Be more cautious about handling invalid battery measurements.

1 files changed, 26 insertions, 7 deletions

diff --git a/src/print_battery_info.c b/src/print_battery_info.c
index e9077ec..e22ca3e 100644
--- a/src/print_battery_info.c
+++ b/src/print_battery_info.c
@@ -175,11 +175,19 @@ static bool slurp_battery_info(struct battery_info *batt_info, yajl_gen json_gen
      * POWER_SUPPLY_CHARGE_NOW is the unit of measurement. The energy is
      * given in mWh, the charge in mAh. So calculate every value given in
      * ampere to watt */
-    if (!watt_as_unit && voltage != -1) {
-        batt_info->present_rate = (((float)voltage / 1000.0) * ((float)batt_info->present_rate / 1000.0));
-        batt_info->remaining = (((float)voltage / 1000.0) * ((float)batt_info->remaining / 1000.0));
-        batt_info->full_design = (((float)voltage / 1000.0) * ((float)batt_info->full_design / 1000.0));
-        batt_info->full_last = (((float)voltage / 1000.0) * ((float)batt_info->full_last / 1000.0));
+    if (!watt_as_unit && voltage >= 0) {
+        if (batt_info->present_rate > 0) {
+            batt_info->present_rate = (((float)voltage / 1000.0) * ((float)batt_info->present_rate / 1000.0));
+        }
+        if (batt_info->remaining > 0) {
+            batt_info->remaining = (((float)voltage / 1000.0) * ((float)batt_info->remaining / 1000.0));
+        }
+        if (batt_info->full_design > 0) {
+            batt_info->full_design = (((float)voltage / 1000.0) * ((float)batt_info->full_design / 1000.0));
+        }
+        if (batt_info->full_last > 0) {
+            batt_info->full_last = (((float)voltage / 1000.0) * ((float)batt_info->full_last / 1000.0));
+        }
     }
 #elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
     int state;
@@ -499,8 +507,19 @@ void print_battery_info(yajl_gen json_gen, char *buffer, int number, const char
             return;
     }
 
-    int full = (last_full_capacity ? batt_info.full_last : batt_info.full_design);
-    if (full < 0 && batt_info.percentage_remaining < 0) {
+    // *Choose* a measure of the 'full' battery. It is whichever is better of
+    // the battery's (hardware-given) design capacity (batt_info.full_design)
+    // and the battery's last known good charge (batt_info.full_last).
+    // We prefer the design capacity, but use the last capacity if we don't have it,
+    // or if we are asked to (last_full_capacity == true); but similarly we use
+    // the design capacity if we don't have the last capacity.
+    // If we don't have either then both full_design and full_last < 0,
+    // which implies full < 0, which bails out on the following line.
+    int full = batt_info.full_design;
+    if (full < 0 || (last_full_capacity && batt_info.full_last >= 0)) {
+        full = batt_info.full_last;
+    }
+    if (full < 0 && batt_info.remaining < 0 && batt_info.percentage_remaining < 0) {
         /* We have no physical measurements and no estimates. Nothing
          * much we can report, then. */
         OUTPUT_FULL_TEXT(format_down);