Fake files "exist" after checking real files? - c++

Question

I have been programming C++ on Linux for a while, but recently moved to a windows 10 computer.
I managed to set up CodeBlocks with w64-mingw.
I have been trying to move programs from linux to windows and I'm having trouble with filenames. For example, I have code to check if files or directories exist, and to create directories. But I get weird results, if a file check comes back as true, then all subsequent file checks come back as true. I have example code, where test.txt and testdir are a file and directory that do not initially exist, but are created by the program. fail.txt and faildir never exist, but my program claims they exist AFTER creating test.txt and testdir. I've seen several questions about checking if files exist on Windows, but I've never run into behavior like this, and I'm not sure what's going on. Does windows fail to reinitialize something when GetFileAttributes() is called? Or have I missed something really basic?
main.cpp
#include <iostream>
#include <fstream>
#include "../include/FileChecker.h"
int main(){
FileChecker fc = FileChecker();
std::cout << "Test Start" << std::endl;
#ifdef _WIN32
std::cout << "OS is windows" << std::endl;
#endif // _WIN32
std::cout << std::endl;
std::cout << "Nothing should exist" << std::endl;
if(fc.file_exists("test.txt")){
std::cout << "test.txt exists." << std::endl;
}else{
std::cout << "test.txt does not exist." << std::endl;
}
if(fc.file_exists("fail.txt")){
std::cout << "fail.txt exists." << std::endl;
}else{
std::cout << "fail.txt does not exist." << std::endl;
}
if(fc.directory_exists("testdir")){
std::cout << "Directory testdir exists." << std::endl;
}else{
std::cout << "Directory testdir does not exist." << std::endl;
}
if(fc.directory_exists("faildir")){
std::cout << "Directory faildir exists." << std::endl;
}else{
std::cout << "Directory faildir does not exist." << std::endl;
}
std::cout << std::endl;
std::cout << "Creating test.txt" << std::endl;
std::ofstream test("test.txt");
test << "HELLO" << std::endl;
test.close();
std::cout << "Only test.txt should exist" << std::endl;
if(fc.file_exists("test.txt")){
std::cout << "test.txt exists." << std::endl;
}else{
std::cout << "test.txt does not exist." << std::endl;
}
if(fc.file_exists("fail.txt")){
std::cout << "fail.txt exists." << std::endl;
}else{
std::cout << "fail.txt does not exist." << std::endl;
}
if(fc.directory_exists("testdir")){
std::cout << "Directory testdir exists." << std::endl;
}else{
std::cout << "Directory testdir does not exist." << std::endl;
}
if(fc.directory_exists("faildir")){
std::cout << "Directory faildir exists." << std::endl;
}else{
std::cout << "Directory faildir does not exist." << std::endl;
}
std::cout << std::endl;
std::cout << "Creating directory testdir" << std::endl;
if(fc.create_directory("testdir")){
std::cout << "Creation Success" << std::endl;
}else{
std::cout << "Creation Failed" << std::endl;
}
std::cout << "Only testdir should exist" << std::endl;
if(fc.directory_exists("testdir")){
std::cout << "Directory testdir exists." << std::endl;
}else{
std::cout << "Directory testdir does not exist." << std::endl;
}
if(fc.directory_exists("faildir")){
std::cout << "Directory faildir exists." << std::endl;
}else{
std::cout << "Directory faildir does not exist." << std::endl;
}
return 0;
}
FileChecker.h
#ifndef FILECHECKER_H
#define FILECHECKER_H
#ifdef _WIN32
#include <windows.h>
#include <tchar.h>
#include <stdio.h>
#include <direct.h>
#endif // _WIN32
#include <string>
class FileChecker
{
public:
FileChecker();
virtual ~FileChecker();
bool file_exists(std::string filename);
bool directory_exists(std::string dirname);
bool create_file(std::string filename);
bool create_directory(std::string dirname);
protected:
private:
};
#endif // FILECHECKER_H
FileChecker.cpp
#include "../include/FileChecker.h"
FileChecker::FileChecker(){
//ctor
}
FileChecker::~FileChecker(){
//dtor
}
#ifdef _WIN32
bool FileChecker::file_exists(std::string filename){
static LPCTSTR szPath = TEXT(filename.c_str());
DWORD dwAttrib = GetFileAttributes(szPath);
return ((dwAttrib != INVALID_FILE_ATTRIBUTES) && !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
}
#endif // _WIN32
#ifdef _WIN32
bool FileChecker::directory_exists(std::string dirname){
static LPCTSTR szPath = TEXT(dirname.c_str());
DWORD dwAttrib = GetFileAttributes(szPath);
return ((dwAttrib != INVALID_FILE_ATTRIBUTES) && (dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
}
#endif // _WIN32
#ifdef _WIN32
bool FileChecker::create_directory(std::string dirname){
static LPCTSTR szPath = TEXT(dirname.c_str());
return(CreateDirectory(szPath, NULL));
}
#endif // _WIN32
Output

Answer 1

You should remove all static keyword in your functions.
bool FileChecker::file_exists(std::string filename){
static LPCTSTR szPath = TEXT(filename.c_str()); // <--- [*]
DWORD dwAttrib = GetFileAttributes(szPath);
when file_exists function is called first time, szPath variable is created and initialized pointing to array of characters of filename. When you call file_exists second time, value of szPath is still the same, and points to invalid data (keeps pointer to data of filename object, which was deleted after calling file_exists first time).
You should read about static variables in functions.

Answer 2

Your code here:
bool FileChecker::file_exists(std::string filename){
static LPCTSTR szPath = TEXT(filename.c_str());
DWORD dwAttrib = GetFileAttributes(szPath);
return ((dwAttrib != INVALID_FILE_ATTRIBUTES) && !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
}
TEXT simply casts, it does not perform any sort of conversion. Make it the following instead:
bool FileChecker::file_exists(std::string filename)
{
DWORD dwAttrib = GetFileAttributesA(filename.c_str());
return ((dwAttrib != INVALID_FILE_ATTRIBUTES) && !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
}