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# NBD client library in userspace
# Copyright Red Hat
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
import traceback
# The NBD shell.
def shell():
import argparse
import code
import os
import sys
import libnbdmod
import nbd
description = '''Network Block Device (NBD) shell'''
epilog = '''Please read the nbdsh(1) manual page for full usage.'''
parser = argparse.ArgumentParser(prog='nbdsh', description=description,
epilog=epilog)
# Allow intermixing of various options for replay in command-line order:
# each option registered with this Action subclass will append a tuple
# to a single list of snippets
class SnippetAction(argparse.Action):
def __init__(self, option_strings, dest, nargs=None,
default=argparse.SUPPRESS, **kwargs):
if nargs not in [0, None]:
raise ValueError("nargs must be 0 or None")
super().__init__(option_strings, dest, nargs=nargs,
default=default, **kwargs)
def __call__(self, parser, namespace, values, option_string=None):
dest = self.dest
if dest != 'command':
setattr(namespace, 'need_handle',
getattr(namespace, 'need_handle') + 1)
elif values == '-':
dest = 'stdin'
snippets = getattr(namespace, 'snippets')[:]
snippets.append((dest, values))
setattr(namespace, 'snippets', snippets)
parser.set_defaults(need_handle=0, snippets=[])
short_options = []
long_options = []
parser.add_argument('--base-allocation', action=SnippetAction, nargs=0,
help='request the "base:allocation" meta context')
long_options.append("--base-allocation")
parser.add_argument('-c', '--command', action=SnippetAction,
help="run a Python statement "
"(may be used multiple times)")
short_options.append("-c")
long_options.append("--command")
parser.add_argument('-n', action='store_true',
help="do not create the implicit handle 'h'")
short_options.append("-n")
parser.add_argument('--opt-mode', action=SnippetAction, nargs=0,
help='request opt mode during connection')
long_options.append("--opt-mode")
parser.add_argument('-u', '--uri', action=SnippetAction,
help="connect to NBD URI")
short_options.append("-u")
long_options.append("--uri")
# For back-compat, provide --connect as an undocumented synonym to --uri
parser.add_argument('--connect', dest='uri', action=SnippetAction,
help=argparse.SUPPRESS)
parser.add_argument('-v', '--verbose', action='store_true',
help="enable verbose debugging")
short_options.append("-v")
long_options.append("--verbose")
parser.add_argument('-V', '--version', action='store_true',
help="display version information")
short_options.append("-V")
long_options.append("--version")
# These hidden options are used by bash tab completion.
parser.add_argument("--short-options", action='store_true',
help=argparse.SUPPRESS)
parser.add_argument("--long-options", action='store_true',
help=argparse.SUPPRESS)
args = parser.parse_args()
# It's an error if -n is passed with certain other options.
if args.n and args.need_handle:
print("error: -n option cannot be used with " +
"--base-allocation, --opt-mode or --uri",
file=sys.stderr)
exit(1)
# Handle the informational options which exit.
if args.version:
libnbdmod.display_version("nbdsh")
exit(0)
if args.short_options:
short_options.sort()
print("\n".join(short_options))
exit(0)
if args.long_options:
long_options.sort()
print("\n".join(long_options))
exit(0)
# If verbose, set LIBNBD_DEBUG=1
if args.verbose:
os.environ["LIBNBD_DEBUG"] = "1"
# Create the handle.
if not args.n:
h = nbd.NBD()
h.set_handle_name("nbdsh")
# Run all snippets
# https://stackoverflow.com/a/11754346
d = dict(locals(), **globals())
do_snippet = {
"command": lambda arg: exec(arg, d, d),
"stdin": lambda arg: exec(sys.stdin.read(), d, d),
"base_allocation": lambda arg: h.add_meta_context(
nbd.CONTEXT_BASE_ALLOCATION),
"opt_mode": lambda arg: h.set_opt_mode(True),
"uri": lambda arg: h.connect_uri(arg),
}
try:
for (act, arg) in args.snippets:
do_snippet[act](arg)
except nbd.Error as ex:
if nbd.NBD().get_debug():
traceback.print_exc()
else:
print("nbdsh: command line script failed: %s" % ex.string,
file=sys.stderr)
sys.exit(1)
# If there are no explicit -c or --command parameters, go interactive.
if len(args.snippets) - args.need_handle == 0:
sys.ps1 = "nbd> "
code.interact(banner=make_banner(args), local=locals(), exitmsg='')
def make_banner(args):
lines = []
def line(x): lines.append(x)
def blank(): line("")
def example(ex, desc): line("%-34s # %s" % (ex, desc))
blank()
line("Welcome to nbdsh, the shell for interacting with")
line("Network Block Device (NBD) servers.")
blank()
if not args.n:
line("The ‘nbd’ module has already been imported and there")
line("is an open NBD handle called ‘h’.")
blank()
else:
line("The ‘nbd’ module has already been imported.")
blank()
example("h = nbd.NBD()", "Create a new handle.")
example("h.get_size()", "Get size of the remote disk.")
example("buf = h.pread(512, 0)", "Read the first sector.")
example("exit() or Ctrl-D", "Quit the shell")
example("help(nbd)", "Display documentation")
blank()
return "\n".join(lines)
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