module-init-tools and chained aliases

module-init-tools and chained aliases

[Andrey Borzenkov]

Apparently modprobe from module-init-tools 0.9.11a does not support chained 
aliases like modutils did, i.e.

alias foo bar
alias bar baz

will result in error doing "modprobe foo" instead of loading "baz".

This is a real problem when converting modules.devfs, because customary

alias /dev/tts* /dev/tts
alias /dev/tts serial

simply does not work for accessing /dev/tts/*. modprobe.devfs as shipped with 
modue-init-tools has exactly the problem in parts.

It is possible to partially work around it by using

install foo /sbin/modprobe bar

consistently instead of alias but it means extra forks every time, besided it 
breaks parsing for many tools (initscripts or mkinitrd make heavy use of 
parsing sometimes, at least on Mandrake).

Is the behaviour intentional? Fixing it is just a one line patch and I fail to 
see why current state would be preferred.

regards

-andrey

--- modprobe.c.orig     2003-06-15 01:32:21.000000000 +0400
+++ modprobe.c  2003-06-15 13:46:25.000000000 +0400
@@ -1021,8 +1021,11 @@ static char *read_config(const char *fil

                        if (!wildcard || !realname)
                                grammar(cmd, filename, linenum);
-                       else if (fnmatch(wildcard,name,0) == 0)
-                               result = NOFAIL(strdup(realname));
+                       else if (fnmatch(wildcard,name,0) == 0) {
+                               if (result)
+                                       free(result);
+                               name = result = NOFAIL(strdup(realname));
+                       }
                } else if (strcmp(cmd, "include") == 0) {
                        char *newresult, *newfilename;

Re: module-init-tools and chained aliases

[Rusty Russell]

In message <200306151352.36226.arvidjaar@mail.ru> you write:
> Apparently modprobe from module-init-tools 0.9.11a does not support chained 
> aliases like modutils did, i.e.
> 
> alias foo bar
> alias bar baz
> 
> will result in error doing "modprobe foo" instead of loading "baz".

Yes, as per the documentation.

> This is a real problem when converting modules.devfs, because customary
> 
> alias /dev/tts* /dev/tts
> alias /dev/tts serial

generate-modutils.conf will do the right thing here, and unroll the
aliases.  And the README in module-init-tools says:

	4) If you are using devfs, copy modprobe.devfs to /etc

And modprobe.devfs gets it right.

> Is the behaviour intentional? Fixing it is just a one line patch and
> I fail to see why current state would be preferred.

Your patch only works for forwards references, not backwards
references.

There may be convincing arguments to adding support for recursive
aliases, but this isn't it.

Sorry,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.