fix opening/saving audio files with non-ASCII char

s on Windows

this required making a wrapper...

src/engine/sfWrapper.cpp

@@ -0,0 +1,112 @@
+/**
+ * Furnace Tracker - multi-system chiptune tracker
+ * Copyright (C) 2021-2022 tildearrow and contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "sfWrapper.h"
+#include "../fileutils.h"
+
+sf_count_t _vioGetSize(void* user) {
+  return ((SFWrapper*)user)->ioGetSize();
+}
+
+sf_count_t _vioSeek(sf_count_t offset, int whence, void* user) {
+  return ((SFWrapper*)user)->ioSeek(offset,whence);
+}
+
+sf_count_t _vioRead(void* ptr, sf_count_t count, void* user) {
+  return ((SFWrapper*)user)->ioRead(ptr,count);
+}
+
+sf_count_t _vioWrite(const void* ptr, sf_count_t count, void* user) {
+  return ((SFWrapper*)user)->ioWrite(ptr,count);
+}
+
+sf_count_t _vioTell(void* user) {
+  return ((SFWrapper*)user)->ioTell();
+}
+
+sf_count_t SFWrapper::ioGetSize() {
+  return (sf_count_t)len;
+}
+
+sf_count_t SFWrapper::ioSeek(sf_count_t offset, int whence) {
+  return fseek(f,offset,whence);
+}
+
+sf_count_t SFWrapper::ioRead(void* ptr, sf_count_t count) {
+  return fread(ptr,1,count,f);
+}
+
+sf_count_t SFWrapper::ioWrite(const void* ptr, sf_count_t count) {
+  return fwrite(ptr,1,count,f);
+}
+
+sf_count_t SFWrapper::ioTell() {
+  return ftell(f);
+}
+
+int SFWrapper::doClose() {
+  int ret=sf_close(sf);
+  fclose(f);
+  return ret;
+}
+
+SNDFILE* SFWrapper::doOpen(const char* path, int mode, SF_INFO* sfinfo) {
+  vio.get_filelen=_vioGetSize;
+  vio.read=_vioRead;
+  vio.seek=_vioSeek;
+  vio.tell=_vioTell;
+  vio.write=_vioWrite;
+
+  const char* modeC="rb";
+  if (mode==SFM_WRITE) {
+    modeC="wb";
+  }
+  if (mode==SFM_RDWR) {
+    modeC="rb+";
+  }
+
+  f=ps_fopen(path,modeC);
+  if (f==NULL) {
+    return NULL;
+  }
+
+  if (fseek(f,0,SEEK_END)==-1) {
+    fclose(f);
+    f=NULL;
+    return NULL;
+  }
+  
+  len=ftell(f);
+  if (len==(SIZE_MAX>>1)) {
+    len=0;
+    fclose(f);
+    f=NULL;
+    return NULL;
+  }
+
+  if (fseek(f,0,SEEK_SET)==-1) {
+    len=0;
+    fclose(f);
+    f=NULL;
+    return NULL;
+  }
+
+  sf=sf_open_virtual(&vio,mode,sfinfo,this);
+  return sf;
+}