Support capturing stdout/stderr for ForkserverExecutor and code clean (#3216)

* Support capture stdout/stderr for ForkserverExecutor

Reduce code duplication for ForkserverExecutor and CommandExecutor

* use memfd_create from nix for macos and remove debug print

* resolve macos issue

* clippy

* fix macos again

* fix docs

* fix imports

* format code

* fix docs again

* fix sample

* fix another wrong import

* restore cargo.lock

* add an inner for target args

* fix and docs

* fix

* rename to ChildArgs and ChildArgsInner

* revert forkserver_simple

* allow debug child with observers

* fmt

* std marker

* fix

* move implementation to observers

* implement serde

* Add a forkserver_capture_stdout

* renaming

* fix

* fmt

* fix CommandExecutor

* add a test to check capture

* fix imports

* clippy

* fix sample

* update sample to make it closer to real usecase

* also CommandExecutor for sample

* format

* add forkserver_capture_stdout to CI

* fix doc

* accidentally remove

* fix non_std

* fix for windows

* remove useless lint

* remove spurious fuzzer

* fix for windows again

* fix imports

* fix doc sample

* fix docs

* fix sample

* fmt

* clippy

* clippy again

* fix msrv

* have cargo.lock for sample fuzzer

* avoid double read

* fix fsrv and cmd

* fix sample

* fix docs for windows

* fix typo

* clippy again

* fix exec

* typo

* clippy

* update

* fix nyx executor

* cliipy

* fmt again

* last clippy

* clippy

.github/workflows/build_and_test.yml

@@ -280,6 +280,7 @@ jobs:
 
           # Forkserver
           - ./fuzzers/forkserver/forkserver_simple
+          - ./fuzzers/forkserver/forkserver_capture_stdout
           - ./fuzzers/forkserver/forkserver_libafl_cc
           - ./fuzzers/forkserver/fuzzbench_forkserver
           - ./fuzzers/forkserver/fuzzbench_forkserver_cmplog

fuzzers/baby/backtrace_baby_fuzzers/command_executor/src/main.rs

@@ -117,8 +117,11 @@ pub fn main() {
     }
 
     let timeout = Duration::from_secs(5);
-    let mut executor =
+    let mut executor = MyExecutor { shmem_id, timeout }.into_executor(
-        MyExecutor { shmem_id, timeout }.into_executor(tuple_list!(observer, bt_observer));
+        tuple_list!(observer, bt_observer),
+        None,
+        None,
+    );
 
     // Generator of printable bytearrays of max size 32
     let mut generator = RandPrintablesGenerator::new(nonzero!(32));

fuzzers/baby/backtrace_baby_fuzzers/forkserver_executor/src/main.rs

@@ -25,7 +25,7 @@ use libafl_bolts::{
     rands::StdRand,
     shmem::{ShMem, ShMemProvider},
     tuples::tuple_list,
-    AsSliceMut, TargetArgs,
+    AsSliceMut, StdTargetArgs,
 };
 
 pub fn main() {

fuzzers/binary_only/intel_pt_command_executor/src/main.rs

@@ -136,6 +136,8 @@ pub fn main() {
             command_configurator,
             tuple_list!(observer),
             tuple_list!(hook),
+            None,
+            None,
         );
 
     // Generator of printable bytearrays of max size 32

fuzzers/forkserver/forkserver_capture_stdout/.gitignore

@@ -0,0 +1 @@
+forkserver_capture_stdout

fuzzers/forkserver/forkserver_capture_stdout/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "forkserver_capture_stdout"
+version = "0.14.1"
+authors = ["tokatoka <tokazerkje@outlook.com>", "Ziqiao Kong <mio@lazym.io>"]
+edition = "2024"
+
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+panic = "abort"
+lto = true
+codegen-units = 1
+opt-level = 3
+
+[dependencies]
+clap = { version = "4.5.18", features = ["derive"] }
+env_logger = "0.11.5"
+libafl = { path = "../../../libafl", features = ["std", "derive"] }
+libafl_bolts = { path = "../../../libafl_bolts" }
+log = { version = "0.4.22", features = ["release_max_level_info"] }
+nix = { version = "0.29.0", features = ["signal"] }
+serde = "1.0.219"
+serde_json = "1.0.140"

fuzzers/forkserver/forkserver_capture_stdout/README.md

@@ -0,0 +1,14 @@
+# Simple Forkserver Fuzzer to Capture Stdout
+
+This is a simple example fuzzer to showcase how to capture stdout(stderr) from `ForkserverExecutor`.
+
+## Usage
+You can build this example by `cargo build --release`.  
+This downloads AFLplusplus/AFLplusplus and compiles the example harness program in src/program.c with afl-cc  
+
+## Run
+After you build it you can run  
+`cp ./target/release/forkserver_capture_stdout .` to copy the fuzzer into this directory,  
+and you can run  
+`taskset -c 1 ./forkserver_capture_stdout ./target/release/program ./corpus/ -t 1000` to run the fuzzer.
+`taskset` binds this process to a specific core to improve the throughput.  

fuzzers/forkserver/forkserver_capture_stdout/build.rs

@@ -0,0 +1,61 @@
+use std::{
+    env,
+    path::Path,
+    process::{Command, exit},
+};
+
+const AFL_URL: &str = "https://github.com/AFLplusplus/AFLplusplus";
+
+fn main() {
+    if cfg!(windows) {
+        println!("cargo:warning=No support for windows yet.");
+        exit(0);
+    }
+
+    unsafe {
+        env::remove_var("DEBUG");
+    }
+    let cwd = env::current_dir().unwrap().to_string_lossy().to_string();
+
+    let afl = format!("{}/AFLplusplus", &cwd);
+    let afl_cc = format!("{}/AFLplusplus/afl-cc", &cwd);
+
+    let afl_path = Path::new(&afl);
+    let afl_cc_path = Path::new(&afl_cc);
+
+    if !afl_path.is_dir() {
+        println!("cargo:warning=AFL++ not found, downloading...");
+        Command::new("git")
+            .arg("clone")
+            .arg(AFL_URL)
+            .status()
+            .unwrap();
+    }
+
+    if !afl_cc_path.is_file() {
+        let mut afl_cc_make = Command::new("make");
+        afl_cc_make.arg("all").current_dir(afl_path);
+        if let Ok(llvm_config) = env::var("LLVM_CONFIG") {
+            if !llvm_config.is_empty() {
+                afl_cc_make.env("LLVM_CONFIG", llvm_config);
+            }
+        }
+        afl_cc_make.status().unwrap();
+    }
+
+    let mut compile_command = Command::new(afl_cc_path);
+    compile_command
+        .args(["src/program.c", "-o"])
+        .arg(format!("{cwd}/target/release/program"));
+
+    if let Ok(llvm_config) = env::var("LLVM_CONFIG") {
+        if !llvm_config.is_empty() {
+            compile_command.env("LLVM_CONFIG", llvm_config);
+        }
+    }
+
+    compile_command.status().unwrap();
+
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed=src/");
+}

