Fix self-replace on windows

Cargo.toml

@@ -219,6 +219,7 @@ rustyline = { version = "12.0.0", features = [] }
 scoped-tls = "1.0.1"
 scopeguard = "1.1.0"
 second-stack = "0.3"
+self-replace = "1.5"
 semver = "1"
 serde = { version = "1.0.136", features = ["derive"] }
 serde_json = { version = "1.0.128", features = ["raw_value", "arbitrary_precision"] }

crates/paths/src/cli.rs

@@ -95,6 +95,7 @@ impl VersionBinDir {
         #[cfg(windows)]
         {
             junction::delete(self).ok();
+            std::fs::remove_dir(self).ok();
             // We won't be able to create a junction if the fs isn't NTFS, so fall back to trying
             // to make a symlink.
             junction::create(path, self)

crates/update/Cargo.toml

@@ -15,6 +15,7 @@ flate2.workspace = true
 http-body-util = "0.1.2"
 indicatif.workspace = true
 reqwest.workspace = true
+self-replace.workspace = true
 semver = { workspace = true, features = ["serde"] }
 serde.workspace = true
 tar.workspace = true

crates/update/src/cli/upgrade.rs

@@ -1,7 +1,6 @@
 use std::io::Write;
 
 use anyhow::Context;
-use bytes::Buf;
 use spacetimedb_paths::SpacetimePaths;
 
 use super::install::{download_and_install, download_with_progress, make_progress_bar};
@@ -26,23 +25,16 @@ impl Upgrade {
                     pb.set_message("installing...");
                     let cli_bin_file = paths.cli_bin_file.clone();
                     tokio::task::spawn_blocking(move || {
+                        // TODO(noa): try and see if `self_replace` could support providing the binary
+                        // in a buffer, instead of an already existing file, since we're doing the same
+                        // work they are right now
                         let mut file = tempfile::NamedTempFile::with_prefix_in(
-                            ".spacetimedb-update-tmp",
+                            ".spacetimedb-self-replace",
                             cli_bin_file.0.parent().unwrap(),
                         )?;
-                        #[cfg(unix)]
-                        file.as_file_mut()
-                            .set_permissions(std::os::unix::fs::PermissionsExt::from_mode(0o755))?;
-                        // TODO(noa): write_all_vectored once stabilized
-                        let mut bin = bin.aggregate();
-                        while bin.has_remaining() {
-                            let chunk = bin.chunk();
-                            file.write_all(chunk)?;
-                            bin.advance(chunk.len());
-                        }
-                        file.persist(cli_bin_file)
-                            .map_err(|e| e.error)
-                            .context("failed to overwrite existing spacetime binary")
+                        file.write_all(&bin.to_bytes())?;
+                        self_replace::self_replace(file.path())
+                            .context("failed to overwrite the original spacetime binary")
                     })
                     .await??;