Find battery dir more flexibly

[batteryviewer] / batteryviewer.c

diff --git a/batteryviewer.c b/batteryviewer.c
index 65d70091b118606d32376ebd92c7472b698dcbe6..5a516218e74ee01eb4dc0697bf12087ba44cfc24 100644 (file)
--- a/batteryviewer.c
+++ b/batteryviewer.c
@@ -1,12 +1,67 @@
+// For vasprintf
+#define _GNU_SOURCE
+
 #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;
+  va_list args;
+  va_start(args, fmt);
+  if (vasprintf(&result, fmt, args) == -1) {
+    fprintf(stderr, "Can't allocate memory!?\n");
+    abort();
+  }
+  va_end(args);
+  return result;
+}
 
 struct State {
+  char *voltage_filename;
+  char *current_filename;
   BVChart *voltage;
   BVChart *current;
 };
 
-static gboolean collect_data(struct State *state __attribute__((unused))) {
+static float fatof(const char *filename) {
+  FILE *f = fopen(filename, "r");
+  if (f == NULL) {
+    return NAN;
+  }
+
+  const int bufsize = 1024;
+  char buf[bufsize];
+  const int read = fread(buf, sizeof(char), bufsize, f);
+  if (read == 0 || read == bufsize || ferror(f)) {
+    fclose(f);
+    return NAN;
+  }
+  fclose(f);
+
+  char *end;
+  errno = 0;
+  float val = strtof(buf, &end);
+  int parsed = end - buf;
+  gboolean parsed_all = parsed == read;
+  gboolean parsed_all_but_space = parsed == read - 1 && isspace(*end);
+  gboolean parse_ok = parsed_all || parsed_all_but_space;
+  if (errno != 0 || parsed == 0 || !parse_ok) {
+    return NAN;
+  }
+  return val;
+}
+
+static gboolean collect_data(struct State *state) {
+  fprintf(stderr, "Voltage: %f, current: %f\n", fatof(state->voltage_filename),
+          fatof(state->current_filename));
   return TRUE;
 }
 
@@ -41,8 +96,30 @@ 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) {
-  struct State state;
+  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),
+  };
 
   GtkApplication *app = gtk_application_new("com.scottworley.batteryviewer",
                                             G_APPLICATION_DEFAULT_FLAGS);