Re: [PATCH v3 1/1] ioctl-fat.2: new manpage for the ioctl fat API

Hello Hirofumi,

On 3 February 2015 at 10:44, OGAWA Hirofumi [off-list ref] wrote:

"Michael Kerrisk (man-pages)" [off-list ref] writes:

quoted

quoted

Quick reviewed, and looks good. However, entry[0].d_reclen == 0 works as
backward compatibility though. The example might be good to use usual
way of getdents().

I.e., "ret" means
        -1 == error
        0  == EOD
        0  >  how many bytes read

Sorry -- I do not really understand what you mean here
"entry[0].d_reclen == 0 works as backward compatibility though"). Is
the line

                    if (ret == -1 || entry[0].d_reclen == 0)

incorrect? If yes, what should the code look like?

Sorry. I meant, "entry[0].d_reclen == 0" check works because fatfs still
have backward compatibility code. However it would not be preferred way.

In ancient version, fatfs didn't return proper return code, so apps (I
know only use is wine) had to check "entry[0].d_reclen == 0" to know
EOD.

But for a long time, fatfs returns proper return code like said in
previous email (previous email was wrong on "0 > how many bytes read",
see below instead). I.e., now user can use "ret" as similar to
getdents(), user can know the result as usual from "ret" without
"entry[0].d_reclen == 0".

        while (1) {
                ret = ioctl();
                if (ret == -1) {
                        /* error */

                if (ret == 0)
                        /* EOD */

                /* got entry (would be ret == 1) */
        }

Thanks for the clarification. I have one other question. Currently the
man page does not document two fields in the __fat_dirent structure:
d_ino and d_offset. d_ino is presumably the inode number. But, what is
d_offset?

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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