Migrate to XDG and Linux strategy for macOS directories (#5806)

This PR moves us to the Linux strategy for our global directories on
macOS. We both feel on the team _and_ have received feedback (in Issues
and Polls) that the `Application Support` directories are more intended
for GUIs, and CLI tools are correct to respect the XDG variables and use
the same directory paths on Linux and macOS.

Namely, we now use:

- `/Users/crmarsh/.local/share/uv/tools` (for tools)
- `/Users/crmarsh/.local/share/uv/python` (for Pythons)
- `/Users/crmarsh/.cache/uv` (for the cache)

The strategy is such that if the `/Users/crmarsh/Library/Application
Support/uv` already exists, we keep using it -- same goes for
`/Users/crmarsh/Library/Caches/uv`, so **it's entirely backwards
compatible**.

If you want to force a migration to the new schema, you can run:

- `uv cache clean`
- `uv tool uninstall --all`
- `uv python uninstall --all`

Which will clean up the macOS-specific directories, paving the way for
the above paths. In other words, once you run those commands, subsequent
`uv` operations will automatically use the `~/.cache` and `~/.local`
variants.

Closes #4411.

---------

Co-authored-by: Zanie Blue <contact@zanie.dev>

Cargo.toml

@@ -84,6 +84,7 @@ dirs-sys = { version = "0.4.1" }
 dunce = { version = "1.0.4" }
 either = { version = "1.12.0" }
 encoding_rs_io = { version = "0.1.7" }
+etcetera = { version = "0.8.0" }
 flate2 = { version = "1.0.28", default-features = false }
 fs-err = { version = "2.11.0" }
 fs2 = { version = "0.4.3" }

crates/uv-cache/Cargo.toml

@@ -22,12 +22,13 @@ uv-normalize = { workspace = true }
 
 clap = { workspace = true, features = ["derive", "env"], optional = true }
 directories = { workspace = true }
+etcetera = { workspace = true }
 fs-err = { workspace = true, features = ["tokio"] }
 nanoid = { workspace = true }
+rmp-serde = { workspace = true }
 rustc-hash = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
 tempfile = { workspace = true }
 tracing = { workspace = true }
 url = { workspace = true }
 walkdir = { workspace = true }
-rmp-serde = { workspace = true }

crates/uv-cache/src/cli.rs

@@ -1,10 +1,10 @@
 use std::io;
 use std::path::PathBuf;
 
+use crate::Cache;
 use clap::Parser;
 use directories::ProjectDirs;
-
-use crate::Cache;
+use etcetera::BaseStrategy;
 
 #[derive(Parser, Debug, Clone)]
 #[command(next_help_heading = "Cache options")]
@@ -40,13 +40,24 @@ impl Cache {
     /// Returns an absolute cache dir.
     pub fn from_settings(no_cache: bool, cache_dir: Option<PathBuf>) -> Result<Self, io::Error> {
         if no_cache {
-            Cache::temp()
+            Self::temp()
         } else if let Some(cache_dir) = cache_dir {
-            Ok(Cache::from_path(cache_dir))
-        } else if let Some(project_dirs) = ProjectDirs::from("", "", "uv") {
-            Ok(Cache::from_path(project_dirs.cache_dir()))
+            Ok(Self::from_path(cache_dir))
+        } else if let Some(cache_dir) = ProjectDirs::from("", "", "uv")
+            .map(|dirs| dirs.cache_dir().to_path_buf())
+            .filter(|dir| dir.exists())
+        {
+            // If the user has an existing directory at (e.g.) `/Users/user/Library/Caches/uv`,
+            // respect it for backwards compatibility. Otherwise, prefer the XDG strategy, even on
+            // macOS.
+            Ok(Self::from_path(cache_dir))
+        } else if let Some(cache_dir) = etcetera::base_strategy::choose_base_strategy()
+            .ok()
+            .map(|dirs| dirs.cache_dir().join("uv"))
+        {
+            Ok(Self::from_path(cache_dir))
         } else {
-            Ok(Cache::from_path(".uv_cache"))
+            Ok(Self::from_path(".uv_cache"))
         }
     }
 }

crates/uv-fs/src/lib.rs

@@ -100,6 +100,24 @@ pub fn replace_symlink(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> std::io:
     }
 }
 
