cmd/snap-discard-ns: add support for per-user mount namespaces #6010
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,72 @@ | ||
| """ | ||
| Pure-python limited-use wrapper around the mount library function. | ||
| """ | ||
| from __future__ import print_function, absolute_import, unicode_literals | ||
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| from argparse import ArgumentParser | ||
| from ctypes import CDLL, c_char_p, c_long, get_errno | ||
| from ctypes.util import find_library | ||
| from os import strerror | ||
| from sys import stderr, version_info | ||
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| try: | ||
| from typing import Text | ||
| except ImportError: | ||
| pass | ||
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| __all__ = ('mount', ) | ||
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| PY2 = version_info[0] == 2 | ||
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| class MountOpts(object): | ||
| """MountOpts contain various flags for the mount system call.""" | ||
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| Bind = 4096 | ||
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| def mount(source, target, fstype, flags=0, data=""): | ||
| # type: (Text, Text, Text, int, Text) -> None | ||
| """mount is a thin wrapper around the mount library function.""" | ||
| if PY2: | ||
| c = b"c" | ||
| else: | ||
| c = "c" | ||
| libc_name = find_library(c) | ||
| if libc_name is None: | ||
| raise Exception("cannot find the C library") | ||
| libc = CDLL(libc_name, use_errno=True) | ||
| retval = libc.mount( | ||
| c_char_p(source.encode("UTF-8")), | ||
| c_char_p(target.encode("UTF-8")), | ||
| c_char_p(fstype.encode("UTF-8")), | ||
| c_long(flags), | ||
| None if data == "" else c_char_p(data.encode("UTF-8"))) | ||
| if retval < 0: | ||
| errno = get_errno() | ||
| raise OSError(errno, strerror(errno)) | ||
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| def main(): | ||
| # type: () -> None | ||
| parser = ArgumentParser() | ||
| parser.add_argument("source", help="path of the device or bind source") | ||
| parser.add_argument("target", help="path of the new mount point") | ||
| group = parser.add_mutually_exclusive_group(required=True) | ||
| group.add_argument("--bind", action="store_const", const="bind", | ||
| help="create a new mount point of existing path") | ||
| group.add_argument("-t", "--type", help="filesystem type to mount") | ||
| opts = parser.parse_args() | ||
| if opts.bind is not None: | ||
| mount(opts.source, opts.target, "", MountOpts.Bind) | ||
| else: | ||
| mount(opts.source, opts.target, opts.fstype) | ||
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| if __name__ == "__main__": | ||
| try: | ||
| main() | ||
| except OSError as err: | ||
| print(err, file=stderr) | ||
| raise SystemExit(1) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,9 @@ | ||
| #!/bin/sh | ||
| if [ "$(command -v python3)" != "" ]; then | ||
| exec python3 ./mount.py "$@"; | ||
| elif [ "$(command -v python2)" != "" ]; then | ||
| exec python2 ./mount.py "$@"; | ||
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There was a problem hiding this comment. Why this logic if it works with both versions of python, why not simply check for There was a problem hiding this comment.
There was a problem hiding this comment. Fair enough, not a problem at all, just looks a little elaborate considering the fact that we don't actually care which python version it is. |
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| else | ||
| echo "cannot mount: Python 2 or 3 required" | ||
| exit 1 | ||
| fi | ||
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Should we make sure snap instance name is sane?
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Good point, we probably should. I will make that adjustment.