this post was submitted on 24 Sep 2023
34 points (92.5% liked)

Programming

17322 readers
238 users here now

Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!

Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.

Hope you enjoy the instance!

Rules

Rules

  • Follow the programming.dev instance rules
  • Keep content related to programming in some way
  • If you're posting long videos try to add in some form of tldr for those who don't want to watch videos

Wormhole

Follow the wormhole through a path of communities [email protected]

founded 1 year ago
MODERATORS
[email protected]
[email protected]
[email protected]
34
What it takes to pass a file path to a Windows API in C++ (mastodon.gamedev.place)
submitted 1 year ago by [email protected] to c/[email protected]
4 comments fedilink hide all child comments
you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 20 points 1 year ago* (last edited 1 year ago)

How are we still not past three-splitting content…

It's not as shit as twitter UI/UX/Accessibility - but this mastodon split-post doesn't make me feel much better.

/edit: Actually, it's a 5-split.

I'll do what lemmy-post-OP didn't and copy the content for accessibility:

Ashley Gullen:

If you thought JavaScript was a mess, here's what it takes to pass a file path to a Windows API in C++: 🧵

  1. Windows uses UTF-16, but most modern software uses UTF-8
  2. Converting UTF-8 to UTF-16 requires calling MultiByteToWideChar twice (once for size, second to convert)
  3. Alternatively you can set the process code page to UTF-8 and call the 'A' variant API directly, but only sometimes, and only with Windows 10 v1903+, and you might still have to change the system locale setting and reboot
  4. Now you can pass a file path! But...
  5. The path is limited to MAX_PATH (260 chars)
  6. Unless you prefix the path with \\?\
  7. However using \\?\ disables automatic conversion of / to \ in the path (and some other normalization)
  8. Alternatively set a reg key LongPathsEnabled, but only with Windows 10 v1607+ and the app needs to opt in to longPathAware, and changing the registry might need a reboot
  9. Even then not all Windows APIs support longer paths, e.g. PathCanonicalize. Swap for PathCchCanonicalizeEx with PATHCCH_ALLOW_LONG_PATHS, etc. Check docs per API.
  10. Congratulations, your app can pass a long file path to Windows! But the shell still doesn't support long paths. So your app can write to long paths, but you can't access them with Windows Explorer. Even in Windows 11.
  11. If the API returns a path, do all that in reverse.

I probably missed a few other details and quirks.

References:

See also individual APIs e.g. https://learn.microsoft.com/en-us/windows/win32/api/shlwapi/nf-shlwapi-pathcanonicalizea

Unrelated promotional text and link