From 5733274876e6f6c0be8b43b4a46bdfeea73fa761 Mon Sep 17 00:00:00 2001 From: Linus Heckemann Date: Thu, 1 Jun 2023 21:22:59 +0200 Subject: fix(tvix/eval): allow negative substring lengths Nix uses string::substr without checking the sign of the length[1]. The NixOS testing infrastructure relies on this[2], and on the implicit conversion of that to the maximum possible value for a size_t. [1]: https://github.com/NixOS/nix/blob/ecae62020b64914d9859a71ce197d03688c6133c/src/libexpr/primops.cc#L3597 [2]: https://github.com/NixOS/nixpkgs/blob/c7c298471676ac1c7789ab3c424fbcebecaa6791/nixos/lib/testing/driver.nix#L29 Change-Id: I6d0caf6830b6bda3fdf44c40c81de6a1befeca7b Reviewed-on: https://cl.tvl.fyi/c/depot/+/8746 Reviewed-by: flokli Tested-by: BuildkiteCI --- tvix/eval/src/builtins/mod.rs | 11 +++++------ tvix/eval/src/errors.rs | 15 --------------- 2 files changed, 5 insertions(+), 21 deletions(-) (limited to 'tvix/eval') diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs index 53ad6f3f8e50..b5c7931768e9 100644 --- a/tvix/eval/src/builtins/mod.rs +++ b/tvix/eval/src/builtins/mod.rs @@ -869,12 +869,11 @@ mod pure_builtins { return Ok(Value::String("".into())); } - if len < 0 { - return Err(ErrorKind::NegativeLength { length: len }); - } - - let len = len as usize; - let end = cmp::min(beg + len, x.as_str().len()); + let end = if len < 0 { + x.as_str().len() as usize + } else { + cmp::min(beg + (len as usize), x.as_str().len()) + }; Ok(Value::String(x.as_str()[beg..end].into())) } diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs index 2fbb6496ceea..76f55d681299 100644 --- a/tvix/eval/src/errors.rs +++ b/tvix/eval/src/errors.rs @@ -108,11 +108,6 @@ pub enum ErrorKind { /// An error occurred when parsing an integer ParseIntError(ParseIntError), - /// A negative integer was used as a value representing length. - NegativeLength { - length: i64, - }, - // Errors specific to nested attribute sets and merges thereof. /// Nested attributes can not be merged with an inherited value. UnmergeableInherit { @@ -396,14 +391,6 @@ to a missing value in the attribute set(s) included via `with`."#, write!(f, "invalid integer: {}", err) } - ErrorKind::NegativeLength { length } => { - write!( - f, - "cannot use a negative integer, {}, for a value representing length", - length - ) - } - ErrorKind::UnmergeableInherit { name } => { write!( f, @@ -765,7 +752,6 @@ impl Error { | ErrorKind::NotCoercibleToString { .. } | ErrorKind::NotAnAbsolutePath(_) | ErrorKind::ParseIntError(_) - | ErrorKind::NegativeLength { .. } | ErrorKind::UnmergeableInherit { .. } | ErrorKind::UnmergeableValue | ErrorKind::ImportParseError { .. } @@ -808,7 +794,6 @@ impl Error { ErrorKind::IndexOutOfBounds { .. } => "E019", ErrorKind::NotAnAbsolutePath(_) => "E020", ErrorKind::ParseIntError(_) => "E021", - ErrorKind::NegativeLength { .. } => "E022", ErrorKind::TailEmptyList { .. } => "E023", ErrorKind::UnmergeableInherit { .. } => "E024", ErrorKind::UnmergeableValue => "E025", -- cgit 1.4.1