## Problem
`xtool setup` fails on Linux Mint (and other distros) with:
```
Error: Error Domain=NSCocoaErrorDomain Code=512 "(null)" UserInfo={
NSUserStringVariant=["Copy"],
NSSourceFilePathErrorKey=/tmp/sh.xtool/tmp-DarwinSDKBuild-.../darwin.artifactbundle/...,
NSDestinationFilePath=/home/<user>/.swiftpm/swift-sdks/darwin.artifactbundle/...,
NSUnderlyingError=Error Domain=NSPOSIXErrorDomain Code=22 "Invalid argument"
}
```
## Root Cause
On Linux Mint (and Ubuntu-based distros), `/tmp` is mounted as **tmpfs**
while the home directory is on **ext4**. Foundation's
`FileManager.copyItem` uses `sendfile(2)` internally, which returns
`EINVAL (22)` when copying between different filesystem types.
`TemporaryDirectoryRoot` defaults to
`FileManager.default.temporaryDirectory` → `/tmp` on Linux. When `swift
sdk install` copies the built SDK from `/tmp/sh.xtool/...` to
`~/.swiftpm/swift-sdks/`, it crosses filesystem boundaries and fails.
## Fix
On Linux, default the temp directory root to `$XDG_CACHE_HOME/xtool`
(falling back to `~/.cache/xtool`) instead of `/tmp`. This keeps the
build directory and install destination on the same filesystem, so the
copy always succeeds.
- `$XTL_TMPDIR` and `$TMPDIR` overrides continue to work as before
- macOS behaviour is unchanged
- Follows XDG Base Directory Specification
## Changes
One file, `Sources/XUtils/TemporaryDirectory.swift` — 11 lines added
inside a `#if os(Linux)` block.
Fixes#181
- We now have a single tmpdir "root" that can be recreated at launch to
clean up old stragglers
- The location of this tmpdir root can be controlled by `XTL_TMPDIR` or
`TMPDIR`. In general the path is `$TMPDIR/sh.xtool`.
With this change it should be possible to `export XTL_TMPDIR=/var/tmp`
if `/tmp` doesn't have enough space, which fixes#23.
Kabir Oberai
Swapnil Nakate