o When stat(2) fails (i.e. the file has been moved) there's no new
file with the same name yet, so keep showing the file that's open.
This yields the same behaviour as -f, for which we don't stat(2).
o When a new file with the same name has been created (i.e stat(2)
succeeds but the inode or device numbers differ from the opened
file), show any new lines in the opened file (i.e. the old or
rotated file) before reopening the new file.
These changes fix the observed behaviour that tail(1) doesn't show
the very last lines of the rotated (log) files.
PR: bin/101979
Tested by: Jos Backus <jos@catnook.com>
MFC after: 2 months
0e4a74aceb