Add new ply_buffer_remove_bytes_at_end

This function is like ply_buffer_remove_bytes, but it
truncates away the end of the buffer instead of shifting
the contents over the start of the buffer.

src/libply/ply-buffer.c

@@ -85,6 +85,17 @@ ply_buffer_remove_bytes (ply_buffer_t *buffer,
     }
 }
 
+void
+ply_buffer_remove_bytes_at_end (ply_buffer_t *buffer,
+                                size_t        bytes_to_remove)
+{
+  assert (buffer != NULL);
+
+  bytes_to_remove = MIN (buffer->size, bytes_to_remove);
+
+  buffer->size -= bytes_to_remove;
+}
+
 ply_buffer_t *
 ply_buffer_new (void)
 {

src/libply/ply-buffer.h

@@ -45,6 +45,8 @@ void ply_buffer_append_with_non_literal_format_string (ply_buffer_t   *buffer,
                                                        const char *format, ...);
 void ply_buffer_remove_bytes (ply_buffer_t *buffer,
                               size_t        number_of_bytes);
+void ply_buffer_remove_bytes_at_end (ply_buffer_t *buffer,
+                                     size_t        number_of_bytes);
 const char *ply_buffer_get_bytes (ply_buffer_t *buffer);
 size_t ply_buffer_get_size (ply_buffer_t *buffer);
 void ply_buffer_clear (ply_buffer_t *buffer);