From: Linus Heckemann <git@sphalerite•org>
To: depot@tvl.su
Cc: Linus Heckemann <git@sphalerite•org>
Subject: [PATCH] fix(tvix/eval): allow negative substring lengths
Date: Thu, 1 Jun 2023 21:22:59 +0200 [thread overview]
Message-ID: <20230601192258.1159372-1-git@sphalerite.org> (raw)
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
---
tvix/eval/src/builtins/mod.rs | 10 +++++-----
tvix/eval/src/errors.rs | 15 ---------------
2 files changed, 5 insertions(+), 20 deletions(-)
diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index 53ad6f3f8..ab19ca5ea 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -869,11 +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 len = if len < 0 {
+ x.as_str().len() as usize
+ } else {
+ len as usize
+ };
let end = cmp::min(beg + len, 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 2fbb6496c..76f55d681 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",
--
2.40.1
next reply other threads:[~2023-06-01 19:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-01 19:22 Linus Heckemann [this message]
2023-06-02 13:02 ` sternenseemann
2023-06-02 13:07 ` Vincent Ambo
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