The history behind the undocumented NetBSD stat syscalls?

[Gleb Kurtsou]

On (13/02/2011 13:39), Garrett Cooper wrote:
> Hi FS folks,
>     I was poking through vfs_syscalls.c and I noticed that there was a
> syscall called nlstat, and nstat, and a kernel-public only helper
> function called cvtnstat:
>     These aren't used anywhere in our source tree (I trimmed out the
> false positives -- i.e. connstat and instat), minus their declarations
> in kern/vfs_syscalls.c, etc:
> 
> $ svngrep -Er 'nl?stat\(' /usr/src/
> /usr/src/sys/kern/kern_descrip.c:		cvtnstat(&ub, &nub);
> /usr/src/sys/kern/syscalls.master:278	AUE_STAT	STD	{ int nstat(char
> *path, struct nstat *ub); }
> /usr/src/sys/kern/syscalls.master:280	AUE_LSTAT	STD	{ int nlstat(char
> *path, struct nstat *ub); }
> /usr/src/sys/kern/vfs_syscalls.c:cvtnstat(sb, nsb)
> /usr/src/sys/kern/vfs_syscalls.c:nstat(td, uap)
> /usr/src/sys/kern/vfs_syscalls.c:	cvtnstat(&sb, &nsb);
> /usr/src/sys/kern/vfs_syscalls.c:nlstat(td, uap)
> /usr/src/sys/kern/vfs_syscalls.c:	cvtnstat(&sb, &nsb);
> /usr/src/sys/compat/freebsd32/syscalls.master:278	AUE_STAT	NOPROTO{
> int nstat(char *path, struct nstat *ub); }
> /usr/src/sys/compat/freebsd32/syscalls.master:280	AUE_LSTAT	NOPROTO{
> int nlstat(char *path, struct nstat *ub); }
> /usr/src/sys/sys/vnode.h:void	cvtnstat(struct stat *sb, struct nstat *nsb);
> /usr/src/sys/sys/sysproto.h:int	nstat(struct thread *, struct nstat_args *);
> /usr/src/sys/sys/sysproto.h:int	nlstat(struct thread *, struct nlstat_args *);
> 
>     And seems like it should be superseded by lstat, et all, which
> were introduced a little earlier on [1].
>     Do they serve a real purpose of some kind today? It was introduced
> in the revision seen in SVN here [2], and looking back in time there
> isn't reference to a NetBSD compat layer in sys/conf/options [3], etc,
> so I was a bit curious why there are dangling undocumented (but
> publicly visible via sysproto.h) VFS-related syscalls entries hanging
> around (in particular because the syscalls aren't declared that way in
> NetBSD either).
These were dropped by Dragonfly as not being used. NetBSD is no longer
compatible with them, afair.

freebsd32 compatibility shims are incorrect, which means that nobody
ever used them.

If you are interested, I have a patch marking them COMPAT8 and OBSOL for
freebsd32, it's part of larger set of changes to make ino_t 64 bit:
https://github.com/downloads/glk/freebsd-ino64/freebsd-ino64-patch-2011-01-20.tgz


> Thanks!
> -Garrett
> 
> 1. http://svn.freebsd.org/viewvc/base/head/sys/kern/vfs_syscalls.c?revision=24438&view=markup
> 2. http://svn.freebsd.org/viewvc/base/head/sys/kern/vfs_syscalls.c?revision=35938&view=markup
> 3. http://svn.freebsd.org/viewvc/base/head/sys/conf/options?view=log
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