buffer: improve size handling

Also handle the case where multiple empty memory blocks are in the buffer.
Add unit test for this.

gst/gstbuffer.c

@@ -784,18 +784,19 @@ gst_buffer_get_sizes (GstBuffer * buffer, gsize * offset, gsize * maxsize)
       mem = GST_BUFFER_MEM_PTR (buffer, i);
       s = gst_memory_get_sizes (mem, &o, &ms);
 
-      /* add sizes */
+      if (s) {
-      size += s;
+        if (size == 0)
-
+          /* first size, take accumulated data before as the offset */
-      /* keep offset of first memory block */
+          offs = extra + o;
-      if (i == 0)
+        /* add sizes */
-        offs = o;
+        size += s;
-      /* this is the amount of extra bytes in this block, we only keep this for
+        /* save the amount of data after this block */
-       * the last block */
-      if (i + 1 == len)
         extra = ms - (o + s);
+      } else {
+        /* empty block, add as extra */
+        extra += ms;
+      }
     }
-
     if (offset)
       *offset = offs;
     if (maxsize)

tests/check/gst/gstbuffer.c

@@ -441,6 +441,84 @@ GST_START_TEST (test_try_new_and_alloc)
 
 GST_END_TEST;
 
+GST_START_TEST (test_size)
+{
+  GstBuffer *buf;
+  GstMemory *mem;
+  gsize maxalloc, maxalloc2, maxalloc3, maxalloc4;
+  gsize size, maxsize, offset;
+
+  /* one memory block */
+  buf = gst_buffer_new_allocate (NULL, 100, 0);
+
+  size = gst_buffer_get_sizes (buf, &offset, &maxalloc);
+  fail_unless (size == 100);
+  fail_unless (offset == 0);
+  fail_unless (maxalloc >= 100);
+
+  mem = gst_buffer_peek_memory (buf, 0, GST_MAP_WRITE);
+  gst_memory_resize (mem, 10, 70);
+
+  size = gst_buffer_get_sizes (buf, &offset, &maxsize);
+  fail_unless (size == 70);
+  fail_unless (offset == 10);
+  fail_unless (maxsize == maxalloc);
+
+  /* new memory */
+  mem = gst_allocator_alloc (NULL, 100, 0);
+  size = gst_memory_get_sizes (mem, &offset, &maxalloc2);
+  fail_unless (size == 100);
+  fail_unless (offset == 0);
+  fail_unless (maxalloc2 >= 100);
+
+  gst_memory_resize (mem, 20, 60);
+  size = gst_memory_get_sizes (mem, &offset, &maxsize);
+  fail_unless (size == 60);
+  fail_unless (offset == 20);
+  fail_unless (maxsize == maxalloc2);
+
+  /* append */
+  gst_buffer_take_memory (buf, -1, mem);
+
+  size = gst_buffer_get_sizes (buf, &offset, &maxalloc);
+  fail_unless (size == 130);
+  fail_unless (offset == 10);
+  /* the maxsize is the size of the first buffer plus the remaining size in the
+   * second buffer */
+  fail_unless (maxalloc == 80 + (maxalloc2 - 20));
+
+  /* appending an empty block */
+  mem = gst_allocator_alloc (NULL, 100, 0);
+  size = gst_memory_get_sizes (mem, &offset, &maxalloc3);
+  gst_memory_resize (mem, 0, 0);
+  gst_buffer_take_memory (buf, -1, mem);
+
+  size = gst_buffer_get_sizes (buf, &offset, &maxalloc);
+  fail_unless (size == 130);
+  fail_unless (offset == 10);
+  /* the maxsize is the size of the first buffer plus the remaining size in the
+   * second buffer and the last empty buffer*/
+  fail_unless (maxalloc == 80 + (maxalloc2 - 20) + maxalloc3);
+
+  /* prepending an empty block */
+  mem = gst_allocator_alloc (NULL, 100, 0);
+  size = gst_memory_get_sizes (mem, &offset, &maxalloc4);
+  gst_memory_resize (mem, 0, 0);
+  gst_buffer_take_memory (buf, 0, mem);
+
+  size = gst_buffer_get_sizes (buf, &offset, &maxalloc);
+  fail_unless (size == 130);
+  /* empty buffer maxsize can be used as offset */
+  fail_unless (offset == 10 + maxalloc4);
+  /* the maxsize is the size of the first buffer plus the remaining size in the
+   * second buffer and the last empty buffer*/
+  fail_unless (maxalloc == 80 + (maxalloc2 - 20) + maxalloc3 + maxalloc4);
+
+  gst_buffer_unref (buf);
+}
+
+GST_END_TEST;
+
 GST_START_TEST (test_resize)
 {
   GstBuffer *buf;
@@ -553,6 +631,7 @@ gst_buffer_suite (void)
   tcase_add_test (tc_chain, test_metadata_writable);
   tcase_add_test (tc_chain, test_copy);
   tcase_add_test (tc_chain, test_try_new_and_alloc);
+  tcase_add_test (tc_chain, test_size);
   tcase_add_test (tc_chain, test_resize);
 
   return s;