() + size_of::<ProgramHeader>()) as u64;
-    let program_pos = header_len;
-    let header = ELF64Header {
+
+    let mut data = ByteEncoder::default();
+    let header = data.reserve::<ELF64Header>();
+
+    let program_header_offset = data.pos() as u64;
+    let program_header = data.reserve::<ProgramHeader>();
+
+    let program_pos = data.pos() as u64;
+    data.extend(program);
+
+    data[header] = ELF64Header {
         magic: 0x7f_45_4c_46u32.swap_bytes(),
         class: 0x2,      // 64 bit
         endianness: 0x1, // little endian
@@ -103,8 +103,8 @@ pub fn create(program: &[u8], start_offset: u64) -> Vec<u8> {
         ty: if pie { EType::Dyn } else { EType::Exec } as u16,
         machine: Arch::X86_64.machine(),
         e_version: 0x1,
-        entry: addr_start + program_pos + start_offset as u64,
-        program_header_offset: size_of::<ELF64Header>() as u64,
+        entry: addr_start + program_pos + start_offset,
+        program_header_offset,
         section_header_offset: 0x0,
         // C ABI (16 bit instruction align) + double precision floats
         flags: 0x1 | 0x4,
@@ -115,11 +115,17 @@ pub fn create(program: &[u8], start_offset: u64) -> Vec<u8> {
         section_header_num: 0x0,
         section_header_str_idx: 0x0,
     };
-    let mut bytes: Vec<u8> = Vec::new();
-    bytes.extend(as_u8_slice(&header));
-    bytes.extend(as_u8_slice(&program_header));
-    bytes.extend(program);
-    bytes
+    data[program_header] = ProgramHeader {
+        ty: 0x1,      // LOAD
+        flags: 0b101, // executable, readable
+        offset: 0x0,
+        vaddr: addr_start,
+        paddr: 0x0,
+        filesz: program_size,
+        memsz: program_size,
+        align: page_size,
+    };
+    data.data
 }
 
 impl LinkedProgram<u64> {