aws iot sample: add program options for application usage and daemonization
https://jira.digi.com/browse/DEL-4149 Signed-off-by: Tatiana Leon <tatiana.leon@digi.com>
This commit is contained in:
Tatiana Leon
parent
089b93cb11
commit
cbbe31f11e
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@ -0,0 +1,280 @@
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/*
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* Copyright (c) 2017 Digi International Inc.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*
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* Digi International Inc. 11001 Bren Road East, Minnetonka, MN 55343
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* =======================================================================
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*
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* From http://www.itp.uzh.ch/~dpotter/howto/daemonize
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*
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*/
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#include <aws_iot_log.h>
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#include <errno.h>
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#include <limits.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/file.h>
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#include <sys/stat.h>
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#include <unistd.h>
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/*------------------------------------------------------------------------------
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F U N C T I O N D E C L A R A T I O N S
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------------------------------------------------------------------------------*/
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static void daemonize(char const *const daemon_name);
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static void signal_handler(int signum);
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static int get_lock(char const *const file_name);
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static void release_lock(int const fd);
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/*------------------------------------------------------------------------------
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G L O B A L V A R I A B L E S
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------------------------------------------------------------------------------*/
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static volatile sig_atomic_t signal_from_child = 0;
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/*------------------------------------------------------------------------------
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F U N C T I O N D E F I N I T I O N S
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------------------------------------------------------------------------------*/
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/**
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* start_daemon() - Start a new daemon.
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*
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* @name: Daemon name.
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*
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* Return: 0 on success, 1 otherwise.
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*/
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int start_daemon(const char *name)
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{
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int result = EXIT_SUCCESS;
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int lock_fd = -1;
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/* Daemonize if requested. */
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lock_fd = get_lock(name);
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if (lock_fd < 0) {
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IOT_ERROR("Unable to start %s. It may be currently running", name);
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result = EXIT_FAILURE;
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goto done;
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}
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daemonize(name);
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done:
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/* Clean up. */
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IOT_INFO("Daemon terminated");
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release_lock(lock_fd);
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return result;
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}
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/**
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* daemonize() - Daemonize the current process using the given name.
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*
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* @name: Daemon name.
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*/
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static void daemonize(char const *const name)
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{
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pid_t pid, sid, parent;
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FILE *pid_fp = NULL;
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char pid_filename[PATH_MAX];
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/* Already a daemon. */
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if (getppid() == 1) {
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return;
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}
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IOT_DEBUG("Start daemon %s", name);
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/* Open .pid file while root. We can write it once we know child PID. */
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umask(0022);
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snprintf(pid_filename, sizeof(pid_filename), "/var/run/%s.pid", name);
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pid_fp = fopen(pid_filename, "w+");
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if (pid_fp == NULL) {
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IOT_ERROR("Unable to open pid file (errno: %d)", errno);
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exit(EXIT_FAILURE);
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}
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/* Trap signals that we expect to receive. */
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signal(SIGCHLD, signal_handler);
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signal(SIGUSR1, signal_handler);
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signal(SIGALRM, signal_handler);
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/* Fork off the parent process. */
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pid = fork();
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if (pid < 0) {
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IOT_ERROR("Unable to fork daemon (errno: %d, %s)", errno, strerror(errno));
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exit(EXIT_FAILURE);
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}
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/* If we got a good PID, then we can exit the parent process. */
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if (pid > 0) {
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int fork_succeeded;
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int exit_code;
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/* Write the PID of the newly created child process into the file. */
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if (fprintf(pid_fp, "%d\n", pid) <= 0) {
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IOT_ERROR("Unable to write pid file (errno: %d)", errno);
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fclose(pid_fp);
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/* Do we want to do anything about the child that has just started
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* at this point. */
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exit(EXIT_FAILURE);
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}
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fclose(pid_fp);
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fork_succeeded = 0;
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/* Wait for confirmation from the child via SIGTERM or SIGCHLD, or
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* for two seconds to elapse (SIGALRM). pause() should return after two
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* seconds at most. */
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alarm(2);
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if (signal_from_child)
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fork_succeeded = 1;
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pause();
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if (signal_from_child)
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fork_succeeded = 1;
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exit_code = fork_succeeded ? EXIT_SUCCESS : EXIT_FAILURE;
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exit(exit_code);
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}
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/* At this point we are executing as the child process. */
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parent = getppid();
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/* Cancel certain signals. */
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signal(SIGCHLD, SIG_DFL); /* A child process dies */
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signal(SIGTSTP, SIG_IGN); /* Various TTY signals */
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signal(SIGTTOU, SIG_IGN);
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signal(SIGTTIN, SIG_IGN);
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signal(SIGHUP, SIG_IGN); /* Ignore hangup signal */
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signal(SIGTERM, SIG_DFL); /* Die on SIGTERM */
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/* Change the file mode mask. */
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umask(0);
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/* Create a new SID for the child process. */
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sid = setsid();
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if (sid < 0) {
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IOT_ERROR("Unable to create a new session (errno %d, %s)",
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errno, strerror(errno));
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exit(EXIT_FAILURE);
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}
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/* Change the current working directory. This prevents the current
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directory from being locked; hence not being able to remove it. */
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if (chdir("/") < 0) {
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IOT_ERROR("Unable to change directory to '%s', (errno %d, %s)", "/",
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errno, strerror(errno));
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exit(EXIT_FAILURE);
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}
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/* Redirect standard files to /dev/null.
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* Log an error, but otherwise ignore it. */
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if (freopen("/dev/null", "r", stdin) == NULL)
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IOT_ERROR("Failed to redirect stdin to /dev/null");
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if (freopen("/dev/null", "w", stdout) == NULL)
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IOT_ERROR("Failed to redirect stdout to /dev/null");
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if (freopen("/dev/null", "w", stderr) == NULL)
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IOT_ERROR("Failed to redirect stderr to /dev/null");
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/* Tell the parent process that we are A-okay. */
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kill(parent, SIGUSR1);
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}
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/**
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* signal_handler() - Manage signal received.
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*
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* @signum: Received signal.
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*/
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static void signal_handler(int signum)
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{
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switch (signum) {
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case SIGALRM:
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/* Ignore this signal.*/
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break;
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case SIGUSR1:
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signal_from_child = 1;
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break;
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case SIGCHLD:
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exit(EXIT_FAILURE);
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break;
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default:
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break;
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}
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}
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/**
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* get_lock() - Try to get lock
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*
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* @file_name: Name of the file used as lock inside '/var/lock'.
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*
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* Return: File descriptor of lock file, or -1 on error.
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*/
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static int get_lock(char const *const file_name)
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{
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static char const path[] = "/var/lock/";
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char full_path[sizeof(path) + strlen(file_name)];
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int fd;
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snprintf(full_path, sizeof(full_path), "%s%s", path, file_name);
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fd = open(full_path, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
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if (fd == -1) {
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IOT_ERROR("Could not open PID file '%s'", full_path);
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goto error;
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}
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if (flock(fd, LOCK_EX | LOCK_NB) != 0) {
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IOT_ERROR("Could not open lock PID file '%s'", full_path);
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goto error;
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}
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if (ftruncate(fd, 0) != 0) {
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IOT_ERROR("Could not truncate PID file '%s'", full_path);
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goto error;
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}
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{
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char buf[50];
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int len = snprintf(buf, sizeof(buf), "%ld", (long) getpid());
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if (write(fd, buf, len) != len) {
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IOT_ERROR("Error writing to PID file '%s'", full_path);
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goto error;
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}
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}
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goto done;
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error:
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release_lock(fd);
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fd = -1;
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done:
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return fd;
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}
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/**
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* release_lock() - Release the lock obtained with 'get_lock(file_name)'
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*
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* @fd: File descriptor of lock file.
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*/
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static void release_lock(int const fd)
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{
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if (fd < 0)
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return;
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if (ftruncate(fd, 0) == -1)
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IOT_ERROR("Could not truncate PID file");
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if (lockf(fd, F_ULOCK, 0) == -1)
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IOT_ERROR("Unable to unlock");
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close(fd);
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}
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@ -0,0 +1,28 @@
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/*
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* Copyright (c) 2017 Digi International Inc.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*
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* Digi International Inc. 11001 Bren Road East, Minnetonka, MN 55343
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* =======================================================================
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*/
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#ifndef DAEMONIZE_H_
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#define DAEMONIZE_H_
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/*------------------------------------------------------------------------------
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F U N C T I O N D E C L A R A T I O N S
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------------------------------------------------------------------------------*/
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int start_daemon(const char *name);
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#endif /* DAEMONIZE_H_ */
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@ -18,16 +18,38 @@
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*/
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#include <aws_iot_log.h>
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#include <getopt.h>
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#include <libgen.h>
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#include <signal.h>
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#include <unistd.h>
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#include "daemonize.h"
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/*------------------------------------------------------------------------------
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D E F I N I T I O N S
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------------------------------------------------------------------------------*/
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#define VERSION "0.1" GIT_REVISION
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#define USAGE \
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"AWS IoT Device SDK demo.\n" \
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"Copyright(c) Digi International Inc.\n" \
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"\n" \
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"Version: %s\n" \
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"\n" \
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"Usage: %s [options]\n\n" \
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" -d --daemon Daemonize the process\n" \
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" -h --help Print help and exit\n" \
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"\n"
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/*------------------------------------------------------------------------------
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F U N C T I O N D E C L A R A T I O N S
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------------------------------------------------------------------------------*/
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static int start_aws_iot(const char *config_file);
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static int check_stop(void);
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static void add_sigkill_signal(void);
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static void graceful_shutdown(void);
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static void sigint_handler(int signum);
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static void usage(char const *const name);
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/*------------------------------------------------------------------------------
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G L O B A L V A R I A B L E S
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@ -38,6 +60,63 @@ static volatile int stop = 0;
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F U N C T I O N D E F I N I T I O N S
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------------------------------------------------------------------------------*/
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int main(int argc, char **argv)
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{
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int result = EXIT_SUCCESS;
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char *name = basename(argv[0]);
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static int opt, opt_index;
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int create_daemon = 0;
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char *config_file = NULL;
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static const char *short_options = "dh";
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static const struct option long_options[] = {
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{"daemon", no_argument, NULL, 'd'},
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{"help", no_argument, NULL, 'h'},
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{NULL, 0, NULL, 0}
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};
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while (1) {
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opt = getopt_long(argc, argv, short_options, long_options,
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&opt_index);
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if (opt == -1)
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break;
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switch (opt) {
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case 'd':
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create_daemon = 1;
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break;
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case 'h':
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usage(name);
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goto done;
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default:
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usage(name);
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result = EXIT_FAILURE;
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goto done;
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}
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}
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/* Daemonize if requested. */
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if (create_daemon) {
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if (start_daemon(name) != 0) {
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result = EXIT_FAILURE;
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goto done;
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}
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}
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/* Do the real work. */
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start_aws_iot(config_file);
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done:
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return result;
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}
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/*
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* start_aws_iot() - Start AWS IoT Device SDK
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*
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* @config_file: Absolute path of the configuration file to use.
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* NULL to use the default one (/etc/awsiotsdk.conf).
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*
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* Return: 0 on success, 1 otherwise.
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*/
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static int start_aws_iot(const char *config_file)
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{
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int result = EXIT_SUCCESS;
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@ -97,3 +176,13 @@ static void sigint_handler(int signum)
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IOT_DEBUG("Received signal %d to close Cloud connection.", signum);
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exit(0);
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}
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/**
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* usage() - Print usage information
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*
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* @name: Application name.
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*/
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static void usage(char const *const name)
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{
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printf(USAGE, VERSION, name);
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}
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