Fix stdin for casr-libafl (#243)

Author: headshog

casr/src/bin/casr-libfuzzer.rs

@@ -177,14 +177,6 @@ fn main() -> Result<()> {
         bail!("casr-gdb-args option is provided with incompatible tool. This option can be used with casr-san or casr-gdb.");
     }
 
-    // Get input file argument index.
-    let at_index = if let Some(idx) = argv.iter().skip(1).position(|s| s.contains("@@")) {
-        idx + 1
-    } else {
-        argv.push("@@");
-        argv.len() - 1
-    };
-
     let crash_files: HashMap<String, PathBuf> = fs::read_dir(input_dir)?
         .flatten()
         .map(|p| p.path())
@@ -193,6 +185,7 @@ fn main() -> Result<()> {
         .collect();
 
     // Determine crash directory format for libfuzzer or LibAFL.
+    let mut is_libafl_based = false;
     let crash_filter = if crash_files
         .iter()
         .any(|(fname, _)| fname.starts_with("crash-") || fname.starts_with("leak-"))
@@ -201,9 +194,20 @@ fn main() -> Result<()> {
             arg.0.starts_with("crash-") || arg.0.starts_with("leak-")
         }
     } else {
+        is_libafl_based = true;
         |arg: &(&std::string::String, &PathBuf)| !arg.0.starts_with(".")
     };
 
+    // Get input file argument index.
+    let at_index = if let Some(idx) = argv.iter().skip(1).position(|s| s.contains("@@")) {
+        Some(idx + 1)
+    } else if is_libafl_based {
+        None
+    } else {
+        argv.push("@@");
+        Some(argv.len() - 1)
+    };
+
     // Get all crashes.
     let crashes: HashMap<String, CrashInfo> = crash_files
         .iter()
@@ -215,7 +219,7 @@ fn main() -> Result<()> {
                     path: p.to_path_buf(),
                     target_args: argv.iter().map(|x| x.to_string()).collect(),
                     envs: envs.clone(),
-                    at_index: Some(at_index),
+                    at_index,
                     casr_tool: tool_path.clone(),
                 },
             )