/* mkgmtime.c - make time corresponding to a GMT timeval struct $Id: mkgmtime.c,v 1.10 2003/10/22 18:50:12 rjs3 Exp $ * Copyright (c) 1998-2003 Carnegie Mellon University. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. 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. * * 3. The name "Carnegie Mellon University" must not be used to * endorse or promote products derived from this software without * prior written permission. For permission or any other legal * details, please contact * Office of Technology Transfer * Carnegie Mellon University * 5000 Forbes Avenue * Pittsburgh, PA 15213-3890 * (412) 268-4387, fax: (412) 268-7395 * tech-transfer@andrew.cmu.edu * * 4. Redistributions of any form whatsoever must retain the following * acknowledgment: * "This product includes software developed by Computing Services * at Carnegie Mellon University (http://www.cmu.edu/computing/)." * * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * * */ /* * Copyright (c) 1987, 1989, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Arthur David Olson of the National Cancer Institute. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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. */ /* ** Adapted from code provided by Robert Elz, who writes: ** The "best" way to do mktime I think is based on an idea of Bob ** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now). ** It does a binary search of the time_t space. Since time_t's are ** just 32 bits, its a max of 32 iterations (even at 64 bits it ** would still be very reasonable). */ #include <config.h> #ifndef WRONG #define WRONG (-1) #endif /* !defined WRONG */ static int tmcomp(atmp, btmp) register const struct tm * const atmp; register const struct tm * const btmp; { register int result; if ((result = (atmp->tm_year - btmp->tm_year)) == 0 && (result = (atmp->tm_mon - btmp->tm_mon)) == 0 && (result = (atmp->tm_mday - btmp->tm_mday)) == 0 && (result = (atmp->tm_hour - btmp->tm_hour)) == 0 && (result = (atmp->tm_min - btmp->tm_min)) == 0) result = atmp->tm_sec - btmp->tm_sec; return result; } time_t mkgmtime(tmp) struct tm * const tmp; { register int dir; register int bits; register int saved_seconds; time_t t; struct tm yourtm, *mytm; yourtm = *tmp; saved_seconds = yourtm.tm_sec; yourtm.tm_sec = 0; /* ** Calculate the number of magnitude bits in a time_t ** (this works regardless of whether time_t is ** signed or unsigned, though lint complains if unsigned). */ for (bits = 0, t = 1; t > 0; ++bits, t <<= 1) ; /* ** If time_t is signed, then 0 is the median value, ** if time_t is unsigned, then 1 << bits is median. */ t = (t < 0) ? 0 : ((time_t) 1 << bits); /* Some gmtime() implementations are broken and will return * NULL for time_ts larger than 40 bits even on 64-bit platforms * so we'll just cap it at 40 bits */ if(bits > 40) bits = 40; for ( ; ; ) { mytm = gmtime(&t); if(!mytm) return WRONG; dir = tmcomp(mytm, &yourtm); if (dir != 0) { if (bits-- < 0) return WRONG; if (bits < 0) --t; else if (dir > 0) t -= (time_t) 1 << bits; else t += (time_t) 1 << bits; continue; } break; } t += saved_seconds; return t; }