cha_core/plugins/
error_handling.rs

1use crate::{AnalysisContext, Finding, Location, Plugin, Severity, SmellCategory};
2
3/// Detect error handling smells:
4/// - Empty catch/except blocks (silently swallowed errors)
5/// - Excessive unwrap()/expect() calls in Rust
6///
7/// ## References
8///
9/// [1] G. Padua and W. Shang, "Revisiting Exception Handling Practices
10///     with Exception Flow Analysis," Empirical Software Engineering,
11///     vol. 23, no. 6, pp. 3337–3383, 2018.
12///     doi: 10.1007/s10664-018-9601-8.
13///
14/// [2] A. Rahman, C. Parnin, and L. Williams, "The Seven Sins: Security
15///     Smells in Infrastructure as Code Scripts," in Proc. 41st Int. Conf.
16///     Software Engineering (ICSE), 2019, pp. 164–175.
17///     doi: 10.1109/ICSE.2019.00033.
18pub struct ErrorHandlingAnalyzer {
19    pub max_unwraps_per_function: usize,
20}
21
22impl Default for ErrorHandlingAnalyzer {
23    fn default() -> Self {
24        Self {
25            max_unwraps_per_function: 3,
26        }
27    }
28}
29
30impl Plugin for ErrorHandlingAnalyzer {
31    fn name(&self) -> &str {
32        "error_handling"
33    }
34
35    fn description(&self) -> &str {
36        "Empty catch blocks, unwrap/expect abuse"
37    }
38
39    fn analyze(&self, ctx: &AnalysisContext) -> Vec<Finding> {
40        let mut findings = Vec::new();
41        let lines: Vec<&str> = ctx.file.content.lines().collect();
42
43        for f in &ctx.model.functions {
44            let unwrap_count = count_unwraps(&lines, f.start_line, f.end_line);
45            if unwrap_count > self.max_unwraps_per_function {
46                findings.push(Finding {
47                    smell_name: "unwrap_abuse".into(),
48                    category: SmellCategory::Security,
49                    severity: Severity::Warning,
50                    location: Location {
51                        path: ctx.file.path.clone(),
52                        start_line: f.start_line,
53                        start_col: f.name_col,
54                        end_line: f.start_line,
55                        end_col: f.name_end_col,
56                        name: Some(f.name.clone()),
57                    },
58                    message: format!(
59                        "Function `{}` has {} unwrap/expect calls (threshold: {})",
60                        f.name, unwrap_count, self.max_unwraps_per_function
61                    ),
62                    suggested_refactorings: vec![
63                        "Use ? operator".into(),
64                        "Handle errors explicitly".into(),
65                    ],
66                    ..Default::default()
67                });
68            }
69        }
70
71        detect_empty_catch(&lines, ctx, &mut findings);
72        findings
73    }
74}
75
76fn count_unwraps(lines: &[&str], start: usize, end: usize) -> usize {
77    let mut count = 0;
78    for line in lines
79        .iter()
80        .take(end.min(lines.len()))
81        .skip(start.saturating_sub(1))
82    {
83        let trimmed = line.trim();
84        if trimmed.starts_with("//") || trimmed.starts_with('#') {
85            continue;
86        }
87        count += line.matches(".unwrap()").count();
88        count += line.matches(".expect(").count();
89    }
90    count
91}
92
93fn detect_empty_catch(lines: &[&str], ctx: &AnalysisContext, findings: &mut Vec<Finding>) {
94    for (i, line) in lines.iter().enumerate() {
95        let trimmed = line.trim();
96        let is_catch = trimmed.starts_with("catch")
97            || trimmed.starts_with("except")
98            || trimmed.starts_with("} catch")
99            || trimmed.starts_with("rescue");
100        if !is_catch {
101            continue;
102        }
103        if let Some(next) = lines.iter().skip(i + 1).find(|l| !l.trim().is_empty()) {
104            let next_trimmed = next.trim();
105            if next_trimmed == "}" || next_trimmed == "pass" || next_trimmed.is_empty() {
106                let col = line.find(trimmed).unwrap_or(0);
107                findings.push(Finding {
108                    smell_name: "empty_catch".into(),
109                    category: SmellCategory::Security,
110                    severity: Severity::Warning,
111                    location: Location {
112                        path: ctx.file.path.clone(),
113                        start_line: i + 1,
114                        start_col: col,
115                        end_line: i + 2,
116                        name: None,
117                        ..Default::default()
118                    },
119                    message: "Empty catch/except block — errors are silently swallowed".into(),
120                    suggested_refactorings: vec![
121                        "Log the error".into(),
122                        "Re-throw or handle explicitly".into(),
123                    ],
124                    ..Default::default()
125                });
126            }
127        }
128    }
129}
cha_core/plugins/error_handling.rs

cha_core/plugins/
error_handling.rs
