fix: rename temp downloaded file to given cache path (#332)

resolves #330

This simply keeps the downloaded temp file in the same directory as the
destination of the downloaded file. When download is done, the file is
renamed to the specified file name.

This also removes the `tempfile` dependency from production code. It is
still used heavily in tests.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Bug Fixes**
* Improved error handling for download operations with clearer,
contextual messages when temporary file or filesystem operations fail.

* **Breaking Changes**
* The shape of download error reporting was changed; integrations that
inspect specific download error variants may need updates.

* **Chores**
* Test/dev setup updated (added a dev dependency for temporary-file
utilities) and CI triggers expanded to include installer-related files
and manifests.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: 2bndy5

.github/workflows/run-dev-tests.yml

@@ -5,13 +5,15 @@ on:
     branches: [main]
     paths:
       - cpp-linter/**
+      - clang-installer/**
       - Cargo.toml
       - Cargo.lock
       - .github/workflows/run-dev-tests.yml
   pull_request:
     branches: [main]
     paths:
       - cpp-linter/**
+      - clang-installer/**
       - Cargo.toml
       - Cargo.lock
       - .github/workflows/run-dev-tests.yml

clang-installer/Cargo.toml

@@ -36,12 +36,12 @@ tokio = { workspace = true, features = ["macros"], optional = true }
 url = "2.5.8"
 which = "8.0.2"
 zip = { version = "8.6.0", default-features = false, features = ["deflate"] }
-tempfile = { workspace = true }
 
 [dev-dependencies]
 colored = { workspace = true }
 mockito = { workspace = true }
 reqwest = { workspace = true, features = ["default-tls"] }
+tempfile = { workspace = true }
 tokio = { workspace = true, features = ["macros", "rt-multi-thread"] }
 
 [features]

clang-installer/src/downloader/mod.rs

@@ -31,9 +31,9 @@ pub enum DownloadError {
     #[error("Hash mismatch for downloaded file. Expected: {expected}, Actual: {actual}")]
     HashMismatch { expected: String, actual: String },
 
-    /// An error that occurred while moving/persisting a temporary file into a cache path.
-    #[error("Error persisting temporary file: {0}")]
-    TempFilePersistence(#[from] tempfile::PersistError),
+    /// An error that occurred while creating or persisting a temporary file into a cache path.
+    #[error("Error when {0}: {1}")]
+    TempFile(&'static str, #[source] std::io::Error),
 }
 
 /// Downloads data from the specified URL and returns the response.
@@ -58,7 +58,15 @@ async fn download(url: &Url, cache_path: &Path, timeout: u64) -> Result<(), Down
         }
         return Err(e.into());
     }
-    let mut tmp_file = tempfile::NamedTempFile::new()?;
+    let tmp_file_path = cache_path.with_extension("tmp");
+    let mut tmp_file = fs::OpenOptions::new()
+        .write(true)
+        .truncate(true)
+        .create(true)
+        .open(&tmp_file_path)
+        .map_err(|e| {
+            DownloadError::TempFile("creating temporary file for download placeholder", e)
+        })?;
     let content_len = response.content_length().and_then(NonZero::new);
     let mut progress_bar = ProgressBar::new(
         content_len,
@@ -79,8 +87,10 @@ async fn download(url: &Url, cache_path: &Path, timeout: u64) -> Result<(), Down
     }
     progress_bar.finish()?;
     tmp_file.flush()?;
-    tmp_file.as_file_mut().set_modified(SystemTime::now())?;
-    tmp_file.persist(cache_path)?;
+    tmp_file.set_modified(SystemTime::now())?;
+    drop(tmp_file); // ensure the file is closed before renaming
+    fs::rename(tmp_file_path, cache_path)
+        .map_err(|e| DownloadError::TempFile("renaming temporary file after download", e))?;
     Ok(())
 }