Add user entropy support

qtlib/src/lib.rs

@@ -1,14 +1,28 @@
 use libc::{c_char};
-use std::ffi::CString;
+use std::ffi::{CStr, CString};
 use zecpaperlib::paper;
 
+/**
+ * Call into rust to generate a paper wallet. Returns the paper wallet in JSON form. 
+ * NOTE: the returned string is owned by rust, so the caller needs to call rust_free_string with it
+ * after using it to free it properly
+ */ 
 #[no_mangle]
-pub extern fn rust_generate_wallet(testnet: bool, count: u32) -> *mut c_char {
-    let c_str = CString::new(paper::generate_wallet(testnet, false, count, &[])).unwrap();
+pub extern fn rust_generate_wallet(testnet: bool, count: u32, entropy: *const c_char) -> *mut c_char {
+    let entropy_str = unsafe {
+        assert!(!entropy.is_null());
+
+        CStr::from_ptr(entropy)
+    };
+
+    let c_str = CString::new(paper::generate_wallet(testnet, false, count, entropy_str.to_bytes())).unwrap();
     return c_str.into_raw();
 }
 
-
+/**
+ * Callers that recieve string return values from other functions should call this to return the string 
+ * back to rust, so it can be freed. Failure to call this function will result in a memory leak
+ */ 
 #[no_mangle]
 pub extern fn rust_free_string(s: *mut c_char) {
     unsafe {
@@ -16,27 +30,3 @@ pub extern fn rust_free_string(s: *mut c_char) {
         CString::from_raw(s)
     };
 }
-
-// #[no_mangle]
-// pub extern fn double_input(input: i32) -> i32 {
-//     input * 2
-// }
-
-// #[no_mangle]
-// pub extern fn say_hello() -> *mut c_char {
-//     let mut hello = String::from("Hello World");
-//     hello.push_str(", ZecWallet!");
-
-//     let c_str_song = CString::new(hello).unwrap();
-//     c_str_song.into_raw()
-// }
-
-// #[no_mangle]
-// pub extern fn free_str(s: *mut c_char) {
-//     let s = unsafe {
-//         if s.is_null() { return }
-//         CString::from_raw(s)
-//     };
-
-//     println!("Freeing {:?}", s);
-// }

qtlib/src/main.cpp

@@ -6,7 +6,7 @@
 using namespace std;
 
 int main() {
-  char * from_rust = rust_generate_wallet(true, 1);
+  char * from_rust = rust_generate_wallet(true, 1, "user-provided-entropy");
   auto stri = string(from_rust);
   cout << stri << endl;
   rust_free_string(from_rust);

qtlib/src/zecpaperrust.h

@@ -5,8 +5,8 @@
 extern "C"{
 #endif
 
-extern char * rust_generate_wallet(bool testnet, unsigned int count);
-extern void   rust_free_string(char * s);
+extern char * rust_generate_wallet(bool testnet, unsigned int count, const char* entropy);
+extern void   rust_free_string(char* s);
 
 #ifdef __cplusplus
 }