From 5de56b3ca1defd9206db8364ecef5f3fd8cc5b38 Mon Sep 17 00:00:00 2001
From: Barosl Lee <vcs@barosl.com>
Date: Tue, 11 Nov 2014 17:13:10 +0900
Subject: [PATCH] Make os::change_dir() return IoResult<()>

os::change_dir() returns bool, without a meaningful error message.
Change it to return IoResult<()> to indicate what IoError caused the
failure.

Fixes #16315.

[breaking-change]
---
 src/libstd/os.rs              | 29 +++++++++++++++--------------
 src/test/run-pass/tempfile.rs |  2 +-
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/libstd/os.rs b/src/libstd/os.rs
index 971138c06fb..cf22b8014ca 100644
--- a/src/libstd/os.rs
+++ b/src/libstd/os.rs
@@ -867,32 +867,33 @@ pub fn make_absolute(p: &Path) -> IoResult<Path> {
 /// use std::path::Path;
 ///
 /// let root = Path::new("/");
-/// assert!(os::change_dir(&root));
+/// assert!(os::change_dir(&root).is_ok());
 /// println!("Successfully changed working directory to {}!", root.display());
 /// ```
-pub fn change_dir(p: &Path) -> bool {
+pub fn change_dir(p: &Path) -> IoResult<()> {
     return chdir(p);
 
     #[cfg(windows)]
-    fn chdir(p: &Path) -> bool {
-        let p = match p.as_str() {
-            Some(s) => {
-                let mut p = s.utf16_units().collect::<Vec<u16>>();
-                p.push(0);
-                p
-            }
-            None => return false,
-        };
+    fn chdir(p: &Path) -> IoResult<()> {
+        let mut p = p.as_str().unwrap().utf16_units().collect::<Vec<u16>>();
+        p.push(0);
+
         unsafe {
-            libc::SetCurrentDirectoryW(p.as_ptr()) != (0 as libc::BOOL)
+            match libc::SetCurrentDirectoryW(p.as_ptr()) != (0 as libc::BOOL) {
+                true => Ok(()),
+                false => Err(IoError::last_error()),
+            }
         }
     }
 
     #[cfg(unix)]
-    fn chdir(p: &Path) -> bool {
+    fn chdir(p: &Path) -> IoResult<()> {
         p.with_c_str(|buf| {
             unsafe {
-                libc::chdir(buf) == (0 as c_int)
+                match libc::chdir(buf) == (0 as c_int) {
+                    true => Ok(()),
+                    false => Err(IoError::last_error()),
+                }
             }
         })
     }
diff --git a/src/test/run-pass/tempfile.rs b/src/test/run-pass/tempfile.rs
index bf47a516bc8..7400c52a73b 100644
--- a/src/test/run-pass/tempfile.rs
+++ b/src/test/run-pass/tempfile.rs
@@ -190,7 +190,7 @@ pub fn dont_double_panic() {
 
 fn in_tmpdir(f: ||) {
     let tmpdir = TempDir::new("test").ok().expect("can't make tmpdir");
-    assert!(os::change_dir(tmpdir.path()));
+    assert!(os::change_dir(tmpdir.path()).is_ok());
 
     f();
 }