This is a regression in 1.0.28 that causes a test failure on armhf.

Upstream bug URL:

https://github.com/erikd/libsndfile/issues/229

Patch copied from upstream source repository:

https://github.com/erikd/libsndfile/commit/9d470ee5577d3ccedb1c28c7e0a7295ba17feaf5

From 9d470ee5577d3ccedb1c28c7e0a7295ba17feaf5 Mon Sep 17 00:00:00 2001
From: Erik de Castro Lopo <erikd@mega-nerd.com>
Date: Sun, 16 Apr 2017 17:54:17 +1000
Subject: [PATCH] src/rf64.c: Fix varargs related bug

C's <stargs.h> functionality isn't type checked so that passing an
`sf_count_t` (64 bits) by mistake in place of a `unit32_t` can cause
errors. This would be fine if it was an error on every architecture
and platform, but its not. This particular problem only manifested
on armhf and some other Arm architectures. It was not an issue on
32 bit x86.

I have now fixed variants of this same bug several times.

Closes: https://github.com/erikd/libsndfile/issues/229
---
 src/rf64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/rf64.c b/src/rf64.c
index b3d637f..02dd904 100644
--- a/src/rf64.c
+++ b/src/rf64.c
@@ -742,7 +742,7 @@ rf64_write_header (SF_PRIVATE *psf, int calc_length)
 
 	pad_size = psf->dataoffset - 16 - psf->header.indx ;
 	if (pad_size >= 0)
-		psf_binheader_writef (psf, "m4z", PAD_MARKER, pad_size, make_size_t (pad_size)) ;
+		psf_binheader_writef (psf, "m4z", PAD_MARKER, (unsigned int) pad_size, make_size_t (pad_size)) ;
 
 	if (wpriv->rf64_downgrade && (psf->filelength < RIFF_DOWNGRADE_BYTES))
 		psf_binheader_writef (psf, "tm8", data_MARKER, psf->datalength) ;