fuzzers/forkserver/forkserver_capture_stdout/src/main.rs

@@ -0,0 +1,261 @@
+use core::time::Duration;
+use std::{ops::Index, path::PathBuf};
+
+use clap::Parser;
+use libafl::{
+    HasMetadata,
+    corpus::{Corpus, InMemoryCorpus, OnDiskCorpus},
+    events::SimpleEventManager,
+    executors::{
+        CommandExecutor, DiffExecutor, HasObservers, StdChildArgs, forkserver::ForkserverExecutor,
+    },
+    feedback_and_fast, feedback_or,
+    feedbacks::{CrashFeedback, MaxMapFeedback, TimeFeedback},
+    fuzzer::{Fuzzer, StdFuzzer},
+    inputs::BytesInput,
+    monitors::SimpleMonitor,
+    mutators::{HavocScheduledMutator, Tokens, havoc_mutations, tokens_mutations},
+    observers::{CanTrack, HitcountsMapObserver, StdMapObserver, StdOutObserver, TimeObserver},
+    schedulers::{IndexesLenTimeMinimizerScheduler, QueueScheduler},
+    stages::mutational::StdMutationalStage,
+    state::{HasCorpus, StdState},
+};
+use libafl_bolts::{
+    AsSliceMut, StdTargetArgs, Truncate, current_nanos,
+    rands::StdRand,
+    shmem::{ShMem, ShMemProvider, UnixShMemProvider},
+    tuples::{Handled, Merge, tuple_list},
+};
+use nix::sys::signal::Signal;
+use serde::Deserialize;
+
+/// The commandline args this fuzzer accepts
+#[derive(Debug, Parser)]
+#[command(
+    name = "forkserver_simple",
+    about = "This is a simple example fuzzer to fuzz a executable instrumented by afl-cc.",
+    author = "tokatoka <tokazerkje@outlook.com>"
+)]
+struct Opt {
+    #[arg(
+        help = "The instrumented binary we want to fuzz",
+        name = "EXEC",
+        required = true
+    )]
+    executable: String,
+
+    #[arg(
+        help = "The directory to read initial inputs from ('seeds')",
+        name = "INPUT_DIR",
+        required = true
+    )]
+    in_dir: PathBuf,
+
+    #[arg(
+        help = "Timeout for each individual execution, in milliseconds",
+        short = 't',
+        long = "timeout",
+        default_value = "1200"
+    )]
+    timeout: u64,
+
+    #[arg(
+        help = "If not set, the child's stdout and stderror will be redirected to /dev/null",
+        short = 'd',
+        long = "debug-child",
+        default_value = "false"
+    )]
+    debug_child: bool,
+
+    #[arg(
+        help = "Arguments passed to the target",
+        name = "arguments",
+        num_args(1..),
+        allow_hyphen_values = true,
+    )]
+    arguments: Vec<String>,
+
+    #[arg(
+        help = "Signal used to stop child",
+        short = 's',
+        long = "signal",
+        value_parser = str::parse::<Signal>,
+        default_value = "SIGKILL"
+    )]
+    signal: Signal,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+struct ProgramOutput {
+    len: i32,
+}
+
+pub fn main() {
+    env_logger::init();
+    const MAP_SIZE: usize = 65536;
+
+    let opt = Opt::parse();
+
+    let corpus_dirs: Vec<PathBuf> = [opt.in_dir].to_vec();
+
+    // The unix shmem provider supported by AFL++ for shared memory
+    let mut shmem_provider = UnixShMemProvider::new().unwrap();
+
+    // The coverage map shared between observer and executor
+    let mut shmem = shmem_provider.new_shmem(MAP_SIZE).unwrap();
+    // let the forkserver know the shmid
+    unsafe {
+        shmem.write_to_env("__AFL_SHM_ID").unwrap();
+    }
+    let shmem_buf = shmem.as_slice_mut();
+
+    // Create an observation channel using the signals map
+    let edges_observer = unsafe {
+        HitcountsMapObserver::new(StdMapObserver::new("shared_mem", shmem_buf)).track_indices()
+    };
+
+    // Create an observation channel to keep track of the execution time
+    let time_observer = TimeObserver::new("time");
+
+    // Feedback to rate the interestingness of an input
+    // This one is composed by two Feedbacks in OR
+    let mut feedback = feedback_or!(
+        // New maximization map feedback linked to the edges observer and the feedback state
+        MaxMapFeedback::new(&edges_observer),
+        // Time feedback, this one does not need a feedback state
+        TimeFeedback::new(&time_observer)
+    );
+
+    // A feedback to choose if an input is a solution or not
+    // We want to do the same crash deduplication that AFL does
+    let mut objective = feedback_and_fast!(
+        // Must be a crash
+        CrashFeedback::new(),
+        // Take it only if trigger new coverage over crashes
+        // Uses `with_name` to create a different history from the `MaxMapFeedback` in `feedback` above
+        MaxMapFeedback::with_name("mapfeedback_metadata_objective", &edges_observer)
+    );
+
+    // create a State from scratch
+    let mut state = StdState::new(
+        // RNG
+        StdRand::with_seed(current_nanos()),
+        // Corpus that will be evolved, we keep it in memory for performance
+        InMemoryCorpus::<BytesInput>::new(),
+        // Corpus in which we store solutions (crashes in this example),
+        // on disk so the user can get them after stopping the fuzzer
+        OnDiskCorpus::new(PathBuf::from("./crashes")).unwrap(),
+        // States of the feedbacks.
+        // The feedbacks can report the data that should persist in the State.
+        &mut feedback,
+        // Same for objective feedbacks
+        &mut objective,
+    )
+    .unwrap();
+
+    // The Monitor trait define how the fuzzer stats are reported to the user
+    let monitor = SimpleMonitor::new(|s| println!("{s}"));
+
+    // The event manager handle the various events generated during the fuzzing loop
+    // such as the notification of the addition of a new item to the corpus
+    let mut mgr = SimpleEventManager::new(monitor);
+
+    // A minimization+queue policy to get testcasess from the corpus
+    let scheduler = IndexesLenTimeMinimizerScheduler::new(&edges_observer, QueueScheduler::new());
+
+    // A fuzzer with feedbacks and a corpus scheduler
+    let mut fuzzer = StdFuzzer::new(scheduler, feedback, objective);
+
+    // If we should debug the child
+    let debug_child = opt.debug_child;
+
+    // Create the executor for the forkserver
+    let args = opt.arguments;
+
+    let observer_ref = edges_observer.handle();
+    let stdout = StdOutObserver::new("stdout".into()).expect("observer");
+    let stdout_handle = stdout.handle();
+
+    let cmd_stdout = StdOutObserver::new("cmd_stdout".into()).expect("observer");
+    let cmd_stdout_handle = cmd_stdout.handle();
+
+    let mut tokens = Tokens::new();
+    let mut executor = ForkserverExecutor::builder()
+        .program(opt.executable.clone())
+        .debug_child(debug_child)
+        .shmem_provider(&mut shmem_provider)
+        .autotokens(&mut tokens)
+        .parse_afl_cmdline(args.clone())
+        .coverage_map_size(MAP_SIZE)
+        .timeout(Duration::from_millis(opt.timeout))
+        .kill_signal(opt.signal)
+        .stdout_observer(stdout_handle.clone())
+        .build(tuple_list!(time_observer, edges_observer, stdout))
+        .unwrap();
+
+    let cmd_executor = CommandExecutor::builder()
+        .program(opt.executable)
+        .debug_child(debug_child)
+        .parse_afl_cmdline(args)
+        .timeout(Duration::from_millis(opt.timeout))
+        .stdout_observer(cmd_stdout_handle.clone())
+        .build(tuple_list!(cmd_stdout))
+        .unwrap();
+
+    if let Some(dynamic_map_size) = executor.coverage_map_size() {
+        executor.observers_mut()[&observer_ref]
+            .as_mut()
+            .truncate(dynamic_map_size);
+    }
+
+    let mut executor = DiffExecutor::new(executor, cmd_executor, ());
+    // In case the corpus is empty (on first run), reset
+    if state.must_load_initial_inputs() {
+        state
+            .load_initial_inputs(&mut fuzzer, &mut executor, &mut mgr, &corpus_dirs)
+            .unwrap_or_else(|err| {
+                panic!(
+                    "Failed to load initial corpus at {:?}: {:?}",
+                    &corpus_dirs, err
+                )
+            });
+        println!("We imported {} inputs from disk.", state.corpus().count());
+    }
+
+    state.add_metadata(tokens);
+
+    // Setup a mutational stage with a basic bytes mutator
+    let mutator =
+        HavocScheduledMutator::with_max_stack_pow(havoc_mutations().merge(tokens_mutations()), 6);
+    let mut stages = tuple_list!(StdMutationalStage::new(mutator));
+
+    for _ in 0..5 {
+        fuzzer
+            .fuzz_one(&mut stages, &mut executor, &mut state, &mut mgr)
+            .unwrap();
+
+        let stdout = executor
+            .observers()
+            .index(&stdout_handle)
+            .output
+            .clone()
+            .expect("no stdout");
+        let out: ProgramOutput = serde_json::from_slice(&stdout).unwrap();
+        println!(
+            "Program output from Forkserver after serde_json::from_slice is {:?}",
+            &out
+        );
+
+        let cmd_stdout = executor
+            .observers()
+            .index(&cmd_stdout_handle)
+            .output
+            .clone()
+            .expect("no stdout");
+        let out: ProgramOutput = serde_json::from_slice(&stdout).unwrap();
+        println!(
+            "Program output from CommandExecutor after serde_json::from_slice is {:?}",
+            &out
+        );
+    }
+}

fuzzers/forkserver/forkserver_capture_stdout/src/program.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+
+// The following line is needed for shared memeory testcase fuzzing
+__AFL_FUZZ_INIT();
+
+int main(int argc, char **argv) {
+  FILE *file = stdin;
+  if (argc > 1) { file = fopen(argv[1], "rb"); }
+
+  // The following three lines are for normal fuzzing.
+  /*
+  char buf[16];
+  char* p = fgets(buf, 16, file);
+  buf[15] = 0;
+  */
+
+  // The following line is also needed for shared memory testcase fuzzing
+  unsigned char *buf = __AFL_FUZZ_TESTCASE_BUF;
+  int            len = __AFL_FUZZ_TESTCASE_LEN;
+
+  printf("{\"len\": %d}", len);
+
+  return 0;
+}

fuzzers/forkserver/forkserver_libafl_cc/src/main.rs

@@ -5,7 +5,7 @@ use clap::Parser;
 use libafl::{
     corpus::{Corpus, InMemoryCorpus, OnDiskCorpus},
     events::SimpleEventManager,
-    executors::{forkserver::ForkserverExecutor, HasObservers},
+    executors::{forkserver::ForkserverExecutor, HasObservers, StdChildArgs},
     feedback_and_fast, feedback_or,
     feedbacks::{CrashFeedback, MaxMapFeedback, TimeFeedback},
     fuzzer::{Fuzzer, StdFuzzer},
@@ -22,7 +22,7 @@ use libafl_bolts::{
     rands::StdRand,
     shmem::{ShMem, ShMemProvider, UnixShMemProvider},
     tuples::{tuple_list, Handled, Merge},
-    AsSliceMut, TargetArgs, Truncate,
+    AsSliceMut, StdTargetArgs, Truncate,
 };
 use libafl_targets::EDGES_MAP_DEFAULT_SIZE;
 use nix::sys::signal::Signal;

fuzzers/forkserver/forkserver_simple/src/main.rs

@@ -6,7 +6,7 @@ use libafl::{
     HasMetadata,
     corpus::{Corpus, InMemoryCorpus, OnDiskCorpus},
     events::SimpleEventManager,
-    executors::{HasObservers, forkserver::ForkserverExecutor},
+    executors::{HasObservers, StdChildArgs, forkserver::ForkserverExecutor},
     feedback_and_fast, feedback_or,
     feedbacks::{CrashFeedback, MaxMapFeedback, TimeFeedback},
     fuzzer::{Fuzzer, StdFuzzer},
@@ -19,7 +19,7 @@ use libafl::{
     state::{HasCorpus, StdState},
 };
 use libafl_bolts::{
-    AsSliceMut, TargetArgs, Truncate, current_nanos,
+    AsSliceMut, StdTargetArgs, Truncate, current_nanos,
     rands::StdRand,
     shmem::{ShMem, ShMemProvider, UnixShMemProvider},
     tuples::{Handled, Merge, tuple_list},

fuzzers/forkserver/fuzzbench_forkserver/src/main.rs

@@ -11,7 +11,10 @@ use clap::{Arg, ArgAction, Command};
 use libafl::{
     corpus::{Corpus, InMemoryOnDiskCorpus, OnDiskCorpus},
     events::SimpleEventManager,
-    executors::forkserver::{ForkserverExecutor, SHM_CMPLOG_ENV_VAR},
+    executors::{
+        forkserver::{ForkserverExecutor, SHM_CMPLOG_ENV_VAR},
+        StdChildArgs,
+    },
     feedback_or,
     feedbacks::{CrashFeedback, MaxMapFeedback, TimeFeedback},
     fuzzer::{Fuzzer, StdFuzzer},
@@ -38,7 +41,7 @@ use libafl_bolts::{
     rands::StdRand,
     shmem::{ShMem, ShMemProvider, UnixShMemProvider},
     tuples::{tuple_list, Merge},
-    AsSliceMut, TargetArgs,
+    AsSliceMut, StdTargetArgs,
 };
 use libafl_targets::cmps::AFLppCmpLogMap;
 use nix::sys::signal::Signal;

fuzzers/forkserver/fuzzbench_forkserver_cmplog/src/main.rs

@@ -11,7 +11,10 @@ use clap::{Arg, ArgAction, Command};
 use libafl::{
     corpus::{Corpus, InMemoryOnDiskCorpus, OnDiskCorpus},
     events::SimpleEventManager,
-    executors::forkserver::{ForkserverExecutor, SHM_CMPLOG_ENV_VAR},
+    executors::{
+        forkserver::{ForkserverExecutor, SHM_CMPLOG_ENV_VAR},
+        StdChildArgs,
+    },
     feedback_or,
     feedbacks::{CrashFeedback, MaxMapFeedback, TimeFeedback},
     fuzzer::{Fuzzer, StdFuzzer},
@@ -37,7 +40,7 @@ use libafl_bolts::{
     rands::StdRand,
     shmem::{ShMem, ShMemProvider, UnixShMemProvider},
     tuples::{tuple_list, Handled, Merge},
-    AsSliceMut, TargetArgs,
+    AsSliceMut, StdTargetArgs,
 };
 use libafl_targets::{
     cmps::{observers::AFLppCmpLogObserver, stages::AFLppCmplogTracingStage},

fuzzers/forkserver/fuzzbench_forkserver_sand/src/main.rs

@@ -14,6 +14,7 @@ use libafl::{
     executors::{
         forkserver::{ForkserverExecutor, SHM_CMPLOG_ENV_VAR},
         sand::SANDExecutor,
+        StdChildArgs,
     },
     feedback_or,
     feedbacks::{CrashFeedback, MaxMapFeedback, TimeFeedback},
@@ -41,7 +42,7 @@ use libafl_bolts::{
     rands::StdRand,
     shmem::{ShMem, ShMemProvider, UnixShMemProvider},
     tuples::{tuple_list, Handled, Merge},
-    AsSliceMut, TargetArgs,
+    AsSliceMut, StdTargetArgs,
 };
 use libafl_targets::cmps::AFLppCmpLogMap;
 use nix::sys::signal::Signal;

