Re: [PATCH] static-nodes: add shell consumable format

[Dave Reisner <d@falconindy.com>]

On Thu, Sep 19, 2013 at 05:48:58PM +0200, Tom Gundersen wrote:
> On Thu, Sep 19, 2013 at 4:48 PM, Dave Reisner <dreisner@archlinux.org> wrote:
> > This adds an additional format to kmod static-nodes, which writes
> > output as shell commands, e.g.:
> >
> >   mknod '/dev/btrfs-control' c 10 234
> >   mknod '/dev/loop-control' c 10 237
> >   mkdir -m 755 -p '/dev/net'
> >   mknod '/dev/net/tun' c 10 200
> >
> > Consumers of this format can simply pipe the output to a shell,
> > creating the necessary static nodes. This could be useful for an
> > initramfs which doesn't have systemd-tmpfiles but which still relies on
> > static node creation which recent udev will no longer handle.
> 
> Seems reasonable enough, so if it is useful no objections from me.
> 
> However, two questions: why not simply ship systemd-tmpfiles in the
> initramfs to do this (which would also do things like selinux labels
> for those who care about that). Alternatively, why not just parse one
> of the existing formats in your shell script?

I started writing the code to parse the raw devname format in shell, and
decided it would be easier to borrow the already existing parser in the
static nodes tool. Other people might get use out of it too if they
don't want to deal with systemd-tmpfiles.

> -t
> 
> >  tools/static-nodes.c | 24 ++++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> >
> > diff --git a/tools/static-nodes.c b/tools/static-nodes.c
> > index 0195390..2d68537 100644
> > --- a/tools/static-nodes.c
> > +++ b/tools/static-nodes.c
> > @@ -43,11 +43,13 @@ struct static_nodes_format {
> >  static const struct static_nodes_format static_nodes_format_human;
> >  static const struct static_nodes_format static_nodes_format_tmpfiles;
> >  static const struct static_nodes_format static_nodes_format_devname;
> > +static const struct static_nodes_format static_nodes_format_shell;
> >
> >  static const struct static_nodes_format *static_nodes_formats[] = {
> >         &static_nodes_format_human,
> >         &static_nodes_format_tmpfiles,
> >         &static_nodes_format_devname,
> > +       &static_nodes_format_shell,
> >  };
> >
> >  static const char cmdopts_s[] = "o:f:h";
> > @@ -126,6 +128,28 @@ static const struct static_nodes_format static_nodes_format_devname = {
> >         .description = "the modules.devname format.",
> >  };
> >
> > +static int write_shell(FILE *out, char modname[], char devname[], char type, unsigned int maj, unsigned int min)
> > +{
> > +       const char *dir = strrchr(devname, '/');
> > +
> > +       if (dir) {
> > +               if (fprintf(out, "mkdir -m 755 -p '/dev/%.*s'\n",
> > +                                       (int)(dir - devname), devname) < 0)
> > +                       return EXIT_FAILURE;
> > +       }
> > +
> > +       if (fprintf(out, "mknod '/dev/%s' %c %u %u\n", devname, type, maj, min) < 0)
> > +               return EXIT_FAILURE;
> > +
> > +       return EXIT_SUCCESS;
> > +}
> > +
> > +static const struct static_nodes_format static_nodes_format_shell = {
> > +       .name = "shell",
> > +       .write = write_shell,
> > +       .description = "mknod commands for consumption by a shell.",
> > +};
> > +
> >  static void help(void)
> >  {
> >         size_t i;
> > --
> > 1.8.4
> >
> > --
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