make use of new float parsing function

i've also moved the input validation checks to the config parser, so that
warnings aren't displayed in the terminal output every time a benchmark is
run with an invalid percentile entry.

src/overlay.cpp

@@ -817,26 +817,31 @@ void calculate_benchmark_data(void *params_void){
       benchmark.total = benchmark.total + fps_;
    }
 
+   size_t max_label_size = 0;
+
    for (std::string percentile : params->benchmark_percentiles) {
       float result;
 
       // special case handling for a mean-based average
-      if (percentile.find("AVG") == 0) {
+      if (percentile == "AVG") {
          result = benchmark.total / sorted.size();
-      }
-      // everything else is used to calculate percentiles
-      else {
-         char *endChar;
-         float fraction = std::strtof(percentile.c_str(), &endChar) / 100;
+      } else {
+         // the percentiles are already validated when they're parsed from the config.
+         float fraction = parse_float(percentile) / 100;
 
-         if (*endChar != '%' || fraction <= 0.0 || fraction > 1.0) {
-            std::cerr << "MANGOHUD: Invalid percentile value for benchmark: '" << percentile << "'\n";
-            continue;
-         }
          result = sorted[(fraction * sorted.size()) - 1];
+         percentile += "%";
       }
+
+      if (percentile.length() > max_label_size)
+         max_label_size = percentile.length();
+
       benchmark.percentile_data.push_back({percentile, result});
    }
+
+   for (auto& entry : benchmark.percentile_data) {
+      entry.first.append(max_label_size - entry.first.length(), ' ');
+   }
 }
 
 void update_hud_info(struct swapchain_stats& sw_stats, struct overlay_params& params, uint32_t vendorID){

src/overlay_params.cpp

@@ -206,27 +206,38 @@ static std::vector<std::string>
 parse_benchmark_percentiles(const char *str)
 {
    std::vector<std::string> percentiles;
-   std::stringstream percentStrings(str);
+   std::stringstream percent_strings(str);
    std::string value;
 
-   size_t maxLength = 0;  // for padding later on
-
-   while (std::getline(percentStrings, value, '+')) {
+   while (std::getline(percent_strings, value, '+')) {
       trim(value);
 
-      // everything except AVG is assumed to be a percentile.
-      if (value != "AVG")
-         value += '%';
+      if (value == "AVG") {
+         percentiles.push_back(value);
+         continue;
+      }
 
-      percentiles.push_back(value);
+      float as_float;
+      size_t float_len = 0;
 
-      if (value.length() > maxLength)
-         maxLength = value.length();
-   }
+      try {
+         as_float = parse_float(value, &float_len);
+      } catch (const std::invalid_argument&) {
+         std::cerr << "MANGOHUD: invalid benchmark percentile: '" << value << "'\n";
+         continue;
+      }
 
-   // now reiterate over the strings and add equal padding
-   for (size_t i = 0; i < percentiles.size(); i++) {
-      percentiles[i].append(maxLength - percentiles[i].length(), ' ');
+      if (float_len != value.length()) {
+         std::cerr << "MANGOHUD: invalid benchmark percentile: '" << value << "'\n";
+         continue;
+      }
+
+      if (as_float > 100 || as_float < 0) {
+         std::cerr << "MANGOHUD: benchmark percentile is not between 0 and 100 (" << value << ")\n";
+         continue;
+      }
+
+      percentiles.push_back(value);
    }
 
    return percentiles;
@@ -423,7 +434,7 @@ parse_overlay_config(struct overlay_params *params,
    params->log_interval = 100;
    params->media_player_order = { MP_ORDER_TITLE, MP_ORDER_ARTIST, MP_ORDER_ALBUM };
    params->permit_upload = 0;
-   params->benchmark_percentiles = { "97% ", "AVG ", "1%  ", "0.1%" };
+   params->benchmark_percentiles = { "97", "AVG", "1", "0.1" };
 
 #ifdef HAVE_X11
    params->toggle_hud = { XK_Shift_R, XK_F12 };