xtask: Add default QEMU executable directory on Windows

The QEMU installer for Windows does not automatically add the directory
containing the QEMU executables to the PATH. Add the default directory
to the PATH to make it more likely that QEMU will be found on
Windows. The directory is appended, so if a different directory on the
PATH already has the QEMU binary this change won't affect anything.

Author: nicholasbishop

xtask/src/qemu.rs

@@ -11,7 +11,7 @@ use std::ffi::OsString;
 use std::io::{BufRead, BufReader, Read, Write};
 use std::path::{Path, PathBuf};
 use std::process::{Child, Command, Stdio};
-use std::thread;
+use std::{env, thread};
 use tempfile::TempDir;
 
 struct OvmfPaths {
@@ -265,6 +265,18 @@ pub fn run_qemu(arch: UefiArch, opt: &QemuOpt) -> Result<()> {
     };
     let mut cmd = Command::new(qemu_exe);
 
+    if platform::is_windows() {
+        // The QEMU installer for Windows does not automatically add the
+        // directory containing the QEMU executables to the PATH. Add
+        // the default directory to the PATH to make it more likely that
+        // QEMU will be found on Windows. (The directory is appended, so
+        // if a different directory on the PATH already has the QEMU
+        // binary this change won't affect anything.)
+        let mut path = env::var_os("PATH").unwrap_or_default();
+        path.push(r";C:\Program Files\qemu");
+        cmd.env("PATH", path);
+    }
+
     // Disable default devices.
     // QEMU by defaults enables a ton of devices which slow down boot.
     cmd.arg("-nodefaults");