Add a wrapper for utimes(2)

PR #944 added wrappers for the more-modern futimens(2) and utimesat(2),
but unfortunately these APIs are not available on old-ish systems.

In particular, macOS Sierra and below don't implement them, making the
new APIs unusable.  Whether we should care about such "old" systems is
debatable, but the problem is that, at the moment, this is the only
macOS version usable on Travis to test kexts and, thus, to test FUSE
file systems.

CHANGELOG.md

@@ -16,8 +16,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#916](https://github.com/nix-rust/nix/pull/916))
 - Added `kmod` module that allows loading and unloading kernel modules on Linux.
   ([#930](https://github.com/nix-rust/nix/pull/930))
-- Added `futimens` and `utimesat` wrappers.
-  ([#944](https://github.com/nix-rust/nix/pull/944))
+- Added `futimens` and `utimesat` wrappers ([#944](https://github.com/nix-rust/nix/pull/944))
+  and a `utimes` wrapper ([#946](https://github.com/nix-rust/nix/pull/946)).
 
 ### Changed
 - Increased required Rust version to 1.22.1/

src/sys/stat.rs

@@ -8,7 +8,7 @@ use libc::{self, mode_t};
 use std::mem;
 use std::os::raw;
 use std::os::unix::io::RawFd;
-use sys::time::TimeSpec;
+use sys::time::{TimeSpec, TimeVal};
 
 libc_bitflags!(
     pub struct SFlag: mode_t {
@@ -190,6 +190,25 @@ pub fn fchmodat<P: ?Sized + NixPath>(
     Errno::result(res).map(|_| ())
 }
 
+/// Change the access and modification times of a file.
+///
+/// `utimes(path, times)` is identical to
+/// `utimensat(None, path, times, UtimensatFlags::FollowSymlink)`. The former
+/// is a deprecated API so prefer using the latter if the platforms you care
+/// about support it.
+///
+/// # References
+///
+/// [utimes(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/utimes.html).
+pub fn utimes<P: ?Sized + NixPath>(path: &P, atime: &TimeVal, mtime: &TimeVal) -> Result<()> {
+    let times: [libc::timeval; 2] = [*atime.as_ref(), *mtime.as_ref()];
+    let res = path.with_nix_path(|cstr| unsafe {
+        libc::utimes(cstr.as_ptr(), &times[0])
+    })?;
+
+    Errno::result(res).map(|_| ())
+}
+
 /// Change the access and modification times of the file specified by a file descriptor.
 ///
 /// # References
@@ -220,7 +239,8 @@ pub enum UtimensatFlags {
 /// then the mode of the symbolic link is changed.
 ///
 /// `utimensat(None, path, times, UtimensatFlags::FollowSymlink)` is identical to
-/// `libc::utimes(path, times)`. That's why `utimes` is unimplemented in the `nix` crate.
+/// `utimes(path, times)`. The latter is a deprecated API so prefer using the
+/// former if the platforms you care about support it.
 ///
 /// # References
 ///

test/test_stat.rs

@@ -6,9 +6,9 @@ use std::time::{Duration, UNIX_EPOCH};
 use libc::{S_IFMT, S_IFLNK};
 
 use nix::fcntl;
-use nix::sys::stat::{self, fchmod, fchmodat, fstat, futimens, lstat, stat, utimensat};
+use nix::sys::stat::{self, fchmod, fchmodat, fstat, futimens, lstat, stat, utimes, utimensat};
 use nix::sys::stat::{FileStat, Mode, FchmodatFlags, UtimensatFlags};
-use nix::sys::time::{TimeSpec, TimeValLike};
+use nix::sys::time::{TimeSpec, TimeVal, TimeValLike};
 use nix::unistd::chdir;
 use nix::Result;
 use tempfile;
@@ -168,6 +168,16 @@ fn assert_times_eq(exp_atime_sec: u64, exp_mtime_sec: u64, attr: &fs::Metadata)
         attr.modified().unwrap().duration_since(UNIX_EPOCH).unwrap());
 }
 
+#[test]
+fn test_utimes() {
+    let tempdir = tempfile::tempdir().unwrap();
+    let fullpath = tempdir.path().join("file");
+    drop(File::create(&fullpath).unwrap());
+
+    utimes(&fullpath, &TimeVal::seconds(9990), &TimeVal::seconds(5550));
+    assert_times_eq(9990, 5550, &fs::metadata(&fullpath).unwrap());
+}
+
 #[test]
 fn test_futimens() {
     let tempdir = tempfile::tempdir().unwrap();