windows: attribute 'archive' only for completed downloads #3354
Description
The archive bit (FILE_ATTRIBUTE_ARCHIVE, 0x20) tells files that shall be backed up from those that are either not ready or have not changed.
Downloads in progress are neither ready to be backed up, nor should they be opened by a different process. Only after a download has been completed it's sensible to include it in any integer snapshot or backup of the system.
For example, if you were downloading a Linux ISO you don't want to carry a fraction of it through the history of your backup sets. Indeed, it will give the wrong impression this were the file's valid state.
Open two command prompts, one to start the download and the second to see attributes. We'll focus on the output of the second while the download is in progress.
curl.exe --remote-name <URL>/<fname>
attrib <fname>
… which gives:
A <fname>
… but the archive bit shouldn't be set at this point, so this is what we'd ideally see (with or without any FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS):
<fname>
Happens with curl 7.61.1 (x86_64-pc-win32)
using Windows 10 1809, though likely not limited to 10 1809 or 7.61.1.