diff options
| -rw-r--r-- | src/unistd.rs | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/unistd.rs b/src/unistd.rs index 71448248..89ba3db9 100644 --- a/src/unistd.rs +++ b/src/unistd.rs @@ -114,8 +114,12 @@ pub fn chdir<P: ?Sized + NixPath>(path: &P) -> Result<()> { #[inline] pub fn chown<P: ?Sized + NixPath>(path: &P, owner: Option<uid_t>, group: Option<gid_t>) -> Result<()> { let res = try!(path.with_nix_path(|cstr| { - // We use `0 - 1` to get `-1 : {u,g}id_t` which is specified as the no-op value for chown(3). - unsafe { libc::chown(cstr.as_ptr(), owner.unwrap_or(0 - 1), group.unwrap_or(0 - 1)) } + // According to the POSIX specification, -1 is used to indicate that + // owner and group, respectively, are not to be changed. Since uid_t and + // gid_t are unsigned types, we use wrapping_sub to get '-1'. + unsafe { libc::chown(cstr.as_ptr(), + owner.unwrap_or((0 as uid_t).wrapping_sub(1)), + group.unwrap_or((0 as gid_t).wrapping_sub(1))) } })); Errno::result(res).map(drop) |