yunohost/src/yunohost/hook.py

# -*- coding: utf-8 -*-

""" License

    Copyright (C) 2013 YunoHost

    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

"""

""" yunohost_hook.py

    Manage hooks
"""
import os
import re
import errno
from glob import iglob

from moulinette import m18n
from moulinette.core import MoulinetteError
from moulinette.utils import log

HOOK_FOLDER = '/usr/share/yunohost/hooks/'
CUSTOM_HOOK_FOLDER = '/etc/yunohost/hooks.d/'

logger = log.getActionLogger('yunohost.hook')


def hook_add(app, file):
    """
    Store hook script to filsystem

    Keyword argument:
        app -- App to link with
        file -- Script to add (/path/priority-file)

    """
    path, filename = os.path.split(file)
    priority, action = _extract_filename_parts(filename)

    try:
        os.listdir(CUSTOM_HOOK_FOLDER + action)
    except OSError:
        os.makedirs(CUSTOM_HOOK_FOLDER + action)

    finalpath = CUSTOM_HOOK_FOLDER + action + '/' + priority + '-' + app
    os.system('cp %s %s' % (file, finalpath))
    os.system('chown -hR admin: %s' % HOOK_FOLDER)

    return {'hook': finalpath}


def hook_remove(app):
    """
    Remove hooks linked to a specific app

    Keyword argument:
        app -- Scripts related to app will be removed

    """
    try:
        for action in os.listdir(CUSTOM_HOOK_FOLDER):
            for script in os.listdir(CUSTOM_HOOK_FOLDER + action):
                if script.endswith(app):
                    os.remove(CUSTOM_HOOK_FOLDER + action + '/' + script)
    except OSError:
        pass


def hook_info(action, name):
    """
    Get information about a given hook

    Keyword argument:
        action -- Action name
        name -- Hook name

    """
    hooks = []
    priorities = set()

    # Search in custom folder first
    for h in iglob('{:s}{:s}/*-{:s}'.format(
            CUSTOM_HOOK_FOLDER, action, name)):
        priority, _ = _extract_filename_parts(os.path.basename(h))
        priorities.add(priority)
        hooks.append({
            'priority': priority,
            'path': h,
        })
    # Append non-overwritten system hooks
    for h in iglob('{:s}{:s}/*-{:s}'.format(
            HOOK_FOLDER, action, name)):
        priority, _ = _extract_filename_parts(os.path.basename(h))
        if priority not in priorities:
            hooks.append({
                'priority': priority,
                'path': h,
            })

    if not hooks:
        raise MoulinetteError(errno.EINVAL, m18n.n('hook_name_unknown', name=name))
    return {
        'action': action,
        'name': name,
        'hooks': hooks,
    }


def hook_list(action, list_by='name', show_info=False):
    """
    List available hooks for an action

    Keyword argument:
        action -- Action name
        list_by -- Property to list hook by
        show_info -- Show hook information

    """
    result = {}

    # Process the property to list hook by
    if list_by == 'priority':
        if show_info:
            def _append_hook(d, priority, name, path):
                # Use the priority as key and a dict of hooks names
                # with their info as value
                value = {'path': path}
                try:
                    d[priority][name] = value
                except KeyError:
                    d[priority] = {name: value}
        else:
            def _append_hook(d, priority, name, path):
                # Use the priority as key and the name as value
                try:
                    d[priority].add(name)
                except KeyError:
                    d[priority] = set([name])
    elif list_by == 'name' or list_by == 'folder':
        if show_info:
            def _append_hook(d, priority, name, path):
                # Use the name as key and a list of hooks info - the
                # executed ones with this name - as value
                l = d.get(name, list())
                for h in l:
                    # Only one priority for the hook is accepted
                    if h['priority'] == priority:
                        # Custom hooks overwrite system ones and they
                        # are appended at the end - so overwite it
                        if h['path'] != path:
                            h['path'] = path
                        return
                l.append({'priority': priority, 'path': path})
                d[name] = l
        else:
            if list_by == 'name':
                result = set()

