feat: allow self renamer to work if tempdir is on a different device

src/self_renamer.rs

@@ -1,6 +1,6 @@
 use color_eyre::eyre::Result;
 use std::{env::current_exe, fs, path::PathBuf};
-use tracing::{debug, error};
+use tracing::{debug, error, warn};
 
 pub struct SelfRenamer {
     exe_path: PathBuf,
@@ -10,12 +10,40 @@ pub struct SelfRenamer {
 impl SelfRenamer {
     pub fn create() -> Result<Self> {
         let tempdir = tempfile::tempdir()?;
-        let temp_path = tempdir.path().join("topgrade.exe");
+        let mut temp_path = tempdir.path().join("topgrade.exe");
         let exe_path = current_exe()?;
 
-        debug!("Current exe in {:?}. Moving it to {:?}", exe_path, temp_path);
+        debug!(
+            "Current exe in {:?}. Attempting to move it to {:?}",
+            exe_path, temp_path
+        );
 
-        fs::rename(&exe_path, &temp_path)?;
+        match fs::rename(&exe_path, &temp_path) {
+            // cross-device error
+            Err(e) if e.raw_os_error() == Some(17) => {
+                debug!("Temporary directory is on a different device. Using the binary parent directory instead");
+
+                let Some(parent_dir) = exe_path.parent() else {
+                    return Err(color_eyre::eyre::Report::msg(
+                        "Could not get parent directory of the current binary",
+                    ));
+                };
+
+                let mut builder = tempfile::Builder::new();
+                builder.prefix("topgrade").suffix(".exe");
+                let temp_file = builder.tempfile_in(parent_dir)?;
+                temp_path = temp_file.path().to_path_buf();
+
+                // Delete the temporary file immediately to free up the name
+                if let Err(e) = temp_file.close() {
+                    warn!("Could not close temporary file: {}", e);
+                }
+
+                debug!("Moving current exe in {:?} to {:?}", exe_path, temp_path);
+                fs::rename(&exe_path, &temp_path)
+            }
+            other => other,
+        }?;
 
         Ok(SelfRenamer { exe_path, temp_path })
     }