On Mon, Aug 10, 2020 at 11:25:31AM -0500, Eric Blake wrote:

Use of - does not need shell quoting, and aids legibility in multi-word plugin or filter names. Permitting both - and _ would be ambiguous (not to mention that things like 'man nbdkit-foo_bar-plugin' would look ugly), so prefer only the character that is easier for human use. Permitting a leading - would be ambiguous with options, but restricting to a letter as the first character would rule out any existing plugins such as a theoretical '9p' plugin for interaction with the 9p filesystem.

Signed-off-by: Eric Blake <eblake@redhat.com> ---

After a bit more IRC chat, I think this is more what we want.

docs/nbdkit-filter.pod | 3 ++- docs/nbdkit-plugin.pod | 3 ++- server/backend.c | 15 +++++++++++---- 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/docs/nbdkit-filter.pod b/docs/nbdkit-filter.pod index 12343dbf..93601088 100644 --- a/docs/nbdkit-filter.pod +++ b/docs/nbdkit-filter.pod @@ -201,7 +201,8 @@ methods. const char *name;

This field (a string) is required, and B<must> contain only ASCII -alphanumeric characters and be unique amongst all filters. +alphanumeric characters or non-leading dashes, and be unique amongst +all filters.

=head2 C<.longname>

diff --git a/docs/nbdkit-plugin.pod b/docs/nbdkit-plugin.pod index 9341f282..a661680c 100644 --- a/docs/nbdkit-plugin.pod +++ b/docs/nbdkit-plugin.pod @@ -471,7 +471,8 @@ an indication of failure. It has the following prototype: const char *name;

This field (a string) is required, and B<must> contain only ASCII -alphanumeric characters and be unique amongst all plugins. +alphanumeric characters or non-leading dashes, and be unique amongst +all filters.

=head2 C<.version>

diff --git a/server/backend.c b/server/backend.c index 75ca53be..b001a9a9 100644 --- a/server/backend.c +++ b/server/backend.c @@ -98,13 +98,20 @@ backend_load (struct backend *b, const char *name, void (*load) (void)) program_name, b->filename, b->type); exit (EXIT_FAILURE); } - for (i = 0; i < len; ++i) { + if (! ascii_isalnum (*name)) { + fprintf (stderr, + "%s: %s: %s.name ('%s') field must begin with an " + "ASCII alphanumeric\n", + program_name, b->filename, b->type, name); + exit (EXIT_FAILURE); + } + for (i = 1; i < len; ++i) { unsigned char c = name[i];

- if (! ascii_isalnum (c)) { + if (! ascii_isalnum (c) && c != '-') { fprintf (stderr, - "%s: %s: %s.name ('%s') field " - "must contain only ASCII alphanumeric characters\n", + "%s: %s: %s.name ('%s') field must contain only " + "ASCII alphanumeric or dash characters\n", program_name, b->filename, b->type, name); exit (EXIT_FAILURE); }

ACK Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html