fix(utils): don't use O_NOFOLLOW in open_dir()

src/toolchain/toolchain.rs

@@ -19,7 +19,7 @@ use crate::{
     currentprocess::{process, varsource::VarSource},
     env_var, install,
     notifications::Notification,
-    utils::{raw::open_dir, utils},
+    utils::{raw::open_dir_following_links, utils},
     RustupError,
 };
 
@@ -62,7 +62,7 @@ impl<'a> Toolchain<'a> {
         let base_name = path
             .file_name()
             .ok_or_else(|| RustupError::InvalidToolchainName(name.to_string()))?;
-        let parent_dir = match open_dir(parent) {
+        let parent_dir = match open_dir_following_links(parent) {
             Ok(d) => d,
             Err(e) if e.kind() == io::ErrorKind::NotFound => return Ok(false),
             e => e?,

src/utils/raw.rs

@@ -31,7 +31,7 @@ pub fn is_file<P: AsRef<Path>>(path: P) -> bool {
 }
 
 #[cfg(windows)]
-pub fn open_dir(p: &Path) -> std::io::Result<File> {
+pub fn open_dir_following_links(p: &Path) -> std::io::Result<File> {
     use std::fs::OpenOptions;
     use std::os::windows::fs::OpenOptionsExt;
 
@@ -42,14 +42,13 @@ pub fn open_dir(p: &Path) -> std::io::Result<File> {
     options.custom_flags(FILE_FLAG_BACKUP_SEMANTICS);
     options.open(p)
 }
+
 #[cfg(not(windows))]
-pub fn open_dir(p: &Path) -> std::io::Result<File> {
+pub fn open_dir_following_links(p: &Path) -> std::io::Result<File> {
     use std::fs::OpenOptions;
-    use std::os::unix::fs::OpenOptionsExt;
 
     let mut options = OpenOptions::new();
     options.read(true);
-    options.custom_flags(libc::O_NOFOLLOW);
     options.open(p)
 }
 

tests/suite/cli_misc.rs

@@ -677,7 +677,33 @@ fn rename_rls_remove() {
     });
 }
 
+// issue #3737
+/// `~/.rustup/toolchains` is permitted to be a symlink.
+#[test]
+#[cfg(any(unix, windows))]
+fn toolchains_symlink() {
+    use rustup::utils::raw::symlink_dir;
+    use std::fs;
+
+    clitools::test(Scenario::SimpleV2, &|config| {
+        let cwd = config.current_dir();
+        let test_toolchains = cwd.join("toolchains-test");
+        fs::create_dir(&test_toolchains).unwrap();
+        symlink_dir(&test_toolchains, &config.rustupdir.join("toolchains")).unwrap();
+
+        config.expect_ok(&["rustup", "default", "nightly"]);
+        config.expect_ok_contains(&["rustup", "toolchain", "list"], "nightly", "");
+        config.expect_ok_contains(&["rustc", "--version"], "hash-nightly-2", "");
+        config.expect_ok(&["rustup", "toolchain", "uninstall", "nightly"]);
+        config.expect_stdout_ok(
+            &["rustup", "toolchain", "list"],
+            "no installed toolchains\n",
+        );
+    });
+}
+
 // issue #1169
+/// A toolchain that is a stale symlink should be correctly uninstalled.
 #[test]
 #[cfg(any(unix, windows))]
 fn toolchain_broken_symlink() {