Re: [PR] feat(bindings/c): Add seek support for c-binding [opendal]

["silver-ymz (via GitHub)" <gi...@apache.org>]

silver-ymz commented on code in PR #6119:
URL: https://github.com/apache/opendal/pull/6119#discussion_r2065244408


##########
bindings/c/src/reader.rs:
##########
@@ -72,6 +76,33 @@ impl opendal_reader {
         }
     }
 
+    /// \brief Seek to an offset, in bytes, in a stream.
+    #[no_mangle]
+    pub unsafe extern "C" fn opendal_reader_seek(
+        &mut self,
+        offset: i64,
+        whence: i32,
+    ) -> *mut opendal_error {
+        let pos = match whence {
+            _x @ OPENDAL_SEEK_SET => SeekFrom::Start(offset as u64),
+            _x @ OPENDAL_SEEK_CUR => SeekFrom::Current(offset),
+            _x @ OPENDAL_SEEK_END => SeekFrom::End(offset),
+            _ => {
+                return opendal_error::new(core::Error::new(
+                    core::ErrorKind::Unexpected,
+                    "undefined whence",
+                ))
+            }
+        };
+
+        match self.deref_mut().seek(pos) {
+            Ok(_) => std::ptr::null_mut(),
+            Err(e) => {
+                opendal_error::new(core::Error::new(core::ErrorKind::Unexpected, e.to_string()))
+            }

Review Comment:
   Setting error source here may be better to show more infomations
   
   ```rust
   opendal_error::new(core::Error::new(core::ErrorKind::Unexpected, "seek failed from reader").set_source(e))
   ```



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