From 3aa6eae594d4963da188631654d2767b41cc9036 Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Sat, 25 Jun 2011 00:45:25 -0400
Subject: Experimental gpsdctl, first cut.

---
 gpsdctl.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 gpsdctl.c

(limited to 'gpsdctl.c')

diff --git a/gpsdctl.c b/gpsdctl.c
new file mode 100644
index 00000000..69545ee1
--- /dev/null
+++ b/gpsdctl.c
@@ -0,0 +1,136 @@
+/* gpsdctl.c -- communicate with the control socket of a gpsd instance
+ *
+ * This file is Copyright (c) 2010 by the GPSD project
+ * BSD terms apply: see the file COPYING in the distribution root for details.
+ *
+ */
+#include <string.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#ifndef S_SPLINT_S
+#include <netdb.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#ifndef INADDR_ANY
+#include <netinet/in.h>
+#endif /* INADDR_ANY */
+#include <unistd.h>
+#endif /* S_SPLINT_S */
+#include <syslog.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "gpsd.h"	/* only for the strlcpy() prototype */
+
+static char *control_socket = "/var/run/gpsd.sock"; 
+static char *gpsd_options = "";
+
+static int gpsd_control_connect(bool complain)
+/* acquire a connection to the gpsd control socket */
+{
+    int sock;
+
+    if (access(control_socket, F_OK) != 0) {
+	(void)syslog(LOG_ERR, "gpsdctl: socket %s doesn't exist", control_socket);
+	return -1;
+    } else if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
+	if (complain)
+	    (void)syslog(LOG_ERR, "gpsdctl: socket creation failed");
+	return -1;
+    } else {
+	struct sockaddr_un saddr;
+
+	memset(&saddr, 0, sizeof(struct sockaddr_un));
+	saddr.sun_family = AF_UNIX;
+	(void)strlcpy(saddr.sun_path, 
+		      control_socket, 
+		      sizeof(saddr.sun_path));
+
+	/*@-unrecog@*/
+	if (connect(sock, (struct sockaddr *)&saddr, SUN_LEN(&saddr)) < 0) {
+	    if (complain)
+		(void)syslog(LOG_ERR, "gpsdctl: socket connect failed");
+	    return -1;
+	}
+	/*@+unrecog@*/
+
+	return sock;
+    }
+}
+
+static int gpsd_control(char *action, char *argument)
+/* pass a command to gpsd; start the daemon if not already running */
+{
+    int connect;
+    char buf[512];
+
+    (void)syslog(LOG_ERR, "gpsd_control(action=%s, arg=%s)", action, argument);
+    connect = gpsd_control_connect(false);
+    if (connect >= 0)
+	syslog(LOG_INFO, "gpsdctl: reached a running gpsd");
+    else if (strcmp(action, "add") == 0) {
+	(void)snprintf(buf, sizeof(buf),
+		       "gpsd %s -F %s", gpsd_options, control_socket);
+	(void)syslog(LOG_NOTICE, "gpsdctl: launching %s", buf);
+	(void)system(buf);
+        connect = gpsd_control_connect(true);
+    }
+    if (connect < 0) {
+	syslog(LOG_ERR, "gpsdctl: can't reach gpsd");
+	return -1;
+    }
+    /*
+     * We've got a live connection to the gpsd control socket.  No
+     * need to parse the response, because gpsd will lock on to the
+     * device if it's really a GPS and ignore it if it's not.
+     */
+    if (strcmp(action, "add") == 0) {
+	/*
+	 * Force the group-read & group-write bits on, so gpsd will still be
+         * able to use this device after dropping root privileges.
+	 */
+	struct stat sb;
+
+	if (stat(argument, &sb) != 1)
+	    (void)chmod(argument, sb.st_mode | S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);
+	(void)snprintf(buf, sizeof(buf), "+%s\r\n", argument);
+	(void)write(connect, buf, strlen(buf));
+	(void)read(connect, buf, 12);
+    } else if (strcmp(action, "remove") == 0) {
+	(void)snprintf(buf, sizeof(buf), "-%s\r\n", argument);
+	(void)write(connect, buf, strlen(buf));
+	(void)read(connect, buf, 12);
+    }  else if (strcmp(action, "send") == 0) {
+	(void)snprintf(buf, sizeof(buf), "%s\r\n", argument);
+	(void)write(connect, buf, strlen(buf));
+	(void)read(connect, buf, 12);
+    }
+    (void)close(connect);
+    //syslog(LOG_DEBUG, "gpsd_control ends");
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 3) {
+	(void)syslog(LOG_ERR, "gpsdctl: requires action and argument");
+	exit(1);
+    } else {
+	/*@-observertrans@*/
+	char *sockenv = getenv("GPSD_SOCKET");
+	char *optenv = getenv("GPSD_OPTIONS");
+
+	if (sockenv != NULL)
+	    control_socket = sockenv;
+	if (optenv != NULL)
+	    gpsd_options = optenv;
+
+	if (gpsd_control(argv[1], argv[2]) < 0)
+	    exit(1);
+	else
+	    exit(0);
+	/*@+observertrans@*/
+    }
+}
-- 
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