Add `std::os::unix::process::CommandExt::chroot` to safely chroot a child process

This adds a `chroot` method to the `CommandExt` extension trait for the
`Command` builder, to set a directory to chroot into. This will chroot
the child process into that directory right before calling chdir for the
`Command`'s working directory.

To avoid allowing a process to have a working directory outside of the
chroot, if the `Command` does not yet have a working directory set,
`chroot` will set its working directory to "/".

1 files changed, 6 insertions, 0 deletions

diff --git a/library/std/src/sys/process/unix/vxworks.rs b/library/std/src/sys/process/unix/vxworks.rs
index fab3b36ebf3..f33b4a375da 100644
--- a/library/std/src/sys/process/unix/vxworks.rs
+++ b/library/std/src/sys/process/unix/vxworks.rs
@@ -27,6 +27,12 @@ impl Command {
                 "nul byte found in provided data",
             ));
         }
+        if self.get_chroot().is_some() {
+            return Err(io::const_error!(
+                ErrorKind::Unsupported,
+                "chroot not supported by vxworks",
+            ));
+        }
         let (ours, theirs) = self.setup_io(default, needs_stdin)?;
         let mut p = Process { pid: 0, status: None };