Starting with a back-story: I wanted[1] to write:
$ nbdkit --tls=require --tls-psk=$dir/tests/keys.psk null --run \
'nbdsh -u "nbds://alice@localhost/?tls-psk-file='"$dir"'/tests/keys.psk" \
-c "h.get_size()"'
but it fails with the latest libnbd release, due to:
nbdsh: unable to connect to uri
'nbds://alice@localhost/?tls-psk-file=/home/eblake/libnbd/tests/keys.psk':
nbd_connect_uri: local file access (tls-psk-file) is not allowed, call
nbd_set_uri_allow_local_file to enable this: Operation not permitted
But without this patch, this obvious attempt at a fix doesn't work:
$ nbdkit --tls=require --tls-psk=$dir/tests/keys.psk null --run \
'nbdsh -c "h.set_uri_allow_local_file(True)" \
-u "nbds://alice@localhost/?tls-psk-file='"$dir"'/tests/keys.psk" \
-c "h.get_size()"'
because nbdsh was performing h.connect_uri() prior to running any of
the -c strings (seen more obviously two patches ago when refactoring
shortcuts to reuse the -c framework), where the attempt to inject -c
to obey the error message is processed too late, even though it
occurred earlier in the command line. The immediate workaround is
thus:
$ nbdkit --tls=require --tls-psk=$dir/tests/keys.psk null --run \
'nbdsh -c "h.set_uri_allow_local_file(True)" \
-c
"h.connect_uri(\"nbds://alice@localhost/?tls-psk-file='"$dir"'/tests/keys.psk\")"
\
-c "h.get_size()"'
which gets awkward because of the multiple layers of quoting required
(--run, -c, and Python each strip a layer). But we can do better. We
can create args.command in command-line order by introducing the use
of a custom Action subclass of argparse. test-context.sh has to be
updated to match our saner processing order. nbdkit's testsuite still
passes even when using this update to nbdsh, so I don't think programs
in the wild were relying on insane command-line rearranging.
[1] Actually, I wanted to use -U- and write -u "$uri" instead of -u
"nbds+unix...", but that involves teaching nbdkit how to display a
more-useful URI when TLS is in use. Not this patch's problem.
---
python/nbdsh.py | 60 ++++++++++++++++++++++++++++++----------------
sh/test-context.sh | 26 ++++++++++----------
2 files changed, 51 insertions(+), 35 deletions(-)
diff --git a/python/nbdsh.py b/python/nbdsh.py
index f23d8bfb..370f3fd2 100644
--- a/python/nbdsh.py
+++ b/python/nbdsh.py
@@ -33,11 +33,37 @@ def shell():
epilog = '''Please read the nbdsh(1) manual page for full usage.'''
parser = argparse.ArgumentParser(prog='nbdsh', description=description,
epilog=epilog)
+
+ # We want to treat some options as shortcuts for longer '-c code'
+ # snippets while preserving relative ordering of the overall command
+ # line; use of the shortcuts does not prevent interactive mode.
+ class ShortcutAction(argparse.Action):
+ def __init__(self, option_strings, dest, nargs=None, const=None,
+ default=argparse.SUPPRESS, **kwargs):
+ if nargs not in [0, 1]:
+ raise ValueError("nargs must be 0 or 1")
+ if const is None:
+ raise ValueError("missing const string for use as shortcut")
+ super().__init__(option_strings, dest, nargs=nargs, const=const,
+ default=default, **kwargs)
+
+ def __call__(self, parser, namespace, values, option_string=None):
+ setattr(namespace, 'shortcuts',
+ getattr(namespace, 'shortcuts') + 1)
+ commands = getattr(namespace, 'command')[:]
+ if self.nargs == 0:
+ commands.append(self.const)
+ else:
+ commands.append(self.const % values[0])
+ setattr(namespace, 'command', commands)
+
+ parser.set_defaults(shortcuts=0)
short_options = []
long_options = []
- shortcuts = 0
- parser.add_argument('--base-allocation', action='store_true',
+ parser.add_argument('--base-allocation', action=ShortcutAction, nargs=0,
+ const='h.add_meta_context' +
+ '(nbd.CONTEXT_BASE_ALLOCATION)',
help='request the "base:allocation" meta context')
long_options.append("--base-allocation")
@@ -51,15 +77,20 @@ def shell():
help="do not create the implicit handle 'h'")
short_options.append("-n")
- parser.add_argument('--opt-mode', action='store_true',
+ parser.add_argument('--opt-mode', action=ShortcutAction, nargs=0,
+ const='h.set_opt_mode(True)',
help='request opt mode during connection')
long_options.append("--opt-mode")
- parser.add_argument('-u', '--uri', help="connect to NBD URI")
+ parser.add_argument('-u', '--uri', action=ShortcutAction, nargs=1,
+ const='h.connect_uri("%s")',
+ 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', help=argparse.SUPPRESS)
+ parser.add_argument('--connect', action=ShortcutAction, nargs=1,
+ const='h.connect_uri("%s")',
+ dest='uri', help=argparse.SUPPRESS)
parser.add_argument('-v', '--verbose', action='store_true',
help="enable verbose debugging")
@@ -80,9 +111,7 @@ def shell():
args = parser.parse_args()
