On Wed, Feb 21, 2024 at 09:20:55PM +0000, Taylor R Campbell wrote: > > Date: Wed, 21 Feb 2024 10:52:55 +0000 > > From: Sad Clouds <cryintotheblue...@gmail.com> > > > > Hello, for most operating systems determining the size of a block > > device can be done with: > > > > lseek(fd, 0, SEEK_END); > > > > However, on NetBSD this does not seem to work. > > Internally, this is happens for more or less the same reason that > stat(2) doesn't return the size of a block device in st_size. > > Each file system on which device nodes can reside implements its own > VOP_GETATTR (used by both lseek(2) and stat(2)), and most of them use > the _inode_ size (more or less) rather than querying the block device > that the device node represents for its physical size. > > I think this is a bug, and it would be great if stat(2) just returned > the physical medium's size in st_size -- currently doing this reliably > takes at least three different ioctls to handle all storage media, if > I counted correctly in sbin/fsck/partutil.c's getdiskinfo.
I am not sure this can be done for all block devices. Tapes have block devices, and open-reel tape drives do not really know the length of the loaded media, while on any other tape drive supporting compression, there may really be no such size.
