Nano sudo-write plugin: Write failure behavior on read-only filesystems

Buffer Persistence and Read-Only Targets

GNU nano employs a temporary file mechanism to ensure atomic saves, writing the buffer to a hidden file before renaming it to the target destination. This process prevents data corruption by ensuring the original file remains intact if a write operation is interrupted.

When utilizing the sudo-write plugin to modify files on read-only filesystems, a conflict arises between the editor's internal buffer management and the filesystem's restrictions. If the plugin fails to secure write permissions or encounters a read-only mount during the final rename phase, the behavior of the internal buffer remains undefined.

Specifically, it is unclear whether nano treats a failed sudo-write as a recoverable error that preserves the modified buffer for another attempt, or if the failure triggers a state that may lead to unintended data loss upon exiting the editor.

• Does the sudo-write plugin maintain the buffer's modified status if the rename operation fails on a read-only filesystem?
• What is the expected behavior for the temporary .save file when the target filesystem prohibits the final atomic rename?