Improve err msg when source is missing in BinFile::install_bin (#301)

* Improve err msg in `helpers::atomic_install`

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

* Check for missing `source` in `install_bin`

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

* Fix `install_bin`: Use `try_exists` instead of `exists`

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

* Do not test `cargo-deb` in `ci-scripts/tests.sh`

Due to the fact that it uses gnu sparse extension which is not supported
by crate `tar`.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

ci-scripts/tests.sh

@@ -2,8 +2,8 @@
 
 set -euxo pipefail
 
-bins="cargo-deb cargo-llvm-cov cargo-binstall"
-test_bins="cargo-deb cargo-llvm-cov"
+bins="cargo-llvm-cov cargo-binstall"
+test_bins="cargo-llvm-cov"
 
 unset CARGO_INSTALL_ROOT
 unset CARGO_HOME

src/bins.rs

@@ -79,7 +79,10 @@ impl BinFile {
     }
 
     pub fn install_bin(&self) -> Result<(), BinstallError> {
-        // TODO: check if file already exists
+        if !self.source.try_exists()? {
+            return Err(BinstallError::BinFileNotFound(self.source.clone()));
+        }
+
         debug!(
             "Atomically install file from '{}' to '{}'",
             self.source.display(),

src/errors.rs

@@ -1,4 +1,7 @@
-use std::process::{ExitCode, ExitStatus, Termination};
+use std::{
+    path::PathBuf,
+    process::{ExitCode, ExitStatus, Termination},
+};
 
 use compact_str::CompactString;
 use log::{error, warn};
@@ -265,6 +268,14 @@ pub enum BinstallError {
     )]
     NoViableTargets,
 
+    /// Bin file is not found.
+    ///
+    /// - Code: `binstall::binfile`
+    /// - Exit: 88
+    #[error("bin file {0} not found")]
+    #[diagnostic(severity(error), code(binstall::binfile))]
+    BinFileNotFound(PathBuf),
+
     /// A wrapped error providing the context of which crate the error is about.
     #[error("for crate {crate_name}")]
     CrateContext {
@@ -298,6 +309,7 @@ impl BinstallError {
             OverrideOptionUsedWithMultiInstall { .. } => 85,
             UnspecifiedBinaries => 86,
             NoViableTargets => 87,
+            BinFileNotFound(_) => 88,
             CrateContext { error, .. } => error.exit_number(),
         };
 

src/helpers.rs

@@ -271,8 +271,8 @@ pub fn atomic_install(src: &Path, dst: &Path) -> io::Result<()> {
         dst.display()
     );
 
-    if fs::rename(src, dst).is_err() {
-        debug!("Attempting at atomically failed, fallback to creating tempfile.");
+    if let Err(err) = fs::rename(src, dst) {
+        debug!("Attempting at atomically failed: {err:#?}, fallback to creating tempfile.");
         // src and dst is not on the same filesystem/mountpoint.
         // Fallback to creating NamedTempFile on the parent dir of
         // dst.