Add install.hard_link_entrypoints config option. (#267)

Fixes #266

Author: zooba

src/manage/aliasutils.py

@@ -85,7 +85,16 @@ def _if_exists(launcher, plat):
     return launcher
 
 
-def _create_alias(cmd, *, name, target, plat=None, windowed=0, script_code=None, _link=os.link):
+def _create_alias(
+    cmd,
+    *,
+    name,
+    target,
+    plat=None,
+    windowed=0,
+    script_code=None,
+    allow_link=True,
+    _link=os.link):
     p = cmd.global_dir / name
     if not p.match("*.exe"):
         p = p.with_name(p.name + ".exe")
@@ -129,12 +138,27 @@ def _create_alias(cmd, *, name, target, plat=None, windowed=0, script_code=None,
         LOGGER.debug("Failed to read existing alias launcher.")
 
     launcher_remap = cmd.scratch.setdefault("aliasutils.create_alias.launcher_remap", {})
-    if existing_bytes == launcher_bytes:
+    if not allow_link or not _link:
+        # If links are disallowed, always replace the target with a copy.
+        unlink(p)
+        try:
+            p.write_bytes(launcher_bytes)
+            LOGGER.debug("Created %s as copy of %s", p.name, launcher.name)
+            launcher_remap[launcher.name] = p
+        except OSError:
+            LOGGER.error("Failed to create global command %s.", name)
+            LOGGER.debug("TRACEBACK", exc_info=True)
+    elif existing_bytes == launcher_bytes:
         # Valid existing launcher, so save its path in case we need it later
         # for a hard link.
         launcher_remap.setdefault(launcher.name, p)
     else:
-        # First try and create a hard link
+        # Links are allowed and we need to create one, so try to make a link,
+        # falling back to a link to another existing alias (that we've checked
+        # already during this run), and then falling back to a copy.
+        # This handles the case where our links are on a different volume to the
+        # install (so hard links don't work), but limits us to only a single
+        # copy (each) of the redirector(s), thus saving space.
         unlink(p)
         try:
             _link(launcher, p)
@@ -305,7 +329,7 @@ def calculate_aliases(cmd, install, *, _scan=_scan):
             yield ai.replace(target=default_alias.target)
 
 
-def create_aliases(cmd, aliases, *, _create_alias=_create_alias):
+def create_aliases(cmd, aliases, *, allow_link=True, _create_alias=_create_alias):
     if not cmd.global_dir:
         return
 
@@ -337,6 +361,7 @@ def create_aliases(cmd, aliases, *, _create_alias=_create_alias):
                 target=target,
                 script_code=alias.script_code,
                 windowed=alias.windowed,
+                allow_link=allow_link,
             )
         except NoLauncherTemplateError:
             if install_matches_any(alias.install, getattr(cmd, "tags", None)):

src/manage/commands.py

@@ -258,6 +258,7 @@ def execute(self):
         "default_install_tag": (str, None),
         "preserve_site_on_upgrade": (config_bool, None),
         "enable_entrypoints": (config_bool, None),
+        "hard_link_entrypoints": (config_bool, None),
     },
 
     "first_run": {
@@ -823,6 +824,7 @@ class InstallCommand(BaseCommand):
     default_install_tag = None
     preserve_site_on_upgrade = True
     enable_entrypoints = True
+    hard_link_entrypoints = True
 
     def __init__(self, args, root=None):
         super().__init__(args, root)

src/manage/install_command.py

@@ -294,7 +294,7 @@ def update_all_shortcuts(cmd, *, _aliasutils=None):
             except LookupError:
                 LOGGER.warn("Failed to process aliases for %s.", i.get("display-name", i["id"]))
                 LOGGER.debug("TRACEBACK", exc_info=True)
-        _aliasutils.create_aliases(cmd, aliases)
+        _aliasutils.create_aliases(cmd, aliases, allow_link=getattr(cmd, "hard_link_entrypoints", True))
         _aliasutils.cleanup_aliases(cmd, preserve=aliases)
 
     for i in installs:

src/pymanager.json

@@ -2,7 +2,8 @@
     "install": {
         "source": "%PYTHON_MANAGER_SOURCE_URL%",
         "fallback_source": "./bundled/fallback-index.json",
-        "default_install_tag": "3"
+        "default_install_tag": "3",
+        "hard_link_entrypoints": false
     },
     "list": {
         "format": "%PYTHON_MANAGER_LIST_FORMAT%"

tests/test_alias.py

@@ -224,6 +224,28 @@ def fake_link(x, y):
     )
 
 
+def test_write_alias_launcher_no_linking(fake_config, assert_log, tmp_path):
+    fake_config.scratch = {
+        "aliasutils.create_alias.launcher_remap": {"launcher.txt": tmp_path / "actual_launcher.txt"},
+    }
+    fake_config.launcher_exe = tmp_path / "launcher.txt"
+    fake_config.launcher_exe.write_bytes(b'Arbitrary contents')
+    (tmp_path / "actual_launcher.txt").write_bytes(b'Arbitrary contents')
+    fake_config.default_platform = '-32'
+    fake_config.global_dir = tmp_path / "bin"
+    AU._create_alias(
+        fake_config,
+        name="test.exe",
+        target=tmp_path / "target.exe",
+        _link=None
+    )
+    assert_log(
+        "Create %s linking to %s",
+        ("Created %s as copy of %s", ("test.exe", "launcher.txt")),
+        assert_log.end_of_log(),
+    )
+
+
 def test_parse_entrypoint_line():
     for line, expect in [
         ("", (None, None, None)),
@@ -305,7 +327,7 @@ def test_create_aliases(fake_config, tmp_path):
 
     created = []
     # Full arguments copied from source to ensure callers only pass valid args
-    def _on_create(cmd, *, name, target, plat=None, windowed=0, script_code=None):
+    def _on_create(cmd, *, name, target, plat=None, windowed=0, script_code=None, allow_link=True):
         created.append((name, windowed, script_code))
 
     aliases = [

tests/test_install_command.py

@@ -199,7 +199,7 @@ class AliasUtils:
         calculate_aliases = staticmethod(AU.calculate_aliases)
 
         @staticmethod
-        def create_aliases(cmd, aliases):
+        def create_aliases(cmd, aliases, *, allow_link=True):
             created.extend(aliases)
 
         @staticmethod