added &str

src/main.rs

@@ -21,6 +21,32 @@ fn log<T: Sized + Any>(s: &T, v: &mut [u8], p: &mut usize) {
     *p += size;
 }
 
+// log str and move write pointer forward
+// notice, to work towards a real target the pointer
+// len and ptr fields will be on u32
+fn log_str(s: &'static str, v: &mut [u8], p: &mut usize) {
+    let type_id = TypeId::of::<str>();
+    let size = s.len();
+
+    // store type_id
+    let bytes: [u8; 8] = unsafe { transmute(type_id) };
+    v[*p..*p + 8].copy_from_slice(&bytes);
+    *p += 8;
+
+    // store len
+    let bytes: [u8; 8] = unsafe { transmute(s.len()) };
+    v[*p..*p + 8].copy_from_slice(&bytes);
+    *p += 8;
+    println!("len {}", s.len());
+
+    // store ptr
+    let bytes: [u8; 8] = unsafe { transmute(s.as_ptr()) };
+    v[*p..*p + 8].copy_from_slice(&bytes);
+    println!("ptr {:?}", s.as_ptr());
+
+    *p += 8;
+}
+
 // helper to expand data and move read pointer forward
 fn exp2<T>(v: &[u8], p: &mut usize)
 where
@@ -32,6 +58,29 @@ where
     *p += size;
 }
 
+use std::slice;
+use std::str;
+
+// helper to expand str and move read pointer forward
+// notice, to work towards a real target we need to adjust
+// the pointer to the pointer in the elf
+fn exp_str(v: &[u8], p: &mut usize) {
+    // get length
+    let bytes: &[u8; 8] = v[*p..*p + 8].try_into().unwrap();
+    let len: usize = unsafe { transmute(*bytes) };
+    *p += 8;
+    println!("len {}", len);
+
+    // get pointer
+    let bytes: &[u8; 8] = v[*p..*p + 8].try_into().unwrap();
+    let ptr: *const u8 = unsafe { transmute(*bytes) };
+    *p += 8;
+    println!("ptr {:?}", ptr);
+
+    let s = str::from_utf8(unsafe { slice::from_raw_parts(ptr, len) }).unwrap();
+    println!("{:?}", s);
+}
+
 // expand data and move read pointer forward
 fn exp(v: &[u8], p: &mut usize) {
     let bytes: &[u8; 8] = v[*p..*p + 8].try_into().unwrap();
@@ -43,6 +92,8 @@ fn exp(v: &[u8], p: &mut usize) {
         exp2::<T1>(v, p);
     } else if *type_id == TypeId::of::<T2>() {
         exp2::<T2>(v, p);
+    } else if *type_id == TypeId::of::<str>() {
+        exp_str(v, p);
     } else {
         unreachable!();
     }
@@ -72,9 +123,11 @@ fn main() {
     println!("{:?}", t2);
     log(&t1, &mut v, &mut w);
     log(&t2, &mut v, &mut w);
+    log_str(&"hello", &mut v, &mut w);
 
     // example expand the logged data
     let mut r = 0;
     exp(&v, &mut r);
     exp(&v, &mut r);
+    exp(&v, &mut r);
 }