fix(node): validate encoded CPU build flags

nodejs/build_support/x86_64_v2.rs

@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: Copyright The LanceDB Authors
+
+use std::collections::{BTreeMap, BTreeSet};
+
+const BASELINE_CPU: &str = "x86-64-v2";
+const BASELINE_FEATURES: [&str; 9] = [
+    "cmpxchg16b",
+    "fxsr",
+    "popcnt",
+    "sse",
+    "sse2",
+    "sse3",
+    "sse4.1",
+    "sse4.2",
+    "ssse3",
+];
+
+pub(crate) fn validate_encoded_rustflags(encoded: &str) -> Result<(), String> {
+    let mut target_cpu = None;
+    let mut feature_states = BTreeMap::new();
+    let mut required_disables = BTreeSet::new();
+    let mut unsupported_features = BTreeSet::new();
+
+    for option in codegen_options(encoded)? {
+        let Some((name, value)) = option.split_once('=') else {
+            continue;
+        };
+
+        match name {
+            "target-cpu" => target_cpu = Some(value),
+            "target-feature" => {
+                for toggle in value.split(',').filter(|toggle| !toggle.is_empty()) {
+                    let (enabled, feature) = match toggle.as_bytes()[0] {
+                        b'+' => (true, &toggle[1..]),
+                        b'-' => (false, &toggle[1..]),
+                        _ => return Err(format!("invalid target feature flag: {toggle}")),
+                    };
+
+                    feature_states.insert(feature, enabled);
+                    if enabled && !BASELINE_FEATURES.contains(&feature) {
+                        match feature {
+                            // These are inherited from the workspace configuration and
+                            // explicitly canceled by the Node configuration. Account for
+                            // their implied AVX prerequisite as well as the named feature.
+                            "avx" => {
+                                required_disables.insert("avx");
+                            }
+                            "avx2" => {
+                                required_disables.extend(["avx", "avx2"]);
+                            }
+                            "f16c" => {
+                                required_disables.extend(["avx", "f16c"]);
+                            }
+                            "fma" => {
+                                required_disables.extend(["avx", "fma"]);
+                            }
+                            _ => {
+                                unsupported_features.insert(feature);
+                            }
+                        }
+                    }
+                }
+            }
+            // LLVM arguments can independently alter the target feature set and
+            // cannot be proven safe by inspecting rustc's target options.
+            "llvm-args" => return Err("LLVM arguments can override the CPU baseline".to_owned()),
+            _ => {}
+        }
+    }
+
+    if target_cpu != Some(BASELINE_CPU) {
+        return Err(format!(
+            "effective target CPU is {}, expected {BASELINE_CPU}",
+            target_cpu.unwrap_or("unset")
+        ));
+    }
+
+    if !unsupported_features.is_empty() {
+        return Err(format!(
+            "features above v2: {}",
+            unsupported_features
+                .into_iter()
+                .collect::<Vec<_>>()
+                .join(", ")
+        ));
+    }
+
+    let not_disabled = required_disables
+        .into_iter()
+        .filter(|feature| feature_states.get(feature) != Some(&false))
+        .collect::<Vec<_>>();
+    if !not_disabled.is_empty() {
+        return Err(format!(
+            "inherited features not fully disabled: {}",
+            not_disabled.join(", ")
+        ));
+    }
+
+    Ok(())
+}
+
+fn codegen_options(encoded: &str) -> Result<Vec<&str>, String> {
+    let arguments = encoded.split('\u{1f}').collect::<Vec<_>>();
+    let mut options = Vec::new();
+    let mut index = 0;
+
+    while index < arguments.len() {
+        let argument = arguments[index];
+        if argument == "-C" || argument == "--codegen" {
+            index += 1;
+            let option = arguments
+                .get(index)
+                .copied()
+                .ok_or_else(|| format!("missing value after {argument}"))?;
+            options.push(option.trim_start_matches('='));
+        } else if let Some(option) = argument.strip_prefix("-C") {
+            if !option.is_empty() {
+                options.push(option.trim_start_matches('='));
+            }
+        } else if let Some(option) = argument.strip_prefix("--codegen=") {
+            options.push(option);
+        }
+        index += 1;
+    }
+
+    Ok(options)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn encoded(arguments: &[&str]) -> String {
+        arguments.join("\u{1f}")
+    }
+
+    #[test]
+    fn accepts_merged_workspace_and_node_flags() {
+        let flags = encoded(&[
+            "-C",
+            "target-cpu=haswell",
+            "-C",
+            "target-feature=+avx2,+fma,+f16c",
+            "-C",
+            "target-cpu=x86-64-v2",
+            "-C",
+            "target-feature=-avx,-avx2,-fma,-f16c",
+        ]);
+
+        assert_eq!(validate_encoded_rustflags(&flags), Ok(()));
+    }
+
+    #[test]
+    fn accepts_non_merging_v2_boundary() {
+        let flags = encoded(&["-Ctarget-cpu=x86-64-v2"]);
+
+        assert_eq!(validate_encoded_rustflags(&flags), Ok(()));
+    }
+
+    #[test]
+    fn accepts_musl_dynamic_crt_configuration() {
+        let flags = encoded(&[
+            "-C",
+            "target-cpu=haswell",
+            "-C",
+            "target-feature=-crt-static,+avx2,+fma,+f16c",
+            "-C",
+            "target-cpu=x86-64-v2",
+            "-C",
+            "target-feature=-crt-static,-avx,-avx2,-fma,-f16c",
+        ]);
+
+        assert_eq!(validate_encoded_rustflags(&flags), Ok(()));
+    }
+
+    #[test]
+    fn rejects_feature_omitted_from_target_cfg() {
+        let flags = encoded(&["-Ctarget-cpu=x86-64-v2", "-Ctarget-feature=+apxf"]);
+
+        assert_eq!(
+            validate_encoded_rustflags(&flags),
+            Err("features above v2: apxf".to_owned())
+        );
+    }
+
+    #[test]
+    fn rejects_unexpected_above_baseline_feature() {
+        let flags = encoded(&[
+            "--codegen=target-cpu=x86-64-v2",
+            "--codegen",
+            "target-feature=+bmi2",
+        ]);
+
+        assert_eq!(
+            validate_encoded_rustflags(&flags),
+            Err("features above v2: bmi2".to_owned())
+        );
+    }
+
+    #[test]
+    fn rejects_incompletely_disabled_feature_implications() {
+        let flags = encoded(&["-Ctarget-cpu=x86-64-v2", "-Ctarget-feature=+avx2,-avx2"]);
+
+        assert_eq!(
+            validate_encoded_rustflags(&flags),
+            Err("inherited features not fully disabled: avx".to_owned())
+        );
+    }
+
+    #[test]
+    fn rejects_llvm_feature_overrides() {
+        let flags = encoded(&["-Ctarget-cpu=x86-64-v2", "-Cllvm-args=-mattr=+apxf"]);
+
+        assert_eq!(
+            validate_encoded_rustflags(&flags),
+            Err("LLVM arguments can override the CPU baseline".to_owned())
+        );
+    }
+}