start gathering snippets into one library

examples/options.c

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+/*
+ * This file is part of the usefull_macros project.
+ * Copyright 2018 Edward V. Emelianoff <eddy@sao.ru>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <usefull_macros.h>
+#include <signal.h>         // signal
+#include <stdlib.h>         // exit, free
+#include <stdio.h>          // printf
+#include <string.h>         // strdup
+#include <unistd.h>         // sleep
+#include "cmdlnopts.h"
+
+/**
+ * This is an example of usage:
+ *  - command line arguments,
+ *  - log file,
+ *  - check of another file version running,
+ *  - signals management,
+ *  - serial port reading/writing.
+ * The `cmdlnopts.[hc]` are intrinsic files of this demo.
+ */
+
+/**
+ * We REDEFINE the default WEAK function of signal processing
+ */
+void signals(int sig){
+    signal(sig, SIG_IGN);
+    restore_console();
+    restore_tty();
+    DBG("Get signal %d, quit.\n", sig);
+    putlog("Exit with status %d", sig);
+    exit(sig);
+}
+
+void iffound_default(pid_t pid){
+    ERRX("Another copy of this process found, pid=%d. Exit.", pid);
+}
+
+int main(int argc, char *argv[]){
+    initial_setup();
+    char *self = strdup(argv[0]);
+    glob_pars *GP = parse_args(argc, argv);
+    if(GP->rest_pars_num){
+        printf("%d extra options:\n", GP->rest_pars_num);
+        for(int i = 0; i < GP->rest_pars_num; ++i)
+            printf("%s\n", GP->rest_pars[i]);
+    }
+    check4running(self, GP->pidfile);
+    free(self);
+    signal(SIGTERM, signals); // kill (-15) - quit
+    signal(SIGHUP, SIG_IGN);  // hup - ignore
+    signal(SIGINT, signals);  // ctrl+C - quit
+    signal(SIGQUIT, signals); // ctrl+\ - quit
+    signal(SIGTSTP, SIG_IGN); // ignore ctrl+Z
+    if(GP->logfile) openlogfile(GP->logfile);
+    setup_con();
+    putlog(("Start application..."));
+    ; // main stuff goes here
+    green("Now I will sleep for 10 seconds. Do whatever you want.\n");
+    sleep(10);
+    ; // clean everything
+    if(GP->pidfile) // remove unnesessary PID file
+        unlink(GP->pidfile);
+    restore_console();
+    restore_tty();
+    return 0;
+}