[pp:exec] add 'session' option (#6582)

https://github.com/mikf/gallery-dl/issues/6582#issuecomment-3067297033

docs/configuration.rst

@@ -6939,6 +6939,26 @@ Description
     See `metadata.event`_ for a list of available events.
 
 
+exec.session
+------------
+Type
+    ``bool``
+Default
+    ``false``
+Description
+    Start subprocesses in a new session.
+
+    On Windows, this means passing
+    `CREATE_NEW_PROCESS_GROUP <https://docs.python.org/3/library/subprocess.html#subprocess.CREATE_NEW_PROCESS_GROUP>`__
+    as a ``creationflags`` argument to
+    `subprocess.Popen <https://docs.python.org/3/library/subprocess.html#subprocess.Popen>`__
+
+    On POSIX systems, this means enabling the
+    ``start_new_session`` argument of
+    `subprocess.Popen <https://docs.python.org/3/library/subprocess.html#subprocess.Popen>`__
+    to have it call ``setsid()``.
+
+
 hash.chunk-size
 ---------------
 Type

gallery_dl/postprocessor/exec.py

@@ -10,12 +10,14 @@
 
 from .common import PostProcessor
 from .. import util, formatter
+import subprocess
 import os
 
 
 if util.WINDOWS:
     def quote(s):
-        return '"' + s.replace('"', '\\"') + '"'
+        s = s.replace('"', '\\"')
+        return f'"{s}"'
 else:
     from shlex import quote
 
@@ -25,14 +27,21 @@ class ExecPP(PostProcessor):
     def __init__(self, job, options):
         PostProcessor.__init__(self, job)
 
-        cmds = options.get("commands")
-        if cmds:
+        if cmds := options.get("commands"):
             self.cmds = [self._prepare_cmd(c) for c in cmds]
             execute = self.exec_many
         else:
             execute, self.args = self._prepare_cmd(options["command"])
             if options.get("async", False):
-                self._exec = self._exec_async
+                self._exec = self._popen
+
+        self.session = None
+        self.creationflags = 0
+        if options.get("session"):
+            if util.WINDOWS:
+                self.creationflags = subprocess.CREATE_NEW_PROCESS_GROUP
+            else:
+                self.session = True
 
         events = options.get("event")
         if events is None:
@@ -83,8 +92,7 @@ class ExecPP(PostProcessor):
         return retcode
 
     def exec_many(self, pathfmt):
-        archive = self.archive
-        if archive:
+        if archive := self.archive:
             if archive.check(pathfmt.kwdict):
                 return
             self.archive = False
@@ -92,8 +100,7 @@ class ExecPP(PostProcessor):
         retcode = 0
         for execute, args in self.cmds:
             self.args = args
-            retcode = execute(pathfmt)
-            if retcode:
+            if retcode := execute(pathfmt):
                 # non-zero exit status
                 break
 
@@ -103,16 +110,19 @@ class ExecPP(PostProcessor):
         return retcode
 
     def _exec(self, args, shell):
-        self.log.debug("Running '%s'", args)
-        retcode = util.Popen(args, shell=shell).wait()
-        if retcode:
+        if retcode := self._popen(args, shell).wait():
             self.log.warning("'%s' returned with non-zero exit status (%d)",
                              args, retcode)
         return retcode
 
-    def _exec_async(self, args, shell):
+    def _popen(self, args, shell):
         self.log.debug("Running '%s'", args)
-        util.Popen(args, shell=shell)
+        return util.Popen(
+            args,
+            shell=shell,
+            creationflags=self.creationflags,
+            start_new_session=self.session,
+        )
 
     def _replace(self, match):
         name = match[1]

test/test_postprocessor.py

@@ -20,7 +20,7 @@ import collections
 from datetime import datetime
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
-from gallery_dl import extractor, output, path  # noqa E402
+from gallery_dl import extractor, output, path, util  # noqa E402
 from gallery_dl import postprocessor, config  # noqa E402
 from gallery_dl.postprocessor.common import PostProcessor  # noqa E402
 
@@ -209,7 +209,10 @@ class ExecTest(BasePostprocessorTest):
                 self.pathfmt.realpath,
                 self.pathfmt.realdirectory,
                 self.pathfmt.filename),
-            shell=True)
+            shell=True,
+            creationflags=0,
+            start_new_session=None,
+        )
         i.wait.assert_called_once_with()
 
     def test_command_list(self):
@@ -231,6 +234,8 @@ class ExecTest(BasePostprocessorTest):
                 self.pathfmt.realdirectory.upper(),
             ],
             shell=False,
+            creationflags=0,
+            start_new_session=None,
         )
 
     def test_command_many(self):
@@ -254,6 +259,8 @@ class ExecTest(BasePostprocessorTest):
                     self.pathfmt.realdirectory,
                     self.pathfmt.filename),
                 shell=True,
+                creationflags=0,
+                start_new_session=None,
             ),
             call(
                 [
@@ -262,6 +269,8 @@ class ExecTest(BasePostprocessorTest):
                     self.pathfmt.realdirectory.upper(),
                 ],
                 shell=False,
+                creationflags=0,
+                start_new_session=None,
             ),
         ])
 
@@ -296,6 +305,47 @@ class ExecTest(BasePostprocessorTest):
         self.assertTrue(p.called)
         self.assertFalse(i.wait.called)
 
+    @unittest.skipIf(util.WINDOWS, "not POSIX")
+    def test_session_posix(self):
+        self._create({
+            "session": True,
+            "command": ["echo", "foobar"],
+        })
+
+        with patch("gallery_dl.util.Popen") as p:
+            i = Mock()
+            p.return_value = i
+            self._trigger(("after",))
+
+        p.assert_called_once_with(
+            ["echo", "foobar"],
+            shell=False,
+            creationflags=0,
+            start_new_session=True,
+        )
+        i.wait.assert_called_once_with()
+
+    @unittest.skipIf(not util.WINDOWS, "not Windows")
+    def test_session_windows(self):
+        self._create({
+            "session": True,
+            "command": ["echo", "foobar"],
+        })
+
+        with patch("gallery_dl.util.Popen") as p:
+            i = Mock()
+            p.return_value = i
+            self._trigger(("after",))
+
+        import subprocess
+        p.assert_called_once_with(
+            ["echo", "foobar"],
+            shell=False,
+            creationflags=subprocess.CREATE_NEW_PROCESS_GROUP,
+            start_new_session=False,
+        )
+        i.wait.assert_called_once_with()
+
 
 class HashTest(BasePostprocessorTest):