--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libervia/backend/tools/common/async_process.py	Fri Jun 02 11:49:51 2023 +0200
@@ -0,0 +1,144 @@
+#!/usr/bin/env python3
+
+
+# SAT: a jabber client
+# Copyright (C) 2009-2021 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program 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 Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""tools to launch process in a async way (using Twisted)"""
+
+import os.path
+from twisted.internet import defer, reactor, protocol
+from twisted.python.failure import Failure
+from libervia.backend.core.i18n import _
+from libervia.backend.core import exceptions
+from libervia.backend.core.log import getLogger
+log = getLogger(__name__)
+
+
+class CommandProtocol(protocol.ProcessProtocol):
+    """handle an external command"""
+    # name of the command (unicode)
+    name = None
+    # full path to the command (bytes)
+    command = None
+    # True to activate logging of command outputs (bool)
+    log = False
+
+    def __init__(self, deferred, stdin=None):
+        """
+        @param deferred(defer.Deferred): will be called when command is completed
+        @param stdin(str, None): if not None, will be push to standard input
+        """
+        self._stdin = stdin
+        self._deferred = deferred
+        self.data = []
+        self.err_data = []
+
+    @property
+    def command_name(self):
+        """returns command name or empty string if it can't be guessed"""
+        if self.name is not None:
+            return self.name
+        elif self.command is not None:
+            return os.path.splitext(os.path.basename(self.command))[0].decode('utf-8',
+                                                                              'ignore')
+        else:
+            return ''
+
+    def connectionMade(self):
+        if self._stdin is not None:
+            self.transport.write(self._stdin)
+            self.transport.closeStdin()
+
+    def outReceived(self, data):
+        if self.log:
+            log.info(data.decode('utf-8', 'replace'))
+        self.data.append(data)
+
+    def errReceived(self, data):
+        if self.log:
+            log.warning(data.decode('utf-8', 'replace'))
+        self.err_data.append(data)
+
+    def processEnded(self, reason):
+        data = b''.join(self.data)
+        if (reason.value.exitCode == 0):
+            log.debug(f'{self.command_name!r} command succeed')
+            # we don't use "replace" on purpose, we want an exception if decoding
+            # is not working properly
+            self._deferred.callback(data)
+        else:
+            err_data = b''.join(self.err_data)
+
+            msg = (_("Can't complete {name} command (error code: {code}):\n"
+                     "stderr:\n{stderr}\n{stdout}\n")
+                   .format(name = self.command_name,
+                           code = reason.value.exitCode,
+                           stderr= err_data.decode(errors='replace'),
+                           stdout = "stdout: " + data.decode(errors='replace')
+                                    if data else '',
+                           ))
+            self._deferred.errback(Failure(exceptions.CommandException(
+                msg, data, err_data)))
+
+    @classmethod
+    def run(cls, *args, **kwargs):
+        """Create a new CommandProtocol and execute the given command.
+
+        @param *args(unicode): command arguments
+            if cls.command is specified, it will be the path to the command to execute
+            otherwise, first argument must be the path
+        @param **kwargs: can be:
+            - stdin(unicode, None): data to push to standard input
+            - verbose(bool): if True stdout and stderr will be logged
+            other keyword arguments will be used in reactor.spawnProcess
+        @return ((D)bytes): stdout in case of success
+        @raise RuntimeError: command returned a non zero status
+            stdin and stdout will be given as arguments
+
+        """
+        stdin = kwargs.pop('stdin', None)
+        if stdin is not None:
+            stdin = stdin.encode('utf-8')
+        verbose = kwargs.pop('verbose', False)
+        args = list(args)
+        d = defer.Deferred()
+        prot = cls(d, stdin=stdin)
+        if verbose:
+            prot.log = True
+        if cls.command is None:
+            if not args:
+                raise ValueError(
+                    "You must either specify cls.command or use a full path to command "
+                    "to execute as first argument")
+            command = args.pop(0)
+            if prot.name is None:
+                name = os.path.splitext(os.path.basename(command))[0]
+                prot.name = name
+        else:
+            command = cls.command
+        cmd_args = [command] + args
+        if "env" not in kwargs:
+            # we pass parent environment by default
+            kwargs["env"] = None
+        reactor.spawnProcess(prot,
+                             command,
+                             cmd_args,
+                             **kwargs)
+        return d
+
+
+run = CommandProtocol.run