fs.mitm: implement ifilesystem wrapper

stratosphere/ams_mitm/source/fs_mitm/fs_path_utils.cpp

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
+ */
+#include <cstring>
+#include <switch.h>
+#include "fs_path_utils.hpp"
+#include "fs_results.hpp"
+
+Result FsPathUtils::VerifyPath(const char *path, size_t max_path_len, size_t max_name_len) {
+    const char *cur = path;
+    size_t name_len = 0;
+
+    for (size_t path_len = 0; path_len <= max_path_len && name_len <= max_name_len; path_len++) {
+        const char c = *cur;
+        /* If terminated, we're done. */
+        if (c == 0) {
+            return 0;
+        }
+
+        /* TODO: Nintendo converts the path from utf-8 to utf-32, one character at a time. */
+        /* We should do this. */
+
+        /* Banned characters: :*?<>| */
+        if (c == ':' || c == '*' || c == '?' || c == '<' || c == '>' || c == '|') {
+            return ResultFsInvalidCharacter;
+        }
+
+        name_len++;
+        /* Check for separator. */
+        if (c == '/' || c == '\\') {
+            name_len = 0;
+        }
+    }
+
+    return ResultFsTooLongPath;
+}
+
+Result FsPathUtils::ConvertPathForServiceObject(FsPath *out, const char *path) {
+    /* Check for nullptr. */
+    if (out == nullptr || path == nullptr) {
+        return ResultFsInvalidPath;
+    }
+
+    /* Copy string, NULL terminate. */
+    /* NOTE: Nintendo adds an extra char at 0x301 for NULL terminator */
+    /* But then forces 0x300 to NULL anyway... */
+    std::strncpy(out->str, path, sizeof(out->str) - 1);
+    out->str[sizeof(out->str)-1] = 0;
+
+    /* Replace any instances of \ with / */
+    for (size_t i = 0; i < sizeof(out->str); i++) {
+        if (out->str[i] == '\\') {
+            out->str[i] = '/';
+        }
+    }
+
+    /* Nintendo allows some liberties if the path is a windows path. Who knows why... */
+    const auto prefix_len = FsPathUtils::IsWindowsAbsolutePath(path) ? 2 : 0;
+    const size_t max_len = (FS_MAX_PATH-1) - prefix_len;
+    return FsPathUtils::VerifyPath(out->str + prefix_len, max_len, max_len);
+}