From eda1f8c1e23dd52af0c095c5657455cc02f53c13 Mon Sep 17 00:00:00 2001
From: Scott Worley <scottworley@scottworley.com>
Date: Thu, 23 Feb 2023 19:27:06 -0800
Subject: [PATCH] Find battery dir more flexibly

---
 batteryviewer.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/batteryviewer.c b/batteryviewer.c
index 9f1dedd..5a51621 100644
--- a/batteryviewer.c
+++ b/batteryviewer.c
@@ -4,11 +4,13 @@
 #include "chart.h"
 #include <ctype.h>
 #include <errno.h>
+#include <glob.h>
 #include <gtk/gtk.h>
 #include <math.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 char *sasprintf(const char *fmt, ...) {
   char *result;
@@ -94,8 +96,26 @@ static void activate(GtkApplication *app, gpointer user_data) {
   g_timeout_add_seconds(1, (GSourceFunc)collect_data, user_data);
 }
 
+char *find_battery_dir() {
+  glob_t globbuf = {.gl_offs = 0};
+  char pattern[] = "/sys/class/power_supply/*[Bb][Aa][Tt]*";
+  if (glob(pattern, GLOB_ERR, NULL, &globbuf) != 0 || globbuf.gl_pathc == 0) {
+    fprintf(stderr, "Could not find battery dir %s\n", pattern);
+    exit(1);
+  }
+  if (globbuf.gl_pathc != 1) {
+    // TODO: Filter for directories that have {voltage,current}_now files.
+    // TODO: Support multiple batteries
+    fprintf(stderr, "Multiple batteries found. Arbitrarily choosing %s\n",
+            globbuf.gl_pathv[0]);
+  }
+  char *dir = strdup(globbuf.gl_pathv[0]);
+  globfree(&globbuf);
+  return dir;
+}
+
 int main(int argc, char **argv) {
-  char *battery_dir = "/sys/class/power_supply/BAT0";
+  char *battery_dir = find_battery_dir();
   struct State state = {
       .voltage_filename = sasprintf("%s/voltage_now", battery_dir),
       .current_filename = sasprintf("%s/current_now", battery_dir),
-- 
2.44.1