fuzzers/forkserver/libafl-fuzz/src/fuzzer.rs

@@ -16,7 +16,10 @@ use libafl::monitors::SimpleMonitor;
 use libafl::{
     corpus::{CachedOnDiskCorpus, Corpus, OnDiskCorpus},
     events::ProgressReporter,
-    executors::forkserver::{ForkserverExecutor, ForkserverExecutorBuilder, SHM_CMPLOG_ENV_VAR},
+    executors::{
+        forkserver::{ForkserverExecutor, ForkserverExecutorBuilder, SHM_CMPLOG_ENV_VAR},
+        StdChildArgs,
+    },
     feedback_and, feedback_or, feedback_or_fast,
     feedbacks::{
         CaptureTimeoutFeedback, ConstFeedback, CrashFeedback, MaxMapFeedback, TimeFeedback,
@@ -51,7 +54,7 @@ use libafl_bolts::{
     rands::StdRand,
     shmem::{ShMem, ShMemProvider, UnixShMemProvider},
     tuples::{tuple_list, Handled, Merge},
-    AsSliceMut, TargetArgs,
+    AsSliceMut, StdTargetArgs,
 };
 #[cfg(feature = "nyx")]
 use libafl_nyx::{executor::NyxExecutor, helper::NyxHelper, settings::NyxSettings};

fuzzers/structure_aware/forkserver_simple_nautilus/src/main.rs

@@ -5,7 +5,7 @@ use clap::Parser;
 use libafl::{
     corpus::{InMemoryCorpus, OnDiskCorpus},
     events::SimpleEventManager,
-    executors::{forkserver::ForkserverExecutor, HasObservers},
+    executors::{forkserver::ForkserverExecutor, HasObservers, StdChildArgs},
     feedback_and_fast, feedback_or,
     feedbacks::{
         CrashFeedback, MaxMapFeedback, NautilusChunksMetadata, NautilusFeedback, TimeFeedback,
@@ -29,7 +29,7 @@ use libafl_bolts::{
     rands::StdRand,
     shmem::{ShMem, ShMemProvider, UnixShMemProvider},
     tuples::{tuple_list, Handled},
-    AsSliceMut, TargetArgs, Truncate,
+    AsSliceMut, StdTargetArgs, Truncate,
 };
 use nix::sys::signal::Signal;
 

fuzzers/structure_aware/libfuzzer_stb_image_concolic/fuzzer/src/main.rs

@@ -217,9 +217,11 @@ fn fuzz(
         let mut stages = tuple_list!(
             // Create a concolic trace
             ConcolicTracingStage::new(
-                TracingStage::new(
+                TracingStage::new(MyCommandConfigurator.into_executor(
-                    MyCommandConfigurator.into_executor(tuple_list!(concolic_observer)),
+                    tuple_list!(concolic_observer),
-                ),
+                    None,
+                    None
+                ),),
                 concolic_ref,
             ),
             // Use the concolic trace for z3-based solving

libafl/src/corpus/inmemory_ondisk.rs

@@ -533,7 +533,10 @@ mod tests {
 
         match try_create_new(&path) {
             Ok(None) => (),
-            Ok(_) => panic!("File {path:?} did not exist even though it should have?"),
+            Ok(_) => panic!(
+                "File {} did not exist even though it should have?",
+                &path.display()
+            ),
             Err(e) => panic!("An unexpected error occurred: {e}"),
         }
         drop(f);

libafl/src/executors/command.rs

@@ -1,6 +1,7 @@
 //! The command executor executes a sub program for each run
 #[cfg(all(feature = "intel_pt", target_os = "linux"))]
 use alloc::ffi::CString;
+#[cfg(all(feature = "intel_pt", target_os = "linux"))]
 use alloc::vec::Vec;
 #[cfg(all(feature = "intel_pt", target_os = "linux"))]
 use core::ffi::CStr;
@@ -13,18 +14,17 @@ use core::{
 #[cfg(all(feature = "intel_pt", target_os = "linux"))]
 use std::os::fd::AsRawFd;
 use std::{
-    ffi::{OsStr, OsString},
+    ffi::OsStr,
     io::{Read, Write},
-    os::unix::ffi::OsStrExt,
+    os::{fd::RawFd, unix::ffi::OsStrExt},
-    path::{Path, PathBuf},
     process::{Child, Command, Stdio},
 };
 
 #[cfg(all(feature = "intel_pt", target_os = "linux"))]
 use libafl_bolts::core_affinity::CoreId;
 use libafl_bolts::{
-    AsSlice, InputLocation, TargetArgs,
+    AsSlice, InputLocation, StdTargetArgs, StdTargetArgsInner,
-    tuples::{Handle, MatchName, RefIndexable},
+    tuples::{Handle, MatchName, MatchNameRef, RefIndexable},
 };
 #[cfg(all(feature = "intel_pt", target_os = "linux"))]
 use libc::STDIN_FILENO;
@@ -46,7 +46,9 @@ use nix::{
 #[cfg(all(feature = "intel_pt", target_os = "linux"))]
 use typed_builder::TypedBuilder;
 
-use super::HasTimeout;
+#[cfg(all(target_family = "unix", feature = "fork"))]
+use super::forkserver::ConfigTarget;
+use super::{HasTimeout, StdChildArgs, StdChildArgsInner};
 #[cfg(target_os = "linux")]
 use crate::executors::hooks::ExecutorHooksTuple;
 use crate::{
@@ -55,9 +57,47 @@ use crate::{
     inputs::HasTargetBytes,
     observers::{ObserversTuple, StdErrObserver, StdOutObserver},
     state::HasExecutions,
-    std::borrow::ToOwned,
 };
 
+/// How do we capture stdout/stderr. Not intended for public use.
+#[derive(Debug, Default)]
+#[allow(dead_code)]
+enum StdCommandCaptureMethod {
+    Fd(RawFd),
+    #[default]
+    Pipe,
+}
+
+impl StdCommandCaptureMethod {
+    fn pipe_capture(cmd: &mut Command, stdout: bool) {
+        if stdout {
+            cmd.stdout(Stdio::piped());
+        } else {
+            cmd.stderr(Stdio::piped());
+        }
+    }
+
+    fn pre_capture(&self, cmd: &mut Command, stdout: bool) {
+        #[cfg(feature = "fork")]
+        {
+            if let Self::Fd(old) = self {
+                if stdout {
+                    cmd.setdup2(*old, libc::STDOUT_FILENO);
+                    cmd.stdout(Stdio::null());
+                } else {
+                    cmd.setdup2(*old, libc::STDERR_FILENO);
+                    cmd.stderr(Stdio::null());
+                }
+            } else {
+                Self::pipe_capture(cmd, stdout);
+            }
+        }
+
+        #[cfg(not(feature = "fork"))]
+        Self::pipe_capture(cmd, stdout);
+    }
+}
+
 /// A simple Configurator that takes the most common parameters
 /// Writes the input either to stdio or to a file
 /// Use [`CommandExecutor::builder()`] to use this configurator.
@@ -66,8 +106,8 @@ pub struct StdCommandConfigurator {
     /// If set to true, the child output will remain visible
     /// By default, the child output is hidden to increase execution speed
     debug_child: bool,
-    stdout_observer: Option<Handle<StdOutObserver>>,
+    stdout_cap: Option<StdCommandCaptureMethod>,
-    stderr_observer: Option<Handle<StdErrObserver>>,
+    stderr_cap: Option<StdCommandCaptureMethod>,
     timeout: Duration,
     /// true: input gets delivered via stdink
     input_location: InputLocation,
@@ -79,30 +119,26 @@ impl<I> CommandConfigurator<I> for StdCommandConfigurator
 where
     I: HasTargetBytes,
 {
-    fn stdout_observer(&self) -> Option<Handle<StdOutObserver>> {
-        self.stdout_observer.clone()
-    }
-
-    fn stderr_observer(&self) -> Option<Handle<StdErrObserver>> {
-        self.stderr_observer.clone()
-    }
-
     fn spawn_child(&mut self, input: &I) -> Result<Child, Error> {
+        let mut cmd = Command::new(self.command.get_program());
         match &mut self.input_location {
             InputLocation::Arg { argnum } => {
                 let args = self.command.get_args();
-                let mut cmd = Command::new(self.command.get_program());
 
-                if !self.debug_child {
+                if self.debug_child {
+                    cmd.stdout(Stdio::inherit());
+                } else if let Some(cap) = &self.stdout_cap {
+                    cap.pre_capture(&mut cmd, true);
+                } else {
                     cmd.stdout(Stdio::null());
-                    cmd.stderr(Stdio::null());
                 }
 
-                if self.stdout_observer.is_some() {
+                if self.debug_child {
-                    cmd.stdout(Stdio::piped());
+                    cmd.stderr(Stdio::inherit());
-                }
+                } else if let Some(cap) = &self.stderr_cap {
-                if self.stderr_observer.is_some() {
+                    cap.pre_capture(&mut cmd, false);
-                    cmd.stderr(Stdio::piped());
+                } else {
+                    cmd.stderr(Stdio::null());
                 }
 
                 for (i, arg) in args.enumerate() {
@@ -269,6 +305,8 @@ pub struct CommandExecutor<I, OT, S, T, HT = (), C = Child> {
     configurer: T,
     /// The observers used by this executor
     observers: OT,
+    stdout_observer: Option<Handle<StdOutObserver>>,
+    stderr_observer: Option<Handle<StdErrObserver>>,
     hooks: HT,
     phantom: PhantomData<(C, I, S)>,
 }
@@ -302,6 +340,8 @@ where
             .field("inner", &self.configurer)
             .field("observers", &self.observers)
             .field("hooks", &self.hooks)
+            .field("stdout_observer", &self.stdout_observer)
+            .field("stderr_observer", &self.stderr_observer)
             .finish()
     }
 }
@@ -323,9 +363,8 @@ where
     fn execute_input_with_command(&mut self, state: &mut S, input: &I) -> Result<ExitKind, Error> {
         use wait_timeout::ChildExt;
 
+        self.observers_mut().pre_exec_all(state, input)?;
         *state.executions_mut() += 1;
-        self.observers.pre_exec_child_all(state, input)?;
-
         let mut child = self.configurer.spawn_child(input)?;
 
         let exit_kind = child
@@ -341,31 +380,28 @@ where
                 ExitKind::Timeout
             });
 
-        self.observers
+        // Manualy update stdout/stderr here if we use piped implementation.
-            .post_exec_child_all(state, input, &exit_kind)?;
+        // Reason of not putting into state and pass by post_exec_all is that
+        // - Save extra at least two hashmap lookups since we already know the handle
+        // - Doesn't pose HasNamedMetadata bound on S (note we might have many stdout/stderr observers)
+        if let Some(mut stderr) = child.stderr {
+            if let Some(stderr_handle) = self.stderr_observer.clone() {
+                let mut buf = vec![];
+                stderr.read_to_end(&mut buf)?;
+                self.observers_mut().index_mut(&stderr_handle).observe(buf);
+            }
+        }
 
