started weather_logger

Daemons/weather_logger/main.c

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+/*
+ * This file is part of the meteologger project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * 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 <linux/prctl.h>
+#include <signal.h>
+#include <stdatomic.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <usefull_macros.h>
+
+#include "parseargs.h"
+#include "server.h"
+
+static volatile atomic_int catchsig = 0;
+static pid_t childpid = 0;
+
+void signals(int signo){
+    signal(signo, SIG_IGN);
+    if(catchsig == 0){
+        DBG("superloop not inited");
+        exit(signo);
+    }
+    if(0 == childpid){
+        if(signo == SIGUSR1){ // reload logs after rotating
+            DBG("Got USR1 -> reinit logs");
+            if(!reinit_logs()){
+                stop_server();
+                catchsig = signo;
+            }else signal(signo, signals);
+        }else{ // kill
+            DBG("Got %d -> kill", signo);
+            stop_server();
+            catchsig = signo; // could be 0 or error code / signo
+        }
+    }else{ // throw signal to child
+        if(signo > 0){
+            kill(childpid, signo);
+            LOGMSG("Send received signal %d to child", signo);
+            if(signo != SIGUSR1) catchsig = signo;
+        }else catchsig = signo;
+    }
+}
+
+static void prepare_and_run(glob_pars *G){
+    if(!G) return;
+    sl_socktype_e stype = (G->isunix) ? SOCKT_UNIX : SOCKT_NET;
+    set_reqinterval(G->req_interval);
+    set_nettimeout(G->net_timeout);
+    DBG("Run server");
+    run_server(G->node, stype, G->bddir);
+    DBG("Server died");
+}
+
+int main(int argc, char **argv){
+    sl_init();
+    glob_pars *G = parseargs(&argc, &argv);
+    if(!G) return 1;
+    sl_check4running(NULL, G->pidfile);
+    signal(SIGTERM, signals);
+    signal(SIGINT, signals);
+    signal(SIGQUIT, signals);
+    signal(SIGPIPE, SIG_IGN); // for sockets
+    signal(SIGUSR1, signals); // reload DB
+#ifndef EBUG
+    if(sl_daemonize()) ERRX("Can't daemonize");
+    catchsig = INT_MAX; // now `signals` won't run exit()
+    while(catchsig == INT_MAX){ // guard for dead processes
+        childpid = fork();
+        if(childpid){
+            LOGDBG("create child with PID %d\n", childpid);
+            DBG("Created child with PID %d\n", childpid);
+            pid_t expid = 0;
+            while(catchsig == INT_MAX){
+                expid = waitpid(childpid, NULL, WNOHANG);
+                if(expid < 0){
+                    LOGERR("waitpid() returns -1; exit");
+                    ERRX("waitpid() returns -1; exit");
+                }
+                if(expid == childpid) break;
+                usleep(50000);
+            }
+            WARNX("Child %d died\n", childpid);
+            LOGWARN("Child %d died\n", childpid);
+            sleep(1);
+        }else{
+            prctl(PR_SET_PDEATHSIG, SIGTERM); // send SIGTERM to child when parent dies
+            break; // go out to normal functional
+        }
+    }
+#else
+    // init for DEBUG mode
+    catchsig = INT_MAX;
+#endif
+
+    if(childpid){
+        LOGERR("Main process exits with status %d", catchsig);
+        if(G->pidfile) unlink(G->pidfile);
+    }else{
+        pid_t self = getpid();
+        prepare_and_run(G);
+        if(catchsig == INT_MAX) LOGERR("Child process %d died", self);
+        else LOGERR("Child process %d exits with status %d", self, catchsig);
+        ; // cleanup child here
+#ifdef EBUG
+        if(G->pidfile) unlink(G->pidfile); // unlink PID-file in debug-mode
+#endif
+        usleep(10000); // wait processes to die
+    }
+    return catchsig;
+}