Fix unaligned memory access (UB which breaks ARM)

With this fix, the test suite runs cleanly with UBSan.

1 files changed, 33 insertions, 1 deletions

diff --git a/src/serd_internal.h b/src/serd_internal.h
index 20700bb8..23fd75b4 100644
--- a/src/serd_internal.h
+++ b/src/serd_internal.h
@@ -1,5 +1,5 @@
 /*
-  Copyright 2011-2014 David Robillard <http://drobilla.net>
+  Copyright 2011-2016 David Robillard <http://drobilla.net>
 
   Permission to use, copy, modify, and/or distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
@@ -123,6 +123,38 @@ serd_stack_pop(SerdStack* stack, size_t n_bytes)
 	stack->size -= n_bytes;
 }
 
+static inline void*
+serd_stack_push_aligned(SerdStack* stack, size_t n_bytes, size_t align)
+{
+	// Push one byte to ensure space for a pad count
+	serd_stack_push(stack, 1);
+
+	// Push padding if necessary
+	const uint8_t pad = align - stack->size % align;
+	if (pad > 0) {
+		serd_stack_push(stack, pad);
+	}
+
+	// Set top of stack to pad count so we can properly pop later
+	stack->buf[stack->size - 1] = pad;
+
+	// Push requested space at aligned location
+	return serd_stack_push(stack, n_bytes);
+}
+
+static inline void
+serd_stack_pop_aligned(SerdStack* stack, size_t n_bytes)
+{
+	// Pop requested space down to aligned location
+	serd_stack_pop(stack, n_bytes);
+
+	// Get amount of padding from top of stack
+	const uint8_t pad = stack->buf[stack->size - 1];
+
+	// Pop padding and pad count
+	serd_stack_pop(stack, pad + 1);
+}
+
 /* Bulk Sink */
 
 typedef struct SerdBulkSinkImpl {