-        if let Some(h) = &mut self.configurer.stdout_observer() {
+        if let Some(mut stdout) = child.stdout {
-            let mut stdout = Vec::new();
+            if let Some(stdout_handle) = self.stdout_observer.clone() {
-            child.stdout.as_mut().ok_or_else(|| {
+                let mut buf = vec![];
-                 Error::illegal_state(
+                stdout.read_to_end(&mut buf)?;
-                     "Observer tries to read stderr, but stderr was not `Stdio::pipe` in CommandExecutor",
+                self.observers_mut().index_mut(&stdout_handle).observe(buf);
-                 )
-             })?.read_to_end(&mut stdout)?;
-            let mut observers = self.observers_mut();
-            let obs = observers.index_mut(h);
-            obs.observe(&stdout);
             }
-        if let Some(h) = &mut self.configurer.stderr_observer() {
-            let mut stderr = Vec::new();
-            child.stderr.as_mut().ok_or_else(|| {
-                 Error::illegal_state(
-                     "Observer tries to read stderr, but stderr was not `Stdio::pipe` in CommandExecutor",
-                 )
-             })?.read_to_end(&mut stderr)?;
-            let mut observers = self.observers_mut();
-            let obs = observers.index_mut(h);
-            obs.observe(&stderr);
         }
+
+        self.observers_mut()
+            .post_exec_child_all(state, input, &exit_kind)?;
         Ok(exit_kind)
     }
 }
@@ -497,48 +533,27 @@ where
 /// The builder for a default [`CommandExecutor`] that should fit most use-cases.
 #[derive(Debug, Clone)]
 pub struct CommandExecutorBuilder {
-    stdout: Option<Handle<StdOutObserver>>,
+    target_inner: StdTargetArgsInner,
-    stderr: Option<Handle<StdErrObserver>>,
+    child_env_inner: StdChildArgsInner,
-    debug_child: bool,
-    program: Option<OsString>,
-    args: Vec<OsString>,
-    input_location: InputLocation,
-    cwd: Option<PathBuf>,
-    envs: Vec<(OsString, OsString)>,
-    timeout: Duration,
 }
 
-impl TargetArgs for CommandExecutorBuilder {
+impl StdTargetArgs for CommandExecutorBuilder {
-    fn arguments_ref(&self) -> &Vec<OsString> {
+    fn inner(&self) -> &StdTargetArgsInner {
-        &self.args
+        &self.target_inner
     }
 
-    fn arguments_mut(&mut self) -> &mut Vec<OsString> {
+    fn inner_mut(&mut self) -> &mut StdTargetArgsInner {
-        &mut self.args
+        &mut self.target_inner
+    }
 }
 
-    fn envs_ref(&self) -> &Vec<(OsString, OsString)> {
+impl StdChildArgs for CommandExecutorBuilder {
-        &self.envs
+    fn inner(&self) -> &StdChildArgsInner {
+        &self.child_env_inner
     }
 
-    fn envs_mut(&mut self) -> &mut Vec<(OsString, OsString)> {
+    fn inner_mut(&mut self) -> &mut StdChildArgsInner {
-        &mut self.envs
+        &mut self.child_env_inner
-    }
-
-    fn program_ref(&self) -> &Option<OsString> {
-        &self.program
-    }
-
-    fn program_mut(&mut self) -> &mut Option<OsString> {
-        &mut self.program
-    }
-
-    fn input_location_ref(&self) -> &InputLocation {
-        &self.input_location
-    }
-
-    fn input_location_mut(&mut self) -> &mut InputLocation {
-        &mut self.input_location
     }
 }
 
@@ -553,49 +568,11 @@ impl CommandExecutorBuilder {
     #[must_use]
     fn new() -> CommandExecutorBuilder {
         CommandExecutorBuilder {
-            stdout: None,
+            target_inner: StdTargetArgsInner::default(),
-            stderr: None,
+            child_env_inner: StdChildArgsInner::default(),
-            program: None,
-            args: vec![],
-            input_location: InputLocation::StdIn,
-            cwd: None,
-            envs: vec![],
-            timeout: Duration::from_secs(5),
-            debug_child: false,
         }
     }
 
-    /// Sets the stdout observer
-    pub fn stdout_observer(&mut self, stdout: Handle<StdOutObserver>) -> &mut Self {
-        self.stdout = Some(stdout);
-        self
-    }
-
-    /// Sets the stderr observer
-    pub fn stderr_observer(&mut self, stderr: Handle<StdErrObserver>) -> &mut Self {
-        self.stderr = Some(stderr);
-        self
-    }
-
-    /// Sets the working directory for the child process.
-    pub fn current_dir<P: AsRef<Path>>(&mut self, dir: P) -> &mut CommandExecutorBuilder {
-        self.cwd = Some(dir.as_ref().to_owned());
-        self
-    }
-
-    /// If set to true, the child's output won't be redirecited to `/dev/null`.
-    /// Defaults to `false`.
-    pub fn debug_child(&mut self, debug_child: bool) -> &mut CommandExecutorBuilder {
-        self.debug_child = debug_child;
-        self
-    }
-
-    /// Sets the execution timeout duration.
-    pub fn timeout(&mut self, timeout: Duration) -> &mut CommandExecutorBuilder {
-        self.timeout = timeout;
-        self
-    }
-
     /// Builds the `CommandExecutor`
     pub fn build<I, OT, S>(
         &self,
@@ -605,14 +582,14 @@ impl CommandExecutorBuilder {
         I: HasTargetBytes,
         OT: MatchName + ObserversTuple<I, S>,
     {
-        let Some(program) = &self.program else {
+        let Some(program) = &self.target_inner.program else {
             return Err(Error::illegal_argument(
                 "CommandExecutor::builder: no program set!",
             ));
         };
 
         let mut command = Command::new(program);
-        match &self.input_location {
+        match &self.target_inner.input_location {
             InputLocation::StdIn => {
                 command.stdin(Stdio::piped());
             }
@@ -620,40 +597,77 @@ impl CommandExecutorBuilder {
                 command.stdin(Stdio::null());
             }
         }
-        command.args(&self.args);
+        command.args(&self.target_inner.arguments);
         command.envs(
-            self.envs
+            self.target_inner
+                .envs
                 .iter()
                 .map(|(k, v)| (k.as_os_str(), v.as_os_str())),
         );
-        if let Some(cwd) = &self.cwd {
+        if let Some(cwd) = &self.child_env_inner.current_directory {
             command.current_dir(cwd);
         }
-        if !self.debug_child {
+
+        let stdout_cap = self.child_env_inner.stdout_observer.as_ref().map(|hdl| {
+            observers
+                .get(hdl)
+                .as_ref()
+                .expect("stdout observer not in observers tuple")
+                .as_raw_fd()
+                .map(StdCommandCaptureMethod::Fd)
+                .unwrap_or_default()
+        });
+
+        let stderr_cap = self.child_env_inner.stderr_observer.as_ref().map(|hdl| {
+            observers
+                .get(hdl)
+                .as_ref()
+                .expect("stderr observer not in observers tuple")
+                .as_raw_fd()
+                .map(StdCommandCaptureMethod::Fd)
+                .unwrap_or_default()
+        });
+
+        if self.child_env_inner.debug_child {
+            command.stdout(Stdio::piped());
+            command.stderr(Stdio::piped());
+        } else {
+            if let Some(cap) = &stdout_cap {
+                cap.pre_capture(&mut command, true);
+            } else {
                 command.stdout(Stdio::null());
-            command.stderr(Stdio::null());
             }
 
-        if self.stdout.is_some() {
+            if let Some(cap) = &stderr_cap {
+                cap.pre_capture(&mut command, false);
+            } else {
+                command.stderr(Stdio::null());
+            }
+        }
+
+        if self.child_env_inner.stdout_observer.is_some() {
             command.stdout(Stdio::piped());
         }
 
-        if self.stderr.is_some() {
+        if self.child_env_inner.stderr_observer.is_some() {
             command.stderr(Stdio::piped());
         }
 
         let configurator = StdCommandConfigurator {
-            debug_child: self.debug_child,
+            debug_child: self.child_env_inner.debug_child,
-            stdout_observer: self.stdout.clone(),
+            stdout_cap,
-            stderr_observer: self.stderr.clone(),
+            stderr_cap,
-            input_location: self.input_location.clone(),
+            input_location: self.target_inner.input_location.clone(),
-            timeout: self.timeout,
+            timeout: self.child_env_inner.timeout,
             command,
         };
+
         Ok(
             <StdCommandConfigurator as CommandConfigurator<I>>::into_executor::<OT, S>(
                 configurator,
                 observers,
+                self.child_env_inner.stdout_observer.clone(),
+                self.child_env_inner.stderr_observer.clone(),
             ),
         )
     }
@@ -705,7 +719,7 @@ impl CommandExecutorBuilder {
 /// where
 ///     S: HasExecutions,
 /// {
-///     MyExecutor.into_executor(())
+///     MyExecutor.into_executor((), None, None)
 /// }
 /// ```
 pub trait CommandConfigurator<I, C = Child>: Sized {
@@ -739,11 +753,18 @@ pub trait CommandConfigurator<I, C = Child>: Sized {
     }
 
     /// Create an `Executor` from this `CommandConfigurator`.
-    fn into_executor<OT, S>(self, observers: OT) -> CommandExecutor<I, OT, S, Self, (), C> {
+    fn into_executor<OT, S>(
+        self,
+        observers: OT,
+        stdout_observer: Option<Handle<StdOutObserver>>,
+        stderr_observer: Option<Handle<StdErrObserver>>,
+    ) -> CommandExecutor<I, OT, S, Self, (), C> {
         CommandExecutor {
             configurer: self,
             observers,
             hooks: (),
+            stderr_observer,
+            stdout_observer,
             phantom: PhantomData,
         }
     }
@@ -753,11 +774,15 @@ pub trait CommandConfigurator<I, C = Child>: Sized {
         self,
         observers: OT,
         hooks: HT,
+        stdout_observer: Option<Handle<StdOutObserver>>,
+        stderr_observer: Option<Handle<StdErrObserver>>,
     ) -> CommandExecutor<I, OT, S, Self, HT, C> {
         CommandExecutor {
             configurer: self,
             observers,
             hooks,
+            stderr_observer,
+            stdout_observer,
             phantom: PhantomData,
         }
     }
@@ -781,17 +806,19 @@ fn waitpid_filtered(pid: Pid, options: Option<WaitPidFlag>) -> Result<WaitStatus
 
 #[cfg(test)]
 mod tests {
-    use libafl_bolts::TargetArgs;
+    use libafl_bolts::{StdTargetArgs, tuples::Handled};
+    use tuple_list::tuple_list;
 
     use crate::{
         events::SimpleEventManager,
         executors::{
-            Executor,
+            Executor, StdChildArgs,
             command::{CommandExecutor, InputLocation},
         },
         fuzzer::NopFuzzer,
         inputs::{BytesInput, NopInput},
         monitors::SimpleMonitor,
+        observers::StdOutObserver,
         state::NopState,
     };
 