# It's an error if -n is passed with certain other options.
- if args.n and (args.base_allocation or
- args.opt_mode or
- args.uri is not None):
+ if args.n and args.shortcuts > 0:
print("error: -n option cannot be used with " +
"--base-allocation, --opt-mode or --uri",
file=sys.stderr)
@@ -111,18 +140,7 @@ def shell():
h.set_handle_name("nbdsh")
cmds = args.command
- # Set other attributes in the handle.
- if args.uri is not None:
- cmds.insert(0, 'h.connect_uri("%s")' % args.uri)
- shortcuts += 1
- if args.base_allocation:
- cmds.insert(0, 'h.add_meta_context(nbd.CONTEXT_BASE_ALLOCATION)')
- shortcuts += 1
- if args.opt_mode:
- cmds.insert(0, 'h.set_opt_mode(True)')
- shortcuts += 1
-
- # Run all -c snippets, including any shortcuts we just added
+ # Run all -c snippets, including shortcuts
# https://stackoverflow.com/a/11754346
d = dict(locals(), **globals())
try:
@@ -140,7 +158,7 @@ def shell():
sys.exit(1)
# If there are no explicit -c or --command parameters, go interactive.
- if len(args.command) - shortcuts == 0:
+ if len(args.command) - args.shortcuts == 0:
sys.ps1 = "nbd> "
if args.n:
h = None
diff --git a/sh/test-context.sh b/sh/test-context.sh
index 168fe487..8f759075 100755
--- a/sh/test-context.sh
+++ b/sh/test-context.sh
@@ -31,15 +31,13 @@ if test "x$output" != xFalse; then
fail=1
fi
-# Use of -c to request context is too late with -u
-output=$(nbdkit -U - null --run 'nbdsh -c "
-try:
- h.add_meta_context(nbd.CONTEXT_BASE_ALLOCATION)
- assert False
-except nbd.Error:
- print(\"okay\")
-" -u "nbd+unix://?socket=$unixsocket"')
-if test "x$output" != xokay; then
+# Can also use manual -c to request context before -u
+output=$(nbdkit -U - null --run 'nbdsh \
+-c "h.add_meta_context(nbd.CONTEXT_BASE_ALLOCATION)" \
+-u "nbd+unix://?socket=$unixsocket" \
+-c "print(h.can_meta_context(nbd.CONTEXT_BASE_ALLOCATION))"
+')
+if test "x$output" != xTrue; then
echo "$0: unexpected output: $output"
fail=1
fi
@@ -53,9 +51,9 @@ if test "x$output" != xTrue; then
fail=1
fi
-# Again, but with --b after -u, and with abbreviated option names
+# Again, but with abbreviated option names
output=$(nbdkit -U - null --run 'nbdsh \
- -u "nbd+unix://?socket=$unixsocket" --b \
+ --b -u "nbd+unix://?socket=$unixsocket" \
-c "print(h.can_meta_context(nbd.CONTEXT_BASE_ALLOCATION))"')
if test "x$output" != xTrue; then
echo "$0: unexpected output: $output"
@@ -65,7 +63,7 @@ fi
if [[ $(nbdkit --help) =~ --no-sr ]]; then
# meta context depends on server cooperation
output=$(nbdkit -U - --no-sr null --run 'nbdsh \
- -u "nbd+unix://?socket=$unixsocket" --base-allocation \
+ --base-allocation -u "nbd+unix://?socket=$unixsocket" \
-c "print(h.can_meta_context(nbd.CONTEXT_BASE_ALLOCATION))"')
if test "x$output" != xFalse; then
echo "$0: unexpected output: $output"
@@ -77,7 +75,7 @@ fi
# Test interaction with opt mode
output=$(nbdkit -U - null --run 'nbdsh \
- -u "nbd+unix://?socket=$unixsocket" --opt-mode --base-allocation \
+ --opt-mode --base-allocation -u "nbd+unix://?socket=$unixsocket" \
-c "
try:
h.can_meta_context(nbd.CONTEXT_BASE_ALLOCATION)
@@ -94,7 +92,7 @@ fi
# And with --opt-mode, we can get away without --base-allocation
output=$(nbdkit -U - null --run 'nbdsh \
- -u "nbd+unix://?socket=$unixsocket" --opt-mode \
+ --opt-mode -u "nbd+unix://?socket=$unixsocket" \
-c "h.add_meta_context(nbd.CONTEXT_BASE_ALLOCATION)" \
-c "h.opt_go()" \
-c "print(h.can_meta_context(nbd.CONTEXT_BASE_ALLOCATION))"')
--
2.37.3
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