Fix the fingerprint filenames.

Fixes the regression in 1054, since previously the fingerprint file name was based off the volume name. Since the volume names rely on the system time, this ensures the fingerprints are specific for only the toolchain and the path of directory.

Author: Alexhuszagh

src/docker/custom.rs

@@ -205,7 +205,7 @@ impl<'a> Dockerfile<'a> {
                 "{}{package_name}:{target_triple}-{path_hash}{custom}",
                 CROSS_CUSTOM_DOCKERFILE_IMAGE_PREFIX,
                 package_name = docker_package_name(metadata),
-                path_hash = path_hash(&metadata.workspace_root)?,
+                path_hash = path_hash(&metadata.workspace_root, 5)?,
                 custom = if matches!(self, Self::File { .. }) {
                     ""
                 } else {

src/docker/remote.rs

@@ -342,7 +342,10 @@ impl<'a, 'b, 'c> ContainerDataVolume<'a, 'b, 'c> {
             VolumeId::Keep(_) => {
                 let parent = temp::dir()?;
                 file::create_dir_all(&parent)?;
-                let fingerprint = parent.join(self.container);
+
+                let toolchain = &self.toolchain_dirs.toolchain();
+                let filename = toolchain.unique_mount_identifier(src)?;
+                let fingerprint = parent.join(filename);
                 let current = Fingerprint::read_dir(src, copy_cache)?;
                 // need to check if the container path exists, otherwise we might
                 // have stale data: the persistent volume was deleted & recreated.
@@ -561,7 +564,7 @@ impl QualifiedToolchain {
             .file_name()
             .expect("should be able to get toolchain name")
             .to_utf8()?;
-        let toolchain_hash = path_hash(self.get_sysroot())?;
+        let toolchain_hash = path_hash(self.get_sysroot(), 5)?;
         Ok(format!(
             "{VOLUME_PREFIX}{toolchain_name}-{toolchain_hash}-{commit_hash}"
         ))
@@ -571,10 +574,17 @@ impl QualifiedToolchain {
     // be generated outside a rust package and run multiple times.
     pub fn unique_container_identifier(&self, triple: &TargetTriple) -> Result<String> {
         let toolchain_id = self.unique_toolchain_identifier()?;
-        let cwd_path = path_hash(&env::current_dir()?)?;
+        let cwd_path = path_hash(&env::current_dir()?, 5)?;
         let system_time = now_as_millis()?;
         Ok(format!("{toolchain_id}-{triple}-{cwd_path}-{system_time}"))
     }
+
+    // unique identifier for a given mounted volume
+    pub fn unique_mount_identifier(&self, path: &Path) -> Result<String> {
+        let toolchain_id = self.unique_toolchain_identifier()?;
+        let mount_hash = path_hash(path, 10)?;
+        Ok(format!("{toolchain_id}-{mount_hash}"))
+    }
 }
 
 pub(crate) fn run(

src/docker/shared.rs

@@ -1417,11 +1417,11 @@ fn path_digest(path: &Path) -> Result<const_sha1::Digest> {
     Ok(const_sha1::sha1(&buffer))
 }
 
-pub fn path_hash(path: &Path) -> Result<String> {
+pub fn path_hash(path: &Path, count: usize) -> Result<String> {
     Ok(path_digest(path)?
         .to_string()
-        .get(..5)
-        .expect("sha1 is expected to be at least 5 characters long")
+        .get(..count)
+        .unwrap_or_else(|| panic!("sha1 is expected to be at least {count} characters long"))
         .to_owned())
 }