fix: Fix the build for zig binding

bindings/c/include/opendal.h

@@ -241,7 +241,7 @@ typedef struct opendal_metadata {
    * The pointer to the opendal::Metadata in the Rust code.
    * Only touch this on judging whether it is NULL.
    */
-  const struct Metadata *inner;
+  struct Metadata *inner;
 } opendal_metadata;
 
 /**
@@ -254,7 +254,7 @@ typedef struct opendal_result_stat {
   /**
    * The metadata output of the stat
    */
-  const struct opendal_metadata *meta;
+  struct opendal_metadata *meta;
   /**
    * The error code, should be OPENDAL_OK if succeeds
    */
@@ -558,7 +558,7 @@ void opendal_bytes_free(const struct opendal_bytes *self);
 /**
  * \brief Free the heap-allocated metadata used by opendal_metadata
  */
-void opendal_metadata_free(const struct opendal_metadata *self);
+void opendal_metadata_free(struct opendal_metadata *self);
 
 /**
  * \brief Return the content_length of the metadata

bindings/c/src/lib.rs

@@ -403,11 +403,11 @@ pub unsafe extern "C" fn opendal_operator_stat(
     let path = unsafe { std::ffi::CStr::from_ptr(path).to_str().unwrap() };
     match op.stat(path) {
         Ok(m) => opendal_result_stat {
-            meta: opendal_metadata::from_metadata(m),
+            meta: Box::into_raw(Box::new(opendal_metadata::new(m))),
             code: opendal_code::OPENDAL_OK,
         },
         Err(err) => opendal_result_stat {
-            meta: std::ptr::null(),
+            meta: std::ptr::null_mut(),
             code: opendal_code::from_opendal_error(err),
         },
     }

bindings/c/src/result.rs

@@ -61,7 +61,7 @@ pub struct opendal_result_is_exist {
 #[repr(C)]
 pub struct opendal_result_stat {
     /// The metadata output of the stat
-    pub meta: *const opendal_metadata,
+    pub meta: *mut opendal_metadata,
     /// The error code, should be OPENDAL_OK if succeeds
     pub code: opendal_code,
 }

bindings/c/src/types.rs

@@ -16,6 +16,7 @@
 // under the License.
 
 use std::collections::HashMap;
+use std::mem;
 use std::os::raw::c_char;
 
 use ::opendal as od;
@@ -143,17 +144,28 @@ impl Into<bytes::Bytes> for opendal_bytes {
 pub struct opendal_metadata {
     /// The pointer to the opendal::Metadata in the Rust code.
     /// Only touch this on judging whether it is NULL.
-    pub inner: *const od::Metadata,
+    pub inner: *mut od::Metadata,
 }
 
 impl opendal_metadata {
+    /// Convert a Rust core [`od::Metadata`] into a heap allocated C-compatible
+    /// [`opendal_metadata`]
+    pub(crate) fn new(m: od::Metadata) -> Self {
+        Self {
+            inner: Box::into_raw(Box::new(m)),
+        }
+    }
+
     /// \brief Free the heap-allocated metadata used by opendal_metadata
     #[no_mangle]
-    pub extern "C" fn opendal_metadata_free(&self) {
-        if self.inner.is_null() {
-            return;
+    pub extern "C" fn opendal_metadata_free(&mut self) {
+        if !self.inner.is_null() {
+            unsafe {
+                mem::drop(Box::from_raw(self.inner));
+            }
         }
-        let _ = unsafe { Box::from_raw(self.inner as *mut od::Metadata) };
+
+        unsafe { mem::drop(Box::from_raw(self as *mut Self)) }
     }
 
     /// \brief Return the content_length of the metadata
@@ -189,7 +201,9 @@ impl opendal_metadata {
     pub extern "C" fn opendal_metadata_is_file(&self) -> bool {
         // Safety: the inner should never be null once constructed
         // The use-after-free is undefined behavior
-        unsafe { (*self.inner).is_file() }
+        let m = unsafe { &*self.inner };
+
+        m.is_file()
     }
 
