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Commit 951dba6

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Skeleton for Exercise 23-4
1 parent 19e57ed commit 951dba6

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9 files changed

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9 files changed

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‎10_Time/curr_time.c‎

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/*************************************************************************\
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* Copyright (C) Michael Kerrisk, 2024. *
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* *
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* This program is free software. You may use, modify, and redistribute it *
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* under the terms of the GNU Lesser General Public License as published *
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* by the Free Software Foundation, either version 3 or (at your option) *
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* any later version. This program is distributed without any warranty. *
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* See the files COPYING.lgpl-v3 and COPYING.gpl-v3 for details. *
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\*************************************************************************/
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/* curr_time.c
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Implement our currTime() function.
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*/
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#include <time.h>
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#include "curr_time.h" /* Declares function defined here */
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#define BUF_SIZE 1000
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/* Return a string containing the current time formatted according to
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the specification in 'format' (see strftime(3) for specifiers).
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If 'format' is NULL, we use "%c" as a specifier (which gives the'
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date and time as for ctime(3), but without the trailing newline).
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Returns NULL on error. */
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char *
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currTime(const char *format)
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{
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static char buf[BUF_SIZE]; /* Nonreentrant */
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time_t t;
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size_t s;
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struct tm *tm;
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t = time(NULL);
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tm = localtime(&t);
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if (tm == NULL)
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return NULL;
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s = strftime(buf, BUF_SIZE, (format != NULL) ? format : "%c", tm);
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return (s == 0) ? NULL : buf;
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}

‎10_Time/curr_time.h‎

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/*************************************************************************\
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* Copyright (C) Michael Kerrisk, 2024. *
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* *
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* This program is free software. You may use, modify, and redistribute it *
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* under the terms of the GNU Lesser General Public License as published *
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* by the Free Software Foundation, either version 3 or (at your option) *
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* any later version. This program is distributed without any warranty. *
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* See the files COPYING.lgpl-v3 and COPYING.gpl-v3 for details. *
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\*************************************************************************/
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/* curr_time.h
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Header file for curr_time.c.
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*/
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#ifndef CURR_TIME_H
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#define CURR_TIME_H /* Prevent accidental double inclusion */
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char *currTime(const char *fmt);
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#endif

‎23_Timers_and_Sleeping/Makefile‎

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./Ex_23_3 EVP
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test_4: ptmr_sigev_thread
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./ptmr_sigev_thread
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./ptmr_sigev_thread 60
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# ------------------------------------------------------------------------------
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# Compile programs

‎23_Timers_and_Sleeping/README.md‎

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```text
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./Ex_23_2.sh
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Using t_nanosleep...
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Remaining: 0.000346101
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Slept for: 61.986514 secs
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Remaining: 0.000715167
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Slept for: 62.077613 secs
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Sleep complete
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Using Ex_23_2...
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Remaining: 0.000576292
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Slept for: 61.888986 secs
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Remaining: 9437184.000000012
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Slept for: 60.000036 secs
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Sleep complete
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Using t_clock_nanosleep...
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Interrupted... Slept: 62.007887 secs... Remaining: 0.000790663... Restarting
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Slept: 62.008789 secs
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Interrupted... Slept: 62.072626 secs... Remaining: 0.002018094... Restarting
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Slept: 62.074727 secs
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Sleep complete
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```
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There is no meaningful difference between the three (3) versions. All of them overran the set interval by about two (2) seconds.
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There is no meaningful difference between the two (2) versions: t_nanosleep; and t_clock_nanosleep. Both of them overran the set interval by about two (2) seconds.
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My solution was close to the set interval.
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## Exercise 23-3
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‎23_Timers_and_Sleeping/curr_time.c‎

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../10_Time/curr_time.c

‎23_Timers_and_Sleeping/curr_time.h‎

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../10_Time/curr_time.h
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/*************************************************************************\
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* Copyright (C) Michael Kerrisk, 2024. *
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* *
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* This program is free software. You may use, modify, and redistribute it *
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* under the terms of the GNU Lesser General Public License as published *
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* by the Free Software Foundation, either version 3 or (at your option) *
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* any later version. This program is distributed without any warranty. *
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* See the files COPYING.lgpl-v3 and COPYING.gpl-v3 for details. *
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\*************************************************************************/
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/* itimerspec_from_str.c
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Implement our itimerspecFromStr() function.
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*/
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#ifndef __APPLE__ /* Mac OS X doesn't define the 'itimerspec' structure
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(or the POSIX timer functions (timer_*()) */
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#include <string.h>
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#include <stdlib.h>
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#include "itimerspec_from_str.h" /* Declares function defined here */
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/* Convert a string of the following form to an itimerspec structure:
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"value.sec[/value.nanosec][:interval.sec[/interval.nanosec]]".
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Optional components that are omitted cause 0 to be assigned to the
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corresponding structure fields. */
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void
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itimerspecFromStr(char *str, struct itimerspec *tsp)
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{
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char *dupstr ,*cptr, *sptr;
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dupstr = strdup(str);
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cptr = strchr(dupstr, ':');
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if (cptr != NULL)
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*cptr = '0円';
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sptr = strchr(dupstr, '/');
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if (sptr != NULL)
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*sptr = '0円';
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tsp->it_value.tv_sec = atoi(dupstr);
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tsp->it_value.tv_nsec = (sptr != NULL) ? atoi(sptr + 1) : 0;
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if (cptr == NULL) {
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tsp->it_interval.tv_sec = 0;
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tsp->it_interval.tv_nsec = 0;
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} else {
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sptr = strchr(cptr + 1, '/');
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if (sptr != NULL)
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*sptr = '0円';
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tsp->it_interval.tv_sec = atoi(cptr + 1);
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tsp->it_interval.tv_nsec = (sptr != NULL) ? atoi(sptr + 1) : 0;
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}
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free(dupstr);
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}
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#endif
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/*************************************************************************\
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* Copyright (C) Michael Kerrisk, 2024. *
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* *
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* This program is free software. You may use, modify, and redistribute it *
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* under the terms of the GNU Lesser General Public License as published *
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* by the Free Software Foundation, either version 3 or (at your option) *
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* any later version. This program is distributed without any warranty. *
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* See the files COPYING.lgpl-v3 and COPYING.gpl-v3 for details. *
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\*************************************************************************/
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/* itimerspec_from_str.h
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Header file for itimerspec_from_str.c.
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*/
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#ifndef ITIMERSPEC_FROM_STR_H
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#define ITIMERSPEC_FROM_STR_H
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#include <time.h>
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void itimerspecFromStr(char *str, struct itimerspec *tsp);
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#endif
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