Horton

Re: Cleaning up historical portability baggage

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew@dunslane.net>, Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-08-06T22:23:17Z
Lists: pgsql-hackers

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On Sat, Aug 6, 2022 at 2:54 AM Robert Haas <robertmhaas@gmail.com> wrote:
> On Fri, Aug 5, 2022 at 10:48 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Hmm ... I agree with you that the end result could be nicer code,
> > but what's making it nicer is a pretty substantial amount of human
> > effort for each and every call site.  Is anybody stepping forward
> > to put in that amount of work?
> >
> > My proposal is to leave the call sites alone until someone feels
> > like doing that sort of detail work.
>
> My plan was to nerd-snipe Thomas Munro into doing it.[1]

Alright, well here's a patch for the setsid() stuff following Robert's
plan, which I think is a pretty good plan.

Did I understand correctly that the places that do kill(-pid) followed
by kill(pid) really only need the kill(-pid)?

I checked that user processes should never have pid 0 (that's a
special system idle process) or 1 (because they're always even,
actually it looks like they're pointers in kernel space or something
like that), since those wouldn't play nice with the coding I used
here.

I note that Windows actually *does* have process groups (in one of the
CI threads, we learned that there were at least two concepts like
that).  Some of our fake signals turn into messages to pipes, and
others turn into process termination, and in theory we could probably
also take advantage of Windows' support for its native "control C" and
"control break" signals here.  It's possible that someone could do
something to make all but the pipe ones propagate to real Windows
process groups.  That might be good for things like nuking archiver
subprocesses and the like when taking out the backend, or something
like that, but I'm not planning to look into that myself.

Commits

  1. Make sure IOV_MAX is defined.

  2. Doc: Abstract AF_UNIX sockets don't work on Windows.

  3. Clean up inconsistent use of fflush().

  4. Remove configure probe for sockaddr_in6 and require AF_INET6.

  5. Remove configure probes for sockaddr_storage members.

  6. Remove configure probe for netinet/tcp.h.

  7. Fix macro problem with gai_strerror on Windows.

  8. Remove configure probe for net/if.h.

  9. mstcpip.h is not missing on MinGW.

  10. Remove dead ifaddr.c fallback code.

  11. Remove configure probe for gethostbyname_r.

  12. Remove replacement code for getaddrinfo.

  13. Remove configure probe for struct sockaddr_storage.

  14. Remove HAVE_UNIX_SOCKETS.

  15. Remove configurability of PPC spinlock assembly code.

  16. Remove configure probe for shl_load library.

  17. Remove configure probe for sys/select.h.

  18. Remove configure probes for sys/un.h and struct sockaddr_un.

  19. Remove configure probes for sys/ipc.h, sys/sem.h, sys/shm.h.

  20. Remove configure probe for sys/resource.h and refactor.

  21. Remove configure probe for sys/uio.h.

  22. Fix obsolete comments in instr_time.h.

  23. aix: fix misreading of condition in 8f12a4e7add

  24. aix: Remove checks for very old OS versions

  25. windows: Remove HAVE_MINIDUMP_TYPE test

  26. solaris: Remove unnecessary gcc / gnu ld vs sun studio differences

  27. Trust a few system headers to stand on their own

  28. Rely on __func__ being supported

  29. Simplify replacement code for strtof.

  30. Simplify gettimeofday for Windows.

  31. Simplify gettimeofday() fallback logic.

  32. Remove fallbacks for strtoll, strtoull.

  33. Remove configure probe for fdatasync.

  34. Remove configure probe for clock_gettime.

  35. Simplify replacement code for preadv and pwritev.

  36. Remove dead pread and pwrite replacement code.

  37. Remove dead setenv, unsetenv replacement code.

  38. Remove configure probes for poll and poll.h.

  39. Remove configure probe for link.

  40. Remove configure probes for symlink/readlink, and dead code.

  41. Remove configure probe for setsid.

  42. Remove configure probe for shm_open.

  43. Remove configure probe and related tests for getrlimit.

  44. Remove configure probe for dlopen, and refactor.

  45. Remove dead getpwuid_r replacement code.

  46. Remove dead handling for pre-POSIX sigwait().

  47. Remove dead getrusage replacement code.

  48. Cygwin and Mingw floating-point fixes.

  49. Support platforms where strtoll/strtoull are spelled __strtoll/__strtoull.

  50. Arrange to supply declarations for strtoll/strtoull if needed.

  51. Lock down regression testing temporary clusters on Windows.

  52. Secure Unix-domain sockets of "make check" temporary clusters.

  53. Add configure checks for strtoll, strtoull (or strto[u]q). Disable

  54. Portability fix for old SunOS releases: fflush(NULL)