Share ignore and storing % tokens in a tdb

[Nicolas Williams]

On Mon, Jan 31, 2000 at 08:35:38AM -0500, David Collier-Brown wrote:
> Nicolas Williams wrote:
> | Actually, that would be useful: a share ignore parameter. It's value
> | might be a % token followed by a value such that if it does not
> match
> | the token's value the share would be ignored.
> 
> 	Cool!  "ignore if = %m bozotron" would be read
> 	"ignore this share if %m is bozotron", much like
> 	the perl idiom. The cost would be a parser change
> 	to skip forward to the beginning of the next section
> 	and a loadparms.c change to invalidate the current 
> 	section and clean up any data structures.

This would be nice... It would cut down on the need for includes.

> | Also, Luke's idea of storing % tokens in a tdb indexed by <PID vuid>
> | tuples is really neat. Not only will it allow the DCE/RPC daemons to
> | implement standard_sub_basic() correctly, but it could even be used
> by
> | user commands run via the preexec/postexec/open/close/etc...
> parameters
> | (this would require a user-level program for retrieving data from a
> TDB
> | as well as a separate library for C programs to use to access the
> TDB in
> | question).
> 
> 	Hmmn: if all the commands which ran external programs 
> 	did "requoting" of all their parameters, and selected 
> 	the right values by <pid vuid>, methinks the common 
> 	case would be covered. 

Is there a function that will safely quote any shell metacharacters in a
string such that that string can then be placed in double quotes and
passed to /bin/sh -c?? I think we could use such a function, but I
wonder how simple it would be.

Hmmm,

int safe_quote(char * dst, char * src, int n)
{
    /* pseudo code */
    for ( c=*str ; str != NULL && n ; str++ )
    {
	if (meta_char_p(c))
	{
	    if (n < 2)
		return 0;
#ifdef BACKSLAH_ALWAYS_OK
	    *dst++ = '\';
	    *dst++ = c;
	    n-=2;
#else
	    strncpy(dst, quoted_meta_chars[c], n);
	    n -= quoted_meta_chars_length[c]);
#endif
	    continue;
	}

	*dst++ = *str;
	n--;
    }
}

> 	The general case would indeed require a library for 
> 	user programs to call.

Yes, but I was thinking of a tool akin to pkgparam(1) (from Solaris
packages). The library would be useful for those who are willing to
write C code. The rest can only be counted on to dabble in Shell scripts
(hmmm, a C lib could be interfaced to Perl5/Tcl/whatever too!).

Example:

/usr/local/bin/share_tdb $SMBD_PID $SHARE_VUID fetch %m | read SRV_NAME
/usr/local/bin/share_tdb $SMBD_PID $SHARE_VUID fetch %f | read FILE

Now "$FILE" is pretty safe to use in a shell script.

> --dave 
> [No, I don't really think smb.conf should be a perl dialect.
> I find perl a bit too write-only (;-))]

Heh!

Nico
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