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87fb310b69
In documentation and comments, be more like POSIX in terminology involving multithreading. Explain the distinction between multithreaded process vs multithreaded program. Change “program” to “process” when the latter wording is more accurate or informative. Simplify the wording for the constraints on processes that use unlocked I/O. Change “multithread-safe” to “thread-safe”. Change “thread-safety” to “thread safety”. However, do not change “multithreaded” to “multi-threaded” even though there are some uses of both spellinga, as there are a whole bunch of uses of “multithreaded”, also in identifier names; perhaps Gnulib should even standardize on “multithreaded” (not “multi-threaded”), contra POSIX.
82 lines
3.3 KiB
C
82 lines
3.3 KiB
C
/* Work around platform bugs in wcsftime.
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Copyright (C) 2017-2026 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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/* Specification. */
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#include <wchar.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#undef wcsftime
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size_t
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rpl_wcsftime (wchar_t *buf, size_t bufsize, const wchar_t *format, const struct tm *tp)
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{
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#if defined _WIN32 && ! defined __CYGWIN__
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/* Rectify the value of the environment variable TZ.
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There are four possible kinds of such values:
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- Traditional US time zone names, e.g. "PST8PDT". Syntax: see
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<https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/tzset>
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- Time zone names based on geography, that contain one or more
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slashes, e.g. "Europe/Moscow".
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- Time zone names based on geography, without slashes, e.g.
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"Singapore".
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- Time zone names that contain explicit DST rules. Syntax: see
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<https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
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The Microsoft CRT understands only the first kind. It produces incorrect
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results if the value of TZ is of the other kinds.
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But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
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of the second kind for most geographies, or of the first kind in a few
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other geographies. If it is of the second kind, neutralize it. For the
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Microsoft CRT, an absent or empty TZ means the time zone that the user
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has set in the Windows Control Panel.
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If the value of TZ is of the third or fourth kind -- Cygwin programs
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understand these syntaxes as well --, it does not matter whether we
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neutralize it or not, since these values occur only when a Cygwin user
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has set TZ explicitly; this case is 1. rare and 2. under the user's
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responsibility. */
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const char *tz = getenv ("TZ");
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if (tz != NULL && strchr (tz, '/') != NULL)
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{
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/* Neutralize it, in a way that is thread-safe.
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(If we were to use _putenv ("TZ="), it would free the memory allocated
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for the environment variable "TZ", and thus other threads that are
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using the previously fetched value of getenv ("TZ") could crash.) */
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char **env = _environ;
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wchar_t **wenv = _wenviron;
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if (env != NULL)
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for (char **ep = env; *ep != NULL; ep++)
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{
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char *s = *ep;
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if (s[0] == 'T' && s[1] == 'Z' && s[2] == '=')
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s[0] = '$';
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}
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if (wenv != NULL)
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for (wchar_t **wep = wenv; *wep != NULL; wep++)
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{
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wchar_t *ws = *wep;
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if (ws[0] == L'T' && ws[1] == L'Z' && ws[2] == L'=')
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ws[0] = L'$';
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}
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}
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#endif
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return wcsftime (buf, bufsize, format, tp);
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}
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