From d03cabfe3c0e1d5f937318d653f5da01e1340b56 Mon Sep 17 00:00:00 2001
From: Siraaj Khandkar <siraaj@khandkar.net>
Date: Tue, 24 Mar 2020 22:43:53 -0400
Subject: [PATCH] Sketch initial battery sensor

---
 x5/.gitignore              |   1 +
 x5/Makefile                |   5 ++
 x5/khatus_sensor_battery.c | 151 +++++++++++++++++++++++++++++++++++++
 3 files changed, 157 insertions(+)
 create mode 100644 x5/khatus_sensor_battery.c

diff --git a/x5/.gitignore b/x5/.gitignore
index 09901ba..adeb40d 100644
--- a/x5/.gitignore
+++ b/x5/.gitignore
@@ -1,3 +1,4 @@
 *.o
 khatus
+khatus_sensor_battery
 khatus_sensor_time
diff --git a/x5/Makefile b/x5/Makefile
index c6a0576..e1c4287 100644
--- a/x5/Makefile
+++ b/x5/Makefile
@@ -6,12 +6,17 @@ LDLIBS   := -lX11
 
 build: \
     khatus \
+    khatus_sensor_battery \
     khatus_sensor_time
 
 khatus: \
 	khatus_lib_log.o \
 	khatus_lib_time.o
 
+khatus_sensor_battery: \
+	khatus_lib_log.o \
+	khatus_lib_time.o
+
 khatus_sensor_time: \
 	khatus_lib_log.o \
 	khatus_lib_time.o
diff --git a/x5/khatus_sensor_battery.c b/x5/khatus_sensor_battery.c
new file mode 100644
index 0000000..b589bef
--- /dev/null
+++ b/x5/khatus_sensor_battery.c
@@ -0,0 +1,151 @@
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.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"
+
+#define usage(...) {print_usage(); fprintf(stderr, "Error:\n    " __VA_ARGS__); exit(EXIT_FAILURE);}
+
+#define MAX_LEN 20
+#define END_OF_MESSAGE '\n'
+
+char *argv0;
+
+char path[PATH_MAX];
+
+double  opt_interval = 1.0;
+char   *opt_battery  = "BAT0";
+char   *opt_fifo     = NULL;
+
+void
+print_usage()
+{
+	printf(
+	    "%s: [OPT ...] FIFO\n"
+	    "\n"
+	    "FIFO = string    # path to fifo file\n"
+	    "OPT = -i int     # interval\n"
+	    "    | -b string  # battery file name from /sys/class/power_supply/\n"
+	    "    | -h         # help message (i.e. what you're reading now :) )\n",
+	    argv0);
+}
+
+void
+opt_parse(int argc, char **argv)
+{
+	char c;
+
+	while ((c = getopt(argc, argv, "f:i:h")) != -1)
+		switch (c) {
+		case 'f':
+			opt_battery = calloc(strlen(optarg), sizeof(char));
+			strcpy(opt_battery, optarg);
+			break;
+		case 'i':
+			opt_interval = atof(optarg);
+			break;
+		case 'h':
+			print_usage();
+			exit(EXIT_SUCCESS);
+		case '?':
+			if (optopt == 'f' || optopt == 'i')
+				fprintf(stderr,
+					"Option -%c requires an argument.\n",
+					optopt);
+			else if (isprint(optopt))
+				fprintf (stderr,
+					"Unknown option `-%c'.\n",
+					optopt);
+			else
+				fprintf(stderr,
+					"Unknown option character `\\x%x'.\n",
+					optopt);
+			exit(EXIT_FAILURE);
+		default:
+			assert(0);
+		}
+	opt_fifo = argv[optind];
+	debug("opt_fifo: %s\n", opt_fifo);
+	if (!opt_fifo)
+		usage("No filename was provided\n");
+}
+
+void
+loop(struct timespec *ti, char *fifo, char *buf, int fun(char *))
+{
+	int fd = -1;
+	int w  = -1;  /* written */
+	int r  = -1;  /* remaining */
+	int i  = -1;  /* buffer position */
+
+	for (;;) {
+		debug("openning \"%s\"\n", fifo);
+		fd = open(fifo, O_WRONLY);
+		if (fd < 0)
+			fatal("Failed to open FIFO file: \"%s\". Error: %s\n",
+			    fifo,
+			    strerror(errno));
+		debug("openned. fd: %d\n", fd);
+		r = fun(buf);
+		buf[r] = END_OF_MESSAGE;
+		for (i = 0; (w = write(fd, buf + i++, 1)) && r; r--)
+			;
+		if (w < 0)
+			fatal("Failed to write to %s. Err num: %d, Err msg: %s\n",
+			    fifo,
+			    errno,
+			    strerror(errno));
+		if (close(fd) < 0)
+			fatal("Failed to close %s. Err num: %d, Err msg: %s\n",
+			    fifo,
+			    errno,
+			    strerror(errno));
+		fd = -1;
+		debug("closed. fd: %d\n", fd);
+		snooze(ti);
+	}
+}
+
+int
+read_capacity(char *buf)
+{
+	FILE *fp;
+	int cap;
+
+	if (!(fp = fopen(path, "r")))
+		fatal("Failed to open %s. errno: %d, msg: %s\n",
+		    path, errno, strerror(errno));
+
+	switch (fscanf(fp, "%d", &cap)) {
+	case -1: fatal("EOF\n");
+	case  0: fatal("Read 0\n");
+	case  1: break;
+	default: assert(0);
+	}
+	fclose(fp);
+	return snprintf(buf, 6, "%3d%%\n", cap);
+}
+
+int
+main(int argc, char **argv)
+{
+	argv0 = argv[0];
+
+	char  buf[10];
+	char *path_fmt = "/sys/class/power_supply/%s/capacity";
+	struct timespec ti = timespec_of_float(opt_interval);
+
+	opt_parse(argc, argv);
+
+	memset(path, '\0', PATH_MAX);
+	snprintf(path, PATH_MAX, path_fmt, opt_battery);
+	loop(&ti, opt_fifo, buf, &read_capacity);
+}
-- 
2.20.1