Make OSDK errors clear if commands don't exist

osdk/src/util.rs

@@ -23,7 +23,7 @@ pub fn ostd_dep() -> String {
 }
 
 fn cargo() -> Command {
-    Command::new("cargo")
+    new_command_checked_exists("cargo")
 }
 
 /// Create a new library crate with cargo
@@ -163,6 +163,22 @@ pub fn get_kernel_crate() -> CrateInfo {
     }
 }
 
+/// Check if an OSDK dependent executable (e.g. QEMU) exists.
+///
+/// If it exists, create a command. If not, print an error message and exit the
+/// process.
+pub fn new_command_checked_exists(executable: impl AsRef<Path>) -> Command {
+    let executable = executable.as_ref();
+    if which::which(executable).is_err() {
+        error_msg!(
+            "Executable {:?} cannot be found in PATH, please install the corresponding package",
+            executable
+        );
+        std::process::exit(Errno::ExecutableNotFound as _);
+    }
+    Command::new(executable)
+}
+
 fn package_contains_ostd_main(package: &serde_json::Value) -> bool {
     let src_path = {
         let targets = package.get("targets").unwrap().as_array().unwrap();
@@ -262,13 +278,15 @@ pub fn trace_panic_from_log(qemu_log: File, bin_path: PathBuf) {
     let mut stack_num = 0;
     let pc_matcher = regex::Regex::new(r" - pc (0x[0-9a-fA-F]+)").unwrap();
     let exe = bin_path.to_string_lossy();
-    let mut addr2line = Command::new("addr2line");
+
+    let mut addr2line = new_command_checked_exists("addr2line");
     addr2line.args(["-e", &exe]);
     let mut addr2line_proc = addr2line
         .stdin(std::process::Stdio::piped())
         .stdout(std::process::Stdio::piped())
         .spawn()
         .unwrap();
+
     for line in lines.into_iter().rev() {
         if line.contains("Printing stack trace:") {
             println!("[OSDK] The kernel seems panicked. Parsing stack trace for source lines:");