curl/m4
Viktor Szakats 32454b954a
localtime: detect thread-safe alternatives and use them
- add local API `toolx_localtime()` to wrap the banned function
  `localtime()`. Used from libcurl, libtests and test servers.
- auto-detect and use `localtime_r()` where available (e.g. Linux).
  Also to support multi-threading.
- use `localtime_s()` on Windows. It requires MSVC or mingw-w64 v4+.
  Also to support multi-threading.
  Use local workaround to also support mingw-w64 v3.
- add `src/toolx` to keep internal APIs used by the curl tool and tests,
  but not by libcurl. `toolx_localtime()` is the first API in it.
- replace `localtime()` calls with `toolx_localtime()`.
  Except in examples.
- note Windows XP's default `msvcrt.dll` doesn't offer secure CRT APIs.
  XP likely needs a newer version of this DLL, or may not run.
- note that `localtime()` mirrors `gmtime()`, with the difference that
  `gmtime()`'s internal wrapper lives in curlx.

Also:
- drop redundant `int` casts.

Refs:
https://learn.microsoft.com/cpp/c-runtime-library/reference/localtime-localtime32-localtime64
https://learn.microsoft.com/cpp/c-runtime-library/reference/localtime-s-localtime32-s-localtime64-s
https://pubs.opengroup.org/onlinepubs/9799919799/functions/localtime.html
https://linux.die.net/man/3/localtime_r

Ref: #19955 (for `gmtime_r()`)
Follow-up to 54d9f060b4
Closes #19957
2025-12-16 14:30:06 +01:00
..
.gitignore tidy-up: .gitignore lines mostly 2025-01-27 20:59:46 +01:00
curl-amissl.m4 tidy-up: miscellaneous 2025-12-12 04:18:48 +01:00
curl-apple-sectrust.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-compilers.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-confopts.m4 autotools: drop reference to deleted CURL_CHECK_CURLDEBUG 2025-12-11 11:42:27 +01:00
curl-functions.m4 localtime: detect thread-safe alternatives and use them 2025-12-16 14:30:06 +01:00
curl-gnutls.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-mbedtls.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-openssl.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-override.m4 badwords: add more contractions, fix fallouts 2025-11-17 19:29:15 +01:00
curl-reentrant.m4 badwords: add more contractions, fix fallouts 2025-11-17 19:29:15 +01:00
curl-rustls.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-schannel.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-sysconfig.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
curl-wolfssl.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
xc-am-iface.m4 misc: cleanup after removing years from copyright 2024-07-30 14:11:48 +02:00
xc-cc-check.m4 misc: cleanup after removing years from copyright 2024-07-30 14:11:48 +02:00
xc-lt-iface.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
xc-val-flgs.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
zz40-xc-ovr.m4 autotools: tidy-up if expressions 2025-12-10 22:29:19 +01:00
zz50-xc-ovr.m4 badwords: add more contractions, fix fallouts 2025-11-17 19:29:15 +01:00