How to hide/un-hide a file without erasing other attributes in C++ on Windows

Question

I would like to be able to hide/un-hide a file in Windows in C++, but I was concerned about erasing other attributes (like FILE_ATTRIBUTE_READONLY, FILE_ATTRIBUTE_ARCHIVE, ...).

Here is the current code:

//Hiding the file
SetFileAttributes(path, FILE_ATTRIBUTE_HIDDEN);

// Un-Hiding the file
SetFileAttributes(path, FILE_ATTRIBUTE_NORMAL);

This works fine for regular files, but will hiding the file remove a READONLY flag for example? Will unhiding the file remove it?

If yes, I was planning on doing something like this:

//Hiding the file
int attr = GetFileAttributes(path);
if ((attr | FILE_ATTRIBUTE_HIDDEN) == 0) {
    SetFileAttributes(path, attr & FILE_ATTRIBUTE_HIDDEN);
}

//Unhiding the file
int attr = GetFileAttributes(path);
if ((attr | FILE_ATTRIBUTE_HIDDEN) == FILE_ATTRIBUTE_HIDDEN) {
    SetFileAttributes(path, attr & FILE_ATTRIBUTE_HIDDEN);
}

Would that work?

One minor thing: don't forget to check `GetFileAttributes` return value (check whether it equals `INVALID_FILE_ATTRIBUTES`). — Bojan Komazec, Apr 30 '12 at 16:47

score 9 · Accepted Answer · edited Apr 30 '12 at 20:33

This test won't work, it will always be false:

if ((attr | FILE_ATTRIBUTE_HIDDEN) == 0)

It should instead say

if ((attr & FILE_ATTRIBUTE_HIDDEN) == 0)

Similarly, to test if a file is already hidden:

if ((attr & FILE_ATTRIBUTE_HIDDEN) == FILE_ATTRIBUTE_HIDDEN)

Final corrected code:

//Hiding the file
int attr = GetFileAttributes(path);
if ((attr & FILE_ATTRIBUTE_HIDDEN) == 0) {
    SetFileAttributes(path, attr | FILE_ATTRIBUTE_HIDDEN);
}

//Unhiding the file
int attr = GetFileAttributes(path);
if ((attr & FILE_ATTRIBUTE_HIDDEN) == FILE_ATTRIBUTE_HIDDEN) {
    SetFileAttributes(path, attr & ~FILE_ATTRIBUTE_HIDDEN);
}

score 3 · Answer 2 · edited Apr 30 '12 at 17:18

3

Yes, the first code will remove all other attributes.

The second code is almost correct, but you've missed ~ symbol:

// Hiding the file

int attr = GetFileAttributes(path);

if ((attr & FILE_ATTRIBUTE_HIDDEN) == 0) {
    SetFileAttributes(path, attr | FILE_ATTRIBUTE_HIDDEN);
}

// Unhiding the file

int attr = GetFileAttributes(path);

// Is it currently visible?
if ((attr & FILE_ATTRIBUTE_HIDDEN) == FILE_ATTRIBUTE_HIDDEN) {
    SetFileAttributes(path, attr & ~FILE_ATTRIBUTE_HIDDEN);
}

edited Apr 30 '12 at 17:18

jnfjnjtj

409
4
10

answered Apr 30 '12 at 16:38

Pavel Strakhov

39,123
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Be aware, though, that code like this, as all file operations, is very prone to race conditions with other processes accessing the same file.. – ltjax Apr 30 '12 at 17:04
1

The & operator is required in the if() statement. – Hans Passant Apr 30 '12 at 17:06

How to hide/un-hide a file without erasing other attributes in C++ on Windows

2 Answers2

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