            def _append_hook(d, priority, name, path):
                # Add only the name
                d.add(name)
    else:
        raise MoulinetteError(errno.EINVAL, m18n.n('hook_list_by_invalid'))

    def _append_folder(d, folder):
        # Iterate over and add hook from a folder
        for f in os.listdir(folder + action):
            if f[0] == '.' or f[-1] == '~':
                continue
            path = '%s%s/%s' % (folder, action, f)
            priority, name = _extract_filename_parts(f)
            _append_hook(d, priority, name, path)

    try:
        # Append system hooks first
        if list_by == 'folder':
            result['system'] = dict() if show_info else set()
            _append_folder(result['system'], HOOK_FOLDER)
        else:
            _append_folder(result, HOOK_FOLDER)
    except OSError:
        logger.debug("system hook folder not found for action '%s' in %s",
                     action, HOOK_FOLDER)

    try:
        # Append custom hooks
        if list_by == 'folder':
            result['custom'] = dict() if show_info else set()
            _append_folder(result['custom'], CUSTOM_HOOK_FOLDER)
        else:
            _append_folder(result, CUSTOM_HOOK_FOLDER)
    except OSError:
        logger.debug("custom hook folder not found for action '%s' in %s",
                     action, CUSTOM_HOOK_FOLDER)

    return {'hooks': result}


def hook_callback(action, hooks=[], args=None, no_trace=False, chdir=None,
                  env=None, pre_callback=None, post_callback=None):
    """
    Execute all scripts binded to an action

    Keyword argument:
        action -- Action name
        hooks -- List of hooks names to execute
        args -- Ordered list of arguments to pass to the scripts
        no_trace -- Do not print each command that will be executed
        chdir -- The directory from where the scripts will be executed
        env -- Dictionnary of environment variables to export
        pre_callback -- An object to call before each script execution with
            (name, priority, path, args) as arguments and which must return
            the arguments to pass to the script
        post_callback -- An object to call after each script execution with
            (name, priority, path, succeed) as arguments

    """
    result = {'succeed': {}, 'failed': {}}
    hooks_dict = {}

    # Retrieve hooks
    if not hooks:
        hooks_dict = hook_list(action, list_by='priority',
                               show_info=True)['hooks']
    else:
        hooks_names = hook_list(action, list_by='name',
                                show_info=True)['hooks']

        # Add similar hooks to the list
        # For example: Having a 16-postfix hook in the list will execute a
        # xx-postfix_dkim as well
        all_hooks = []
        for n in hooks:
            for key in hooks_names.keys():
                if key == n or key.startswith("%s_" % n) \
                        and key not in all_hooks:
                    all_hooks.append(key)

        # Iterate over given hooks names list
        for n in all_hooks:
            try:
                hl = hooks_names[n]
            except KeyError:
                raise MoulinetteError(errno.EINVAL,
                                      m18n.n('hook_name_unknown', n))
            # Iterate over hooks with this name
            for h in hl:
                # Update hooks dict
                d = hooks_dict.get(h['priority'], dict())
                d.update({n: {'path': h['path']}})
                hooks_dict[h['priority']] = d
    if not hooks_dict:
        return result

    # Validate callbacks
    if not callable(pre_callback):
        pre_callback = lambda name, priority, path, args: args
    if not callable(post_callback):
        post_callback = lambda name, priority, path, succeed: None

