From cdd77b999612d4c3e3fb5db1ff7fb11cf449dc6f Mon Sep 17 00:00:00 2001
From: Tom Schoonjans <Tom.Schoonjans@diamond.ac.uk>
Date: Thu, 2 Nov 2017 16:55:22 +0000
Subject: [PATCH] Use UTF-8 filenames on Windows

Until now fopen was used on Windows to open files for reading and
writing. This assumed however that the filename would be encoded in the
current codepage, which is a major inconvenience and makes it even
impossible to use filenames that use characters from more than one
codepage. This patch enforces the use of UTF-8 filenames on all
platforms.

Based on the work of Owen Taylor (https://lists.cairographics.org/archives/cairo/2007-February/009591.html)
---
 src/cairo-output-stream.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++-
 src/cairo-png.c           | 10 +++++----
 src/cairoint.h            |  4 ++++
 3 files changed, 61 insertions(+), 5 deletions(-)

diff --git a/src/cairo-output-stream.c b/src/cairo-output-stream.c
index f43f212ed..123142787 100644
--- a/src/cairo-output-stream.c
+++ b/src/cairo-output-stream.c
@@ -661,7 +661,7 @@ _cairo_output_stream_create_for_filename (const char *filename)
     if (filename == NULL)
 	return _cairo_null_stream_create ();
 
-    file = fopen (filename, "wb");
+    file = _cairo_fopen (filename, "wb");
     if (file == NULL) {
 	switch (errno) {
 	case ENOMEM:
@@ -804,3 +804,53 @@ _cairo_null_stream_create (void)
 
     return stream;
 }
+
+/**
+ * _cairo_fopen:
+ * @filename: filename to open
+ * @mode: mode string with which to open the file
+ * 
+ * Exactly like the C library function, but possibly doing encoding
+ * conversion on the filename. On Unix platforms, the filename is
+ * passed directly to the system, but on Windows, the filename is
+ * interpreted as UTF-8, rather than in a codepage that would depend
+ * on system settings.
+ * 
+ * Return value: The newly opened file, or NULL if an error occured.
+ **/
+FILE *
+_cairo_fopen (const char *filename, const char *mode)
+{
+#ifdef _WIN32 /* also defined on x86_64 */
+    uint16_t *filename_w;
+    uint16_t *mode_w;
+    FILE *result;
+
+    if (filename == NULL || mode == NULL) {
+	errno = EINVAL;
+	return NULL;
+    }
+    
+    if (_cairo_utf8_to_utf16 (filename, -1, &filename_w, NULL) != CAIRO_STATUS_SUCCESS) {
+	errno = EINVAL;
+	return NULL;
+    }
+
+    if (_cairo_utf8_to_utf16 (mode, -1, &mode_w, NULL) != CAIRO_STATUS_SUCCESS) {
+	free (filename_w);
+	errno = EINVAL;
+	return NULL;
+    }
+
+    result = _wfopen(filename_w, mode_w);
+
+    free (filename_w);
+    free (mode_w);
+
+    return result;
+    
+#else /* Use fopen directly */
+    return fopen (filename, mode);
+#endif  
+}
+
diff --git a/src/cairo-png.c b/src/cairo-png.c
index eab2537bc..8aaf49c76 100644
--- a/src/cairo-png.c
+++ b/src/cairo-png.c
@@ -345,7 +345,8 @@ stdio_write_func (png_structp png, png_bytep data, png_size_t size)
 /**
  * cairo_surface_write_to_png:
  * @surface: a #cairo_surface_t with pixel contents
- * @filename: the name of a file to write to
+ * @filename: the name of a file to write to; on Windows this filename
+ *   is encoded in UTF-8. See cairo_win32_filename_from_unicode().
  *
  * Writes the contents of @surface to a new file @filename as a PNG
  * image.
@@ -373,7 +374,7 @@ cairo_surface_write_to_png (cairo_surface_t	*surface,
     if (surface->finished)
 	return _cairo_error (CAIRO_STATUS_SURFACE_FINISHED);
 
-    fp = fopen (filename, "wb");
+    fp = _cairo_fopen (filename, "wb");
     if (fp == NULL) {
 	switch (errno) {
 	case ENOMEM:
@@ -738,7 +739,8 @@ read_png (struct png_read_closure_t *png_closure)
 
 /**
  * cairo_image_surface_create_from_png:
- * @filename: name of PNG file to load
+ * @filename: name of PNG file to load. On Windows this filename
+ *   is encoded in UTF-8. See cairo_win32_filename_from_unicode().
  *
  * Creates a new image surface and initializes the contents to the
  * given PNG file.
@@ -765,7 +767,7 @@ cairo_image_surface_create_from_png (const char *filename)
     struct png_read_closure_t png_closure;
     cairo_surface_t *surface;
 
-    png_closure.closure = fopen (filename, "rb");
+    png_closure.closure = _cairo_fopen (filename, "rb");
     if (png_closure.closure == NULL) {
 	cairo_status_t status;
 	switch (errno) {
diff --git a/src/cairoint.h b/src/cairoint.h
index 6f8303c3c..68ae75f07 100644
--- a/src/cairoint.h
+++ b/src/cairoint.h
@@ -1919,6 +1919,10 @@ _cairo_matrix_multiply (cairo_matrix_t *r,
 cairo_private void
 _cairo_observers_notify (cairo_list_t *observers, void *arg);
 
+/* Open a file with a UTF-8 filename */
+cairo_private FILE *
+_cairo_fopen (const char *filename, const char *mode);
+
 /* Avoid unnecessary PLT entries.  */
 slim_hidden_proto (cairo_clip_preserve);
 slim_hidden_proto (cairo_close_path);
-- 
2.14.2