Automatically set execute permissions on generated scripts that contain a shebang [POLYGLOT]

cdist/core/cdist_object.py

@@ -239,9 +239,9 @@ class CdistObject:
             lambda obj: os.path.join(obj.absolute_path, "state"))
     source = fsproperty.FileListProperty(
             lambda obj: os.path.join(obj.absolute_path, "source"))
-    code_local = fsproperty.FileStringProperty(
+    code_local = fsproperty.FileScriptProperty(
             lambda obj: os.path.join(obj.base_path, obj.code_local_path))
-    code_remote = fsproperty.FileStringProperty(
+    code_remote = fsproperty.FileScriptProperty(
             lambda obj: os.path.join(obj.base_path, obj.code_remote_path))
     typeorder = fsproperty.FileListProperty(
             lambda obj: os.path.join(obj.absolute_path, 'typeorder'))

cdist/util/filesystem.py

@@ -0,0 +1,68 @@
+# -*- coding: utf-8 -*-
+#
+# 2023 Tabulon (dev-cdist at tabulon.net)
+#
+# This file is part of cdist.
+#
+# cdist is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cdist is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with cdist. If not, see <http://www.gnu.org/licenses/>.
+#
+#
+
+import os
+import stat
+
+def ensure_file_is_executable_by_all(path):
+    """Ensure (and if needed, add) execute permissions
+       for everyone (user, group, others) on the given file
+       Similar to : chmod a+x <path>
+    """
+    ensure_file_permissions(path, stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
+
+def ensure_file_permissions(path, permissions):
+    """Ensure (and if needed, add) the given permissions
+       for the given filesystem object.
+       Similar to using '+' with chmod
+    """
+    perm = os.stat(path).st_mode & 0o777 # only the last 3 bits relate to permissions
+
+    # If desired permissions were already set, don't meddle.
+    if ( (perm & permissions ) != permissions ):
+        os.chmod(path, perm | permissions)
+
+    # return a mask of desired permissions that are/were actually set
+    return os.stat(path).st_mode & 0o777 & permissions
+
+def file_has_shebang(path):
+    """Does the given file start with a shebang ?
+    """
+    return read_from_file(path, size=2) == '#!'
+
+def read_from_file(path, size=-1, ignore=None):
+    """Read and return a number of bytes from the given file.
+       If size is '-1' (the default) the entire contents are returned.
+    """
+    value = ""
+    try:
+        with open(path, "r") as fd:
+            value = fd.read(size)
+    except ignore:
+        pass
+    finally:
+        fd.close()
+    return value
+
+def slurp_file(path, ignore=None):
+    """Read and return the entire contents of a given file
+    """
+    return read_from_file(path, size=-1, ignore=ignore)

cdist/util/fsproperty.py

@@ -23,7 +23,7 @@ import os
 import collections
 
 import cdist
-
+import cdist.util.filesystem as fs
 
 class AbsolutePathRequiredError(cdist.Error):
     def __init__(self, path):
@@ -319,3 +319,26 @@ class FileStringProperty(FileBasedProperty):
                 os.remove(path)
             except EnvironmentError:
                 pass
+
+class FileScriptProperty(FileStringProperty):
+    """A property specially tailored for script text,
+       which stores its value in a file.
+    """
+    # Descriptor Protocol
+    def __set__(self, instance, value):
+        super().__set__(instance, value)
+
+        # -------------------------------------------------------------------
+        # NOTE [tabulon@2023-03-31]: If the file starts with a shebang (#!),
+        # mark it as an executable (chmod a+x), so that exec.(local|remote)
+        # can decide to invoke it directly (instead of feeding it to /bin/sh)
+        # -------------------------------------------------------------------
+        # NOTE that this enables cdist to become completely language-agnostic,
+        # even with regard to code generated via (gencode-*) that end up being
+        # stored as a `FileScriptProperty`; since most Unix/Linux systems are
+        # able to detect the **shebang**
+        # -------------------------------------------------------------------
+        if value:
+            path = self._get_path(instance)
+            if fs.file_has_shebang(path):
+                fs.ensure_file_is_executable_by_all(path)