Accept SRC:DST remap syntax in --ro/--rw

src/errors.rs

@@ -27,6 +27,7 @@ pub enum SandboxError {
     UnknownConfigKey(String),
     ConfigPathNotAbsolute(PathBuf),
     InvalidBwrapArg(String),
+    InvalidBindSpec(String),
     NoCommand,
     Seccomp(String),
     SeccompUnsupportedArch(String),
@@ -80,6 +81,9 @@ impl std::fmt::Display for SandboxError {
             Self::InvalidBwrapArg(s) => {
                 write!(f, "invalid quoting in --bwrap-arg: {s}")
             }
+            Self::InvalidBindSpec(s) => {
+                write!(f, "invalid bind spec (expected SRC or SRC:DST): {s:?}")
+            }
             Self::NoCommand => write!(
                 f,
                 "no command to run; specify a command via config, entrypoint, or pass one after --"