+#[cfg(unix)]
+pub fn remove_symlink(path: impl AsRef<Path>) -> std::io::Result<()> {
+    fs_err::remove_file(path.as_ref())
+}
+
+#[cfg(windows)]
+pub fn remove_symlink(path: impl AsRef<Path>) -> std::io::Result<()> {
+    match junction::delete(dunce::simplified(path.as_ref())) {
+        Ok(()) => match fs_err::remove_dir_all(path.as_ref()) {
+            Ok(()) => Ok(()),
+            Err(err) if err.kind() == std::io::ErrorKind::NotFound => Ok(()),
+            Err(err) => Err(err),
+        },
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => Ok(()),
+        Err(err) => Err(err),
+    }
+}
+
 /// Return a [`NamedTempFile`] in the specified directory.
 ///
 /// Sets the permissions of the temporary file to `0o666`, to match the non-temporary file default.
@@ -283,6 +301,14 @@ pub fn files(path: impl AsRef<Path>) -> impl Iterator<Item = PathBuf> {
         .map(|entry| entry.path())
 }
 
+/// Returns `true` if a path is a temporary file or directory.
+pub fn is_temporary(path: impl AsRef<Path>) -> bool {
+    path.as_ref()
+        .file_name()
+        .and_then(|name| name.to_str())
+        .map_or(false, |name| name.starts_with(".tmp"))
+}
+
 /// A file lock that is automatically released when dropped.
 #[derive(Debug)]
 pub struct LockedFile(fs_err::File);

crates/uv-state/Cargo.toml

@@ -14,5 +14,6 @@ workspace = true
 
 [dependencies]
 directories = { workspace = true }
+etcetera = { workspace = true }
 tempfile = { workspace = true }
 fs-err = { workspace = true }

crates/uv-state/src/lib.rs

@@ -5,6 +5,7 @@ use std::{
 };
 
 use directories::ProjectDirs;
+use etcetera::BaseStrategy;
 use fs_err as fs;
 use tempfile::{tempdir, TempDir};
 
@@ -84,8 +85,19 @@ impl StateStore {
     pub fn from_settings(state_dir: Option<PathBuf>) -> Result<Self, io::Error> {
         if let Some(state_dir) = state_dir {
             StateStore::from_path(state_dir)
-        } else if let Some(project_dirs) = ProjectDirs::from("", "", "uv") {
-            StateStore::from_path(project_dirs.data_dir())
+        } else if let Some(data_dir) = ProjectDirs::from("", "", "uv")
+            .map(|dirs| dirs.data_dir().to_path_buf())
+            .filter(|dir| dir.exists())
+        {
+            // If the user has an existing directory at (e.g.) `/Users/user/Library/Application Support/uv`,
+            // respect it for backwards compatibility. Otherwise, prefer the XDG strategy, even on
+            // macOS.
+            StateStore::from_path(data_dir)
+        } else if let Some(data_dir) = etcetera::base_strategy::choose_base_strategy()
+            .ok()
+            .map(|dirs| dirs.data_dir().join("uv"))
+        {
+            StateStore::from_path(data_dir)
         } else {
             StateStore::from_path(".uv")
         }

crates/uv/src/commands/python/uninstall.rs

@@ -22,11 +22,42 @@ pub(crate) async fn uninstall(
 
     printer: Printer,
 ) -> Result<ExitStatus> {
-    let start = std::time::Instant::now();
-
     let installations = ManagedPythonInstallations::from_settings()?.init()?;
     let _lock = installations.acquire_lock()?;
 
