migrating execpolicy -> execpolicy-legacy and execpolicy2 -> execpolicy (#6956)

codex-rs/execpolicy/src/rule.rs

@@ -0,0 +1,147 @@
+use crate::decision::Decision;
+use crate::error::Error;
+use crate::error::Result;
+use serde::Deserialize;
+use serde::Serialize;
+use shlex::try_join;
+use std::any::Any;
+use std::fmt::Debug;
+use std::sync::Arc;
+
+/// Matches a single command token, either a fixed string or one of several allowed alternatives.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum PatternToken {
+    Single(String),
+    Alts(Vec<String>),
+}
+
+impl PatternToken {
+    fn matches(&self, token: &str) -> bool {
+        match self {
+            Self::Single(expected) => expected == token,
+            Self::Alts(alternatives) => alternatives.iter().any(|alt| alt == token),
+        }
+    }
+
+    pub fn alternatives(&self) -> &[String] {
+        match self {
+            Self::Single(expected) => std::slice::from_ref(expected),
+            Self::Alts(alternatives) => alternatives,
+        }
+    }
+}
+
+/// Prefix matcher for commands with support for alternative match tokens.
+/// First token is fixed since we key by the first token in policy.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct PrefixPattern {
+    pub first: Arc<str>,
+    pub rest: Arc<[PatternToken]>,
+}
+
+impl PrefixPattern {
+    pub fn matches_prefix(&self, cmd: &[String]) -> Option<Vec<String>> {
+        let pattern_length = self.rest.len() + 1;
+        if cmd.len() < pattern_length || cmd[0] != self.first.as_ref() {
+            return None;
+        }
+
+        for (pattern_token, cmd_token) in self.rest.iter().zip(&cmd[1..pattern_length]) {
+            if !pattern_token.matches(cmd_token) {
+                return None;
+            }
+        }
+
+        Some(cmd[..pattern_length].to_vec())
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum RuleMatch {
+    PrefixRuleMatch {
+        #[serde(rename = "matchedPrefix")]
+        matched_prefix: Vec<String>,
+        decision: Decision,
+    },
+}
+
+impl RuleMatch {
+    pub fn decision(&self) -> Decision {
+        match self {
+            Self::PrefixRuleMatch { decision, .. } => *decision,
+        }
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct PrefixRule {
+    pub pattern: PrefixPattern,
+    pub decision: Decision,
+}
+
+pub trait Rule: Any + Debug + Send + Sync {
+    fn program(&self) -> &str;
+
+    fn matches(&self, cmd: &[String]) -> Option<RuleMatch>;
+}
+
+pub type RuleRef = Arc<dyn Rule>;
+
+impl Rule for PrefixRule {
+    fn program(&self) -> &str {
+        self.pattern.first.as_ref()
+    }
+
+    fn matches(&self, cmd: &[String]) -> Option<RuleMatch> {
+        self.pattern
+            .matches_prefix(cmd)
+            .map(|matched_prefix| RuleMatch::PrefixRuleMatch {
+                matched_prefix,
+                decision: self.decision,
+            })
+    }
+}
+
+/// Count how many rules match each provided example and error if any example is unmatched.
+pub(crate) fn validate_match_examples(rules: &[RuleRef], matches: &[Vec<String>]) -> Result<()> {
+    let mut unmatched_examples = Vec::new();
+
+    for example in matches {
+        if rules.iter().any(|rule| rule.matches(example).is_some()) {
+            continue;
+        }
+
+        unmatched_examples.push(
+            try_join(example.iter().map(String::as_str))
+                .unwrap_or_else(|_| "unable to render example".to_string()),
+        );
+    }
+
+    if unmatched_examples.is_empty() {
+        Ok(())
+    } else {
+        Err(Error::ExampleDidNotMatch {
+            rules: rules.iter().map(|rule| format!("{rule:?}")).collect(),
+            examples: unmatched_examples,
+        })
+    }
+}
+
+/// Ensure that no rule matches any provided negative example.
+pub(crate) fn validate_not_match_examples(
+    rules: &[RuleRef],
+    not_matches: &[Vec<String>],
+) -> Result<()> {
+    for example in not_matches {
+        if let Some(rule) = rules.iter().find(|rule| rule.matches(example).is_some()) {
+            return Err(Error::ExampleDidMatch {
+                rule: format!("{rule:?}"),
+                example: try_join(example.iter().map(String::as_str))
+                    .unwrap_or_else(|_| "unable to render example".to_string()),
+            });
+        }
+    }
+
+    Ok(())
+}