godot/drivers/windows/file_access_windows.cpp

/**************************************************************************/
/*  file_access_windows.cpp                                               */
/**************************************************************************/
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#ifdef WINDOWS_ENABLED

#include "file_access_windows.h"

#include "core/os/os.h"
#include "core/string/print_string.h"
#include <share.h> // _SH_DENYNO
#include <shlwapi.h>
#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <tchar.h>
#include <wchar.h>

#ifdef _MSC_VER
#define S_ISREG(m) ((m)&_S_IFREG)
#endif

void FileAccessWindows::check_errors() const {
	ERR_FAIL_COND(!f);

	if (feof(f)) {
		last_error = ERR_FILE_EOF;
	}
}

bool FileAccessWindows::is_path_invalid(const String &p_path) {
	// Check for invalid operating system file.
	String fname = p_path;
	int dot = fname.find(".");
	if (dot != -1) {
		fname = fname.substr(0, dot);
	}
	fname = fname.to_lower();
	return invalid_files.has(fname);
}

String FileAccessWindows::fix_path(const String &p_path) const {
	String r_path = FileAccess::fix_path(p_path);
	if (r_path.is_absolute_path() && !r_path.is_network_share_path() && r_path.length() > MAX_PATH) {
		r_path = "\\\\?\\" + r_path.replace("/", "\\");
	}
	return r_path;
}

Error FileAccessWindows::open_internal(const String &p_path, int p_mode_flags) {
	if (is_path_invalid(p_path)) {
#ifdef DEBUG_ENABLED
		if (p_mode_flags != READ) {
			WARN_PRINT("The path :" + p_path + " is a reserved Windows system pipe, so it can't be used for creating files.");
		}
#endif
		return ERR_INVALID_PARAMETER;
	}

	_close();

	path_src = p_path;
	path = fix_path(p_path);

	const WCHAR *mode_string;

	if (p_mode_flags == READ) {
		mode_string = L"rb";
	} else if (p_mode_flags == WRITE) {
		mode_string = L"wb";
	} else if (p_mode_flags == READ_WRITE) {
		mode_string = L"rb+";
	} else if (p_mode_flags == WRITE_READ) {
		mode_string = L"wb+";
	} else {
		return ERR_INVALID_PARAMETER;
	}

	/* Pretty much every implementation that uses fopen as primary
	   backend supports utf8 encoding. */

	struct _stat st;
	if (_wstat((LPCWSTR)(path.utf16().get_data()), &st) == 0) {
		if (!S_ISREG(st.st_mode)) {
			return ERR_FILE_CANT_OPEN;
		}
	}

#ifdef TOOLS_ENABLED
	// Windows is case insensitive, but all other platforms are sensitive to it
	// To ease cross-platform development, we issue a warning if users try to access
	// a file using the wrong case (which *works* on Windows, but won't on other
	// platforms).
	if (p_mode_flags == READ) {
		WIN32_FIND_DATAW d;
		HANDLE fnd = FindFirstFileW((LPCWSTR)(path.utf16().get_data()), &d);
		if (fnd != INVALID_HANDLE_VALUE) {
			String fname = String::utf16((const char16_t *)(d.cFileName));
			if (!fname.is_empty()) {
				String base_file = path.get_file();
				if (base_file != fname && base_file.findn(fname) == 0) {
					WARN_PRINT("Case mismatch opening requested file '" + base_file + "', stored as '" + fname + "' in the filesystem. This file will not open when exported to other case-sensitive platforms.");
				}
			}
			FindClose(fnd);
		}
	}
#endif

	if (is_backup_save_enabled() && p_mode_flags == WRITE) {
		save_path = path;
		path = path + ".tmp";
	}

	f = _wfsopen((LPCWSTR)(path.utf16().get_data()), mode_string, _SH_DENYNO);

	if (f == nullptr) {
		switch (errno) {
			case ENOENT: {
				last_error = ERR_FILE_NOT_FOUND;
			} break;
			default: {
				last_error = ERR_FILE_CANT_OPEN;
			} break;
		}
		return last_error;
	} else {
		last_error = OK;
		flags = p_mode_flags;
		return OK;
	}
}

void FileAccessWindows::_close() {
	if (!f) {
		return;
	}

	fclose(f);
	f = nullptr;

	if (!save_path.is_empty()) {
		bool rename_error = true;
		int attempts = 4;
		while (rename_error && attempts) {
			// This workaround of trying multiple times is added to deal with paranoid Windows
			// antiviruses that love reading just written files even if they are not executable, thus
			// locking the file and preventing renaming from happening.

#ifdef UWP_ENABLED
			// UWP has no PathFileExists, so we check attributes instead
			DWORD fileAttr;

			fileAttr = GetFileAttributesW((LPCWSTR)(save_path.utf16().get_data()));
			if (INVALID_FILE_ATTRIBUTES == fileAttr) {
#else
			if (!PathFileExistsW((LPCWSTR)(save_path.utf16().get_data()))) {
#endif
				// Creating new file
				rename_error = _wrename((LPCWSTR)((save_path + ".tmp").utf16().get_data()), (LPCWSTR)(save_path.utf16().get_data())) != 0;
			} else {
				// Atomic replace for existing file
				rename_error = !ReplaceFileW((LPCWSTR)(save_path.utf16().get_data()), (LPCWSTR)((save_path + ".tmp").utf16().get_data()), nullptr, 2 | 4, nullptr, nullptr);
			}
			if (rename_error) {
				attempts--;
				OS::get_singleton()->delay_usec(100000); // wait 100msec and try again
			}
		}

		if (rename_error) {
			if (close_fail_notify) {
				close_fail_notify(save_path);
			}
		}

		save_path = "";

