[FS] Implement SetSize

include/io_file.hpp

@@ -18,6 +18,12 @@
 #define _CRT_SECURE_NO_WARNINGS
 #endif
 
+#ifdef WIN32
+#include <io.h> // For _chsize_s
+#else
+#include <unistd.h> // For ftruncate
+#endif
+
 class IOFile {
     FILE* handle = nullptr;
     static inline std::filesystem::path appData = ""; // Directory for holding app data. AppData on Windows
@@ -112,5 +118,19 @@ public:
         appData = dir;
     }
 
+    // Sets the size of the file to "size" and returns whether it succeeded or not
+    bool setSize(std::uint64_t size) {
+        if (!isOpen()) return false;
+        bool success;
+
+#ifdef WIN32
+        success = _chsize_s(_fileno(handle), size) == 0;
+#else
+        success = ftruncate(fileno(handle), size) == 0;
+#endif
+        fflush(handle);
+        return success;
+    }
+
     static std::filesystem::path getAppData() { return IOFile::appData; }
 };

include/kernel/kernel.hpp

@@ -127,6 +127,7 @@ private:
 	void writeFile(u32 messagePointer, Handle file);
 	void getFileSize(u32 messagePointer, Handle file);
 	void openLinkFile(u32 messagePointer, Handle file);
+	void setFileSize(u32 messagePointer, Handle file);
 	void setFilePriority(u32 messagePointer, Handle file);
 
 	// Directory operations

src/core/kernel/file_operations.cpp

@@ -5,6 +5,7 @@ namespace FileOps {
 		Read = 0x080200C2,
 		Write = 0x08030102,
 		GetSize = 0x08040000,
+		SetSize = 0x08050080,
 		Close = 0x08080000,
 		SetPriority = 0x080A0040,
 		OpenLinkFile = 0x080C0000
@@ -25,6 +26,7 @@ void Kernel::handleFileOperation(u32 messagePointer, Handle file) {
 		case FileOps::GetSize: getFileSize(messagePointer, file); break;
 		case FileOps::OpenLinkFile: openLinkFile(messagePointer, file); break;
 		case FileOps::Read: readFile(messagePointer, file); break;
+		case FileOps::SetSize: setFileSize(messagePointer, file); break;
 		case FileOps::SetPriority: setFilePriority(messagePointer, file); break;
 		case FileOps::Write: writeFile(messagePointer, file); break;
 		default: Helpers::panic("Unknown file operation: %08X", cmd);
@@ -132,6 +134,34 @@ void Kernel::writeFile(u32 messagePointer, Handle fileHandle) {
 	}
 }
 
+void Kernel::setFileSize(u32 messagePointer, Handle fileHandle) {
+	logFileIO("Setting size of file %X\n", fileHandle);
+
+	const auto p = getObject(fileHandle, KernelObjectType::File);
+	if (p == nullptr) [[unlikely]] {
+		Helpers::panic("Called SetFileSize on non-existent file");
+	}
+
+	FileSession* file = p->getData<FileSession>();
+	if (!file->isOpen) {
+		Helpers::panic("Tried to get size of closed file");
+	}
+
+	if (file->fd) {
+		const u64 newSize = mem.read64(messagePointer + 4);
+		IOFile f(file->fd);
+		bool success = f.setSize(newSize);
+
+		if (success) {
+			mem.write32(messagePointer + 4, Result::Success);
+		} else {
+			Helpers::panic("FileOp::SetFileSize failed");
+		}
+	} else {
+		Helpers::panic("Tried to set file size of file without file descriptor");
+	}
+}
+
 void Kernel::getFileSize(u32 messagePointer, Handle fileHandle) {
 	logFileIO("Getting size of file %X\n", fileHandle);