reading header

Cargo.lock

@@ -40,6 +40,15 @@ version = "1.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
 
+[[package]]
+name = "byteordered"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32687ee8ab498526e3ef07dfbede151650ce202dc83c53494645a24677d89b37"
+dependencies = [
+ "byteorder",
+]
+
 [[package]]
 name = "clap"
 version = "2.33.3"
@@ -60,7 +69,7 @@ name = "elf"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "byteorder",
+ "byteordered",
 ]
 
 [[package]]

elf/Cargo.toml

@@ -5,4 +5,4 @@ edition = "2018"
 
 [dependencies]
 anyhow = "1.0.41"
-byteorder = "1.4.3"
+byteordered = "0.5.0"

elf/src/elf.rs

@@ -0,0 +1,37 @@
+use std::io::Read;
+use std::mem::MaybeUninit;
+
+use anyhow::Result;
+
+use crate::constants::*;
+use crate::header::E_IDENT;
+
+macro_rules! elf {
+    ($size:ty) => {
+        #[derive(Debug, Default)]
+        pub struct Elf {
+            pub header: Header,
+        }
+
+        impl Elf {
+            pub(crate) fn continue_read<R: Read>(e_ident: E_IDENT, mut r: R) -> Result<Self> {
+                let mut elf: Self = unsafe { MaybeUninit::zeroed().assume_init() };
+                elf.header = Header::continue_read(e_ident, r)?;
+
+                Ok(elf)
+            }
+        }
+    };
+}
+
+pub mod elf32 {
+    use super::*;
+    use crate::header::header32::Header;
+    elf!(u32);
+}
+
+pub mod elf64 {
+    use super::*;
+    use crate::header::header64::Header;
+    elf!(u64);
+}

elf/src/header.rs

@@ -0,0 +1,81 @@
+use std::io::Read;
+use std::mem::MaybeUninit;
+
+use anyhow::Result;
+use byteordered::{ByteOrdered, Endianness};
+
+use crate::constants::*;
+
+pub type E_IDENT = [u8; EI_NIDENT];
+
+macro_rules! elf_header {
+    ($size:ty, $read_size:ident) => {
+        #[derive(Debug)]
+        pub struct Header {
+            pub e_ident: E_IDENT,
+            pub e_type: u16,
+            pub e_machine: u16,
+            pub e_version: u32,
+            pub e_entry: $size,
+            pub e_phoff: $size,
+            pub e_shoff: $size,
+            pub e_flags: u32,
+            pub e_ehsize: u16,
+            pub e_phentsize: u16,
+            pub e_phnum: u16,
+            pub e_shentsize: u16,
+            pub e_shnum: u16,
+            pub e_shstrndx: u16,
+        }
+
+        impl Default for Header {
+            fn default() -> Self {
+                let mut header: Self = unsafe { MaybeUninit::zeroed().assume_init() };
+                header.e_ident[EI_MAG0] = ELFMAG0;
+                header.e_ident[EI_MAG1] = ELFMAG1;
+                header.e_ident[EI_MAG2] = ELFMAG2;
+                header.e_ident[EI_MAG3] = ELFMAG3;
+                header
+            }
+        }
+
+        impl Header {
+            pub(crate) fn continue_read<R: Read>(e_ident: E_IDENT, mut r: R) -> Result<Self> {
+                let mut header = Header::default();
+
+                header.e_ident = e_ident;
+                let mut r = match header.e_ident[EI_DATA] {
+                    ELFDATA2LSB => ByteOrdered::runtime(r, Endianness::Little),
+                    ELFDATA2MSB => ByteOrdered::runtime(r, Endianness::Big),
+                    _ => bail!("unknown endianness"),
+                };
+
+                header.e_type = r.read_u16()?;
+                header.e_machine = r.read_u16()?;
+                header.e_version = r.read_u32()?;
+                header.e_entry = r.$read_size()?;
+                header.e_phoff = r.$read_size()?;
+                header.e_shoff = r.$read_size()?;
+                header.e_flags = r.read_u32()?;
+                header.e_ehsize = r.read_u16()?;
+                header.e_phentsize = r.read_u16()?;
+                header.e_phnum = r.read_u16()?;
+                header.e_shentsize = r.read_u16()?;
+                header.e_shnum = r.read_u16()?;
+                header.e_shstrndx = r.read_u16()?;
+
+                Ok(header)
+            }
+        }
+    };
+}
+
+pub mod header32 {
+    pub use super::*;
+    elf_header!(u32, read_u32);
+}
+
+pub mod header64 {
+    pub use super::*;
+    elf_header!(u64, read_u64);
+}

