fileutil.which implementation

4 files changed, 200 insertions, 0 deletions

diff --git a/src/leap/util/__init__.py b/src/leap/util/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/leap/util/__init__.py
diff --git a/src/leap/util/coroutines.py b/src/leap/util/coroutines.py
new file mode 100644
index 00000000..5e25eb63
--- /dev/null
+++ b/src/leap/util/coroutines.py
@@ -0,0 +1,107 @@
+# the problem of watching a stdout pipe from
+# openvpn binary: using subprocess and coroutines
+# acting as event consumers
+
+from __future__ import division, print_function
+
+from subprocess import PIPE, Popen
+import sys
+from threading import Thread
+
+ON_POSIX = 'posix' in sys.builtin_module_names
+
+
+#
+# Coroutines goodies
+#
+
+def coroutine(func):
+    def start(*args, **kwargs):
+        cr = func(*args, **kwargs)
+        cr.next()
+        return cr
+    return start
+
+
+@coroutine
+def process_events(callback):
+    """
+    coroutine loop that receives
+    events sent and dispatch the callback.
+    :param callback: callback to be called\
+for each event
+    :type callback: callable
+    """
+    try:
+        while True:
+            m = (yield)
+            if callable(callback):
+                callback(m)
+            else:
+                #XXX log instead
+                print('not a callable passed')
+    except GeneratorExit:
+        return
+
+#
+# Threads
+#
+
+
+def launch_thread(target, args):
+    """
+    launch and demonize thread.
+    :param target: target function that will run in thread
+    :type target: function
+    :param args: args to be passed to thread
+    :type args: list
+    """
+    t = Thread(target=target,
+               args=args)
+    t.daemon = True
+    t.start()
+    return t
+
+
+def watch_output(out, observers):
+    """
+    initializes dict of observer coroutines
+    and pushes lines to each of them as they are received
+    from the watched output.
+    :param out: stdout of a process.
+    :type out: fd
+    :param observers: tuple of coroutines to send data\
+for each event
+    :type ovservers: tuple
+    """
+    observer_dict = {observer: process_events(observer)
+                     for observer in observers}
+    for line in iter(out.readline, b''):
+        for obs in observer_dict:
+            observer_dict[obs].send(line)
+    out.close()
+
+
+def spawn_and_watch_process(command, args, observers=None):
+    """
+    spawns a subprocess with command, args, and launch
+    a watcher thread.
+    :param command: command to be executed in the subprocess
+    :type command: str
+    :param args: arguments
+    :type args: list
+    :param observers: tuple of observer functions to be called \
+for each line in the subprocess output.
+    :type observers: tuple
+    :return: a tuple containing the child process instance, and watcher_thread,
+    :rtype: (Subprocess, Thread)
+    """
+    subp = Popen([command] + args,
+                 stdout=PIPE,
+                 stderr=PIPE,
+                 bufsize=1,
+                 close_fds=ON_POSIX)
+    watcher = launch_thread(
+        watch_output,
+        (subp.stdout, observers))
+    return subp, watcher
diff --git a/src/leap/util/fileutil.py b/src/leap/util/fileutil.py
new file mode 100644
index 00000000..86a44a89
--- /dev/null
+++ b/src/leap/util/fileutil.py
@@ -0,0 +1,73 @@
+from itertools import chain
+import os
+import platform
+import stat
+
+
+def is_user_executable(fpath):
+    st = os.stat(fpath)
+    return bool(st.st_mode & stat.S_IXUSR)
+
+
+def extend_path():
+    ourplatform = platform.system()
+    if ourplatform == "Linux":
+        return "/usr/local/sbin:/usr/sbin"
+    # XXX add mac / win extended search paths?
+
+
+def which(program):
+    """
+    an implementation of which
+    that extends the path with
+    other locations, like sbin
+    (f.i., openvpn binary is likely to be there)
+    @param program: a string representing the binary we're looking for.
+    """
+    def is_exe(fpath):
+        """
+        check that path exists,
+        it's a file,
+        and is executable by the owner
+        """
+        # we would check for access,
+        # but it's likely that we're
+        # using uid 0 + polkitd
+
+        return os.path.isfile(fpath)\
+            and is_user_executable(fpath)
+
+    def ext_candidates(fpath):
+        yield fpath
+        for ext in os.environ.get("PATHEXT", "").split(os.pathsep):
+            yield fpath + ext
+
+    def iter_path(pathset):
+        """
+        returns iterator with
+        full path for a given path list
+        and the current target bin.
+        """
+        for path in pathset.split(os.pathsep):
+            exe_file = os.path.join(path, program)
+            #print 'file=%s' % exe_file
+            for candidate in ext_candidates(exe_file):
+                if is_exe(candidate):
+                    yield candidate
+
+    fpath, fname = os.path.split(program)
+    if fpath:
+        if is_exe(program):
+            return program
+    else:
+        # extended iterator
+        # with extra path
+        extended_path = chain(
+            iter_path(os.environ["PATH"]),
+            iter_path(extend_path()))
+        for candidate in extended_path:
+            if candidate is not None:
+                return candidate
+
+    # sorry bro.
+    return None
diff --git a/src/leap/util/leap_argparse.py b/src/leap/util/leap_argparse.py
new file mode 100644
index 00000000..9c355134
--- /dev/null
+++ b/src/leap/util/leap_argparse.py
@@ -0,0 +1,20 @@
+import argparse
+
+
+def build_parser():
+    epilog = "Copyright 2012 The Leap Project"
+    parser = argparse.ArgumentParser(description="""
+Launches main LEAP Client""", epilog=epilog)
+    parser.add_argument('--debug', action="store_true",
+                        help='launches in debug mode')
+    parser.add_argument('--config', metavar="CONFIG FILE", nargs='?',
+                        action="store", dest="config_file",
+                        type=argparse.FileType('r'),
+                        help='optional config file')
+    return parser
+
+
+def init_leapc_args():
+    parser = build_parser()
+    opts = parser.parse_args()
+    return parser, opts