Add API for retrieval of encoded buffer length.

Closes #7.

2 files changed, 32 insertions, 1 deletions

diff --git a/include/ecbor.h.in b/include/ecbor.h.in
index 2f71dc9..b9e4726 100644
--- a/include/ecbor.h.in
+++ b/include/ecbor.h.in
@@ -40,6 +40,7 @@ typedef enum {
   ECBOR_ERR_NULL_VALUE                      = 14,
   ECBOR_ERR_NULL_ARRAY                      = 15,
   ECBOR_ERR_NULL_MAP                        = 16,
+  ECBOR_ERR_NULL_PARAMETER                  = 17,
   
   ECBOR_ERR_NULL_ITEM                       = 20,
   
@@ -169,6 +170,9 @@ typedef enum {
 typedef struct {
   /* mode of operation for this context */
   ecbor_mode_t mode;
+
+  /* output buffer base pointer */
+  uint8_t *base;
   
   /* output buffer position */
   uint8_t *out_position;
@@ -235,6 +239,9 @@ ecbor_initialize_decode_tree (ecbor_decode_context_t *context,
 extern ecbor_error_t
 ecbor_encode (ecbor_encode_context_t *context, ecbor_item_t *item);
 
+extern ecbor_error_t
+ecbor_get_encoded_buffer_size(const ecbor_encode_context_t *context, size_t *out_size);
+
 /*
  * Decoding routines
  */
@@ -407,6 +414,8 @@ ecbor_get_bool (ecbor_item_t *item, uint8_t *value);
 /*
  * Inline API
  */
+#define ECBOR_GET_ENCODED_BUFFER_SIZE(c) \
+  (size_t)((c)->out_position - (c)->base)
 #define ECBOR_GET_TYPE(i) \
   ((i)->type)
 #define ECBOR_GET_LENGTH(i) \
@@ -472,4 +481,4 @@ ecbor_get_bool (ecbor_item_t *item, uint8_t *value);
 }
 #endif
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/libecbor/ecbor_encoder.c b/src/libecbor/ecbor_encoder.c
index 2b01094..eca207a 100644
--- a/src/libecbor/ecbor_encoder.c
+++ b/src/libecbor/ecbor_encoder.c
@@ -18,6 +18,7 @@ ecbor_initialize_encode (ecbor_encode_context_t *context,
     return ECBOR_ERR_NULL_OUTPUT_BUFFER;
   }
   
+  context->base = buffer;
   context->out_position = buffer;
   context->bytes_left = buffer_size;
   context->mode = ECBOR_MODE_ENCODE;
@@ -35,6 +36,7 @@ ecbor_initialize_encode_streamed (ecbor_encode_context_t *context,
     return ECBOR_ERR_NULL_OUTPUT_BUFFER;
   }
   
+  context->base = buffer;
   context->out_position = buffer;
   context->bytes_left = buffer_size;
   context->mode = ECBOR_MODE_ENCODE_STREAMED;
@@ -42,6 +44,26 @@ ecbor_initialize_encode_streamed (ecbor_encode_context_t *context,
   return ECBOR_OK;
 }
 
+
+ecbor_error_t
+ecbor_get_encoded_buffer_size(const ecbor_encode_context_t *context, size_t *out_size)
+{
+  /* check parameters */
+  if (context == NULL) {
+    return ECBOR_ERR_NULL_CONTEXT;
+  }
+  if (out_size == NULL) {
+    return ECBOR_ERR_NULL_PARAMETER;
+  }
+  /* check sanity */
+  if (context->base > context->out_position) {
+    return ECBOR_ERR_INVALID_END_OF_BUFFER;
+  }
+  /* return length */
+  *out_size = context->out_position - context->base;
+  return ECBOR_OK;
+}
+
 static ecbor_error_t
 ecbor_encode_uint (ecbor_encode_context_t *context, uint8_t major_type,
                    uint64_t value)