Thanks for your replay.
however I don’t understand the intention of the manual.
real needs in exporting is to export some different directories.
it is impossible to do so under current code.
can anyone show an example that exports two or more directories?

> 2015/12/17 20:40、Peter Hull <peterhull90@gmail.com> のメール：
>
> On Wed, Dec 16, 2015 at 11:31 PM, arisawa <arisawa@ar.aichi-u.ac.jp> wrote:
>> It seems cpu command is buggy in -P option.
>> the sources of the problem is in command option -P of exportfs.
>
> I had a look at the manpage for exportfs(4), it says: "For a file to
> be exported, all lines with a prefix + must match and all those with
> prefix - must not match." (http://man.9front.org/4/exportfs)
>
> So isn't the original code correct according to the manpage? If any of
> the regexps in 'include' fail to match, the function returns -1, then
> if any in 'exclude' do match, -1 is returned.
>
>> patternfile sample
>> + /usr/arisawa
>> + /usr/glenda
>> - /adm
>> - /sys/log
>> - /mail
>> - /usr/.*
>>
> Is this sample invalid - no path could match /usr/arisawa and
> /usr/glenda at the same time?
>
> Pete

I said:

> int
> excludefile(char *path)
> {
>       Reprog **re;
>       char *p;
>
>       if(*(path+1) == 0)
>               p = "/";
>       else
>               p = path+1;
>
>       DEBUG(DFD, "checking %s\n", p);
>       for(re = include; *re != nil; re++){
> -             if(regexec(*re, p, nil, 0) != 1){
> +             if(regexec(*re, p, nil, 0) == 1){
>                       DEBUG(DFD, "excluded+ %s\n", p);
> -                     return -1;
> +                     return 0;
>               }
>       }
>       for(re = exclude; *re != nil; re++){
>               if(regexec(*re, p, nil, 0) == 1){
>                       DEBUG(DFD, "excluded- %s\n", p);
>                       return -1;
>               }
>       }
>       return 0;
> }
>
>
> patternfile sample
> + /usr/arisawa
> + /usr/glenda
> - /adm
> - /sys/log
> - /mail
> - /usr/.*

however this code has still a problem.

trailing ‘/‘ is removed in p even if p is a directory.
assume we have users:
/usr/rob
and
/usr/robin
then we cannot export only /usr/rob.
if we wish control this problem, we need tailing ‘/‘ for directory.
then the code should be

excludefile(char *path)
{
        Reprog **re;
        char *p,*s;
        Dir *dir;

        if(*(path+1) == 0)
                p = "/";
        else
                p = path+1;

        s = p + strlen(p) - 1; /* tail */
        dir = dirstat(p);
        /* should not be nil */
        if((dir->mode)&DMDIR){
                /* we have room to append '/'
                *  look makepath() in exportfs.c */
                *++s = '/';
                *++s = 0;
        }

        DEBUG(DFD, "checking %s\n", p);
        for(re = include; *re != nil; re++){
                if(regexec(*re, p, nil, 0) == 1){
                        DEBUG(DFD, "excluded+ %s\n", p);
                        return 0;
                }
        }
        for(re = exclude; *re != nil; re++){
                if(regexec(*re, p, nil, 0) == 1){
                        DEBUG(DFD, "excluded- %s\n", p);
                        return -1;
                }
        }
        return 0;
}

then patternfile sample become:

+ /usr/arisawa/.*
+ /usr/glenda/.*
- /adm/
- /sys/log/
- /mail/
- /usr/.+

adding tailing ‘/‘ in p makes the pattern file incompatible to existing one.
I don’t know it is better to do so.