On Mon, 4 Mar 2024 at 07:45, Mark Geisert via Cygwin <cygwin@cygwin.com> wrote: > > On 3/3/2024 7:27 PM, Dan Shelton via Cygwin wrote: > > On Tue, 27 Feb 2024 at 07:34, <gs-cygwin....@gluelogic.com> wrote: > >> > >> On Tue, Feb 27, 2024 at 06:54:42AM +0100, Dan Shelton via Cygwin wrote: > >>> On Tue, 27 Feb 2024 at 06:47, Brian Inglis via Cygwin <cygwin@cygwin.com> > >>> wrote: > >>>> > >>>> On 2024-02-26 20:23, Dan Shelton via Cygwin wrote: > >>>>> Does Cygwin implement a native, i.e. without form(),exec(), > >>>>> implementation of posix_spawn()? > >>>> > >>>> Check the API compatibility docs online: > >>>> > >>>> https://cygwin.com/cygwin-api/compatibility.html#std-susv4 > >>>> > >>>> or optional locally installed package cygwin-doc: > >>>> > >>>> > >>>> /usr/share/doc/cygwin-doc/html/cygwin-api/compatibility.html#std-susv4 > >>> > >>> That document does not answer my question. > >>> > >>> I know posix_spawn() is there. But the question is: Does it use just > >>> Cygwin fork(),exec(), or the native Win32 spawn() api? > >>> > >>> Dan > >>> -- > >>> Dan Shelton - Cluster Specialist Win/Lin/Bsd > >> > >> If you were going to make a small effort to answer the question > >> yourself, you could use strace, you could step through a debugger, or > >> you could check the source code. Have you tried any of these? What did > >> you find? If you are unable to take any of those steps, why does > >> posix_spawn() matter to you? > > > > strace does not help, as I need the Win32 calls BELOW posix_spawn(), > > to see the implementation details. > > Check the source code, then. It's at: > https://cygwin.com/cgit/newlib-cygwin/tree/winsup/cygwin/fork.cc > > Look at line 587; there's the static function dofork(). Look at the > thirty or so lines above that; there's both fork() and > __posix_spawn_fork() calling dofork(). So both those user-level > functions call into the exact same internals. (BTW __posix_spawn_fork() > is called from posix_spawn(); the latter is in newlib and not Cygwin.) > > You can even see the reason it's done this way by reading the comment.
Yes, but it is as I feared, Cygwin posix_spawn() does not use Win32 spawn() at all, and instead uses a rather inefficient vfork() solution. posix_spawn() was added to POSIX so a Win32 implementation can use Win32 spawn() Dan -- Dan Shelton - Cluster Specialist Win/Lin/Bsd -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
