removing fixed size for output vector

src/assembler.rs

@@ -18,7 +18,8 @@ mod extern_def {
  #[link(name = "assemble")]
  extern "C" {
  pub fn assemble(arch: Enum_Arch, instructions: *const ::libc::c_char,
- out: *mut byte, out_len: *mut size_t) -> ::libc::c_int;
+ out: *mut *mut byte, out_len: *mut size_t) -> ::libc::c_int;
+ pub fn free_vec(vec: *mut byte);
  }
 }
 
@@ -50,25 +51,28 @@ impl Arch {
 pub fn assemble(arch: Arch, input: &str) -> Option<Vec<u8>> {
  use std::ffi::CString;
  use std::slice;
+ use std::mem;
  use libc;
 
  let e_arch = arch.to_c();
  let ins = CString::new(input).unwrap();
 
  unsafe {
- let mut out_len = 0x100;
- let out_arr: *mut u8 = libc::malloc(out_len) as (*mut u8);
+ let mut out_len = 0;
+ let out_arr: *mut *mut u8 =
+ libc::malloc(mem::size_of::<usize>() as libc::size_t)
+ as *mut *mut u8;
 
  let res = extern_def::assemble(e_arch, ins.as_ptr(), out_arr, &mut out_len);
  if res == 0 {
- Some(slice::from_raw_parts(out_arr, out_len as usize).to_vec())
+ let vec = Some(
+ slice::from_raw_parts(*out_arr, out_len as usize).to_vec());
+
+ extern_def::free_vec(*out_arr);
+ libc::free(out_arr as *mut libc::c_void);
+ vec
  } else {
  None
  }
  }
 }
-
-#[test]
-fn test_assemble() {
- assert_eq!(assemble(Arch::X86, "int3").unwrap(), [0xcc]);
-}

src/c/assemble.cc

@@ -314,7 +314,11 @@ static int assemble_llvm(StringRef &arch, StringRef &input_str, std::vector<byte
  return Res;
 }
 
-int assemble(enum Arch arch, const char *instructions, byte *out, size_t *out_len) {
+void free_vec(byte *vec) {
+ free(vec);
+}
+
+int assemble(enum Arch arch, const char *instructions, byte **out, size_t *out_len) {
  StringRef s_arch;
  std::vector<byte> out_vec;
 
@@ -351,13 +355,12 @@ int assemble(enum Arch arch, const char *instructions, byte *out, size_t *out_le
  return -1;
  }
 
- if (*out_len >= out_vec.size()) {
- memcpy(out, out_vec.data(), out_vec.size());
- *out_len = out_vec.size();
- return 0;
- } else {
- return -1;
- }
+ *out = (byte *)malloc(out_vec.size());
+ *out_len = out_vec.size();
+
+ memcpy(*out, out_vec.data(), out_vec.size());
+
+ return 0;
 }
 
 /*

src/c/assemble.h

@@ -52,7 +52,8 @@ extern "C" {
  ppc32,
  };
 
- int assemble(enum Arch arch, const char *instructions, byte *out, size_t *out_len);
+ void free_vec(byte *vec);
+ int assemble(enum Arch arch, const char *instructions, byte **out, size_t *out_len);
 
 #ifdef __cplusplus
 }

src/lib.rs

@@ -4,5 +4,6 @@ pub mod assembler;
 pub use assembler::{Arch, assemble};
 
 #[test]
-fn it_works() {
+fn x86_int3() {
+ assert_eq!(assemble(Arch::X86, "int3").unwrap(), [0xcc]);
 }