elf/src/lib.rs

@@ -1,52 +1,59 @@
+#[macro_use]
+extern crate anyhow;
+
+#[allow(dead_code, non_upper_case_globals, non_camel_case_types)]
+pub mod constants;
+pub mod elf;
+pub mod header;
+
 use std::io::{Read, Write};
 use std::mem::MaybeUninit;
 
 use anyhow::Result;
-use byteorder::{LittleEndian, ReadBytesExt};
 
-const EI_DATA: i32 = 5;
+use crate::constants::*;
+pub use crate::elf::{elf32, elf64};
+use crate::header::E_IDENT;
 
-#[derive(Debug, Default)]
-pub struct Elf {
-    header: Header,
-    program_header: Option<ProgramHeader>,
+enum Bitness {
+    Bits32,
+    Bits64,
 }
 
+#[cfg(target_pointer_width = "64")]
+const SYSTEM_BITNESS: Bitness = Bitness::Bits64;
+#[cfg(not(target_pointer_width = "64"))]
+const SYSTEM_BITNESS: Bitness = Bitness::Bits32;
+
 #[derive(Debug)]
-pub struct Header {
-    e_ident: [u8; 16],
-    e_type: u16,
-    e_machine: u16,
-    e_version: u32,
+pub enum Elf {
+    Elf32(crate::elf::elf32::Elf),
+    Elf64(crate::elf::elf64::Elf),
 }
 
-impl Default for Header {
+impl Default for Elf {
     fn default() -> Self {
-        let mut header: Self = unsafe { MaybeUninit::zeroed().assume_init() };
-        header.e_ident[0] = 0x7f;
-        header.e_ident[1] = b'E';
-        header.e_ident[2] = b'L';
-        header.e_ident[3] = b'F';
-        header
+        match SYSTEM_BITNESS {
+            Bitness::Bits32 => Elf::Elf32(elf32::Elf::default()),
+            Bitness::Bits64 => Elf::Elf64(elf64::Elf::default()),
+        }
     }
 }
-
-#[derive(Debug, Default)]
-pub struct ProgramHeader {}
 
 impl Elf {
-    pub fn read<R: Read>(mut r: R) -> Result<Elf> {
-        let mut elf = Elf::default();
+    pub fn read<R: Read>(mut r: R) -> Result<Self> {
+        let mut e_ident: E_IDENT = [0u8; EI_NIDENT];
+        r.read_exact(&mut e_ident);
 
-        // header
-        r.read_exact(&mut elf.header.e_ident)?;
-        elf.header.e_type = r.read_u16::<LittleEndian>()?;
-
-        Ok(elf)
+        let res = match e_ident[EI_CLASS] {
+            ELFCLASS32 => Elf::Elf32(elf32::Elf::continue_read(e_ident, r)?),
+            ELFCLASS64 => Elf::Elf64(elf64::Elf::continue_read(e_ident, r)?),
+            n => bail!("invalid class: {}", n),
+        };
+        Ok(res)
     }
 
     pub fn write<W: Write>(&self, mut w: W) -> Result<()> {
-        w.write(&self.header.e_ident)?;
         w.flush()?;
 
         Ok(())

src/link.rs

@@ -14,6 +14,7 @@ pub(crate) fn link(opt: &Opt) -> Result<()> {
             LinkUnit::Path(path) => {
                 let file = File::open(path)?;
                 let elf = Elf::read(&file)?;
+                println!("elf: {:?}", elf);
             }
             _ => {}
         }

src/utils.rs

@@ -1,4 +1,4 @@
-use std::path::{Path, PathBuf, Component};
+use std::path::{Component, Path, PathBuf};
 
 pub fn normalize_path(path: &Path) -> PathBuf {
     let mut components = path.components().peekable();