@@ -818,4 +845,33 @@ mod tests {
             )
             .unwrap();
     }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_capture() {
+        let mut mgr: SimpleEventManager<NopInput, _, NopState<NopInput>> =
+            SimpleEventManager::new(SimpleMonitor::new(|status| {
+                log::info!("{status}");
+            }));
+
+        let stdout = StdOutObserver::new("stdout".into()).unwrap();
+        let handle = stdout.handle();
+        let executor = CommandExecutor::builder()
+            .program("ls")
+            .stdout_observer(handle.clone())
+            .input(InputLocation::Arg { argnum: 0 });
+        let executor = executor.build(tuple_list!(stdout));
+        let mut executor = executor.unwrap();
+
+        executor
+            .run_target(
+                &mut NopFuzzer::new(),
+                &mut NopState::<NopInput>::new(),
+                &mut mgr,
+                &BytesInput::new(b".".to_vec()),
+            )
+            .unwrap();
+
+        assert!(executor.observers.0.output.is_some());
+    }
 }

libafl/src/executors/forkserver.rs

@@ -14,17 +14,18 @@ use std::{
         fd::{AsRawFd, BorrowedFd},
         unix::{io::RawFd, process::CommandExt},
     },
+    path::PathBuf,
     process::{Child, Command, Stdio},
 };
 
 #[cfg(feature = "regex")]
-use libafl_bolts::tuples::{Handle, Handled, MatchNameRef};
+use libafl_bolts::tuples::{Handle, Handled};
 use libafl_bolts::{
-    AsSlice, AsSliceMut, InputLocation, TargetArgs, Truncate,
+    AsSlice, AsSliceMut, InputLocation, StdTargetArgs, StdTargetArgsInner, Truncate,
     fs::{InputFile, get_unique_std_input_file},
     os::{dup2, pipes::Pipe},
     shmem::{ShMem, ShMemProvider, UnixShMem, UnixShMemProvider},
-    tuples::{Prepend, RefIndexable},
+    tuples::{MatchNameRef, Prepend, RefIndexable},
 };
 use libc::RLIM_INFINITY;
 use nix::{
@@ -37,7 +38,7 @@ use nix::{
     unistd::Pid,
 };
 
-use super::HasTimeout;
+use super::{HasTimeout, StdChildArgs, StdChildArgsInner};
 #[cfg(feature = "regex")]
 use crate::observers::{
     AsanBacktraceObserver, get_asan_runtime_flags, get_asan_runtime_flags_with_log_path,
@@ -161,8 +162,6 @@ pub trait ConfigTarget {
     fn setlimit(&mut self, memlimit: u64) -> &mut Self;
     /// enables core dumps (rlimit = infinity)
     fn set_coredump(&mut self, enable: bool) -> &mut Self;
-    /// Sets the stdin
-    fn setstdin(&mut self, fd: RawFd, use_stdin: bool) -> &mut Self;
     /// Sets the AFL forkserver pipes
     fn setpipe(
         &mut self,
@@ -171,6 +170,8 @@ pub trait ConfigTarget {
         ctl_read: RawFd,
         ctl_write: RawFd,
     ) -> &mut Self;
+    /// dup2 the specific fd, used for stdio
+    fn setdup2(&mut self, old_fd: RawFd, new_fd: RawFd) -> &mut Self;
 }
 
 impl ConfigTarget for Command {
@@ -216,23 +217,6 @@ impl ConfigTarget for Command {
         unsafe { self.pre_exec(func) }
     }
 
-    fn setstdin(&mut self, fd: RawFd, use_stdin: bool) -> &mut Self {
-        if use_stdin {
-            let func = move || {
-                match dup2(fd, libc::STDIN_FILENO) {
-                    Ok(()) => (),
-                    Err(_) => {
-                        return Err(io::Error::last_os_error());
-                    }
-                }
-                Ok(())
-            };
-            unsafe { self.pre_exec(func) }
-        } else {
-            self
-        }
-    }
-
     #[expect(trivial_numeric_casts)]
     fn setlimit(&mut self, memlimit: u64) -> &mut Self {
         if memlimit == 0 {
@@ -277,6 +261,19 @@ impl ConfigTarget for Command {
         // This calls our non-shady function from above.
         unsafe { self.pre_exec(func) }
     }
+
+    fn setdup2(&mut self, old_fd: RawFd, new_fd: RawFd) -> &mut Self {
+        let func = move || {
+            let ret = unsafe { libc::dup2(old_fd, new_fd) };
+            if ret < 0 {
+                return Err(io::Error::last_os_error());
+            }
+            Ok(())
+        };
+        // # Safety
+        // This calls our non-shady function from above.
+        unsafe { self.pre_exec(func) }
+    }
 }
 
 /// The [`Forkserver`] is communication channel with a child process that forks on request of the fuzzer.
@@ -358,6 +355,9 @@ impl Forkserver {
         coverage_map_size: Option<usize>,
         debug_output: bool,
         kill_signal: Signal,
+        stdout_memfd: Option<RawFd>,
+        stderr_memfd: Option<RawFd>,
+        cwd: Option<PathBuf>,
     ) -> Result<Self, Error> {
         let Some(coverage_map_size) = coverage_map_size else {
             return Err(Error::unknown(
@@ -385,19 +385,32 @@ impl Forkserver {
         let mut st_pipe = Pipe::new().unwrap();
         let mut ctl_pipe = Pipe::new().unwrap();
 
-        let (stdout, stderr) = if debug_output {
-            (Stdio::inherit(), Stdio::inherit())
-        } else {
-            (Stdio::null(), Stdio::null())
-        };
-
         let mut command = Command::new(target);
         // Setup args, stdio
-        command
+        command.args(args);
-            .args(args)
+        if use_stdin {
-            .stdin(Stdio::null())
+            command.setdup2(input_filefd, libc::STDIN_FILENO);
-            .stdout(stdout)
+        } else {
-            .stderr(stderr);
+            command.stdin(Stdio::null());
+        }
+
+        if debug_output {
+            command.stdout(Stdio::inherit());
+        } else if let Some(fd) = &stdout_memfd {
+            command.setdup2(*fd, libc::STDOUT_FILENO);
+            command.stdout(Stdio::null());
+        } else {
+            command.stdout(Stdio::null());
+        }
+
+        if debug_output {
+            command.stderr(Stdio::inherit());
+        } else if let Some(fd) = &stderr_memfd {
+            command.setdup2(*fd, libc::STDERR_FILENO);
+            command.stderr(Stdio::null());
+        } else {
+            command.stderr(Stdio::null());
+        }
 
         command.env("AFL_MAP_SIZE", format!("{coverage_map_size}"));
 
@@ -422,13 +435,16 @@ impl Forkserver {
         #[cfg(not(feature = "regex"))]
         let _ = dump_asan_logs;
 
+        if let Some(cwd) = cwd {
+            command.current_dir(cwd);
+        }
+
         let fsrv_handle = match command
             .env("LD_BIND_NOW", "1")
             .envs(envs)
             .setlimit(memlimit)
             .set_coredump(afl_debug)
             .setsid()
-            .setstdin(input_filefd, use_stdin)
             .setpipe(
                 st_pipe.read_end().unwrap(),
                 st_pipe.write_end().unwrap(),
@@ -798,58 +814,40 @@ where
 
 /// The builder for `ForkserverExecutor`
 #[derive(Debug)]
-#[expect(clippy::struct_excessive_bools)]
 pub struct ForkserverExecutorBuilder<'a, SP> {
-    program: Option<OsString>,
+    target_inner: StdTargetArgsInner,
-    arguments: Vec<OsString>,
+    child_env_inner: StdChildArgsInner,
-    envs: Vec<(OsString, OsString)>,
-    debug_child: bool,
     uses_shmem_testcase: bool,
     is_persistent: bool,
     is_deferred_frksrv: bool,
     autotokens: Option<&'a mut Tokens>,
-    input_location: InputLocation,
     shmem_provider: Option<&'a mut SP>,
     max_input_size: usize,
     min_input_size: usize,
     map_size: Option<usize>,
     kill_signal: Option<Signal>,
-    timeout: Option<Duration>,
     #[cfg(feature = "regex")]
     asan_obs: Option<Handle<AsanBacktraceObserver>>,
     crash_exitcode: Option<i8>,
 }
 
-impl<SP> TargetArgs for ForkserverExecutorBuilder<'_, SP> {
+impl<SP> StdChildArgs for ForkserverExecutorBuilder<'_, SP> {
-    fn arguments_ref(&self) -> &Vec<OsString> {
+    fn inner(&self) -> &StdChildArgsInner {
-        &self.arguments
+        &self.child_env_inner
-    }
-    fn arguments_mut(&mut self) -> &mut Vec<OsString> {
-        &mut self.arguments
     }
 
-    fn envs_ref(&self) -> &Vec<(OsString, OsString)> {
+    fn inner_mut(&mut self) -> &mut StdChildArgsInner {
-        &self.envs
+        &mut self.child_env_inner
+    }
 }
 
-    fn envs_mut(&mut self) -> &mut Vec<(OsString, OsString)> {
+impl<SP> StdTargetArgs for ForkserverExecutorBuilder<'_, SP> {
-        &mut self.envs
+    fn inner(&self) -> &StdTargetArgsInner {
+        &self.target_inner
     }
 
-    fn program_ref(&self) -> &Option<OsString> {
+    fn inner_mut(&mut self) -> &mut StdTargetArgsInner {
-        &self.program
+        &mut self.target_inner
-    }
-
-    fn program_mut(&mut self) -> &mut Option<OsString> {
-        &mut self.program
-    }
-
-    fn input_location_ref(&self) -> &InputLocation {
-        &self.input_location
-    }
-
-    fn input_location_mut(&mut self) -> &mut InputLocation {
-        &mut self.input_location
     }
 
     fn arg_input_arg(self) -> Self {
@@ -875,13 +873,13 @@ where
     where
         OT: ObserversTuple<I, S>,
     {
-        let (forkserver, input_file, map) = self.build_helper()?;
+        let (forkserver, input_file, map) = self.build_helper(&observers)?;
 
-        let target = self.program.take().unwrap();
+        let target = self.target_inner.program.take().unwrap();
         log::info!(
             "ForkserverExecutor: program: {:?}, arguments: {:?}, use_stdin: {:?}",
             target,
-            self.arguments.clone(),
+            self.target_inner.arguments.clone(),
             self.use_stdin()
         );
 
@@ -891,10 +889,7 @@ where
             ));
         }
 
-        let timeout: TimeSpec = match self.timeout {
+        let timeout: TimeSpec = self.child_env_inner.timeout.into();
-            Some(t) => t.into(),
-            None => Duration::from_millis(5000).into(),
-        };
         if self.min_input_size > self.max_input_size {
             return Err(Error::illegal_argument(
                 format!(
@@ -907,7 +902,7 @@ where
 
         Ok(ForkserverExecutor {
             target,
-            args: self.arguments.clone(),
+            args: self.target_inner.arguments.clone(),
             input_file,
             uses_shmem_testcase: self.uses_shmem_testcase,
             forkserver,
@@ -940,13 +935,13 @@ where
         MO: MapObserver + Truncate, // TODO maybe enforce Entry = u8 for the cov map
         OT: ObserversTuple<I, S> + Prepend<MO>,
     {
-        let (forkserver, input_file, map) = self.build_helper()?;
+        let (forkserver, input_file, map) = self.build_helper(&other_observers)?;
 
-        let target = self.program.take().unwrap();
+        let target = self.target_inner.program.take().unwrap();
         log::info!(
             "ForkserverExecutor: program: {:?}, arguments: {:?}, use_stdin: {:?}, map_size: {:?}",
             target,
-            self.arguments.clone(),
+            self.target_inner.arguments.clone(),
             self.use_stdin(),
             self.map_size
         );
@@ -963,14 +958,11 @@ where
             ));
         }
 
