Patch edflib.c on Windows to enable opening UTF-8 encoded paths

This should fix file opening issue with non-ASCII characters in paths
when local encoding is not UTF-8.

.gitignore

@@ -29,6 +29,7 @@ pip-log.txt
 # Project working files
 _edflib.[ch]
 _pyedflib.[ch]
+edflib_utf8.c
 
 edf.[ch]
 cythonize.dat

pyedflib/_extensions/c/fopen_utf8.c

@@ -0,0 +1,57 @@
+#ifdef _WIN32
+
+#include "fopen_utf8.h"
+
+#include <stdlib.h>
+#include <windows.h>
+
+
+wchar_t* utf8_to_utf16(const char* str)
+{
+    wchar_t* wstr;
+
+    int require = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
+    if (require == 0)
+        return NULL;
+
+    wstr = malloc(require * sizeof(wchar_t));
+    if (wstr == NULL)
+        return NULL;
+
+    if (MultiByteToWideChar(CP_UTF8, 0, str, -1, wstr, require) == 0)
+    {
+        free(wstr);
+        return NULL;
+    }
+
+    return wstr;
+}
+
+
+FILE* fopen_utf8(const char* filename, const char* mode)
+{
+    errno_t error;
+    FILE* file;
+    wchar_t* wfilename;
+    wchar_t* wmode;
+
+    wfilename = utf8_to_utf16(filename);
+    if (wfilename == NULL)
+        return NULL;
+
+    wmode = utf8_to_utf16(mode);
+    if (wmode == NULL)
+    {
+        free(wfilename);
+        return NULL;
+    }
+
+    error = _wfopen_s(&file, wfilename, wmode);
+
+    free(wfilename);
+    free(wmode);
+
+    return error == 0 ? file : NULL;
+}
+
+#endif

pyedflib/_extensions/c/fopen_utf8.h

@@ -0,0 +1,20 @@
+#ifndef FOPEN_UTF8_H_
+#define FOPEN_UTF8_H_
+
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef _WIN32
+FILE* fopen_utf8(const char* filename, const char* mode);
+#else
+#define fopen_utf8 fopen
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

setup.py

@@ -177,9 +177,30 @@ def write_version_py(filename='pyedflib/version.py'):
 
 make_ext_path = partial(os.path.join, "pyedflib", "_extensions")
 
-sources = ["c/edflib.c"]
+if os.name == "nt":
+    # Patch edflib.c
+    with open(make_ext_path("c/edflib.c"), "rb") as fin:
+        with open(make_ext_path("c/edflib_utf8.c"), "wb") as fout:
+            for line in fin:
+                line = line.replace(
+                    b'#include "edflib.h"',
+                    b'#include "edflib.h"\r\n#include "fopen_utf8.h"')
+                line = line.replace(
+                    b'file = fopeno(path, "rb");',
+                    b'file = fopen_utf8(path, "rb");')
+                line = line.replace(
+                    b'file = fopeno(path, "wb");',
+                    b'file = fopen_utf8(path, "wb");')
+
+                fout.write(line)
+
+    sources = ["c/edflib_utf8.c", "c/fopen_utf8.c"]
+    headers = ["c/edflib.h", "c/fopen_utf8.h"]
+else:
+    sources = ["c/edflib.c"]
+    headers = ["c/edflib.h"]
+
 sources = list(map(make_ext_path, sources))
-headers = ["c/edflib.h"]
 headers = list(map(make_ext_path, headers))
 
 cython_modules = ['_pyedflib']