     /// \brief Return whether the path represents a directory
@@ -216,16 +230,6 @@ impl opendal_metadata {
     }
 }
 
-impl opendal_metadata {
-    /// Convert a Rust core [`od::Metadata`] into a heap allocated C-compatible
-    /// [`opendal_metadata`]
-    pub(crate) fn from_metadata(m: od::Metadata) -> *const Self {
-        &Self {
-            inner: Box::leak(Box::new(m)),
-        }
-    }
-}
-
 /// \brief The configuration for the initialization of opendal_operator_ptr.
 ///
 /// \note This is also a heap-allocated struct, please free it after you use it

bindings/c/tests/bdd.cpp

@@ -69,7 +69,7 @@ TEST_F(OpendalBddTest, FeatureTest)
     // The blocking file "test" entry mode must be file
     opendal_result_stat s = opendal_operator_stat(this->p, this->path.c_str());
     EXPECT_EQ(s.code, OPENDAL_OK);
-    const opendal_metadata *meta = s.meta;
+    opendal_metadata *meta = s.meta;
     EXPECT_TRUE(opendal_metadata_is_file(meta));
 
     // The blocking file "test" content length must be 13

bindings/zig/test/bdd.zig

@@ -24,7 +24,7 @@ test "Opendal BDD test" {
     const c_str = [*:0]const u8; // define a type for 'const char*' in C
 
     const OpendalBDDTest = struct {
-        p: opendal.c.opendal_operator_ptr,
+        p: [*c]const opendal.c.opendal_operator_ptr,
         scheme: c_str,
         path: c_str,
         content: c_str,
@@ -35,19 +35,18 @@ test "Opendal BDD test" {
             self.path = "test";
             self.content = "Hello, World!";
 
-            var options: opendal.c.opendal_operator_options = opendal.c.opendal_operator_options_new();
-            defer opendal.c.opendal_operator_options_free(&options);
-            opendal.c.opendal_operator_options_set(&options, "root", "/myroot");
+            var options: [*c]opendal.c.opendal_operator_options = opendal.c.opendal_operator_options_new();
+            defer opendal.c.opendal_operator_options_free(options);
+            opendal.c.opendal_operator_options_set(options, "root", "/myroot");
 
             // Given A new OpenDAL Blocking Operator
-            self.p = opendal.c.opendal_operator_new(self.scheme, &options);
-            std.debug.assert(self.p.ptr != null);
+            self.p = opendal.c.opendal_operator_new(self.scheme, options);
 
             return self;
         }
 
         pub fn deinit(self: *Self) void {
-            opendal.c.opendal_operator_free(&self.p);
+            opendal.c.opendal_operator_free(self.p);
         }
 
         const Self = @This();
@@ -73,12 +72,12 @@ test "Opendal BDD test" {
     // The blocking file "test" entry mode must be file
     var s: opendal.c.opendal_result_stat = opendal.c.opendal_operator_stat(testkit.p, testkit.path);
     try testing.expectEqual(s.code, @enumToInt(Code.OK));
-    var meta: opendal.c.opendal_metadata = s.meta;
-    try testing.expect(opendal.c.opendal_metadata_is_file(&meta));
+    var meta: [*c] opendal.c.opendal_metadata = s.meta;
+    try testing.expect(opendal.c.opendal_metadata_is_file(meta));
 
     // The blocking file "test" content length must be 13
-    try testing.expectEqual(opendal.c.opendal_metadata_content_length(&meta), 13);
-    defer opendal.c.opendal_metadata_free(&meta);
+    try testing.expectEqual(opendal.c.opendal_metadata_content_length(meta), 13);
+    defer opendal.c.opendal_metadata_free(meta);
 
     // The blocking file "test" must have content "Hello, World!"
     var r: opendal.c.opendal_result_read = opendal.c.opendal_operator_blocking_read(testkit.p, testkit.path);