Fix T43275: Crash on Render when using 'save buffer' and render layer name contains a '/'

Added a new BLI_path_utils func, `BLI_filename_make_safe()`, which for now simply
replaces unsafe chars for paths (like '\' or '/') by an underscore...

source/blender/blenlib/BLI_path_util.h

@@ -108,6 +108,8 @@ void BLI_cleanup_dir(const char *relabase, char *dir) ATTR_NONNULL(2);
 /* doesn't touch trailing slash */
 void BLI_cleanup_path(const char *relabase, char *path) ATTR_NONNULL(2);
 
+void BLI_filename_make_safe(char *fname) ATTR_NONNULL(1);
+
 /* go back one directory */
 bool BLI_parent_dir(char *path) ATTR_NONNULL();
 

source/blender/blenlib/intern/path_util.c

@@ -428,6 +428,24 @@ void BLI_cleanup_file(const char *relabase, char *path)
 	BLI_del_slash(path);
 }
 
+
+/**
+ * Make given name safe to be used in paths.
+ *
+ * For now, simply replaces reserved chars (as listed in
+ * http://en.wikipedia.org/wiki/Filename#Reserved_characters_and_words )
+ * by underscores ('_').
+ */
+void BLI_filename_make_safe(char *fname)
+{
+	char *invalid = "/\\?%*:|\"<>. ";
+	char *c;
+
+	for (; *fname && (fname = strpbrk(fname, invalid)); fname++) {
+		*fname = '_';
+	}
+}
+
 /**
  * Does path begin with the special "//" prefix that Blender uses to indicate
  * a path relative to the .blend file.

source/blender/render/intern/source/render_result.c

@@ -1074,6 +1074,9 @@ void render_result_exr_file_path(Scene *scene, const char *layname, int sample,
 		BLI_snprintf(name, sizeof(name), "%s_%s_%s%d.exr", fi, scene->id.name + 2, layname, sample);
 	}
 
+	/* Make name safe for paths, see T43275. */
+	BLI_filename_make_safe(name);
+
 	BLI_make_file_string("/", filepath, BKE_tempdir_session(), name);
 }