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: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-07-12T01:10:29Z
Lists: pgsql-hackers 
On Tue, Jul 12, 2022 at 4:46 AM Robert Haas <robertmhaas@gmail.com> wrote:
> I don't think that 0001 is buying us a whole lot, really. I prefer the
> style where we have PG-specific functions that behave differently on
> different platforms to the one where we call something that looks like
> a native OS function call on all platforms but on some of them it is
> secretly invoking a replacement implementation in src/port. The
> problem with the latter is it looks like you're using something that's
> universally supported and works the same way everywhere, but you're
> really not. If it were up to me, we'd have more pg_whatever() that
> calls whatever() on non-Windows and something else on Windows, rather
> than going in the direction that this patch takes us.

Hmm, but that's not what we're doing in general.  For example, on
Windows we're redirecting open() to a replacement function of our own,
we're not using "pg_open()" in our code.  That's not an example based
on AC_REPLACE_FUNCS, but there are plenty of those too.  Isn't this
quite well established?

AFAIK we generally only use pg_whatever() when there's a good reason,
such as an incompatibility, a complication or a different abstraction
that you want to highlight to a reader.  The reason here was
temporary: we couldn't implement standard pread/pwrite perfectly on
ancient HP-UX, but we *can* implement it on Windows, so the reason is
gone.

These particular pg_ prefixes have only been in our tree for a few
years and I was hoping to boot them out again before they stick, like
"Size".  I like using standard interfaces where possible for the very
basic stuff, to de-weird our stuff.

> I like all of the other patches. Reducing the number of configure
> tests that we need seems like a really good idea.

Thanks for looking.  Yeah, we could also be a little more aggressive
about removing configure tests, in the cases where it's just Windows
vs !Windows.  "HAVE_XXX" tests that are always true on POSIX systems
at the level we require would then be unnecessary.

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)