-        let timeout: TimeSpec = match self.timeout {
+        let timeout: TimeSpec = self.child_env_inner.timeout.into();
-            Some(t) => t.into(),
-            None => Duration::from_millis(5000).into(),
-        };
 
         Ok(ForkserverExecutor {
             target,
-            args: self.arguments.clone(),
+            args: self.target_inner.arguments.clone(),
             input_file,
             uses_shmem_testcase: self.uses_shmem_testcase,
             forkserver,
@@ -991,8 +983,14 @@ where
     }
 
     #[expect(clippy::pedantic)]
-    fn build_helper(&mut self) -> Result<(Forkserver, InputFile, Option<SHM>), Error> {
+    fn build_helper<I, OT, S>(
-        let input_file = match &self.input_location {
+        &mut self,
+        obs: &OT,
+    ) -> Result<(Forkserver, InputFile, Option<SHM>), Error>
+    where
+        OT: ObserversTuple<I, S>,
+    {
+        let input_file = match &self.target_inner.input_location {
             InputLocation::StdIn => InputFile::create(OsString::from(get_unique_std_input_file()))?,
             InputLocation::Arg { argnum: _ } => {
                 return Err(Error::illegal_argument(
@@ -1019,11 +1017,11 @@ where
             }
         };
 
-        let mut forkserver = match &self.program {
+        let mut forkserver = match &self.target_inner.program {
             Some(t) => Forkserver::new(
                 t.clone(),
-                self.arguments.clone(),
+                self.target_inner.arguments.clone(),
-                self.envs.clone(),
+                self.target_inner.envs.clone(),
                 input_file.as_raw_fd(),
                 self.use_stdin(),
                 0,
@@ -1031,8 +1029,23 @@ where
                 self.is_deferred_frksrv,
                 self.has_asan_obs(),
                 self.map_size,
-                self.debug_child,
+                self.child_env_inner.debug_child,
                 self.kill_signal.unwrap_or(KILL_SIGNAL_DEFAULT),
+                self.child_env_inner.stdout_observer.as_ref().map(|t| {
+                    obs.get(t)
+                        .as_ref()
+                        .expect("stdout observer not passed in the builder")
+                        .as_raw_fd()
+                        .expect("only memory fd backend is allowed for forkserver executor")
+                }),
+                self.child_env_inner.stderr_observer.as_ref().map(|t| {
+                    obs.get(t)
+                        .as_ref()
+                        .expect("stderr observer not passed in the builder")
+                        .as_raw_fd()
+                        .expect("only memory fd backend is allowed for forkserver executor")
+                }),
+                self.child_env_inner.current_directory.clone(),
             )?,
             None => {
                 return Err(Error::illegal_argument(
@@ -1278,13 +1291,6 @@ where
         self
     }
 
-    #[must_use]
-    /// set the timeout for the executor
-    pub fn timeout(mut self, timeout: Duration) -> Self {
-        self.timeout = Some(timeout);
-        self
-    }
-
     /// Set the max input size
     #[must_use]
     pub fn max_input_size(mut self, size: usize) -> Self {
@@ -1299,13 +1305,6 @@ where
         self
     }
 
-    /// If `debug_child` is set, the child will print to `stdout`/`stderr`.
-    #[must_use]
-    pub fn debug_child(mut self, debug_child: bool) -> Self {
-        self.debug_child = debug_child;
-        self
-    }
-
     /// Call this if you want to run it under persistent mode; default is false
     #[must_use]
     pub fn is_persistent(mut self, is_persistent: bool) -> Self {
@@ -1366,21 +1365,17 @@ impl<'a> ForkserverExecutorBuilder<'a, UnixShMemProvider> {
     #[must_use]
     pub fn new() -> ForkserverExecutorBuilder<'a, UnixShMemProvider> {
         ForkserverExecutorBuilder {
-            program: None,
+            target_inner: StdTargetArgsInner::default(),
-            arguments: vec![],
+            child_env_inner: StdChildArgsInner::default(),
-            envs: vec![],
-            debug_child: false,
             uses_shmem_testcase: false,
             is_persistent: false,
             is_deferred_frksrv: false,
             autotokens: None,
-            input_location: InputLocation::StdIn,
             shmem_provider: None,
             map_size: None,
             max_input_size: MAX_INPUT_SIZE_DEFAULT,
             min_input_size: MIN_INPUT_SIZE_DEFAULT,
             kill_signal: None,
-            timeout: None,
             #[cfg(feature = "regex")]
             asan_obs: None,
             crash_exitcode: None,
@@ -1398,20 +1393,16 @@ impl<'a> ForkserverExecutorBuilder<'a, UnixShMemProvider> {
             // Set the new provider
             shmem_provider: Some(shmem_provider),
             // Copy all other values from the old Builder
-            program: self.program,
+            target_inner: self.target_inner,
-            arguments: self.arguments,
+            child_env_inner: self.child_env_inner,
-            envs: self.envs,
-            debug_child: self.debug_child,
             uses_shmem_testcase: self.uses_shmem_testcase,
             is_persistent: self.is_persistent,
             is_deferred_frksrv: self.is_deferred_frksrv,
             autotokens: self.autotokens,
-            input_location: InputLocation::StdIn,
             map_size: self.map_size,
             max_input_size: self.max_input_size,
             min_input_size: self.min_input_size,
             kill_signal: self.kill_signal,
-            timeout: self.timeout,
             #[cfg(feature = "regex")]
             asan_obs: self.asan_obs,
             crash_exitcode: self.crash_exitcode,
@@ -1443,7 +1434,11 @@ where
     ) -> Result<ExitKind, Error> {
         let converter = fuzzer.converter_mut();
         let bytes = converter.to_bytes(input);
-        self.execute_input(state, bytes.as_slice())
+        self.observers_mut().pre_exec_child_all(state, input)?;
+        let exit = self.execute_input(state, bytes.as_slice())?;
+        self.observers_mut()
+            .post_exec_child_all(state, input, &exit)?;
+        Ok(exit)
     }
 }
 
@@ -1481,7 +1476,7 @@ mod tests {
     use std::ffi::OsString;
 
     use libafl_bolts::{
-        AsSliceMut, TargetArgs,
+        AsSliceMut, StdTargetArgs,
         shmem::{ShMem, ShMemProvider, UnixShMemProvider},
         tuples::tuple_list,
     };
@@ -1490,7 +1485,10 @@ mod tests {
     use crate::{
         Error,
         corpus::NopCorpus,
-        executors::forkserver::{FAILED_TO_START_FORKSERVER_MSG, ForkserverExecutor},
+        executors::{
+            StdChildArgs,
+            forkserver::{FAILED_TO_START_FORKSERVER_MSG, ForkserverExecutor},
+        },
         inputs::BytesInput,
         observers::{ConstMapObserver, HitcountsMapObserver},
     };

libafl/src/executors/mod.rs

@@ -2,6 +2,8 @@
 
 use alloc::vec::Vec;
 use core::{fmt::Debug, time::Duration};
+#[cfg(feature = "std")]
+use std::path::PathBuf;
 
 pub use combined::CombinedExecutor;
 #[cfg(all(feature = "std", unix))]
@@ -14,12 +16,16 @@ pub use inprocess::InProcessExecutor;
 pub use inprocess_fork::InProcessForkExecutor;
 #[cfg(unix)]
 use libafl_bolts::os::unix_signals::Signal;
+#[cfg(feature = "std")]
+use libafl_bolts::tuples::Handle;
 use libafl_bolts::tuples::RefIndexable;
 use serde::{Deserialize, Serialize};
 pub use shadow::ShadowExecutor;
 pub use with_observers::WithObservers;
 
 use crate::Error;
+#[cfg(feature = "std")]
+use crate::observers::{StdErrObserver, StdOutObserver};
 
 pub mod combined;
 #[cfg(all(feature = "std", unix))]
@@ -227,6 +233,87 @@ pub fn common_signals() -> Vec<Signal> {
     ]
 }
 
+#[cfg(feature = "std")]
+/// The inner shared members of [`StdChildArgs`]
+#[derive(Debug, Clone)]
+pub struct StdChildArgsInner {
+    /// The timeout of the children
+    pub timeout: Duration,
+    /// The stderr handle of the children
+    pub stderr_observer: Option<Handle<StdErrObserver>>,
+    /// The stdout handle of the children
+    pub stdout_observer: Option<Handle<StdOutObserver>>,
+    /// The current directory of the spawned children
+    pub current_directory: Option<PathBuf>,
+    /// Whether debug child by inheriting stdout/stderr
+    pub debug_child: bool,
+}
+
+#[cfg(feature = "std")]
+impl Default for StdChildArgsInner {
+    fn default() -> Self {
+        Self {
+            timeout: Duration::from_millis(5000),
+            stderr_observer: None,
+            stdout_observer: None,
+            current_directory: None,
+            debug_child: false,
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+/// The shared implementation for children with stdout/stderr/timeouts.
+pub trait StdChildArgs: Sized {
+    /// The inner struct of child environment.
+    fn inner(&self) -> &StdChildArgsInner;
+
+    /// The mutable inner struct of child environment.
+    fn inner_mut(&mut self) -> &mut StdChildArgsInner;
+
+    #[must_use]
+    /// Sets the execution timeout duration.
+    fn timeout(mut self, timeout: Duration) -> Self {
+        self.inner_mut().timeout = timeout;
+        self
+    }
+
+    #[must_use]
+    /// Sets the stdout observer
+    fn stdout_observer(mut self, stdout: Handle<StdOutObserver>) -> Self {
+        self.inner_mut().stdout_observer = Some(stdout);
+        self
+    }
+
+    #[must_use]
+    /// Sets the stderr observer
+    fn stderr_observer(mut self, stderr: Handle<StdErrObserver>) -> Self {
+        self.inner_mut().stderr_observer = Some(stderr);
+        self
+    }
+
+    #[must_use]
+    /// Sets the working directory for the child process.
+    fn current_dir(mut self, current_dir: PathBuf) -> Self {
+        self.inner_mut().current_directory = Some(current_dir);
+        self
+    }
+
+    #[must_use]
+    /// If set to true, the child's output won't be redirecited to `/dev/null` and will go to parent's stdout/stderr
+    /// Defaults to `false`.
+    fn debug_child(mut self, debug_child: bool) -> Self {
+        if debug_child {
+            assert!(
+                self.inner().stderr_observer.is_none() && self.inner().stdout_observer.is_none(),
+                "you can not set debug_child when you have stderr_observer or stdout_observer"
+            );
+        }
+        self.inner_mut().debug_child = debug_child;
+        self
+    }
+}
+
 #[cfg(test)]
 /// Tester for executor
 pub mod test {

libafl/src/observers/stdio.rs

@@ -4,14 +4,18 @@
 //! The executor must explicitly support these observers.
 #![cfg_attr(
     unix,
-    doc = r"For example, they are supported on the [`crate::executors::CommandExecutor`]."
+    doc = r"For example, they are supported on the [`crate::executors::CommandExecutor`] and [`crate::executors::ForkserverExecutor`]."
 )]
 
