feat: add calltoc

__ffi/calltoc/.cargo/config.toml

@@ -0,0 +1,3 @@
+[build]
+rustflags = ["-C", "link-args=-L/Users/hatterjiang/Code/hattergit/simple-rust-tests/__ffi/calltoc -lmyc"]
+

__ffi/calltoc/Cargo.lock

@@ -0,0 +1,16 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "calltoc"
+version = "0.1.0"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.139"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "201de327520df007757c1f0adce6e827fe8562fbc28bfd9c15571c66ca1f5f79"

__ffi/calltoc/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "calltoc"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libc = "0.2.139"

__ffi/calltoc/justfile

@@ -0,0 +1,7 @@
+_:
+  @just --list
+
+compile_c:
+  gcc -c myc.c -o myc.o
+  ar -r libmyc.a myc.o
+

__ffi/calltoc/myc.c

@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+char* hello() {
+  char* ptr = (char*)malloc(13);
+  if (ptr == NULL) {
+    return ptr;
+  }
+  ptr[0] = 'H';
+  ptr[1] = 'e';
+  ptr[2] = 'l';
+  ptr[3] = 'l';
+  ptr[4] = 'o';
+  ptr[5] = ' ';
+  ptr[6] = 'w';
+  ptr[7] = 'o';
+  ptr[8] = 'r';
+  ptr[9] = 'l';
+  ptr[10] = 'd';
+  ptr[11] = '!';
+  ptr[12] = '\0';
+
+  return ptr;
+}
+
+void goodbye(char* ptr) {
+  if (ptr != NULL) {
+    free(ptr);
+  }
+}

__ffi/calltoc/src/main.rs

@@ -0,0 +1,37 @@
+use std::ffi::{c_char, CStr};
+use std::ops::Deref;
+
+extern "C" {
+    fn hello() -> *const c_char;
+    fn goodbye(s: *const c_char);
+}
+
+struct Greeting {
+    message: *const c_char,
+}
+
+impl Drop for Greeting {
+    fn drop(&mut self) {
+        unsafe { goodbye(self.message); }
+    }
+}
+
+impl Greeting {
+    fn new() -> Greeting {
+        Greeting { message: unsafe { hello() } }
+    }
+}
+
+impl Deref for Greeting {
+    type Target = str;
+    fn deref<'a>(&'a self) -> &'a str {
+        let c_str = unsafe{ CStr::from_ptr(self.message) };
+        c_str.to_str().unwrap()
+    }
+}
+
+
+fn main() {
+    let greeting = Greeting::new();
+    println!("{}", greeting.deref());
+}