[Toybox] Question regarding multiple NEW_TOY

[Rob Landley]

On 02/22/2012 05:45 AM, Daniel Walter wrote:
> hi,
> 
> I've seen multiple NEWTOY in toysh.c and would need the same for id.c 
> to add groups and whoami, but I can't figure out how to use them.
> make will always tell me that whoami.c and groups.c are missing.

If you want to alias them to the same main() function, this is what
OLDTOY is for.  It lets you specify a second command implemented by the
same file, calling an existing main() function.

Look at toys/netcat.c for an example, aliasing "nc" to "netcat".  (Since
it generates a second entry in the command dispatch table, it needs its
own optargs string.  I'm hoping the compiler is smart enough to merge
identical string constants...)

> used code snip
> 
> USE_ID(NEWTOY(id, "nGgru", TOYFLAG_BIN))
> USE_ID(NEWTOY(whoami, NULL, TOYFLAG_NOFORK))
> USE_ID(NEWTOY(groups, NULL, TOYFLAG_NOFORK))
>
> config GROUPS
> 	bool "groups"
> 	default y
> 	depends on ID
> ....

It's actually the GROUPS config symbol causing you a problem.  here's a
badly wordwrapped cut and paste from scripts/make.sh:

----------------

# Extract a list of toys/*.c files to compile from the data in ".config"
with
# sed, sort, and tr:

# 1) Grab the XXX part of all CONFIG_XXX entries, removing everything
after the
# second underline
# 2) Sort the list, keeping only one of each entry.
# 3) Convert to lower case.
# 4) Remove toybox itself from the list (as that indicates global symbols).
# 5) Add "toys/" prefix and ".c" suffix.

TOYFILES=$(cat .config | sed -nre 's/^CONFIG_(.*)=y/\1/;t
skip;b;:skip;s/_.*//;p' | sort -u | tr A-Z a-z | grep -v '^toybox$' |
sed 's@\(.*\)@toys/\1.c@' )

--------------------

Basically it's taking all the CONFIG_BLAH (and CONFIG_BLAH_*) symbols,
chopping out the "BLAH" part, smashing it to lower case, and looking for
a toys/*.c file with that name. (This is going to cause a problem for
switch_root, pivot_root, nbd-client, and so on. I need to fix it up a
bit...)

What you need to do is have the config symbols be CONFIG_ID_GROUPS and
CONFIG_ID_WHOAMI, and make them depend on CONFIG_ID.  Or just _not_ give
them their own symbols, since they're all in the same .c file and you're
making it hard to build one without the others...

That said, _why_ do you want to do multiple commands with separate
main() functions in the same file?  Is there an advantage to it?

Rob

 1330012099.0