For what it's worth, here's my understanding of why this happens:

Linux/unix has a concept of "unlinking" rather than "deleting" files. This basically removes the file from the directory tree, but it doesn't delete the file object (inode¹) in the kernel or free the file's data on disk until all open file descriptors are closed and hard links are unlinked. Basically each inode has a reference count consisting of all open file descriptors and all hard links (including the hard link you might consider the original path to the file). This means you can unlink the executable file for a running process on unix without the actual inode being deleted yet.

Windows doesn't really have this concept of unlinking. There is FILE_SHARE_DELETE²³, which is an attribute you can set on an opened file that does something sort of similar to unix's ref-counted inodes, although I'm not entirely sure of the specifics. It doesn't seem like the loader for .exe and .dll files sets this attribute, and even if it did older versions of NTFS would keep a tombstone around⁴, preventing you from replacing the file with one with the same name. I'm not entirely sure why the loader doesn't specify FILE_SHARE_DELETE. I know windows uses the actual PE images (the format of .exe, .dll, and .sys files) as page files for text/static data at runtime, but assuming it ref-counts the actual file object I don't think this should provide a reason not to delete them? Unsure.

The reason why renaming works is because you're not actually deleting the underlying file data, you're just moving it to a new location in the directory tree. This doesn't require special permissions since it does not remove the file from disk.

My current workaround is this powershell script:

# tool-sync.ps1

$local:ErrorActionPreference = 'Stop'

$currentToolPath = (Get-Command tool).Source
$newToolDir = "$env:TEMP/$((New-Guid).Guid)"
$newToolPath = "$newToolDir/tool.exe"

mkdir $newToolDir > $null
Copy-Item $currentToolPath $newToolDir
& $newToolPath sync
Remove-Item -Force -Recurse $newToolDir

Footnotes

Uh oh!

Self update under windows issues. #115

Description

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions