logger library and flag to run as daemon

7 files changed, 280 insertions, 26 deletions

diff --git a/Makefile b/Makefile
index f4ec5b6..21e82a8 100644
--- a/Makefile
+++ b/Makefile
@@ -2,9 +2,11 @@
 #
 # SPDX-License-Identifier: BSD-2-Clause
 
+# all 3 values commented, using make's default or export CC
 # CC = cc -fno-caret-diagnostics -fno-color-diagnostics
-CC = gcc -fno-diagnostics-show-caret -fdiagnostics-color=never
+# CC = gcc -fno-diagnostics-show-caret -fdiagnostics-color=never
 # CC = gcc
+
 CFLAGS = -Wall -Wextra -pedantic -std=c99
 
 # DEBUG = -g
@@ -36,17 +38,24 @@ dist:
 		bzip2 > $(DIST_NAME).tar.bz2
 
 clean:
-	rm -f $(MAINBINARIES) *.o *.test tags
+	$(MAKE) -C $(LIBSDIR)/logger clean
+	rm -f $(MAINBINARIES) *.o *.test tags $(DIST_NAME)
 
 rebuild: clean all
 
 .c.o:
-	$(CC) $(DEBUG) $(CFLAGS) -c $< -o $@
+	$(CC) $(DEBUG) $(CFLAGS) -I$(LIBSDIR) -c $< -o $@
+
+LIBSDIR = ./lib
+LDFLAGS = -L$(LIBSDIR)/logger
 
+$(LIBSDIR)/logger/liblogger.a:
+	$(MAKE) -C $(LIBSDIR)/logger
 
 BTASKTD_OBJECTS = btasktd.o cliflags.o codes.o
-BTASKTD_LIBS = -lc
+BTASKTD_LIBDEPS = $(LIBSDIR)/logger/liblogger.a
+BTASKTD_LIBS = -lc -llogger
 
-btasktd: $(BTASKTD_OBJECTS)
-	$(CC) $(DEBUG) $(CFLAGS) $(STATIC) $(BTASKTD_OBJECTS) -o $@ \
-		$(BTASKTD_LIBS)
+btasktd: $(BTASKTD_OBJECTS) $(BTASKTD_LIBDEPS)
+	$(CC) $(DEBUG) $(CFLAGS) $(STATIC) $(LDFLAGS) \
+		$(BTASKTD_OBJECTS) -o $@ $(BTASKTD_LIBS)
diff --git a/README b/README
index fe86d3c..d3a0710 100644
--- a/README
+++ b/README
@@ -19,3 +19,31 @@ BUILD DEPENDENCIES
 RUNTIME DEPENDENCIES
 -------------------------------------------------------------------------
 * OS Kernel
+
+-------------------------------------------------------------------------
+QUICK START
+-------------------------------------------------------------------------
+There is no even MVP yet, just an echo server.
+
+Try:
+
+ $ make
+ $ ./btasktd -u 2 -p 5500 -b
+
+Then:
+
+ $ telnet 127.0.0.1 5500
+
+If can open two more terminals, in them also:
+
+ $ telnet 127.0.0.1 5500
+
+There should be error response for last and working echo server for
+2 others. To stop:
+
+ $ pkill -2 btasktd
+
+To allow more users change ``2'' after ``-u'' to other number, to
+change port change ``5500'' to your port.
+
+For more info please read the program's man page.
diff --git a/btasktd.1 b/btasktd.1
index d7ee07c..1287e62 100644
--- a/btasktd.1
+++ b/btasktd.1
@@ -1,4 +1,4 @@
-.Dd September 19, 2026
+.Dd October 1, 2026
 .Dt BTASKTD 1
 .Os
 .
@@ -9,7 +9,7 @@
 .Sh SYNOPSIS
 .Nm
 .BK -words
-.Op Fl \&Vh
+.Op Fl \&Vhb
 .Op Fl p Ar port
 .Op Fl u Ar users
 .Ek
@@ -24,6 +24,8 @@ The options are as follows:
 Show version
 .It Fl h
 Show help message
+.It Fl b
+Run server as daemon (in background)
 .It Fl p Ar port
 Set port for server to listen to
 .It Fl u Ar users
diff --git a/btasktd.c b/btasktd.c
index b8b9fd9..388d655 100644
--- a/btasktd.c
+++ b/btasktd.c
@@ -40,13 +40,14 @@
 #include <unistd.h>
 #include <errno.h>
 #include <signal.h>
+#include <logger/logger.h>
 #include "cliflags.h"
 #include "codes.h"
 