-use alloc::{borrow::Cow, vec::Vec};
+use alloc::{borrow::Cow, string::ToString, vec::Vec};
 use core::marker::PhantomData;
+use std::{
+    fs::File,
+    io::{Read, Seek, SeekFrom},
+};
 
 use libafl_bolts::Named;
-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize};
 
 use crate::{Error, observers::Observer};
 
@@ -26,7 +30,7 @@ use crate::{Error, observers::Observer};
 ///     Error, Fuzzer, StdFuzzer,
 ///     corpus::{Corpus, InMemoryCorpus, Testcase},
 ///     events::{EventFirer, NopEventManager},
-///     executors::{CommandExecutor, ExitKind},
+///     executors::{StdChildArgs, CommandExecutor, ExitKind},
 ///     feedbacks::{Feedback, StateInitializer},
 ///     inputs::BytesInput,
 ///     mutators::{MutationResult, NopMutator},
@@ -36,7 +40,7 @@ use crate::{Error, observers::Observer};
 /// };
 /// use libafl_bolts::{
 ///     Named, current_nanos,
-///     TargetArgs,
+///     StdTargetArgs,
 ///     rands::StdRand,
 ///     tuples::{Handle, Handled, MatchNameRef, tuple_list},
 /// };
@@ -87,8 +91,8 @@ use crate::{Error, observers::Observer};
 ///    let input_text = "Hello, World!";
 ///    let encoded_input_text = "SGVsbG8sIFdvcmxkIQo=";
 ///
-///    let stdout_observer = StdOutObserver::new("stdout-observer");
+///    let stdout_observer = StdOutObserver::new("stdout-observer".into()).unwrap();
-///    let stderr_observer = StdErrObserver::new("stderr-observer");
+///    let stderr_observer = StdErrObserver::new("stderr-observer".into()).unwrap();
 ///
 ///    let mut feedback = ExportStdXObserver {
 ///        stdout_observer: stdout_observer.handle(),
@@ -170,16 +174,30 @@ use crate::{Error, observers::Observer};
 /// }
 /// ```
 ///
-#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[derive(Debug, Serialize, Deserialize)]
 pub struct OutputObserver<T> {
     /// The name of the observer.
     pub name: Cow<'static, str>,
     /// The captured stdout/stderr data during last execution.
     pub output: Option<Vec<u8>>,
+    #[serde(skip_serializing, deserialize_with = "new_file::<_, T>")]
+    /// File backend of the memory to capture output, if [`None`] we use portable piped output
+    pub file: Option<File>,
+    #[serde(skip)]
     /// Phantom data to hold the stream type
     phantom: PhantomData<T>,
 }
 
+/// Blanket implementation for a [`std::fs::File`]. Fortunately the contents of the file
+/// is transient and thus we can safely create a new one on deserialization (and skip it)
+/// when doing serialization
+fn new_file<'de, D, T>(_d: D) -> Result<Option<File>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    OutputObserver::<T>::file().map_err(|e| serde::de::Error::custom(e.to_string()))
+}
+
 /// Marker traits to mark stdout for the `OutputObserver`
 #[derive(Debug, Clone)]
 pub struct StdOutMarker;
@@ -189,19 +207,80 @@ pub struct StdOutMarker;
 pub struct StdErrMarker;
 
 impl<T> OutputObserver<T> {
-    /// Create a new `OutputObserver` with the given name.
+    // This is the best we can do on macOS because
-    #[must_use]
+    // - macos doesn't have memfd_create
-    pub fn new(name: &'static str) -> Self {
+    // - fd returned from shm_open can't be written (https://stackoverflow.com/questions/73752631/cant-write-to-fd-from-shm-open-on-macos)
-        Self {
+    // - there is even no native tmpfs implementation!
-            name: Cow::from(name),
+    // therefore we create a file and immediately remove it to get a writtable fd.
+    //
+    // In most cases, capturing stdout/stderr every loop is very slow and mostly for debugging purpose and thus this should be acceptable.
+    #[cfg(target_os = "macos")]
+    fn file() -> Result<Option<File>, Error> {
+        let fp = File::create_new("fsrvmemfd")?;
+        nix::unistd::unlink("fsrvmemfd")?;
+        Ok(Some(fp))
+    }
+
+    /// Cool, we can have [`MemfdShMemProvider`] to create a memfd.
+    #[cfg(target_os = "linux")]
+    fn file() -> Result<Option<File>, Error> {
+        Ok(Some(
+            libafl_bolts::shmem::unix_shmem::memfd::MemfdShMemProvider::new_file()?,
+        ))
+    }
+
+    /// This will use standard but portable pipe mechanism to capture outputs
+    #[cfg(not(any(target_os = "linux", target_os = "macos")))]
+    pub fn file() -> Result<Option<File>, Error> {
+        Ok(None)
+    }
+
+    /// Create a new [`OutputObserver`] with the given name. This will use the memory fd backend
+    /// on Linux and macOS, which is compatible with forkserver.
+    pub fn new(name: Cow<'static, str>) -> Result<Self, Error> {
+        Ok(Self {
+            name,
             output: None,
+            file: Self::file()?,
+            phantom: PhantomData,
+        })
+    }
+
+    /// Create a new `OutputObserver` with the given name. This use portable piped backend, which
+    /// only works with [`std::process::Command`].
+    pub fn new_piped(name: Cow<'static, str>) -> Result<Self, Error> {
+        Ok(Self {
+            name,
+            output: None,
+            file: None,
+            phantom: PhantomData,
+        })
+    }
+
+    /// Create a new `OutputObserver` with given name and file.
+    /// Useful for targets like nyx which writes to the same file again and again.
+    #[must_use]
+    pub fn new_file(name: Cow<'static, str>, file: File) -> Self {
+        Self {
+            name,
+            output: None,
+            file: Some(file),
             phantom: PhantomData,
         }
     }
 
     /// React to new stream data
-    pub fn observe(&mut self, data: &[u8]) {
+    pub fn observe(&mut self, data: Vec<u8>) {
-        self.output = Some(data.into());
+        self.output = Some(data);
+    }
+
+    #[must_use]
+    /// Return the raw fd, if any
+    pub fn as_raw_fd(&self) -> Option<i32> {
+        #[cfg(target_family = "unix")]
+        return self.file.as_ref().map(std::os::fd::AsRawFd::as_raw_fd);
+        #[cfg(not(target_family = "unix"))]
+        return None;
     }
 }
 
@@ -211,16 +290,53 @@ impl<T> Named for OutputObserver<T> {
     }
 }
 
-impl<I, S, T> Observer<I, S> for OutputObserver<T> {
+impl<I, S, T> Observer<I, S> for OutputObserver<T>
+where
+    T: 'static,
+{
     fn pre_exec_child(&mut self, _state: &mut S, _input: &I) -> Result<(), Error> {
+        if let Some(file) = self.file.as_mut() {
+            file.seek(SeekFrom::Start(0))?;
+        }
         self.output = None;
         Ok(())
     }
 
     fn pre_exec(&mut self, _state: &mut S, _input: &I) -> Result<(), Error> {
-        self.output = None;
+        self.pre_exec_child(_state, _input)
+    }
+
+    fn post_exec_child(
+        &mut self,
+        _state: &mut S,
+        _input: &I,
+        _exit_kind: &crate::executors::ExitKind,
+    ) -> Result<(), Error> {
+        if let Some(file) = self.file.as_mut() {
+            if self.output.is_none() {
+                let pos = file.stream_position()?;
+
+                if pos != 0 {
+                    file.seek(SeekFrom::Start(0))?;
+
+                    let mut buf = vec![0; pos as usize];
+                    file.read_exact(&mut buf)?;
+
+                    self.observe(buf);
+                }
+            }
+        }
         Ok(())
     }
+
+    fn post_exec(
+        &mut self,
+        _state: &mut S,
+        _input: &I,
+        _exit_kind: &crate::executors::ExitKind,
+    ) -> Result<(), Error> {
+        self.post_exec_child(_state, _input, _exit_kind)
+    }
 }
 
 /// An observer that captures stdout of a target.

libafl_bolts/src/argparse.rs

@@ -4,50 +4,23 @@ use core::{
     ffi::{c_char, c_int},
     pin::Pin,
 };
-use std::{ffi::OsString, os::unix::ffi::OsStrExt};
+use std::os::unix::ffi::OsStrExt;
 
-use crate::{Error, InputLocation, TargetArgs};
+use crate::{Error, StdTargetArgs, StdTargetArgsInner};
 
 /// For creating an C-compatible argument
 #[derive(Debug)]
 pub struct CMainArgsBuilder {
-    program: Option<OsString>,
+    inner: StdTargetArgsInner,
-    input_location: InputLocation,
-    envs: Vec<(OsString, OsString)>,
-    args: Vec<OsString>,
 }
 
-impl TargetArgs for CMainArgsBuilder {
+impl StdTargetArgs for CMainArgsBuilder {
-    fn arguments_ref(&self) -> &Vec<OsString> {
+    fn inner(&self) -> &StdTargetArgsInner {
-        &self.args
+        &self.inner
     }
 
-    fn arguments_mut(&mut self) -> &mut Vec<OsString> {
+    fn inner_mut(&mut self) -> &mut StdTargetArgsInner {
-        &mut self.args
+        &mut self.inner
-    }
-
-    fn input_location_ref(&self) -> &InputLocation {
-        &self.input_location
-    }
-
-    fn input_location_mut(&mut self) -> &mut InputLocation {
-        &mut self.input_location
-    }
-
-    fn envs_ref(&self) -> &Vec<(OsString, OsString)> {
-        &self.envs
-    }
-
-    fn envs_mut(&mut self) -> &mut Vec<(OsString, OsString)> {
-        &mut self.envs
-    }
-
-    fn program_ref(&self) -> &Option<OsString> {
-        &self.program
-    }
-
-    fn program_mut(&mut self) -> &mut Option<OsString> {
-        &mut self.program
     }
 }
 
@@ -62,10 +35,7 @@ impl CMainArgsBuilder {
     #[must_use]
     pub fn new() -> Self {
         Self {
-            program: None,
+            inner: StdTargetArgsInner::default(),
-            input_location: InputLocation::StdIn,
-            envs: Vec::new(),
-            args: Vec::new(),
         }
     }
 
@@ -73,13 +43,13 @@ impl CMainArgsBuilder {
     pub fn build(&self) -> Result<CMainArgs, Error> {
         let mut argv: Vec<Pin<Box<CString>>> = Vec::new();
 
-        if let Some(program) = &self.program {
+        if let Some(program) = &self.inner().program {
             argv.push(Box::pin(CString::new(program.as_bytes()).unwrap()));
         } else {
             return Err(Error::illegal_argument("Program not specified"));
         }
 
-        for args in &self.args {
+        for args in &self.inner().arguments {
             argv.push(Box::pin(CString::new(args.as_bytes()).unwrap()));
         }
 

libafl_bolts/src/shmem.rs

@@ -1390,7 +1390,7 @@ pub mod unix_shmem {
             ops::{Deref, DerefMut},
             ptr, slice,
         };
-        use std::os::fd::IntoRawFd;
+        use std::{fs::File, os::fd::IntoRawFd};
 
         use libc::{MAP_SHARED, PROT_READ, PROT_WRITE, close, fstat, ftruncate, mmap, munmap};
         use nix::sys::memfd::{MemFdCreateFlag, memfd_create};
@@ -1533,6 +1533,21 @@ pub mod unix_shmem {
             }
         }
 