+    // Perform the uninstallation.
+    do_uninstall(&installations, targets, all, printer).await?;
+
+    // Clean up any empty directories.
+    if uv_fs::directories(installations.root()).all(|path| uv_fs::is_temporary(&path)) {
+        fs_err::tokio::remove_dir_all(&installations.root()).await?;
+
+        if let Some(top_level) = installations.root().parent() {
+            // Remove the `toolchains` symlink.
+            match uv_fs::remove_symlink(top_level.join("toolchains")) {
+                Ok(()) => {}
+                Err(err) if err.kind() == std::io::ErrorKind::NotFound => {}
+                Err(err) => return Err(err.into()),
+            }
+
+            if uv_fs::directories(top_level).all(|path| uv_fs::is_temporary(&path)) {
+                fs_err::tokio::remove_dir_all(top_level).await?;
+            }
+        }
+    }
+
+    Ok(ExitStatus::Success)
+}
+
+/// Perform the uninstallation of managed Python installations.
+async fn do_uninstall(
+    installations: &ManagedPythonInstallations,
+    targets: Vec<String>,
+    all: bool,
+    printer: Printer,
+) -> Result<ExitStatus> {
+    let start = std::time::Instant::now();
+
     let requests = if all {
         vec![PythonRequest::Any]
     } else {
@@ -108,6 +139,7 @@ pub(crate) async fn uninstall(
         }
     }
 
+    // Report on any uninstalled installations.
     if !uninstalled.is_empty() {
         if let [uninstalled] = uninstalled.as_slice() {
             // Ex) "Uninstalled Python 3.9.7 in 1.68s"

crates/uv/src/commands/tool/uninstall.rs

@@ -27,6 +27,28 @@ pub(crate) async fn uninstall(name: Option<PackageName>, printer: Printer) -> Re
         Err(err) => return Err(err.into()),
     };
 
+    // Perform the uninstallation.
+    do_uninstall(&installed_tools, name, printer).await?;
+
+    // Clean up any empty directories.
+    if uv_fs::directories(installed_tools.root()).all(|path| uv_fs::is_temporary(&path)) {
+        fs_err::tokio::remove_dir_all(&installed_tools.root()).await?;
+        if let Some(top_level) = installed_tools.root().parent() {
+            if uv_fs::directories(top_level).all(|path| uv_fs::is_temporary(&path)) {
+                fs_err::tokio::remove_dir_all(top_level).await?;
+            }
+        }
+    }
+
+    Ok(ExitStatus::Success)
+}
+
+/// Perform the uninstallation.
+async fn do_uninstall(
+    installed_tools: &InstalledTools,
+    name: Option<PackageName>,
+    printer: Printer,
+) -> Result<()> {
     let mut dangling = false;
     let mut entrypoints = if let Some(name) = name {
         let Some(receipt) = installed_tools.get_tool_receipt(&name)? else {
@@ -37,7 +59,7 @@ pub(crate) async fn uninstall(name: Option<PackageName>, printer: Printer) -> Re
                         printer.stderr(),
                         "Removed dangling environment for `{name}`"
                     )?;
-                    return Ok(ExitStatus::Success);
+                    return Ok(());
                 }
                 Err(uv_tool::Error::Io(err)) if err.kind() == std::io::ErrorKind::NotFound => {
                     bail!("`{name}` is not installed");
@@ -48,7 +70,7 @@ pub(crate) async fn uninstall(name: Option<PackageName>, printer: Printer) -> Re
             }
         };
 
-        uninstall_tool(&name, &receipt, &installed_tools).await?
+        uninstall_tool(&name, &receipt, installed_tools).await?
     } else {
         let mut entrypoints = vec![];
         for (name, receipt) in installed_tools.tools()? {
@@ -72,7 +94,7 @@ pub(crate) async fn uninstall(name: Option<PackageName>, printer: Printer) -> Re
                 }
             };
 
-            entrypoints.extend(uninstall_tool(&name, &receipt, &installed_tools).await?);
+            entrypoints.extend(uninstall_tool(&name, &receipt, installed_tools).await?);
         }
         entrypoints
     };
@@ -83,7 +105,7 @@ pub(crate) async fn uninstall(name: Option<PackageName>, printer: Printer) -> Re
         if !dangling {
             writeln!(printer.stderr(), "Nothing to uninstall")?;
         }
-        return Ok(ExitStatus::Success);
+        return Ok(());
     }
 
     let s = if entrypoints.len() == 1 { "" } else { "s" };
@@ -97,7 +119,7 @@ pub(crate) async fn uninstall(name: Option<PackageName>, printer: Printer) -> Re
             .join(", ")
     )?;
 
-    Ok(ExitStatus::Success)
+    Ok(())
 }
 
 /// Uninstall a tool.