 #define BTASKTD_HELP_STR \
 	"Copyright (c) 2026, Mr. Goblin\n" \
 	"btasktd - task tracking TCP-server\n" \
-	"Usage: btasktd [-Vh] [-p port] [-u users]\n" \
+	"Usage: btasktd [-Vhb] [-p port] [-u users]\n" \
 	"For more info read the program's man page\n"
 
 #define BTASKTD_VERSION_STR \
@@ -132,7 +133,7 @@ send_to_client(int fd, const char *s)
 	int len = strlen(s);
 	int code = send(fd, s, len, 0);
 	if (-1 == code)
-		perror("send");
+		logger_perror("send");
 }
 
 static void
@@ -162,16 +163,21 @@ handle_accept(struct btasktd *this)
 	socklen_t addrlen = sizeof(user_addr);
 	int fd = accept(this->fd, (struct sockaddr*)&user_addr, &addrlen);
 	if (-1 == fd) {
-		perror("accept");
+		logger_perror("accept");
 		return;
 	}
 	set_nonblock(fd);
 	idx = find_free_user(this->users, this->users_cnt);
 	if (-1 == idx) {
+		logger_log(log_lvl_warning,
+			"rejected user connection because "
+			"working at users limit\n");
 		send_response_code(fd, CODE_503_SERVICE_UNAVAILABLE);
 		close(fd);
 		return;
 	}
+	logger_log(log_lvl_info,
+		"new connection successfully accepted\n");
 	this->users[idx].fd = fd;
 	this->users[idx].bi = 0;
 }
@@ -217,7 +223,7 @@ handle_user(struct btasktd *this, int id)
 		reset_user(pu);
 		return;
 	} else if (-1 == valread) {
-		perror("recv");
+		logger_perror("recv");
 		close(pu->fd);
 		reset_user(pu);
 		return;
@@ -239,22 +245,54 @@ bye_all_clients(struct btasktd *this)
 	}
 }
 
-static volatile int last_sig = 0;
+static volatile sig_atomic_t last_sig = 0;
 
 static void
 handle_sigint(int sig)
 {
 	signal(sig, handle_sigint);
-	fprintf(stderr, "Caught signal %d, shutting down...\n", sig);
+	logger_log(log_lvl_info,
+		"Caught signal %d, shutting down...\n", sig);
 	last_sig = SIGINT;
 }
 
+static void
+make_me_daemon(void)
+{
+	int fd = open("/dev/null", O_RDWR), pid;
+	if (fd < 0) {
+		logger_perror("open");
+		exit(1);
+	}
+	dup2(fd, 0);
+	dup2(fd, 1);
+	dup2(fd, 2);
+	chdir("/");
+	if (fd > 2)
+		close(fd);
+	pid = fork();
+	if (pid < 0) {
+		logger_perror("fork");
+		exit(1);
+	} else if (pid > 0) {
+		exit(0);
+	}
+	setsid();
+	pid = fork();
+	if (pid < 0) {
+		logger_perror("fork");
+		exit(1);
+	} else if (pid > 0) {
+		exit(0);
+	}
+}
+
 int
 main(int argc, char **argv)
 {
 	struct btasktd server;
 	int server_fd, opt = 1, res, port, passed_flags = 1, users_cnt;
-	int max_fd;
+	int is_daemon = 0, max_fd;
 	struct user *users = NULL;
 	int i;
 	struct sockaddr_in addr = {0};
@@ -262,6 +300,7 @@ main(int argc, char **argv)
 	struct bool_flag_val bool_res;
 	fd_set readfds;
 
+
 	bool_res = extract_bool_flag('V', argc, argv);
 	if (fvr_ok == bool_res.code && bool_res.data) {
 		printf("btasktd version %s\n", BTASKTD_VERSION_STR);
@@ -274,6 +313,13 @@ main(int argc, char **argv)
 		return 0;
 	}
 
