Re: [fuse-devel] Trying to use overlay in chroot construction.

[Stef B. <st...@gm...>]

Well,

Ive added code like:

static int do_open(fuse_ino_t ino, struct fuse_file_info *fi)
{
        struct xmpfs_entry_struct *entry = find_inode(ino)->alias;
        int fd;
        struct stat st;
        int flags = (fi->flags & O_ACCMODE) | O_NOFOLLOW;
        int res;

        if ( DEBUG > 0 ) syslog(LOG_DEBUG, "do_open");

        if (xmpfs_options.o_direct) flags |= O_DIRECT;

        fd = open_ino(entry, flags);

        if (fd < 0) return fd;

        fi->fh = fd;
        fi->keep_cache = 0;
        fi->nonseekable=1;

        res=fstat(fd, &st);

        if ( res != -1 ) {
            if ( S_ISREG(st.st_mode) ); {
                // is seekable

                if ( DEBUG > 0 ) syslog(LOG_DEBUG, "open: a normal file");
                fi->nonseekable = 0;
                fi->keep_cache = 1;
                }
            }

        return 0;
}


and

static void xmpfs_read(fuse_req_t req, fuse_ino_t ino, size_t size,
                       off_t off, struct fuse_file_info *fi)
{
        int res;
        void *buf;

        (void) ino;

        if ( DEBUG > 0 ) syslog(LOG_DEBUG, "read");

        res = posix_memalign(&buf, pagesize, size);
        if (res != 0) {
                fuse_reply_err(req, res);
                return;
        }

        if ( fi->nonseekable == 1) {

            // non seekable -> use the default read command

            if ( DEBUG > 0 ) syslog(LOG_DEBUG, "read: normal read,
without offset");

            res = read(fi->fh, buf, size);

        } else {

            // seekable -> use the pread command using the offset

            if ( DEBUG > 0 ) syslog(LOG_DEBUG, "read: pread with offset");

            res = pread(fi->fh, buf, size, off);

        }

        if (res == -1)
                fuse_reply_err(req, errno);
        else
                fuse_reply_buf(req, buf, res);
        free(buf);
}

this does not work either.
Files in /proc are still seen as normal files (S_ISREG), and thus seekable.

I've read some articles on the Internet, and it looks like files in
/proc are only readable through fgets in stead of read or pread.

Stef

2010/5/30 Stef Bon <st...@gm...>:
> I've found that this value (fuse_file_info->nonseekable) is already
> available (in 2.8).
>
>
> 2010/5/30 Stef Bon <st...@gm...>:
>> Well,
>>
>> I've found already this in the documentation on:
>>
>> http://fuse.sourceforge.net/doxygen/structfuse__file__info.html
>>
>> saying:
>>
>> unsigned int fuse_file_info::nonseekable
>>
>> Can be filled in by open, to indicate that the file is not seekable.
>> Introduced in version 2.9
>> So this is probably what I need.
>> Based on this value I can use pread (when seekable) or "normal" read when not.
>>
>>
>> But 2.9 is still in development?
>>
>> Stef
>>
>>
>>
>