Initial vid-repair scaffold

vid-repair-core/src/scan/decode.rs

@@ -0,0 +1,72 @@
+use std::io::{BufRead, BufReader};
+use std::path::Path;
+use std::process::{Command, Stdio};
+use std::sync::{Arc, atomic::{AtomicBool, Ordering}};
+
+use anyhow::{Context, Result};
+
+use crate::rules::RuleSet;
+
+#[derive(Debug)]
+pub struct DecodeOutput {
+    pub lines: Vec<String>,
+    pub early_stop: bool,
+}
+
+pub fn run_decode(path: &Path, ffmpeg_path: &str, ruleset: &RuleSet) -> Result<DecodeOutput> {
+    let mut child = Command::new(ffmpeg_path)
+        .arg("-v")
+        .arg("error")
+        .arg("-i")
+        .arg(path)
+        .arg("-f")
+        .arg("null")
+        .arg("-")
+        .stderr(Stdio::piped())
+        .stdout(Stdio::null())
+        .spawn()
+        .with_context(|| format!("Failed to run ffmpeg decode for {}", path.display()))?;
+
+    let stderr = child.stderr.take().context("Failed to capture ffmpeg stderr")?;
+    let reader = BufReader::new(stderr);
+
+    let early_stop = Arc::new(AtomicBool::new(false));
+    let early_stop_flag = early_stop.clone();
+
+    let mut lines = Vec::new();
+
+    for line in reader.lines() {
+        let line = line.unwrap_or_default();
+        if line.is_empty() {
+            continue;
+        }
+
+        lines.push(line.clone());
+
+        if should_stop(&line, ruleset) {
+            early_stop_flag.store(true, Ordering::SeqCst);
+            let _ = child.kill();
+            break;
+        }
+    }
+
+    let _ = child.wait();
+
+    Ok(DecodeOutput {
+        lines,
+        early_stop: early_stop.load(Ordering::SeqCst),
+    })
+}
+
+fn should_stop(line: &str, ruleset: &RuleSet) -> bool {
+    for rule in &ruleset.rules {
+        if !rule.rule.stop_scan {
+            continue;
+        }
+
+        if rule.patterns.iter().any(|re| re.is_match(line)) {
+            return true;
+        }
+    }
+    false
+}