		ERR_FAIL_COND_MSG(rename_error, "Safe save failed. This may be a permissions problem, but also may happen because you are running a paranoid antivirus. If this is the case, please switch to Windows Defender or disable the 'safe save' option in editor settings. This makes it work, but increases the risk of file corruption in a crash.");
	}
}

String FileAccessWindows::get_path() const {
	return path_src;
}

String FileAccessWindows::get_path_absolute() const {
	return path;
}

bool FileAccessWindows::is_open() const {
	return (f != nullptr);
}

void FileAccessWindows::seek(uint64_t p_position) {
	ERR_FAIL_COND(!f);

	last_error = OK;
	if (_fseeki64(f, p_position, SEEK_SET)) {
		check_errors();
	}
	prev_op = 0;
}

void FileAccessWindows::seek_end(int64_t p_position) {
	ERR_FAIL_COND(!f);

	if (_fseeki64(f, p_position, SEEK_END)) {
		check_errors();
	}
	prev_op = 0;
}

uint64_t FileAccessWindows::get_position() const {
	int64_t aux_position = _ftelli64(f);
	if (aux_position < 0) {
		check_errors();
	}
	return aux_position;
}

uint64_t FileAccessWindows::get_length() const {
	ERR_FAIL_COND_V(!f, 0);

	uint64_t pos = get_position();
	_fseeki64(f, 0, SEEK_END);
	uint64_t size = get_position();
	_fseeki64(f, pos, SEEK_SET);

	return size;
}

bool FileAccessWindows::eof_reached() const {
	check_errors();
	return last_error == ERR_FILE_EOF;
}

uint8_t FileAccessWindows::get_8() const {
	ERR_FAIL_COND_V(!f, 0);

	if (flags == READ_WRITE || flags == WRITE_READ) {
		if (prev_op == WRITE) {
			fflush(f);
		}
		prev_op = READ;
	}
	uint8_t b;
	if (fread(&b, 1, 1, f) == 0) {
		check_errors();
		b = '\0';
	}

	return b;
}

uint64_t FileAccessWindows::get_buffer(uint8_t *p_dst, uint64_t p_length) const {
	ERR_FAIL_COND_V(!p_dst && p_length > 0, -1);
	ERR_FAIL_COND_V(!f, -1);

	if (flags == READ_WRITE || flags == WRITE_READ) {
		if (prev_op == WRITE) {
			fflush(f);
		}
		prev_op = READ;
	}
	uint64_t read = fread(p_dst, 1, p_length, f);
	check_errors();
	return read;
}

Error FileAccessWindows::get_error() const {
	return last_error;
}

void FileAccessWindows::flush() {
	ERR_FAIL_COND(!f);

	fflush(f);
	if (prev_op == WRITE) {
		prev_op = 0;
	}
}

void FileAccessWindows::store_8(uint8_t p_dest) {
	ERR_FAIL_COND(!f);

	if (flags == READ_WRITE || flags == WRITE_READ) {
		if (prev_op == READ) {
			if (last_error != ERR_FILE_EOF) {
				fseek(f, 0, SEEK_CUR);
			}
		}
		prev_op = WRITE;
	}
	fwrite(&p_dest, 1, 1, f);
}

void FileAccessWindows::store_buffer(const uint8_t *p_src, uint64_t p_length) {
	ERR_FAIL_COND(!f);
	ERR_FAIL_COND(!p_src && p_length > 0);

	if (flags == READ_WRITE || flags == WRITE_READ) {
		if (prev_op == READ) {
			if (last_error != ERR_FILE_EOF) {
				fseek(f, 0, SEEK_CUR);
			}
		}
		prev_op = WRITE;
	}
	ERR_FAIL_COND(fwrite(p_src, 1, p_length, f) != (size_t)p_length);
}

bool FileAccessWindows::file_exists(const String &p_name) {
	if (is_path_invalid(p_name)) {
		return false;
	}

	String filename = fix_path(p_name);
	FILE *g = _wfsopen((LPCWSTR)(filename.utf16().get_data()), L"rb", _SH_DENYNO);
	if (g == nullptr) {
		return false;
	} else {
		fclose(g);
		return true;
	}
}

uint64_t FileAccessWindows::_get_modified_time(const String &p_file) {
	if (is_path_invalid(p_file)) {
		return 0;
	}

	String file = fix_path(p_file);
	if (file.ends_with("/") && file != "/") {
		file = file.substr(0, file.length() - 1);
	}

	struct _stat st;
	int rv = _wstat((LPCWSTR)(file.utf16().get_data()), &st);

	if (rv == 0) {
		return st.st_mtime;
	} else {
		print_verbose("Failed to get modified time for: " + p_file + "");
		return 0;
	}
}

uint32_t FileAccessWindows::_get_unix_permissions(const String &p_file) {
	return 0;
}

Error FileAccessWindows::_set_unix_permissions(const String &p_file, uint32_t p_permissions) {
	return ERR_UNAVAILABLE;
}

void FileAccessWindows::close() {
	_close();
}

FileAccessWindows::~FileAccessWindows() {
	_close();
}

HashSet<String> FileAccessWindows::invalid_files;

void FileAccessWindows::initialize() {
	static const char *reserved_files[]{
		"con", "prn", "aux", "nul", "com0", "com1", "com2", "com3", "com4", "com5", "com6", "com7", "com8", "com9", "lpt0", "lpt1", "lpt2", "lpt3", "lpt4", "lpt5", "lpt6", "lpt7", "lpt8", "lpt9", nullptr
	};
	int reserved_file_index = 0;
	while (reserved_files[reserved_file_index] != nullptr) {
		invalid_files.insert(reserved_files[reserved_file_index]);
		reserved_file_index++;
	}
}

void FileAccessWindows::finalize() {
	invalid_files.clear();
}

#endif // WINDOWS_ENABLED