    # Iterate over hooks and execute them
    for priority in sorted(hooks_dict):
        for name, info in iter(hooks_dict[priority].items()):
            state = 'succeed'
            path = info['path']
            try:
                hook_args = pre_callback(name=name, priority=priority,
                                         path=path, args=args)
                hook_exec(path, args=hook_args, chdir=chdir, env=env,
                          no_trace=no_trace, raise_on_error=True, user="root")
            except MoulinetteError as e:
                state = 'failed'
                logger.error(e.strerror, exc_info=1)
                post_callback(name=name, priority=priority, path=path,
                              succeed=False)
            else:
                post_callback(name=name, priority=priority, path=path,
                              succeed=True)
            try:
                result[state][name].append(path)
            except KeyError:
                result[state][name] = [path]
    return result


def hook_exec(path, args=None, raise_on_error=False, no_trace=False,
              chdir=None, env=None, user="admin"):
    """
    Execute hook from a file with arguments

    Keyword argument:
        path -- Path of the script to execute
        args -- Ordered list of arguments to pass to the script
        raise_on_error -- Raise if the script returns a non-zero exit code
        no_trace -- Do not print each command that will be executed
        chdir -- The directory from where the script will be executed
        env -- Dictionnary of environment variables to export
        user -- User with which to run the command

    """
    from moulinette.utils.process import call_async_output

    # Validate hook path
    if path[0] != '/':
        path = os.path.realpath(path)
    if not os.path.isfile(path):
        raise MoulinetteError(errno.EIO, m18n.g('file_not_exist', path=path))

    # Construct command variables
    cmd_args = ''
    if args and isinstance(args, list):
        # Concatenate escaped arguments
        cmd_args = ' '.join(shell_quote(s) for s in args)
    if not chdir:
        # use the script directory as current one
        chdir, cmd_script = os.path.split(path)
        cmd_script = './{0}'.format(cmd_script)
    else:
        cmd_script = path

    # Add Execution dir to environment var
    if env is None:
        env = {}
    env['YNH_CWD'] = chdir

    # Construct command to execute
    if user == "root":
        command = ['sh', '-c']
    else:
        command = ['sudo', '-n', '-u', user, '-H', 'sh', '-c']

    if no_trace:
        cmd = '/bin/bash "{script}" {args}'
    else:
        # use xtrace on fd 7 which is redirected to stdout
        cmd = 'BASH_XTRACEFD=7 /bin/bash -x "{script}" {args} 7>&1'

    # prepend environment variables
    cmd = '{0} {1}'.format(
        ' '.join(['{0}={1}'.format(k, shell_quote(v))
                for k, v in env.items()]), cmd)
    command.append(cmd.format(script=cmd_script, args=cmd_args))

    if logger.isEnabledFor(log.DEBUG):
        logger.info(m18n.n('executing_command', command=' '.join(command)))
    else:
        logger.info(m18n.n('executing_script', script=path))

    # Define output callbacks and call command
    callbacks = (
        lambda l: logger.info(l.rstrip()),
        lambda l: logger.warning(l.rstrip()),
    )
    returncode = call_async_output(
        command, callbacks, shell=False, cwd=chdir
    )

    # Check and return process' return code
    if returncode is None:
        if raise_on_error:
            raise MoulinetteError(
                errno.EIO, m18n.n('hook_exec_not_terminated', path=path))
        else:
            logger.error(m18n.n('hook_exec_not_terminated', path=path))
            return 1
    elif raise_on_error and returncode != 0:
        raise MoulinetteError(
            errno.EIO, m18n.n('hook_exec_failed', path=path))
    return returncode


def _extract_filename_parts(filename):
    """Extract hook parts from filename"""
    if '-' in filename:
        priority, action = filename.split('-', 1)
    else:
        priority = '50'
        action = filename
    return priority, action


# Taken from Python 3 shlex module --------------------------------------------

_find_unsafe = re.compile(r'[^\w@%+=:,./-]', re.UNICODE).search


def shell_quote(s):
    """Return a shell-escaped version of the string *s*."""
    s = str(s)
    if not s:
        return "''"
    if _find_unsafe(s) is None:
        return s

    # use single quotes, and put single quotes into double quotes
    # the string $'b is then quoted as '$'"'"'b'
    return "'" + s.replace("'", "'\"'\"'") + "'"