+        /// Dedicated Implementation to yield a [`std::fs::File`]
+        #[cfg(unix)]
+        impl MemfdShMemProvider {
+            /// Unlike [`MemfdShMemProvider::new`], this returns a file instead, without any mmap and truncate.
+            /// By default, the file size is capped by the tmpfs installed by the operating system, which is big
+            /// enough to hold all output and avoid spurious read/write errors from children. However, you are free
+            /// to set the size via [`std::fs::File::set_len`]
+            pub fn new_file() -> Result<File, Error> {
+                Ok(File::from(memfd_create(
+                    c"libafl_file",
+                    MemFdCreateFlag::empty(),
+                )?))
+            }
+        }
+
         /// Implement [`ShMemProvider`] for [`MemfdShMemProvider`]
         #[cfg(unix)]
         impl ShMemProvider for MemfdShMemProvider {

libafl_bolts/src/target_args.rs

@@ -29,27 +29,26 @@ pub enum InputLocation {
     },
 }
 
+/// The shared inner structs of trait [`StdTargetArgs`]
+#[derive(Debug, Clone, Default)]
+pub struct StdTargetArgsInner {
+    /// Program arguments
+    pub arguments: Vec<OsString>,
+    /// Program main program
+    pub program: Option<OsString>,
+    /// Input location, might be stdin or file or cli arg
+    pub input_location: InputLocation,
+    /// Program environments
+    pub envs: Vec<(OsString, OsString)>,
+}
+
 /// The main implementation trait of afl style arguments handling
-pub trait TargetArgs: Sized {
+pub trait StdTargetArgs: Sized {
-    /// Gets the arguments
+    /// Get inner common arguments
-    fn arguments_ref(&self) -> &Vec<OsString>;
+    fn inner(&self) -> &StdTargetArgsInner;
-    /// Gets the mutable arguments
-    fn arguments_mut(&mut self) -> &mut Vec<OsString>;
 
-    /// Gets the main program
+    /// Get mutable inner common arguments
-    fn program_ref(&self) -> &Option<OsString>;
+    fn inner_mut(&mut self) -> &mut StdTargetArgsInner;
-    /// Gets the mutable main program
-    fn program_mut(&mut self) -> &mut Option<OsString>;
-
-    /// Gets the input file
-    fn input_location_ref(&self) -> &InputLocation;
-    /// Gets the mutable input file
-    fn input_location_mut(&mut self) -> &mut InputLocation;
-
-    /// Get the environments
-    fn envs_ref(&self) -> &Vec<(OsString, OsString)>;
-    /// Get the mutable environments
-    fn envs_mut(&mut self) -> &mut Vec<(OsString, OsString)>;
 
     /// Adds an environmental var to the harness's commandline
     #[must_use]
@@ -58,7 +57,8 @@ pub trait TargetArgs: Sized {
         K: AsRef<OsStr>,
         V: AsRef<OsStr>,
     {
-        self.envs_mut()
+        self.inner_mut()
+            .envs
             .push((key.as_ref().to_owned(), val.as_ref().to_owned()));
         self
     }
@@ -75,20 +75,20 @@ pub trait TargetArgs: Sized {
         for (ref key, ref val) in vars {
             res.push((key.as_ref().to_owned(), val.as_ref().to_owned()));
         }
-        self.envs_mut().append(&mut res);
+        self.inner_mut().envs.append(&mut res);
         self
     }
 
     /// If use stdin
     #[must_use]
     fn use_stdin(&self) -> bool {
-        matches!(self.input_location_ref(), InputLocation::StdIn)
+        matches!(self.inner().input_location, InputLocation::StdIn)
     }
 
     /// Set input
     #[must_use]
     fn input(mut self, input: InputLocation) -> Self {
-        *self.input_location_mut() = input;
+        self.inner_mut().input_location = input;
         self
     }
 
@@ -97,7 +97,7 @@ pub trait TargetArgs: Sized {
     /// Use [`Self::arg_input_file_std`] if you want to provide the input as a file instead.
     #[must_use]
     fn arg_input_arg(mut self) -> Self {
-        let argnum = self.arguments_ref().len();
+        let argnum = self.inner().arguments.len();
         self = self.input(InputLocation::Arg { argnum });
         // Placeholder arg that gets replaced with the input name later.
         self = self.arg("PLACEHOLDER");
@@ -112,7 +112,7 @@ pub trait TargetArgs: Sized {
     fn arg_input_file<P: AsRef<Path>>(self, path: P) -> Self {
         let mut moved = self.arg(path.as_ref());
         assert!(
-            match moved.input_location_ref() {
+            match &moved.inner().input_location {
                 InputLocation::File { out_file } => out_file.path.as_path() == path.as_ref(),
                 InputLocation::StdIn => true,
                 InputLocation::Arg { argnum: _ } => false,
@@ -137,7 +137,7 @@ pub trait TargetArgs: Sized {
     where
         O: AsRef<OsStr>,
     {
-        *self.program_mut() = Some(program.as_ref().to_owned());
+        self.inner_mut().program = Some(program.as_ref().to_owned());
         self
     }
 
@@ -150,7 +150,7 @@ pub trait TargetArgs: Sized {
     where
         O: AsRef<OsStr>,
     {
-        self.arguments_mut().push(arg.as_ref().to_owned());
+        self.inner_mut().arguments.push(arg.as_ref().to_owned());
         self
     }
 
@@ -168,7 +168,7 @@ pub trait TargetArgs: Sized {
         for arg in args {
             res.push(arg.as_ref().to_owned());
         }
-        self.arguments_mut().append(&mut res);
+        self.inner_mut().arguments.append(&mut res);
         self
     }
 
@@ -189,7 +189,7 @@ pub trait TargetArgs: Sized {
         let mut moved = self;
 
         let mut use_arg_0_as_program = false;
-        if moved.program_ref().is_none() {
+        if moved.inner().program.is_none() {
             use_arg_0_as_program = true;
         }
 
@@ -200,7 +200,7 @@ pub trait TargetArgs: Sized {
                 // subsequent arguments as regular arguments
                 use_arg_0_as_program = false;
             } else if item.as_ref() == "@@" {
-                match moved.input_location_ref().clone() {
+                match moved.inner().input_location.clone() {
                     InputLocation::File { out_file } => {
                         // If the input file name has been modified, use this one
                         moved = moved.arg_input_file(&out_file.path);

libafl_nyx/src/executor.rs

@@ -1,6 +1,7 @@
 use core::marker::PhantomData;
 use std::{
     io::{Read, Seek},
+    ops::IndexMut,
     os::fd::AsRawFd,
 };
 
@@ -11,7 +12,10 @@ use libafl::{
     observers::{ObserversTuple, StdOutObserver},
     state::HasExecutions,
 };
-use libafl_bolts::{AsSlice, tuples::RefIndexable};
+use libafl_bolts::{
+    AsSlice,
+    tuples::{Handle, RefIndexable},
+};
 use libnyx::NyxReturnValue;
 
 use crate::{cmplog::CMPLOG_ENABLED, helper::NyxHelper};
@@ -21,7 +25,7 @@ pub struct NyxExecutor<S, OT> {
     /// implement nyx function
     pub helper: NyxHelper,
     /// stdout
-    stdout: Option<StdOutObserver>,
+    stdout: Option<Handle<StdOutObserver>>,
     /// stderr
     // stderr: Option<StdErrObserver>,
     /// observers
@@ -112,7 +116,7 @@ where
             }
         };
 
-        if let Some(ob) = self.stdout.as_mut() {
+        if let Some(ob) = self.stdout.clone() {
             let mut stdout = Vec::new();
             self.helper.nyx_stdout.rewind()?;
             self.helper
@@ -120,7 +124,7 @@ where
                 .read_to_end(&mut stdout)
                 .map_err(|e| Error::illegal_state(format!("Failed to read Nyx stdout: {e}")))?;
 
-            ob.observe(&stdout);
+            self.observers_mut().index_mut(&ob).observe(stdout);
         }
 
         unsafe {
@@ -169,7 +173,7 @@ impl<S, OT> NyxExecutor<S, OT> {
 }
 
 pub struct NyxExecutorBuilder {
-    stdout: Option<StdOutObserver>,
+    stdout: Option<Handle<StdOutObserver>>,
     // stderr: Option<StdErrObserver>,
 }
 
@@ -188,7 +192,7 @@ impl NyxExecutorBuilder {
         }
     }
 
-    pub fn stdout(&mut self, stdout: StdOutObserver) -> &mut Self {
+    pub fn stdout(&mut self, stdout: Handle<StdOutObserver>) -> &mut Self {
         self.stdout = Some(stdout);
         self
     }

libafl_sugar/src/forkserver.rs

@@ -7,7 +7,10 @@ use libafl::{
     Error, HasMetadata,
     corpus::{CachedOnDiskCorpus, Corpus, OnDiskCorpus},
     events::{EventConfig, LlmpRestartingEventManager, launcher::Launcher},
-    executors::forkserver::{ForkserverExecutor, SHM_CMPLOG_ENV_VAR},
+    executors::{
+        StdChildArgs,
+        forkserver::{ForkserverExecutor, SHM_CMPLOG_ENV_VAR},
+    },
     feedback_and_fast, feedback_or, feedback_or_fast,
     feedbacks::{CrashFeedback, MaxMapFeedback, TimeFeedback, TimeoutFeedback},
     fuzzer::{Fuzzer, StdFuzzer},
@@ -28,7 +31,7 @@ use libafl::{
     state::{HasCorpus, StdState},
 };
 use libafl_bolts::{
-    AsSliceMut, TargetArgs,
+    AsSliceMut, StdTargetArgs,
     core_affinity::Cores,
     nonzero,
     ownedref::OwnedRefMut,

libafl_sugar/src/qemu.rs

@@ -131,11 +131,11 @@ where
 
         let mut out_dir = self.output_dir.clone();
         if fs::create_dir(&out_dir).is_err() {
-            log::info!("Out dir at {:?} already exists.", &out_dir);
+            log::info!("Out dir at {} already exists.", &out_dir.display());
             assert!(
                 out_dir.is_dir(),
-                "Out dir at {:?} is not a valid directory!",
+                "Out dir at {} is not a valid directory!",
-                &out_dir
+                &out_dir.display()
             );
         }
         let mut crashes = out_dir.clone();

utils/gdb_qemu/gdb_qemu/src/child.rs

@@ -6,7 +6,7 @@ use std::{
 use anyhow::{anyhow, Result};
 use nix::unistd::{dup2, execvp};
 
-use crate::{args::ChildArgs, exit::Exit};
+use crate::{args::StdChildArgs, exit::Exit};
 
 pub struct Child {
     argv: Vec<String>,
@@ -47,7 +47,7 @@ impl Child {
         Ok(())
     }
 
-    pub fn new(args: &impl ChildArgs, fd1: RawFd, fd2: RawFd) -> Child {
+    pub fn new(args: &impl StdChildArgs, fd1: RawFd, fd2: RawFd) -> Child {
         Child {
             argv: args.argv().to_vec(),
             fd1,