Add more transition messages

To README.md and help message.

README.md

@@ -6,6 +6,14 @@
 
 <h4 align="center">Fuzzing <a href="https://www.rust-lang.org">Rust</a> code with <a href="https://aflplus.plus/">AFLplusplus</a></h4>
 
+**Notice:** A future version of afl.rs will require you to install the `cargo-afl` binary with:
+
+```sh
+cargo install cargo-afl
+```
+
+You can use the new command now, if you like. If the binary is already installed, you may need to add `--force`.
+
 ## What is it?
 
 [Fuzz testing][] is a software testing technique used to find security and stability issues by providing pseudo-random data as input to the software. [AFLplusplus][] is a popular, effective, and modern fuzz testing tool based on [AFL][american-fuzzy-lop]. This library, afl.rs, allows one to run AFLplusplus on code written in [the Rust programming language][rust].

afl/build.rs

@@ -23,7 +23,7 @@ fn main() {
 
     let building_on_docs_rs = env::var("DOCS_RS").is_ok();
 
-    let out_dir = env::var("OUT_DIR").unwrap();
+    let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
 
     if installing && !building_cargo_afl {
         println!("cargo:warning=You appear to be installing the `cargo-afl` binary with:");
@@ -36,6 +36,16 @@ fn main() {
         );
     }
 
+    std::fs::write(
+        out_dir.join("help.txt"),
+        if building_cargo_afl {
+            String::new()
+        } else {
+            String::from("\n\n") + common::HELP_MSG
+        },
+    )
+    .unwrap();
+
     // smoelius: Build AFLplusplus in a temporary directory when installing or when building on docs.rs.
     let work_dir = if installing || building_on_docs_rs {
         let tempdir = tempfile::tempdir_in(&out_dir).unwrap();

afl/src/bin/cargo-afl.rs

@@ -87,6 +87,11 @@ fn main() {
 fn clap_app() -> clap::Command {
     use clap::{value_parser, Arg, Command};
 
+    let help = String::from(
+        "In addition to the subcommands above, Cargo subcommands are also \
+         supported (see `cargo help` for a list of all Cargo subcommands).",
+    ) + include_str!(concat!(env!("OUT_DIR"), "/help.txt"));
+
     Command::new("cargo afl")
         .display_name("cargo")
         .subcommand_required(true)
@@ -99,10 +104,7 @@ fn clap_app() -> clap::Command {
                 .allow_external_subcommands(true)
                 .external_subcommand_value_parser(value_parser!(OsString))
                 .override_usage("cargo afl [SUBCOMMAND or Cargo SUBCOMMAND]")
-                .after_help(
-                    "In addition to the subcommands above, Cargo subcommands are also \
-                 supported (see `cargo help` for a list of all Cargo subcommands).",
-                )
+                .after_help(help)
                 .subcommand(
                     Command::new("analyze")
                         .about("Invoke afl-analyze")

afl/src/common.rs

@@ -1,6 +1,14 @@
 use std::env;
 use std::path::{Path, PathBuf};
 
+#[allow(dead_code)]
+pub static HELP_MSG: &str = "Note: This binary appears to have been installed with:
+    cargo install afl
+A future version of afl.rs will require you to use:
+    cargo install cargo-afl
+You can use the new command now, if you like. You may need to add --force.
+";
+
 fn xdg_dir() -> xdg::BaseDirectories {
     let prefix = Path::new("afl.rs")
         .join(afl_rustc_version())

cargo-afl/tests/crates_io.rs

@@ -3,12 +3,15 @@ use predicates::prelude::*;
 use std::path::Path;
 use tempfile::tempdir;
 
+#[path = "../src/common.rs"]
+mod common;
+
 struct Test {
     subdir: &'static str,
-    should_contain_msg: bool,
+    should_contain_msgs: bool,
 }
 
-static MSG: &str = "warning: You appear to be installing the `cargo-afl` binary with:
+static INSTALL_MSG: &str = "warning: You appear to be installing the `cargo-afl` binary with:
 warning:     cargo install afl
 warning: A future version of afl.rs will require you to use:
 warning:     cargo install cargo-afl
@@ -19,19 +22,19 @@ warning: Note: If the binary is already installed, you may need to add --force.
 static TESTS: &[Test] = &[
     Test {
         subdir: "afl",
-        should_contain_msg: true,
+        should_contain_msgs: true,
     },
     Test {
         subdir: "cargo-afl",
-        should_contain_msg: false,
+        should_contain_msgs: false,
     },
 ];
 
 #[test]
 fn install() {
     for &Test {
         subdir,
-        should_contain_msg,
+        should_contain_msgs,
     } in TESTS
     {
         let tempdir = tempdir().unwrap();
@@ -52,16 +55,22 @@ fn install() {
             .assert()
             .success();
 
-        if should_contain_msg {
-            assert.stderr(predicates::str::contains(MSG));
+        if should_contain_msgs {
+            assert.stderr(predicates::str::contains(INSTALL_MSG));
         } else {
-            assert.stderr(predicates::str::contains(MSG).not());
+            assert.stderr(predicates::str::contains(INSTALL_MSG).not());
         }
 
-        Command::new(cargo_afl)
+        let assert = Command::new(cargo_afl)
             .args(["afl", "--help"])
             .assert()
             .success();
+
+        if should_contain_msgs {
+            assert.stdout(predicates::str::contains(common::HELP_MSG));
+        } else {
+            assert.stdout(predicates::str::contains(common::HELP_MSG).not());
+        }
     }
 }