From 8345f2b388e0986829ceeae50ecf186d5d540a9c Mon Sep 17 00:00:00 2001
From: Siraaj Khandkar <siraaj@khandkar.net>
Date: Mon, 16 Mar 2020 18:48:38 -0400
Subject: [PATCH] Implement time sensor

---
 x5/.gitignore           |  1 +
 x5/Makefile             |  7 ++++-
 x5/khatus_lib_time.c    | 14 +++++++++
 x5/khatus_lib_time.h    |  2 ++
 x5/khatus_sensor_time.c | 65 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 x5/khatus_sensor_time.c

diff --git a/x5/.gitignore b/x5/.gitignore
index fa71cac..09901ba 100644
--- a/x5/.gitignore
+++ b/x5/.gitignore
@@ -1,2 +1,3 @@
 *.o
 khatus
+khatus_sensor_time
diff --git a/x5/Makefile b/x5/Makefile
index 1a356f5..c6a0576 100644
--- a/x5/Makefile
+++ b/x5/Makefile
@@ -5,12 +5,17 @@ LDLIBS   := -lX11
 .PHONY: build clean rebuild
 
 build: \
-    khatus
+    khatus \
+    khatus_sensor_time
 
 khatus: \
 	khatus_lib_log.o \
 	khatus_lib_time.o
 
+khatus_sensor_time: \
+	khatus_lib_log.o \
+	khatus_lib_time.o
+
 khatus_lib_time.o: khatus_lib_log.o
 
 clean:
diff --git a/x5/khatus_lib_time.c b/x5/khatus_lib_time.c
index ba74226..a169471 100644
--- a/x5/khatus_lib_time.c
+++ b/x5/khatus_lib_time.c
@@ -7,6 +7,20 @@
 #include "khatus_lib_log.h"
 #include "khatus_lib_time.h"
 
+struct timespec
+timespec_of_float(double n)
+{
+	double integral;
+	double fractional;
+	struct timespec t;
+
+	fractional = modf(n, &integral);
+	t.tv_sec = (int) integral;
+	t.tv_nsec = (int) (1E9 * fractional);
+
+	return t;
+}
+
 void
 snooze(struct timespec *t)
 {
diff --git a/x5/khatus_lib_time.h b/x5/khatus_lib_time.h
index 2d16d65..1d4bb44 100644
--- a/x5/khatus_lib_time.h
+++ b/x5/khatus_lib_time.h
@@ -1 +1,3 @@
+struct timespec timespec_of_float(double);
+
 void snooze(struct timespec *);
diff --git a/x5/khatus_sensor_time.c b/x5/khatus_sensor_time.c
new file mode 100644
index 0000000..f156f45
--- /dev/null
+++ b/x5/khatus_sensor_time.c
@@ -0,0 +1,65 @@
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "khatus_lib_log.h"
+#include "khatus_lib_time.h"
+
+char *argv0;
+
+void
+usage()
+{
+	printf(
+	    "%s: [OPT ...]\n"
+	    "\n"
+	    "OPT = -i int     # interval\n"
+	    "    | -f string  # format string\n"
+	    "    | -h         # help message (i.e. what you're reading now :) )\n",
+	    argv0);
+	fatal("usage\n");
+}
+
+int
+main(int argc, char **argv)
+{
+	argv0 = argv[0];
+
+	double opt_interval = 1.0;
+	char *opt_fmt = "%a %b %d %H:%M:%S";
+
+	time_t t;
+	struct timespec ti;
+	char buf[128];
+	char c;
+
+	memset(buf, '\0', 128);
+	while ((c = getopt(argc, argv, "f:i:h")) != -1)
+		switch (c) {
+		case 'f':
+			opt_fmt = calloc(strlen(optarg), sizeof(char));
+			strcpy(opt_fmt, optarg);
+			break;
+		case 'i':
+			opt_interval = atof(optarg);
+			break;
+		case 'h':
+			usage();
+			break;
+		default:
+			usage();
+		}
+	ti = timespec_of_float(opt_interval);
+	for (;;) {
+		t = time(NULL);
+		strftime(buf, sizeof(buf), opt_fmt, localtime(&t));
+		puts(buf);
+		fflush(stdout);
+		snooze(&ti);
+	}
+	return EXIT_SUCCESS;
+}
-- 
2.20.1