feat: give a more useful error message when VM image already exists

Sponsored-by: author

1 files changed, 17 insertions, 0 deletions

diff --git a/src/image.rs b/src/image.rs
index 7b7c2ce..ffe5b56 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -1,5 +1,6 @@
 //! Virtual machine image handling.
 
+use log::debug;
 use std::fs::copy;
 use std::path::{Path, PathBuf};
 use std::process::Command;
@@ -8,6 +9,10 @@ use std::result::Result;
 /// Errors from this module.
 #[derive(Debug, thiserror::Error)]
 pub enum ImageError {
+    /// The image file for a new VM already exists.
+    #[error("image file already exists: {0}")]
+    ImageExists(PathBuf),
+
     /// Error resizing image.
     #[error("qemu-img resize failed: {0}")]
     ResizeError(String),
@@ -34,9 +39,21 @@ pub struct VirtualMachineImage {
 impl VirtualMachineImage {
     /// Create new image from a base image.
     pub fn new_from_base(base_image: &Path, image: &Path) -> Result<Self, ImageError> {
+        debug!(
+            "creating new image {} from base image {}",
+            image.display(),
+            base_image.display()
+        );
+        debug!("does {} exixt? {}", image.display(), image.exists());
+        if image.exists() {
+            debug!("image already exists: {}", image.display());
+            return Err(ImageError::ImageExists(image.to_path_buf()));
+        }
+        debug!("copying base image to new image");
         copy(base_image, image).map_err(|err| {
             ImageError::BaseImageCopy(base_image.to_path_buf(), image.to_path_buf(), err)
         })?;
+        debug!("all good");
         Ok(Self {
             filename: image.to_path_buf(),
         })