battery plugin: Only report "current" when actually supplied by the battery.

I think the commend in the file sums it up pretty good, read that ;)

diff --git a/src/battery.c b/src/battery.c
index 1d0757d..87f2043 100644 (file)
--- a/src/battery.c
+++ b/src/battery.c
@@ -461,10 +461,11 @@ static int read_acpi_callback (char const *dir, /* {{{ */
 {
        int *battery_index = user_data;
 
-       gauge_t current = NAN;
+       gauge_t power = NAN;
        gauge_t voltage = NAN;
        gauge_t charge  = NAN;
        _Bool charging = 0;
+       _Bool is_current = 0;
 
        char const *plugin_instance;
        char filename[PATH_MAX];
@@ -510,14 +511,18 @@ static int read_acpi_callback (char const *dir, /* {{{ */
                        continue;
                }
 
-               /* FIXME: The unit of "present rate" depends on the battery.
-                * Modern batteries export watts, not amperes, i.e. it's not a
-                * current anymore. We should check if the fourth column
-                * contains "mA" and only use a current then. Otherwise, export
-                * a power. */
+               /* The unit of "present rate" depends on the battery. Modern
+                * batteries export power (watts), older batteries (used to)
+                * export current (amperes). We check the fourth column and try
+                * to find old batteries this way. */
                if ((strcmp (fields[0], "present") == 0)
                                && (strcmp (fields[1], "rate:") == 0))
-                       strtogauge (fields[2], &current);
+               {
+                       strtogauge (fields[2], &power);
+
+                       if ((numfields >= 4) && (strcmp ("mA", fields[3]) == 0))
+                               is_current = 1;
+               }
                else if ((strcmp (fields[0], "remaining") == 0)
                                && (strcmp (fields[1], "capacity:") == 0))
                        strtogauge (fields[2], &charge);
@@ -529,7 +534,7 @@ static int read_acpi_callback (char const *dir, /* {{{ */
        fclose (fh);
 
        if (!charging)
-               current *= -1.0;
+               power *= -1.0;
 
        /* FIXME: This is a dirty hack for backwards compatibility: The battery
         * plugin, for a very long time, has had the plugin_instance
@@ -540,7 +545,9 @@ static int read_acpi_callback (char const *dir, /* {{{ */
        (*battery_index)++;
 
        battery_submit (plugin_instance, "charge", charge / 1000.0);
-       battery_submit (plugin_instance, "current", current / 1000.0);
+       battery_submit (plugin_instance,
+                       is_current ? "current" : "power",
+                       power / 1000.0);
        battery_submit (plugin_instance, "voltage", voltage / 1000.0);
 
        return 0;