Understanding Unicode Normalization

Oct 13, 2025 by talynt.org 76 views

Understanding Unicode Normalization

Unicode normalization is a process that converts a Unicode string into a standard form. There are two main forms of Unicode normalization: Normalization Form C (NFC) and Normalization Form D (NFD). NFC is a compatibility decomposition, where characters are decomposed into their base form and then recomposed. NFD is a compatibility decomposition, where characters are decomposed into their base form, but not recomposed.

The Problem with Folders with the Same Name, Different Unicode Normalization

When two folders with the same name but different Unicode normalization are encountered, it can cause problems for the client. For example, a folder with two subfolders named "Fälder" (NFC) and "Fälder" (NFD) will end up synced to the client as one single folder, with their contents merged. This can lead to data loss and other issues.

Consequences of the Problem

The consequences of this problem can be severe. When the client syncs the folder, it will discover that there are new files in that folder, and upload them. However, the folder that doesn't exist locally is deleted on the remote. This can lead to data loss and other issues.

Fixing the Problem

To fix this problem, the client should detect the normalization collision when running the discovery on the remote, and refuse to sync one of the two folders. Additionally, an error should be shown explaining the situation to the end-user.

How to Detect Normalization Collision

To detect normalization collision, the client can use the following steps:

Compare folder names: Compare the names of the two folders to see if they are the same.
Check Unicode normalization: Check the Unicode normalization of the two folder names to see if they are different.
Refuse to sync: If the folder names are the same but the Unicode normalization is different, refuse to sync one of the two folders.

Error Message

When the client detects a normalization collision, it should show an error message to the end-user. The error message should explain the situation and provide instructions on how to resolve the issue.

Example Error Message

"Error: Normalization collision detected

Two folders with the same name but different Unicode normalization have been detected. This can cause data loss and other issues. To resolve this issue, please rename one of the folders to a unique name."

Benefits of Fixing the Problem

Fixing this problem has several benefits, including:

Prevents data loss: By refusing to sync one of the two folders, the client can prevent data loss and other issues.
Improves user experience: By showing an error message and providing instructions on how to resolve the issue, the client can improve the user experience.
Reduces support requests: By fixing this problem, the client can reduce the number of support requests related to this issue.

Conclusion

In conclusion, the problem with folders with the same name, different Unicode normalization is a serious issue that can cause data loss and other problems. To fix this problem, the client should detect the normalization collision when running the discovery on the remote, and refuse to sync one of the two folders. Additionally, an error should be shown explaining the situation to the end-user. By fixing this problem, the client can prevent data loss, improve the user experience, and reduce support requests.

Technical Details

Unicode Normalization

Normalization Collision

A normalization collision occurs when two folders with the same name but different Unicode normalization are encountered. This can cause problems for the client, including data loss and other issues.

Detection of Normalization Collision

To detect normalization collision, the client can use the following steps:

Compare folder names: Compare the names of the two folders to see if they are the same.
Check Unicode normalization: Check the Unicode normalization of the two folder names to see if they are different.
Refuse to sync: If the folder names are the same but the Unicode normalization is different, refuse to sync one of the two folders.

Error Message

Implementation

To implement the fix for this problem, the client should:

Detect normalization collision: Use the steps outlined above to detect normalization collision.
Refuse to sync: If a normalization collision is detected, refuse to sync one of the two folders.
Show error message: Show an error message to the end-user explaining the situation and providing instructions on how to resolve the issue.

Testing

To test the fix for this problem, the client should:

Create test folders: Create two folders with the same name but different Unicode normalization.
Run discovery: Run the discovery on the remote to detect the normalization collision.
Verify behavior: Verify that the client refuses to sync one of the two folders and shows an error message to the end-user.

Conclusion

Q: What is Unicode normalization?

A: Unicode normalization is a process that converts a Unicode string into a standard form. There are two main forms of Unicode normalization: Normalization Form C (NFC) and Normalization Form D (NFD). NFC is a compatibility decomposition, where characters are decomposed into their base form and then recomposed. NFD is a compatibility decomposition, where characters are decomposed into their base form, but not recomposed.

Q: What is a normalization collision?

A: A normalization collision occurs when two folders with the same name but different Unicode normalization are encountered. This can cause problems for the client, including data loss and other issues.

Q: How does the client detect a normalization collision?

A: The client detects a normalization collision by comparing the names of the two folders and checking their Unicode normalization. If the folder names are the same but the Unicode normalization is different, the client refuses to sync one of the two folders.

Q: What happens when the client detects a normalization collision?

A: When the client detects a normalization collision, it refuses to sync one of the two folders and shows an error message to the end-user. The error message explains the situation and provides instructions on how to resolve the issue.

Q: How can I prevent normalization collisions?

A: To prevent normalization collisions, you can rename one of the folders to a unique name. Alternatively, you can use a tool that normalizes folder names to a standard form before syncing.

Q: What are the benefits of fixing the problem of folders with the same name, different Unicode normalization?

A: The benefits of fixing this problem include:

Prevents data loss: By refusing to sync one of the two folders, the client can prevent data loss and other issues.
Improves user experience: By showing an error message and providing instructions on how to resolve the issue, the client can improve the user experience.
Reduces support requests: By fixing this problem, the client can reduce the number of support requests related to this issue.

Q: How can I test the fix for this problem?

A: To test the fix for this problem, you can create two folders with the same name but different Unicode normalization, run the discovery on the remote, and verify that the client refuses to sync one of the two folders and shows an error message to the end-user.

Q: What are the technical details of the fix for this problem?

A: The technical details of the fix for this problem include:

Detection of normalization collision: The client detects a normalization collision by comparing the names of the two folders and checking their Unicode normalization.
Refusal to sync: If a normalization collision is detected, the client refuses to sync one of the two folders.
Error message: The client shows an error message to the end-user explaining the situation and providing instructions on how to resolve the issue.

Q: How can I implement the fix for this problem?

A: To implement the fix for this problem, you can:

Detect normalization collision: Use the steps outlined above to detect normalization collision.
Refuse to sync: If a normalization collision is detected, refuse to sync one of the two folders.
Show error message: Show an error message to the end-user explaining the situation and providing instructions on how to resolve the issue.

Conclusion

In conclusion, the problem of folders with the same name, different Unicode normalization is a serious issue that can cause data loss and other problems. To fix this problem, the client should detect the normalization collision when running the discovery on the remote, and refuse to sync one of the two folders. Additionally, an error should be shown explaining the situation to the end-user. By fixing this problem, the client can prevent data loss, improve the user experience, and reduce support requests.