Auto merge of #9164 - ehuss:config-search-stop, r=Eh2406

Prevent testsuite from loading config out of sandbox.

This adds a limit to prevent config loading from walking outside of the test sandbox root. There was an environment variable for this, but that doesn't work too well for tests that were loading the config directly.

Fixes #9107

src/bin/cargo/commands/install.rs

@@ -78,6 +78,7 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     if let Some(path) = args.value_of_path("path", config) {
         config.reload_rooted_at(path)?;
     } else {
+        // TODO: Consider calling set_search_stop_path(home).
         config.reload_rooted_at(config.home().clone().into_path_unlocked())?;
     }
 

src/cargo/core/workspace.rs

@@ -461,7 +461,7 @@ impl<'cfg> Workspace<'cfg> {
             }
         }
 
-        for path in paths::ancestors(manifest_path).skip(2) {
+        for path in paths::ancestors(manifest_path, None).skip(2) {
             if path.ends_with("target/package") {
                 break;
             }

src/cargo/ops/cargo_new.rs

@@ -872,7 +872,7 @@ fn find_tests_git_config(path: &Path) -> Option<GitConfig> {
     // Don't escape the test sandbox when looking for a git repository.
     // NOTE: libgit2 has support to define the path ceiling in
     // git_repository_discover, but the git2 bindings do not expose that.
-    for path in paths::ancestors(path) {
+    for path in paths::ancestors(path, None) {
         if let Ok(repo) = GitRepository::open(path) {
             return Some(repo.config().expect("test repo should have valid config"));
         }

src/cargo/util/config/mod.rs

@@ -132,6 +132,8 @@ pub struct Config {
     cli_config: Option<Vec<String>>,
     /// The current working directory of cargo
     cwd: PathBuf,
+    /// Directory where config file searching should stop (inclusive).
+    search_stop_path: Option<PathBuf>,
     /// The location of the cargo executable (path to current process)
     cargo_exe: LazyCell<PathBuf>,
     /// The location of the rustdoc executable
@@ -218,6 +220,7 @@ impl Config {
             home_path: Filesystem::new(homedir),
             shell: RefCell::new(shell),
             cwd,
+            search_stop_path: None,
             values: LazyCell::new(),
             cli_config: None,
             cargo_exe: LazyCell::new(),
@@ -422,6 +425,14 @@ impl Config {
         }
     }
 
+    /// Sets the path where ancestor config file searching will stop. The
+    /// given path is included, but its ancestors are not.
+    pub fn set_search_stop_path<P: Into<PathBuf>>(&mut self, path: P) {
+        let path = path.into();
+        debug_assert!(self.cwd.starts_with(&path));
+        self.search_stop_path = Some(path);
+    }
+
     /// Reloads on-disk configuration values, starting at the given path and
     /// walking up its ancestors.
     pub fn reload_rooted_at<P: AsRef<Path>>(&mut self, path: P) -> CargoResult<()> {
@@ -1028,7 +1039,7 @@ impl Config {
     {
         let mut stash: HashSet<PathBuf> = HashSet::new();
 
-        for current in paths::ancestors(pwd) {
+        for current in paths::ancestors(pwd, self.search_stop_path.as_deref()) {
             if let Some(path) = self.get_file_path(&current.join(".cargo"), "config", true)? {
                 walk(&path)?;
                 stash.insert(path);

src/cargo/util/important_paths.rs

@@ -5,7 +5,7 @@ use std::path::{Path, PathBuf};
 /// Finds the root `Cargo.toml`.
 pub fn find_root_manifest_for_wd(cwd: &Path) -> CargoResult<PathBuf> {
     let file = "Cargo.toml";
-    for current in paths::ancestors(cwd) {
+    for current in paths::ancestors(cwd, None) {
         let manifest = current.join(file);
         if manifest.exists() {
             return Ok(manifest);

src/cargo/util/paths.rs

@@ -306,8 +306,8 @@ pub fn bytes2path(bytes: &[u8]) -> CargoResult<PathBuf> {
     }
 }
 
-pub fn ancestors(path: &Path) -> PathAncestors<'_> {
-    PathAncestors::new(path)
+pub fn ancestors<'a>(path: &'a Path, stop_root_at: Option<&Path>) -> PathAncestors<'a> {
+    PathAncestors::new(path, stop_root_at)
 }
 
 pub struct PathAncestors<'a> {
@@ -316,11 +316,15 @@ pub struct PathAncestors<'a> {
 }
 
 impl<'a> PathAncestors<'a> {
-    fn new(path: &Path) -> PathAncestors<'_> {
+    fn new(path: &'a Path, stop_root_at: Option<&Path>) -> PathAncestors<'a> {
+        let stop_at = env::var("__CARGO_TEST_ROOT")
+            .ok()
+            .map(PathBuf::from)
+            .or_else(|| stop_root_at.map(|p| p.to_path_buf()));
         PathAncestors {
             current: Some(path),
             //HACK: avoid reading `~/.cargo/config` when testing Cargo itself.
-            stop_at: env::var("__CARGO_TEST_ROOT").ok().map(PathBuf::from),
+            stop_at,
         }
     }
 }

tests/testsuite/config.rs

@@ -77,6 +77,7 @@ impl ConfigBuilder {
         let homedir = paths::home();
         let mut config = Config::new(shell, cwd, homedir);
         config.set_env(self.env.clone());
+        config.set_search_stop_path(paths::root());
         config.configure(
             0,
             false,