refactor(tvix/nix-compat): support non-unicode Derivations r/6449

Derivations can have non-unicode strings in their env values, so the
ATerm representations are not necessarily String anymore, but Vec<u8>.

Change-Id: Ic23839471eb7f68d9c3c30667c878830946b6607
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8990
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: flokli <flokli@flokli.de>

1 files changed, 31 insertions, 0 deletions

diff --git a/tvix/nix-compat/src/derivation/escape.rs b/tvix/nix-compat/src/derivation/escape.rs
new file mode 100644
index 0000000000..03106c4420
--- /dev/null
+++ b/tvix/nix-compat/src/derivation/escape.rs
@@ -0,0 +1,31 @@
+use bstr::{BString, ByteSlice};
+
+pub fn escape_bstr(s: &[u8]) -> BString {
+    let mut s: Vec<u8> = s.to_owned();
+
+    s = s.replace(b"\\", b"\\\\");
+    s = s.replace(b"\n", b"\\n");
+    s = s.replace(b"\r", b"\\r");
+    s = s.replace(b"\t", b"\\t");
+    s = s.replace(b"\"", b"\\\"");
+
+    let mut out: Vec<u8> = Vec::new();
+    out.push(b'\"');
+    out.append(&mut s);
+    out.push(b'\"');
+
+    out.into()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::escape_bstr;
+    use test_case::test_case;
+
+    #[test_case(b"", b"\"\""; "empty")]
+    #[test_case(b"\"", b"\"\\\"\""; "doublequote")]
+    #[test_case(b":", b"\":\""; "colon")]
+    fn escape(input: &[u8], expected: &[u8]) {
+        assert_eq!(expected, escape_bstr(input))
+    }
+}