libvirt: Remove predictable named file in /tmp

This one shouldn't have gotten through code review, I noticed
it when debugging something else.

Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

crates/kit/src/libvirt/run.rs

@@ -9,6 +9,7 @@ use clap::{Parser, ValueEnum};
 use color_eyre::eyre;
 use color_eyre::{eyre::Context, Result};
 use std::fs;
+use std::io::Write;
 use std::str::FromStr;
 use tracing::{debug, info};
 
@@ -1296,8 +1297,13 @@ fn create_libvirt_domain_from_disk(
         .with_context(|| "Failed to build domain XML")?;
 
     // Write XML to temporary file
-    let xml_path = format!("/tmp/{}.xml", domain_name);
-    std::fs::write(&xml_path, domain_xml).with_context(|| "Failed to write domain XML")?;
+    let mut tmp_domain_file = tempfile::NamedTempFile::with_prefix("bcvk-libvirt")?;
+    tmp_domain_file
+        .as_file_mut()
+        .write_all(domain_xml.as_bytes())
+        .with_context(|| "Failed to write domain XML")?;
+    let xml_path: &Utf8Path = tmp_domain_file.path().try_into()?;
+    let xml_path = xml_path.as_str();
 
     let connect_uri = global_opts.connect.as_deref();
 
@@ -1323,8 +1329,5 @@ fn create_libvirt_domain_from_disk(
         )?;
     }
 
-    // Clean up temporary XML file
-    let _ = std::fs::remove_file(&xml_path);
-
     Ok(())
 }