add z_bytes_get_contiguous_view function (#838)

docs/api.rst

@@ -223,6 +223,7 @@ see details at :ref:`owned_types_concept`
 .. c:type:: z_moved_bytes_writter_t
 
 .. autoctype:: types.h::z_bytes_reader_t
+.. autoctype:: types.h::z_bytes_slice_iterator_t
 
 Functions
 ^^^^^^^^^
@@ -241,6 +242,10 @@ Functions
 .. autocfunction:: primitives.h::z_bytes_to_slice
 .. autocfunction:: primitives.h::z_bytes_to_string
 
+.. autocfunction:: primitives.h::z_bytes_get_contiguous_view
+.. autocfunction:: primitives.h::z_bytes_get_slice_iterator
+.. autocfunction:: primitives.h::z_bytes_slice_iterator_next
+
 .. autocfunction:: primitives.h::z_bytes_get_reader
 .. autocfunction:: primitives.h::z_bytes_reader_read
 .. autocfunction:: primitives.h::z_bytes_reader_remaining

include/zenoh-pico/api/primitives.h

@@ -457,7 +457,7 @@ z_result_t z_slice_from_buf(z_owned_slice_t *slice, uint8_t *data, size_t len,
  * Return:
  *   ``0`` if creation is successful, ``negative value`` otherwise.
  */
-z_result_t z_view_slice_from_buf(z_view_slice_t *slice, uint8_t *data, size_t len);
+z_result_t z_view_slice_from_buf(z_view_slice_t *slice, const uint8_t *data, size_t len);
 
 /**
  * Builds an empty :c:type:`z_owned_slice_t`.
@@ -685,6 +685,23 @@ size_t z_bytes_len(const z_loaned_bytes_t *bytes);
  */
 bool z_bytes_is_empty(const z_loaned_bytes_t *bytes);
 
+#if defined(Z_FEATURE_UNSTABLE_API)
+/**
+ * Attempts to get a contiguous view to the underlying bytes (unstable).
+ *
+ * This is only possible if data is not fragmented, otherwise the function will fail.
+ * In case of fragmented data, consider using `z_bytes_get_slice_iterator()`.
+ *
+ * Parameters:
+ *   bytes: An instance of Zenoh data.
+ *   view: An uninitialized memory location where a contiguous view on data will be constructed.
+ *
+ * Return:
+ *   ``0`` in case of success, ``negative value`` otherwise.
+ */
+z_result_t z_bytes_get_contiguous_view(const z_loaned_bytes_t *bytes, z_view_slice_t *view);
+#endif
+
 /**
  * Returns an iterator on raw bytes slices contained in the `z_loaned_bytes_t`.
  *

src/api/api.c

@@ -235,7 +235,7 @@ z_result_t z_slice_from_buf(z_owned_slice_t *slice, uint8_t *data, size_t len,
     return _Z_RES_OK;
 }
 
-z_result_t z_view_slice_from_buf(z_view_slice_t *slice, uint8_t *data, size_t len) {
+z_result_t z_view_slice_from_buf(z_view_slice_t *slice, const uint8_t *data, size_t len) {
     slice->_val = _z_slice_alias_buf(data, len);
     return _Z_RES_OK;
 }
@@ -355,6 +355,22 @@ z_bytes_slice_iterator_t z_bytes_get_slice_iterator(const z_loaned_bytes_t *byte
     return (z_bytes_slice_iterator_t){._bytes = bytes, ._slice_idx = 0};
 }
 
+#if defined(Z_FEATURE_UNSTABLE_API)
+z_result_t z_bytes_get_contiguous_view(const z_loaned_bytes_t *bytes, z_view_slice_t *view) {
+    size_t num_slices = _z_bytes_num_slices(bytes);
+    if (num_slices > 1) {
+        return _Z_ERR_INVALID;
+    } else if (num_slices == 1) {
+        _z_arc_slice_t *slice = _z_bytes_get_slice(bytes, 0);
+        z_view_slice_from_buf(view, _z_arc_slice_data(slice), _z_arc_slice_len(slice));
+        return _Z_RES_OK;
+    } else {
+        z_view_slice_empty(view);
+        return _Z_RES_OK;
+    }
+}
+#endif
+
 bool z_bytes_slice_iterator_next(z_bytes_slice_iterator_t *iter, z_view_slice_t *out) {
     if (iter->_slice_idx >= _z_bytes_num_slices(iter->_bytes)) {
         return false;

tests/z_api_bytes_test.c

@@ -234,15 +234,18 @@ bool check_slice(const z_loaned_bytes_t *b, const uint8_t *data, size_t len) {
 void test_slices(void) {
     uint8_t data[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
     z_owned_bytes_t payload;
-
-    z_owned_bytes_writer_t writer;
-    z_bytes_writer_empty(&writer);
-    z_bytes_writer_write_all(z_bytes_writer_loan_mut(&writer), data, 10);
-    z_bytes_writer_finish(z_bytes_writer_move(&writer), &payload);
-
+    z_bytes_copy_from_buf(&payload, data, 10);
     assert(check_slice(z_bytes_loan(&payload), data, 10));
 
+#if defined(Z_FEATURE_UNSTABLE_API)
+    z_view_slice_t view;
+    assert(z_bytes_get_contiguous_view(z_bytes_loan(&payload), &view) == Z_OK);
+    assert(z_slice_len(z_view_slice_loan(&view)) == 10);
+    assert(memcmp(data, z_slice_data(z_view_slice_loan(&view)), 10) == 0);
+#endif
     z_bytes_drop(z_bytes_move(&payload));
+
+    z_owned_bytes_writer_t writer;
     z_bytes_writer_empty(&writer);
 
     // possible multiple slices
@@ -255,6 +258,9 @@ void test_slices(void) {
 
     z_bytes_writer_finish(z_bytes_writer_move(&writer), &payload);
     assert(check_slice(z_bytes_loan(&payload), data, 10));
+#if defined(Z_FEATURE_UNSTABLE_API)
+    assert(z_bytes_get_contiguous_view(z_bytes_loan(&payload), &view) != Z_OK);
+#endif
     z_bytes_drop(z_bytes_move(&payload));
 }