Generalize --use-libafl into --fuzz-engine

src/options.rs

@@ -14,8 +14,9 @@ pub use self::{
     list::List, run::Run, tmin::Tmin,
 };
 
+use anyhow::{bail, Error, Result};
 use clap::{Parser, ValueEnum};
-use std::{fmt as stdfmt, path::PathBuf};
+use std::{fmt as stdfmt, path::PathBuf, str::FromStr};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq, ValueEnum)]
 pub enum Sanitizer {
@@ -279,6 +280,24 @@ impl stdfmt::Display for FuzzDirWrapper {
     }
 }
 
+#[derive(Clone, Debug)]
+pub enum FuzzEngine {
+    LibFuzzer,
+    LibAfl,
+}
+
+impl FromStr for FuzzEngine {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        match s {
+            "libfuzzer" => Ok(Self::LibFuzzer),
+            "libafl" => Ok(Self::LibAfl),
+            _ => bail!("invalid fuzz engine: '{s}'. Must be one of: 'libfuzzer', 'libafl'"),
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

src/options/init.rs

@@ -1,4 +1,8 @@
-use crate::{options::FuzzDirWrapper, project::FuzzProject, RunCommand};
+use crate::{
+    options::{FuzzDirWrapper, FuzzEngine},
+    project::FuzzProject,
+    RunCommand,
+};
 use anyhow::Result;
 use clap::Parser;
 
@@ -12,9 +16,11 @@ pub struct Init {
     /// Whether to create a separate workspace for fuzz targets crate
     pub fuzzing_workspace: Option<bool>,
 
-    #[arg(long, value_parser = clap::builder::BoolishValueParser::new(), default_value = "false")]
-    /// Whether to use libafl's libfuzzer_sys-compatible API for improved fuzzing performance
-    pub use_libafl: Option<bool>,
+    #[arg(long, default_value = "libfuzzer")]
+    /// The fuzz engine that the project should use.
+    ///
+    /// Options: libfuzzer, libafl
+    pub fuzz_engine: FuzzEngine,
 
     #[command(flatten)]
     pub fuzz_dir_wrapper: FuzzDirWrapper,

src/project.rs

@@ -70,7 +70,7 @@ impl FuzzProject {
             .write_fmt(toml_template!(
                 manifest.crate_name,
                 manifest.edition,
-                init.use_libafl,
+                init.fuzz_engine,
                 init.fuzzing_workspace
             ))
             .with_context(|| format!("failed to write to {}", cargo_toml.display()))?;

src/templates.rs

@@ -1,5 +1,5 @@
 macro_rules! toml_template {
-    ($name:expr, $edition:expr, $use_libafl:expr, $fuzzing_workspace:expr) => {
+    ($name:expr, $edition:expr, $fuzz_engine:expr, $fuzzing_workspace:expr) => {
         format_args!(
             r##"[package]
 name = "{name}-fuzz"
@@ -21,10 +21,11 @@ path = ".."
             } else {
                 String::new()
             },
-            libfuzzer_sys_dep = if let Some(true) = $use_libafl {
-                r##"libfuzzer-sys = { version = "0.15.3", package = "libafl_libfuzzer" }"##
-            } else {
-                r##"libfuzzer-sys = "0.4""##
+            libfuzzer_sys_dep = match $fuzz_engine {
+                crate::options::FuzzEngine::LibFuzzer => r#"libfuzzer-sys = "0.4""#,
+                crate::options::FuzzEngine::LibAfl => {
+                    r#"libfuzzer-sys = { version = "0.15.3", package = "libafl_libfuzzer" }"#
+                }
             },
             workspace = if let Some(true) = $fuzzing_workspace {
                 r##"

tests/tests/main.rs

@@ -159,7 +159,21 @@ fn init_defines_correct_dependency() {
     let expected_dependency_attrs =
         &format!("[dependencies.{name}]\npath = \"..\"", name = project_name);
     assert!(cargo_toml.contains(expected_dependency_attrs));
-    assert!(cargo_toml.contains(r#"libfuzzer-sys = "0.4""#))
+    assert!(cargo_toml.contains(r#"libfuzzer-sys = "0.4""#));
+}
+
+#[test]
+fn init_with_libfuzzer() {
+    let project = project("init_with_libfuzzer").build();
+    project
+        .cargo_fuzz()
+        .arg("init")
+        .arg("--fuzz-engine=libfuzzer")
+        .assert()
+        .success();
+
+    let cargo_toml = fs::read_to_string(project.fuzz_cargo_toml()).unwrap();
+    assert!(cargo_toml.contains(r#"libfuzzer-sys = "0.4""#));
 }
 
 #[test]
@@ -168,7 +182,7 @@ fn init_with_libafl() {
     project
         .cargo_fuzz()
         .arg("init")
-        .arg("--use-libafl=true")
+        .arg("--fuzz-engine=libafl")
         .assert()
         .success();