Add exists feature

codex/storage.go

@@ -24,6 +24,10 @@ import (
    static int cGoCodexStorageDelete(void* codexCtx, char* cid, void* resp) {
        return codex_storage_delete(codexCtx, cid, (CodexCallback) callback, resp);
    }
+
+   static int cGoCodexStorageExists(void* codexCtx, char* cid, void* resp) {
+       return codex_storage_exists(codexCtx, cid, (CodexCallback) callback, resp);
+   }
 */
 import "C"
 
@@ -142,3 +146,19 @@ func (node CodexNode) Delete(cid string) error {
 	_, err := bridge.wait()
 	return err
 }
+
+// Exists checks if a given cid exists in the local storage.
+func (node CodexNode) Exists(cid string) (bool, error) {
+	bridge := newBridgeCtx()
+	defer bridge.free()
+
+	var cCid = C.CString(cid)
+	defer C.free(unsafe.Pointer(cCid))
+
+	if C.cGoCodexStorageExists(node.ctx, cCid, bridge.resp) != C.RET_OK {
+		return false, bridge.callError("cGoCodexStorageExists")
+	}
+
+	result, err := bridge.wait()
+	return result == "true", err
+}

codex/storage_test.go

@@ -119,3 +119,30 @@ func TestDelete(t *testing.T) {
 		t.Fatal("expected manifests to be empty after deletion")
 	}
 }
+
+func TestExists(t *testing.T) {
+	codex := newCodexNode(t)
+
+	cid, _ := uploadHelper(t, codex)
+
+	exists, err := codex.Exists(cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !exists {
+		t.Fatal("expected cid to exist")
+	}
+
+	err = codex.Delete(cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	exists, err = codex.Exists(cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if exists {
+		t.Fatal("expected cid to not exist after deletion")
+	}
+}

vendor/nim-codex

@@ -1 +1 @@
-Subproject commit a86d8586456d5eb6805b228e80e264ee736a6a90
+Subproject commit 72e9a3f85dd6cf43240bf3e0fbdcf27e704d3ca6