+	bool_res = extract_bool_flag('b', argc, argv);
+	if (fvr_ok == bool_res.code && bool_res.data) {
+		is_daemon = 1;
+	}
+
+	logger_init("btasktd", is_daemon);
+
 	int_res = extract_int_flag('p', argc, argv);
 	switch (int_res.code) {
 	case fvr_not_found:
@@ -301,7 +347,8 @@ main(int argc, char **argv)
 #		ifdef BTASKTD_DEFAULT_USERS_CNT
 			users_cnt = BTASKTD_DEFAULT_USERS_CNT;
 #		else
-			fprintf(stderr, "No users count specified!\n");
+			fprintf(stderr,
+				"No users count specified!\n");
 			passed_flags = 0;
 #		endif
 		break;
@@ -313,18 +360,23 @@ main(int argc, char **argv)
 	case fvr_invalid:
 		fprintf(stderr, "Invalid users count!\n");
 		return 1;
-		break;
 	}
 
+	logger_init("btasktd", is_daemon);
+
 	if (!passed_flags) {
+		logger_log(log_lvl_err,
+			"FATAL: didn't passed flags check\n");
 		fprintf(stderr, "-\n");
 		fprint_help(stderr);
+		logger_close();
 		return 1;
 	}
 
 	users = (struct user*)calloc(users_cnt, sizeof(struct user));
 	if (NULL == users) {
-		fprintf(stderr, "No memory!\n");
+		logger_log(log_lvl_err, "No memory!\n");
+		logger_close();
 		return 1;
 	}
 	for (i = 0; i < users_cnt; i++) {
@@ -333,8 +385,9 @@ main(int argc, char **argv)
 
 	server_fd = socket(AF_INET, SOCK_STREAM, 0);
 	if (server_fd < 0) {
+		logger_perror("socket");
 		free(users);
-		perror("socket");
+		logger_close();
 		return 1;
 	}
 	addr.sin_family = AF_INET;
@@ -345,21 +398,24 @@ main(int argc, char **argv)
 	if (0 != res) {
 		close(server_fd);
 		free(users);
-		perror("setsockopt");
+		logger_perror("setsockopt");
+		logger_close();
 		return 1;
 	}
 	res = bind(server_fd, (struct sockaddr*)&addr, sizeof(addr));
 	if (0 != res) {
 		close(server_fd);
 		free(users);
-		perror("bind");
+		logger_perror("bind");
+		logger_close();
 		return 1;
 	}
 	res = listen(server_fd, BTASKTD_QUEUE_LEN);
 	if (0 != res) {
 		close(server_fd);
 		free(users);
-		perror("listen");
+		logger_perror("listen");
+		logger_close();
 		return 1;
 	}
 
@@ -368,7 +424,12 @@ main(int argc, char **argv)
 	server.fd = server_fd;
 	server.users_cnt = users_cnt;
 	server.users = users;
-	printf("btaskt server btasktd started on port %d\n", port);
+
+	if (is_daemon)
+		make_me_daemon();
+	logger_log(log_lvl_info,
+		"btaskt server btasktd started on port %d. pid - %d\n",
+			port, getpid());
 
 	signal(SIGINT, handle_sigint);
 
@@ -393,7 +454,7 @@ main(int argc, char **argv)
 					break;
 				}
 			} else {
-				perror("select");
+				logger_perror("select");
 			}
 			continue;
 		} else if (0 == res) {
@@ -410,7 +471,8 @@ main(int argc, char **argv)
 		}
 	}
 
