DocumentProvider does not allow createDocument()

[x0b]

Problem description
When using the Termux DocumentProvider from another app, you can not save files into the termux user directory or its children.

Steps to reproduce

1. Start a write request to the Termux' DocumentProvider
2. An error message appears and logcat writes:

E/DatabaseUtils: Writing exception to parcel
    java.lang.UnsupportedOperationException: Create not supported
        at android.provider.DocumentsProvider.createDocument(DocumentsProvider.java:227)
        at android.provider.DocumentsProvider.callUnchecked(DocumentsProvider.java:757)
        at android.provider.DocumentsProvider.call(DocumentsProvider.java:716)
        at android.content.ContentProvider$Transport.call(ContentProvider.java:492)
        at android.content.ContentProviderNative.onTransact(ContentProviderNative.java:283)
        at android.os.Binder.execTransact(Binder.java:565)
W/DocumentsActivity: Failed to create document
    java.lang.UnsupportedOperationException: Create not supported
        at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:167)
        at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:135)
        at android.content.ContentProviderProxy.call(ContentProviderNative.java:646)
        at android.content.ContentProviderClient.call(ContentProviderClient.java:456)
        at android.provider.DocumentsContract.createDocument(DocumentsContract.java:1083)
        at com.android.documentsui.DocumentsActivity$CreateFinishTask.run(DocumentsActivity.java:573)
        at com.android.documentsui.DocumentsActivity$CreateFinishTask.run(DocumentsActivity.java:564)
        at com.android.documentsui.PairedTask.doInBackground(PairedTask.java:67)
        at android.os.AsyncTask$2.call(AsyncTask.java:304)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at com.android.documentsui.ProviderExecutor.run(ProviderExecutor.java:104)

Cause:
Flag indicates create support:

termux-app/app/src/main/java/com/termux/filepicker/TermuxDocumentsProvider.java

Line 225 in 7056945

flags |= Document.FLAG_SUPPORTS_WRITE | Document.FLAG_SUPPORTS_DELETE;

2.:

termux-app/app/src/main/java/com/termux/filepicker/TermuxDocumentsProvider.java

Line 74 in 7056945

row.add(Root.COLUMN_FLAGS, Root.FLAG_SUPPORTS_CREATE | Root.FLAG_SUPPORTS_SEARCH);

but no create is implemented.

Expected behavior
Termux allows me to write to the user directory if the user has granted permissions to do so by selecting the Termux' DocumentProvider in DocumentsUI.

Additional information

What am I trying to achieve?

I'm currently trying to introduce support for shared config files into RcloneExplorer so that users can use Termux for the full shell experience and rcloneExplorer for the day to day browsing.

EDIT
Is there interest in implementing createDocument()? If so, I could probably submit a pull request. openDocument() is not restricted to reads anyway, so either this a implementation or security error since you could do a openDocumentStream() on the underlying file anyways.

[x0b]

bump

Is there interest in implementing createDocument()? If so, I could probably submit a pull request. openDocument() is not restricted to reads anyway, so either this a implementation or security error since you could do a openDocumentStream() on the underlying file anyways.

[chrysn]

As a termux user, I'd appreciate this a lot, as together with #1424 it'd give back sone UNIX experience to Android 10+, and make git-annex usable more easily across appiications.

[fornwall]

Fixed by @x0b (great work!) in #1460, which has just been released in version 0.92 of the app.