Print error message if archive file can't be found. (#124)

Fixes #122.

build.rs

@@ -7,12 +7,12 @@ use std::process::Command;
 
 static AFL_SRC_PATH: &str = "afl-2.52b";
 
-#[path = "src/dirs.rs"]
-mod dirs;
+#[path = "src/common.rs"]
+mod common;
 
 fn main() {
-    build_afl(&dirs::afl());
-    build_afl_llvm_runtime(&dirs::afl_llvm_rt());
+    build_afl(&common::afl_dir());
+    build_afl_llvm_runtime();
 }
 
 fn build_afl(out_dir: &Path) {
@@ -29,10 +29,7 @@ fn build_afl(out_dir: &Path) {
     assert!(status.success());
 }
 
-fn build_afl_llvm_runtime(out_dir: &Path) {
-    let object_file_path = out_dir.join("libafl-llvm-rt.o");
-    let archive_file_path = out_dir.join("libafl-llvm-rt.a");
-
+fn build_afl_llvm_runtime() {
     let status = Command::new("cc")
         .current_dir(AFL_SRC_PATH)
         .arg("-c")
@@ -41,15 +38,15 @@ fn build_afl_llvm_runtime(out_dir: &Path) {
         .arg("-fno-omit-frame-pointer")
         .arg("llvm_mode/afl-llvm-rt.o.c")
         .arg("-fpermissive")
-        .args(&[OsStr::new("-o"), object_file_path.as_os_str()])
+        .args(&[OsStr::new("-o"), common::object_file_path().as_os_str()])
         .status()
         .expect("could not run 'gcc'");
     assert!(status.success());
 
     let status = Command::new("ar")
         .arg("r")
-        .arg(archive_file_path)
-        .arg(object_file_path)
+        .arg(common::archive_file_path())
+        .arg(common::object_file_path())
         .status()
         .expect("could not run 'ar'");
     assert!(status.success());

src/bin/cargo-afl.rs

@@ -7,10 +7,17 @@ use std::env;
 use std::ffi::OsStr;
 use std::process::{self, Command};
 
-#[path = "../dirs.rs"]
-mod dirs;
+#[path = "../common.rs"]
+mod common;
 
 fn main() {
+    if !common::archive_file_path().exists() {
+        let version = common::rustc_version();
+        eprintln!("AFL LLVM runtime is not built with Rust {}, run `cargo \
+                   install --force afl` to build it.", version);
+        process::exit(1);
+    }
+
     let _ = clap_app().get_matches();
 
     let mut args = env::args().skip(2).peekable(); // skip `cargo` and `afl`
@@ -127,7 +134,7 @@ where
     I: IntoIterator<Item = S>,
     S: AsRef<OsStr>,
 {
-    let cmd_path = dirs::afl().join("bin").join(cmd);
+    let cmd_path = common::afl_dir().join("bin").join(cmd);
     let status = Command::new(cmd_path)
         .args(args.into_iter().skip(1)) // skip afl sub-command
         .status()
@@ -149,7 +156,7 @@ where
          -C panic=abort \
          -l afl-llvm-rt \
          -L {}",
-        dirs::afl_llvm_rt().display()
+        common::afl_llvm_rt_dir().display()
     );
     let status = Command::new(cargo_path)
         .args(args) // skip `cargo` and `afl`

src/dirs.rs → src/common.rs

@@ -10,7 +10,7 @@ fn xdg_dir() -> xdg::BaseDirectories {
     xdg::BaseDirectories::with_prefix(prefix).unwrap()
 }
 
-fn rustc_version() -> String {
+pub fn rustc_version() -> String {
     let mut ret = String::from("rustc-");
     ret.push_str(&rustc_version::version().unwrap().to_string());
     ret
@@ -26,10 +26,19 @@ fn pkg_version() -> String {
     ret
 }
 
-pub fn afl() -> PathBuf {
+pub fn afl_dir() -> PathBuf {
     xdg_dir().create_data_directory("afl").unwrap()
 }
 
-pub fn afl_llvm_rt() -> PathBuf {
+pub fn afl_llvm_rt_dir() -> PathBuf {
     xdg_dir().create_data_directory("afl-llvm-rt").unwrap()
 }
+
+#[allow(dead_code)]
+pub fn object_file_path() -> PathBuf {
+    afl_llvm_rt_dir().join("libafl-llvm-rt.o")
+}
+
+pub fn archive_file_path() -> PathBuf {
+    afl_llvm_rt_dir().join("libafl-llvm-rt.a")
+}