diff --git a/src/localtime.c b/src/localtime.c new file mode 100644 index 00000000..f03d9563 --- /dev/null +++ b/src/localtime.c @@ -0,0 +1,44 @@ +/* + * Copyright (c) 2018, Salvatore Sanfilippo + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * * Neither the name of Redis nor the names of its contributors may be used + * to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include + +/* This is a safe version of localtime() which contains no locks and is + * fork() friendly. Even the _r version of localtime() cannot be used safely + * in Redis. Another thread may be calling localtime() while the main thread + * forks(). Later when the child process calls localtime() again, for instance + * in order to log something to the Redis log, it may deadlock: in the copy + * of the address space of the forked process the lock will never be released. + * + * This function takes the timezone 'tz' as argument, and the 'dst' flag is + * used to check if daylight saving time is currently in effect. The caller + * of this function should obtain such information calling tzset() ASAP in the + * main() function, and later accessing the globals 'timezone' and 'daylight'. */ +void nolocks_localtime(struct tm *tmptr, time_t t, time_t tz, int dst) { +}