From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson To: passt-dev@passt.top Subject: Re: [PATCH 8/8] Allow pasta to take a command to execute Date: Tue, 30 Aug 2022 11:16:05 +1000 Message-ID: In-Reply-To: <20220829211658.3fb87bf6@elisabeth> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6776295945438564762==" --===============6776295945438564762== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Mon, Aug 29, 2022 at 09:16:58PM +0200, Stefano Brivio wrote: > On Fri, 26 Aug 2022 14:58:39 +1000 > David Gibson wrote: >=20 > > When not given an existing PID or network namspace to attach to, pasta > > spawns a shell. Most commands which can spawn a shell in an altered > > environment can also run other commands in that same environment, which c= an > > be useful in automation. > >=20 > > Allow pasta to do the same thing; it can be given an arbitrary command to > > run in the network and user namespace which pasta creates. If neither a > > command nor an existing PID or netns to attach to is given, continue to > > spawn a default shell, as before. > >=20 > > Signed-off-by: David Gibson > > --- > > conf.c | 27 ++++++++++++++++++--------- > > passt.1 | 14 +++++++++----- > > pasta.c | 33 +++++++++++++++++++++++---------- > > pasta.h | 2 +- > > 4 files changed, 51 insertions(+), 25 deletions(-) > >=20 > > diff --git a/conf.c b/conf.c > > index 2a18124..162c2dd 100644 > > --- a/conf.c > > +++ b/conf.c > > @@ -550,7 +550,8 @@ static int conf_ns_pid(char *userns, char *netns, con= st char *arg) > > return 0; > > } > > =20 > > - return -EINVAL; > > + /* Not a PID, later code will treat as a command */ > > + return 0; > > } > > =20 > > /** > > @@ -1480,14 +1481,18 @@ void conf(struct ctx *c, int argc, char **argv) > > =20 > > check_root(c); > > =20 > > - if (c->mode =3D=3D MODE_PASTA && optind + 1 =3D=3D argc) { > > - ret =3D conf_ns_pid(userns, netns, argv[optind]); > > - if (ret < 0) > > + if (c->mode =3D=3D MODE_PASTA) { > > + if (*netns && optind !=3D argc) { > > + err("Both --netns and PID or command given"); > > usage(argv[0]); > > - } else if (c->mode =3D=3D MODE_PASTA && *userns > > - && !*netns && optind =3D=3D argc) { > > - err("--userns requires --netns or PID"); > > - usage(argv[0]); > > + } else if (optind + 1 =3D=3D argc) { > > + ret =3D conf_ns_pid(userns, netns, argv[optind]); > > + if (ret < 0) > > + usage(argv[0]); > > + } else if (*userns && !*netns && optind =3D=3D argc) { > > + err("--userns requires --netns or PID"); > > + usage(argv[0]); > > + } > > } else if (optind !=3D argc) { > > usage(argv[0]); > > } > > > > [...] >=20 > I haven't really looked into this yet, but I guess we should now > handle getopts return codes a bit differently, because this works: >=20 > $ ./pasta --config-net -- sh -c 'sleep 1; ip li sh' > 1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode = DEFAULT group default qlen 1000 > link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 > 2: enp9s0: mtu 65520 qdisc pfifo_fast s= tate UNKNOWN mode DEFAULT group default qlen 1000 > link/ether aa:3e:39:5f:c6:15 brd ff:ff:ff:ff:ff:ff >=20 > while this doesn't: >=20 > $ ./pasta --config-net sh -c 'sleep 1; ip li sh' > ./pasta: invalid option -- 'c' > [...] >=20 > despite the fact that there's no ambiguity. You mean because pasta itself doesn't have a -c option? Attempting to account for that sounds like a bad idea. Requiring -- when the command given has options of its own that aren't supposed to go to the wrapper is pretty common for these sorts of tools. Basically the trade-off is that you either need to require that, or you have to require that all non-option arguments of the wrapper come last (old style POSIXish command line parsing, as opposed to GNUish conventions). The latter is usually more awkward than the former. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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