Implement LOB read and write support using OCI callbacks

1 files changed, 50 insertions, 6 deletions

diff --git a/odb/oracle/oracle-types.hxx b/odb/oracle/oracle-types.hxx
index 4cdd7bb..1f5fe57 100644
--- a/odb/oracle/oracle-types.hxx
+++ b/odb/oracle/oracle-types.hxx
@@ -17,13 +17,57 @@ namespace odb
   {
     struct bind
     {
-      ub2 type;          // The type stored by buffer. This must be an
-                         // external OCI type identifier of the form SQLT_XXX.
+      ub2 type;       // The type stored by buffer. This must be an external
+                      // OCI type identifier of the form SQLT_XXX.
       void* buffer;
-      ub2* size;         // The number of bytes in buffer.
-      sb4 capacity;      // The maximum number of bytes that can be stored in
-                         // buffer.
-      sb2* indicator;    // Pointer to an OCI indicator variable.
+      ub2* size;      // The number of bytes in buffer. Due to
+                      // inconsistencies in the OCI interface, this will be
+                      // interpreted as a ub4 when callbacks are in use.
+      sb4 capacity;   // The maximum number of bytes that can be stored in
+                      // buffer.
+      sb2* indicator; // Pointer to an OCI indicator variable.
+
+      // Callback function signature used to specify parameters that are
+      // passed to the database.
+      //
+      typedef bool (*param_callback_type) (
+        void** context,    // [in/out] The user context.
+        void** buffer,     // [out] A a buffer containing the parameter data
+                           // to write to the database.
+        ub4* size,         // [out] The parameter data length in bytes.
+        bool* null,        // [out] True if the parameter is null. Both buffer
+                           // and size are ignored is this is true.
+        bool* last,        // [out] True if buffer contains the last piece of
+                           // data.
+        void* temp_buffer, // [in] A temporary buffer that may be used if
+                           // required. The 'buffer' parameter should specify
+                           // this buffer on return if it is used.
+        ub4 capacity);     // [in] The temporary buffer length in bytes.
+
+      // Callback function signature used to specify values returned from the
+      // database.
+      //
+      typedef bool (*result_callback_type) (
+        void** context, // [in/out] The user context.
+        void* buffer,   // [in] A buffer containing the result data.
+        ub4 size,       // [in] The result data length in bytes.
+        bool null,      // [in] True if the result data is NULL.
+        bool last);     // [in] True if this is the last piece of result data.
+
+      param_callback_type param_callback;
+      result_callback_type result_callback;
+
+      // This pointer is provided to the user through the 'context' parameter
+      // in both parameter and result callback functions.
+      //
+      void* callback_context;
+
+      // This flag is used exclusively during parameter callback invocation.
+      // If set, it indicates that this is the first time the callback is
+      // being invoked for this bind instance, and thus OCI is requesting
+      // the first piece of parameter data.
+      //
+      bool first_piece;
     };
   }
 }