> Date: Thu, 18 Apr 2013 21:57:56 +0300 > From: Eli Zaretskii <e...@gnu.org> > Cc: bug-make@gnu.org, bo...@kolpackov.net > > > Date: Thu, 18 Apr 2013 19:09:06 +0200 > > From: Frank Heckenbach <f.heckenb...@fh-soft.de> > > > > > . calculation of combined_output in start_job_command will need to be > > > reimplemented for Windows, since the reliance on st_dev and st_ino > > > makes assumptions that are false on Windows. > > > > What we need is basically "is_same_file (fd1, fd2)" (which we > > probably could refactor into a separate function). Eli, can you try: > > > > test file1 -ef file2 > > > > where test is either a standalone utility or a built-in of bash or > > any other shell. If any of these works, you can see how they do it. > > Otherwise, a bit of googling turned up this page which has code (in > > Python, but it seems like a thin layer around the system calls, so > > it can probably easily be ported to C): > > > > http://timgolden.me.uk/python/win32_how_do_i/see_if_two_files_are_the_same_file.html > > I know about this method, but I'm not sure it does what we want here. > The number used by this method is not guaranteed to be unique on some > versions of Windows. More importantly, it only works for disk files, > I don't know whether it reports a meaningful value for the console > device or the null device.
Testing clearly shows it doesn't: GetFileInformationByHandle simply fails for handles open on console devices and the null device. And we will be comparing handles for console devices in the majority of use cases here. I researched this a bit, and eventually succeeded in finding a way that is good enough for both disk files, pipes, and console devices. > > > > > . STREAM_OK uses fcntl and F_GETFD which both don't exist on Windows. > > > > > > > > This is to test if somehow make's stdout or stderr has been closed (not > > > > just redirected to /dev/null, but closed). > > > > > > Right, got that; but Windows needs a different test for that, as > > > there's no fcntl. > > > > Basically we need just any call that succees for a valid file and > > fails otherwise. fstat() might be a good candidate. > > fstat is too heavy on Windows; there are better methods. > > > If that isn't available, maybe even lseek() (as used in > > FD_NOT_EMPTY) will do if we keep the "|| errno != EBADF" test. > > lseek fails for the console as well, so it's not a good candidate. > But this problem is not difficult, I just mentioned that the code as > committed won't compile. > > > Eli, can you do some tests to see if you find something that works > > reliably? > > Don't worry about that. My worst problem is lack of time, not lack of > ideas ;-) Found a reasonable solution for that as well. _______________________________________________ Bug-make mailing list Bug-make@gnu.org https://lists.gnu.org/mailman/listinfo/bug-make
