Add some handy filesystem related code for plugins

Signed-off-by: falkTX <falktx@falktx.com>

distrho/extra/Filesystem.hpp

@@ -0,0 +1,107 @@
+/*
+ * DISTRHO Plugin Framework (DPF)
+ * Copyright (C) 2012-2025 Filipe Coelho <falktx@falktx.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any purpose with
+ * or without fee is hereby granted, provided that the above copyright notice and this
+ * permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
+ * TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
+ * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef DISTRHO_FILESYSTEM_UTILS_HPP_INCLUDED
+#define DISTRHO_FILESYSTEM_UTILS_HPP_INCLUDED
+
+#include "String.hpp"
+
+#include <cstdio>
+
+#ifdef DISTRHO_OS_WINDOWS
+# include <stringapiset.h>
+#endif
+
+START_NAMESPACE_DISTRHO
+
+// --------------------------------------------------------------------------------------------------------------------
+// filesystem related calls
+
+/*
+ * Wrapper around `fopen` call, needed on Windows because its C standard functions use ASCII instead of UTF-8.
+ */
+static inline
+FILE* d_fopen(const char* const pathname, const char* const mode)
+{
+   #ifdef DISTRHO_OS_WINDOWS
+    WCHAR lpathname[MAX_PATH];
+    WCHAR lmode[4];
+    if (MultiByteToWideChar(CP_UTF8, 0, pathname, -1, lpathname, ARRAY_SIZE(lpathname)) != 0 &&
+        MultiByteToWideChar(CP_UTF8, 0, mode, -1, lmode, ARRAY_SIZE(lmode)) != 0)
+        return _wfopen(lpathname, lmode);
+   #endif
+
+    return fopen(pathname, mode);
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+// filesystem related classes
+
+/**
+   Handy class to help write files in a safe way, which does:
+    - open pathname + ".tmp" instead of opening a file directly (so partial writes are safe)
+    - on close, flush data to disk and rename file to remove ".tmp"
+
+   To use it, create a local variable (on the stack) and call ok() or manually check @a fd variable.
+   @code
+    if (const SafeFileWriter file("/path/to/file.txt"); file.ok())
+        file.write("Success!");
+   @endcode
+ */
+struct SafeFileWriter
+{
+    /** Parameters from the run function, adjusted for event sync */
+    String filename;
+    FILE* const fd;
+
+    /**
+       Constructor, opening @a pathname + ".tmp" for writing.
+    */
+    SafeFileWriter(const char* const pathname, const char* const mode = "w")
+        : filename(pathname),
+          fd(d_fopen(filename + ".tmp", mode)) {}
+
+    /**
+       Destructor, will flush file data contents, close and rename file.
+    */
+    ~SafeFileWriter()
+    {
+        if (fd == nullptr)
+            return;
+
+        std::fflush(fd);
+        std::fclose(fd);
+        std::rename(filename + ".tmp", filename);
+    }
+
+    /** Check if the file was opened successfully. */
+    inline bool ok() const noexcept
+    {
+        return fd != nullptr;
+    }
+
+    /** Wrapper around `fwrite`, purely for convenience. */
+    inline size_t write(const void* const ptr, const size_t size, const size_t nmemb = 1) const
+    {
+        return std::fwrite(ptr, size, nmemb, fd);
+    }
+};
+
+// --------------------------------------------------------------------------------------------------------------------
+
+END_NAMESPACE_DISTRHO
+
+#endif // DISTRHO_FILESYSTEM_UTILS_HPP_INCLUDED