From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Fri,  3 Oct 2008 12:18:19 -0700
From: "Roman V. Shaposhnik" <rvs@Sun.COM>
To: 9fans <9fans@9fans.net>
Message-id: <1223061499.22031.9.camel@goose.sun.com>
MIME-version: 1.0
Content-type: text/plain
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Subject: [9fans] mounting stdin using 9pfuse
Topicbox-Message-UUID: 16f46dc8-ead4-11e9-9d60-3106f5b1d025

Guys,

it appears that I'm missing something fundamental in how
9pfuse (the one written by Russ) works when it is given
"-" as an address. The source looks like it should be
simply using stdin for R/W instead of dialing out the
connection first, but it doesn't really seem to work.
Here's the simplest way of reproducing what I'm
seeing:

$ cat connector.c
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <error.h>
#include <errno.h>

void socket012(int fd)
{
   int i;
   for (i=0; i<3; i++) {
        close(i);
        dup2(fd, i);
   }
   close(fd);
}

int main()
{
    int fd[2];

    if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNIX, fd) < 0)
        error(-1, errno, "socketpair failed");

    if (fork()) {
        socket012(fd[0]);
        execlp("9pfuse", "9pfuse", "-", "/tmp/fuse", (char*)0);
    } else {
        socket012(fd[1]);
        execlp("ramfs", "ramfs", "-i", (char*)0);
    }
}
$ cc connector.c
$ ./a.out

Now, in a different terminal I do this:

# ls /tmp/fuse
ls: cannot access /tmp/fuse: Permission denied

Also apparently the processes are there (although
a zombie ramfs looks suspicious -- the second ramfs
is fully functional):

$ ps -alef | egrep "9p|ramfs"
0 S roman    22661 18264  0  78   0 -  2575 wait   12:13 pts/4   00:00:00 9pfuse -D - /tmp/fuse
1 S roman    22663 22661  0  78   0 - 12906 stext  12:13 ?        00:00:00 9pfuse -D - /tmp/fuse
1 S roman    22666     1  0  79   0 -  2725 -      12:13 pts/4   00:00:00 ramfs -i
0 Z roman    22662 22661  0  78   0 -     0 exit   12:13 pts/4    00:00:00 [ramfs] <defunct>

Now, if I enable -D in 9pfuse (by dup2'ing only 0 instead of
0,1 and 2) here's the output I get:
<- Tversion tag 0 msize 8192 version '9P2000.u'
-> Rversion tag 65535 msize 8192 version '9P2000'
<- Tattach tag 0 fid 0 afid -1 uname roman aname
-> Rattach tag 0 qid (0000000000000000 0 d)
FUSE -> len 16 unique 0x1 uid 0 gid 0 pid 0 Init major 7 minor 8
FUSE <- unique 0x1 (Init) major 7 minor 5 max_write 4096

And it stops there no matter what I do from then on.

Well, I'm baffled. Any help would be tremendously appreciated.

Thanks,
Roman.