Add documentation, expand error handling, implement file and buffer io

include/bh/internal/buffer.h

@@ -0,0 +1,20 @@
+#ifndef BH_INTERNAL_BUFFER_H
+#define BH_INTERNAL_BUFFER_H
+
+#include <bh/buffer.h>
+
+struct bh_buffer_s
+{
+    bh_io_t base;
+    char *data;
+    size_t capacity;
+    size_t size;
+    size_t at;
+    int mode;
+};
+
+int bh_buffer_init(bh_buffer_t *buffer);
+
+void bh_buffer_destroy(bh_buffer_t *buffer);
+
+#endif /* BH_INTERNAL_BUFFER_H */