Martin Pieuchot wrote:
> On 28/02/16(Sun) 13:14, Martin Natano wrote:
> > The ext2fs_read() and ffs_read() functions return EFBIG when uio_offset
> > if smaller than zero or larger than the maxium file size. However this
> > doesn't seem to be in accordance with the POSIX read(2) specification,
> > which requires EINVAL for an invalid offset (< 2) and a return of 0
> > (zero bytes transferred) for an offset that's at or paste the EOF. EFBIG
> > actually means "File too large", which is clearly not true in both
> > cases.
>
> This seems to be coherent with MSDOSFS.
>
> I'm also wondering when you say "an offset that's at or paste the
> EOF" does that include ``uio_resid''? I mean shouldn't you check
> for:
>
> if ((uio->uio_offset + uio->uio_resid) > fs->fs_maxfilesize)
> ...
I think if uio->uio_offset < fs->fs_maxfilesize, then
min(uio->uio_resid, fs->fs_maxfilesize - uio->uio_offset)
bytes should be read.
Maybe the check should be if (uio_offset >= fs->fs_maxfilesize)
though. Otherwise access flags of the inode are changed at the end
if ext2_ind_read() and ffs_read() even though there was no real access.
> > Index: ufs/ext2fs/ext2fs_readwrite.c
> > ===================================================================
> > RCS file: /cvs/src/sys/ufs/ext2fs/ext2fs_readwrite.c,v
> > retrieving revision 1.39
> > diff -u -p -r1.39 ext2fs_readwrite.c
> > --- ufs/ext2fs/ext2fs_readwrite.c 27 Feb 2016 18:50:38 -0000 1.39
> > +++ ufs/ext2fs/ext2fs_readwrite.c 28 Feb 2016 09:10:16 -0000
> > @@ -100,9 +100,9 @@ ext2_ind_read(struct vnode *vp, struct i
> > } else if (vp->v_type != VREG && vp->v_type != VDIR)
> > panic("%s: type %d", "ext2fs_read", vp->v_type);
> > #endif
> > - if (e2fs_overflow(fs, 0, uio->uio_offset))
> > - return (EFBIG);
> > - if (uio->uio_resid == 0)
> > + if (uio->uio_offset < 0)
> > + return (EINVAL);
> > + if (uio->uio_offset > fs->e2fs_maxfilesize || uio->uio_resid == 0)
> > return (0);
> >
> > for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
> > @@ -163,7 +163,6 @@ ext4_ext_read(struct vnode *vp, struct i
> > struct ext4_extent_path path;
> > struct ext4_extent nex, *ep;
> > struct buf *bp;
> > - size_t orig_resid;
> > daddr_t lbn, pos;
> > off_t bytesinfile;
> > int size, xfersize, blkoffset;
> > @@ -171,12 +170,10 @@ ext4_ext_read(struct vnode *vp, struct i
> >
> > memset(&path, 0, sizeof path);
> >
> > - orig_resid = uio->uio_resid;
> > - if (orig_resid == 0)
> > + if (uio->uio_offset < 0)
> > + return (EINVAL);
> > + if (uio->uio_offset > fs->e2fs_maxfilesize || uio->uio_resid == 0)
> > return (0);
> > -
> > - if (e2fs_overflow(fs, 0, uio->uio_offset))
> > - return (EFBIG);
> >
> > while (uio->uio_resid > 0) {
> > if ((bytesinfile = ext2fs_size(ip) - uio->uio_offset) <= 0)
> > Index: ufs/ffs/ffs_vnops.c
> > ===================================================================
> > RCS file: /cvs/src/sys/ufs/ffs/ffs_vnops.c,v
> > retrieving revision 1.84
> > diff -u -p -r1.84 ffs_vnops.c
> > --- ufs/ffs/ffs_vnops.c 27 Feb 2016 18:50:38 -0000 1.84
> > +++ ufs/ffs/ffs_vnops.c 28 Feb 2016 09:10:16 -0000
> > @@ -214,10 +214,9 @@ ffs_read(void *v)
> > panic("ffs_read: type %d", vp->v_type);
> > #endif
> > fs = ip->i_fs;
> > - if ((u_int64_t)uio->uio_offset > fs->fs_maxfilesize)
> > - return (EFBIG);
> > -
> > - if (uio->uio_resid == 0)
> > + if (uio->uio_offset < 0)
> > + return (EINVAL);
> > + if (uio->uio_offset > fs->fs_maxfilesize || uio->uio_resid == 0)
> > return (0);
> >
> > for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
> >
>
