feat(c): add write/commit C FFI bindings (#522)

Add write-side C FFI bindings following the existing read-side patterns:

API surface (14 functions):
- WriteBuilder: new_write_builder, free, with_overwrite, new_write, new_commit
- TableWrite: free, write_arrow_batch (via Arrow C Data Interface), prepare_commit
- TableCommit: free, commit, overwrite, truncate_table, abort
- CommitMessages: free

Author: suxiaogang223

bindings/c/Cargo.toml

@@ -25,11 +25,13 @@ license.workspace = true
 version.workspace = true
 
 [lib]
-crate-type = ["cdylib", "staticlib"]
+crate-type = ["cdylib", "staticlib", "rlib"]
 doc = false
 
 [dependencies]
 paimon = { path = "../../crates/paimon" }
 tokio = { workspace = true, features = ["rt-multi-thread"] }
 futures = "0.3"
+arrow = { workspace = true }
 arrow-array = { workspace = true }
+arrow-schema = { workspace = true }

bindings/c/src/error.rs

@@ -58,6 +58,7 @@ impl paimon_error {
             | paimon::Error::ColumnAlreadyExist { .. } => PaimonErrorCode::AlreadyExists,
             paimon::Error::ConfigInvalid { .. }
             | paimon::Error::DataTypeInvalid { .. }
+            | paimon::Error::DataInvalid { .. }
             | paimon::Error::IdentifierInvalid { .. } => PaimonErrorCode::InvalidInput,
             paimon::Error::IoUnexpected { .. } => PaimonErrorCode::IoError,
             _ => PaimonErrorCode::Unexpected,

bindings/c/src/lib.rs

@@ -24,7 +24,10 @@ mod error;
 mod identifier;
 mod result;
 mod table;
+#[cfg(test)]
+mod tests;
 mod types;
+mod write;
 
 use std::sync::OnceLock;
 use tokio::runtime::Runtime;

bindings/c/src/result.rs

@@ -77,3 +77,29 @@ pub struct paimon_result_next_batch {
     pub batch: paimon_arrow_batch,
     pub error: *mut paimon_error,
 }
+
+// === Write/Commit result types ===
+
+#[repr(C)]
+pub struct paimon_result_write_builder {
+    pub write_builder: *mut paimon_write_builder,
+    pub error: *mut paimon_error,
+}
+
+#[repr(C)]
+pub struct paimon_result_table_write {
+    pub write: *mut paimon_table_write,
+    pub error: *mut paimon_error,
+}
+
+#[repr(C)]
+pub struct paimon_result_table_commit {
+    pub commit: *mut paimon_table_commit,
+    pub error: *mut paimon_error,
+}
+
+#[repr(C)]
+pub struct paimon_result_prepare_commit {
+    pub messages: *mut paimon_commit_messages,
+    pub error: *mut paimon_error,
+}