libstd: add fs::change_dir()

src/lib/fs.rs

@@ -178,6 +178,21 @@ fn remove_dir(p: path) -> bool {
     }
 }
 
+fn change_dir(p: path) -> bool {
+    ret chdir(p);
+
+    #[cfg(target_os = "win32")]
+    fn chdir(_p: path) -> bool {
+        ret str::as_buf(_p, {|buf| os::kernel32::SetCurrentDirectory(buf)});
+    }
+
+    #[cfg(target_os = "linux")]
+    #[cfg(target_os = "macos")]
+    fn chdir(_p: path) -> bool {
+        ret str::as_buf(_p, {|buf| os::libc::chdir(buf) == 0i32 });
+    }
+}
+
 /*
 Function: path_is_absolute
 

src/lib/linux_os.rs

@@ -53,6 +53,7 @@ native mod libc {
     fn readlink(path: str::sbuf, buf: str::sbuf, bufsize: size_t) -> ssize_t;
     fn mkdir(path: str::sbuf, mode: c_int) -> c_int;
     fn rmdir(path: str::sbuf) -> c_int;
+    fn chdir(path: str::sbuf) -> c_int;
 }
 
 mod libc_constants {

src/lib/macos_os.rs

@@ -46,6 +46,7 @@ native mod libc {
     fn waitpid(pid: pid_t, &status: c_int, options: c_int) -> c_int;
     fn mkdir(s: str::sbuf, mode: c_int) -> c_int;
     fn rmdir(s: str::sbuf) -> c_int;
+    fn chdir(s: str::sbuf) -> c_int;
 }
 
 mod libc_constants {

src/lib/win32_os.rs

@@ -55,6 +55,7 @@ native mod kernel32 {
     fn CreateDirectoryA(lpPathName: LPCTSTR,
                         lpSecurityAttributes: LPSECURITY_ATTRIBUTES) -> bool;
     fn RemoveDirectoryA(lpPathName: LPCTSTR) -> bool;
+    fn SetCurrentDirectory(lpPathName: LPCTSTR) -> bool;
 }
 
 // FIXME turn into constants