config: introduce rust cache

chroot/build.py

@@ -142,6 +142,20 @@ class BuildChroot(Chroot):
             fail_if_mounted=fail_if_mounted,
         )
 
+    def mount_rust(self, user: str = 'kupfer', fail_if_mounted: bool = False) -> list[str]:
+        results = []
+        mount_source_base = config.file.paths.rust  # apparently arch-agnostic
+        for rust_dir in ['cargo', 'rustup']:
+            mount_source = os.path.join(mount_source_base, rust_dir)
+            mount_dest = os.path.join(f'/home/{user}' if user != 'root' else '/root', f'.{rust_dir}')
+            makedir(mount_source)
+            results.append(self.mount(
+                absolute_source=mount_source,
+                relative_destination=mount_dest,
+                fail_if_mounted=fail_if_mounted,
+            ))
+        return results
+
 
 def get_build_chroot(arch: Arch, add_kupfer_repos: bool = True, **kwargs) -> BuildChroot:
     name = build_chroot_name(arch)

config/scheme.py

@@ -142,6 +142,7 @@ class PathsSection(DataClass):
     jumpdrive: str
     images: str
     ccache: str
+    rust: str
 
 
 class ProfilesSection(DataClass):

config/state.py

@@ -43,6 +43,7 @@ CONFIG_DEFAULTS_DICT = {
         'jumpdrive': os.path.join('%cache_dir%', 'jumpdrive'),
         'images': os.path.join('%cache_dir%', 'images'),
         'ccache': os.path.join('%cache_dir%', 'ccache'),
+        'rust': os.path.join('%cache_dir%', 'rust'),
     },
     'profiles': {
         'current': 'default',

packages/__init__.py

@@ -461,6 +461,8 @@ def build_package(
     repo_dir = repo_dir if repo_dir else config.get_path('pkgbuilds')
     foreign_arch = config.runtime.arch != arch
     deps = (list(set(package.depends) - set(package.names())))
+    needs_rust = 'rust' in deps
+    build_root: BuildChroot
     target_chroot = setup_build_chroot(
         arch=arch,
         extra_packages=deps,
@@ -517,6 +519,8 @@ def build_package(
 
     if enable_ccache:
         build_root.mount_ccache(user=build_user)
+    if needs_rust:
+        build_root.mount_rust(user=build_user)
     setup_git_insecure_paths(build_root)
     makepkg_conf_absolute = os.path.join('/', makepkg_conf_path)
     setup_sources(package, build_root, makepkg_conf_path=makepkg_conf_absolute)