-	printf("btaskt server btasktd stopped\n");
+	logger_log(log_lvl_info, "btaskt server btasktd stopped\n");
+	logger_close();
 	close(server_fd);
 	free(users);
 	return 0;
diff --git a/lib/logger/Makefile b/lib/logger/Makefile
new file mode 100644
index 0000000..e5e7682
--- /dev/null
+++ b/lib/logger/Makefile
@@ -0,0 +1,54 @@
+# Copyright (c) 2026, Mr. Goblin
+#
+# SPDX-License-Identifier: BSD-2-Clause
+
+# all 3 values commented, using make's default or export CC
+# CC = cc -fno-caret-diagnostics -fno-color-diagnostics
+# CC = gcc -fno-diagnostics-show-caret -fdiagnostics-color=never
+# CC = gcc
+
+CFLAGS = -Wall -Wextra -pedantic -std=gnu89
+ARFLAGS = rcs
+
+# DEBUG = -g
+# DEBUG = -ggdb
+DEBUG =
+
+# STATIC = -static
+STATIC = -static -s
+# STATIC =
+
+PROG_NAME=liblogger
+VER=0.0.0
+DIST_NAME=$(PROG_NAME)-$(VER)
+
+
+MAINBINARIES = liblogger.a
+
+.SUFFIXES:
+.SUFFIXES: .c .o
+.PHONY: all clean dist ctags rebuild
+
+all: $(MAINBINARIES)
+
+ctags:
+	ctags *.c *.h *.cpp *.hpp
+
+dist:
+	git archive --format=tar --prefix=$(DIST_NAME)/ HEAD | \
+		bzip2 > $(DIST_NAME).tar.bz2
+
+clean:
+	rm -f $(MAINBINARIES) *.o *.test tags $(DIST_NAME)
+
+rebuild: clean all
+
+.c.o:
+	$(CC) $(DEBUG) $(CFLAGS) -c $< -o $@
+
+
+LIBLOGGER_OBJECTS = logger.o
+LIBLOGGER_LIBS = -lc
+
+liblogger.a: $(LIBLOGGER_OBJECTS)
+	$(AR) $(ARFLAGS) $@ $(LIBLOGGER_OBJECTS)
diff --git a/lib/logger/logger.c b/lib/logger/logger.c
new file mode 100644
index 0000000..64a6754
--- /dev/null
+++ b/lib/logger/logger.c
@@ -0,0 +1,78 @@
+#include <syslog.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include "logger.h"
+
+static int use_syslog = 0;
+
+void
+logger_init(const char *name, int daemon_flag)
+{
+	use_syslog = daemon_flag;
+	if (use_syslog)
+		openlog(name, LOG_PID, LOG_DAEMON);
+}
+
+void
+logger_close(void)
+{
+	if (use_syslog)
+		closelog();
+}
+
+void
+logger_log(enum logger_lvl level, const char *format, ...)
+{
+	int saved_errno = errno;
+	va_list vargs;
+	va_start(vargs, format);
+	if (use_syslog) {
+		switch (level) {
+		case log_lvl_info:
+			vsyslog(LOG_INFO, format, vargs);
+			break;
+		case log_lvl_warning:
+			vsyslog(LOG_WARNING, format, vargs);
+			break;
+		case log_lvl_err:
+			vsyslog(LOG_ERR, format, vargs);
+			break;
+		}
+	} else {
+		FILE *f = NULL;
+		switch (level) {
+		case log_lvl_info:
+			f = stdout;
+			fprintf(f, "[INFO] ");
+			break;
+		case log_lvl_warning:
+			f = stderr;
+			fprintf(f, "[WARNING] ");
+			break;
+		case log_lvl_err:
+			f = stderr;
+			fprintf(f, "[ERROR] ");
+			break;
+		default:
+			f = stderr;
+			fprintf(f, "[UNKNOWN] ");
+			break;
+		}
+		vfprintf(f, format, vargs);
+	}
+	errno = saved_errno;
+}
+
+void
+logger_perror(const char *s)
+{
+	int saved_errno = errno;
+	if (use_syslog) {
+		syslog(LOG_ERR, "%s: %s\n", s, strerror(errno));
+	} else {
+		perror(s);
+	}
+	errno = saved_errno;
+}
diff --git a/lib/logger/logger.h b/lib/logger/logger.h
new file mode 100644
index 0000000..6c9ed7d
--- /dev/null
+++ b/lib/logger/logger.h
@@ -0,0 +1,21 @@
+#ifndef LIB_LOGGER_H_SENTRY
+#define LIB_LOGGER_H_SENTRY
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum logger_lvl {
+	log_lvl_info,
+	log_lvl_warning,
+	log_lvl_err
+};
+
+void logger_init(const char *name, int daemon_flag);
+void logger_close(void);
+void logger_log(enum logger_lvl, const char *format, ...);
+void logger_perror(const char *s);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* LIB_LOGGER_H_SENTRY */