[OTA] Fix minimal OTA size computations (#2707)

Fixes: #2707

The computations did not take into account the needed extra space for 4k block alignment for OTA.

before_deploy

@@ -74,12 +74,12 @@ for ENV in \
 do
   MAX_FILESIZE=1044464
   if [[ ${ENV} == *"_1M"* ]]; then
-    # max 871 kiB
+    # max 872 kiB - 16 bytes
     MAX_FILESIZE=892912
   fi
   if [[ ${ENV} == *"_1M_OTA"* ]]; then
-    # max 602 kiB
-    MAX_FILESIZE=616448
+    # max 600 kiB - 16 bytes
+    MAX_FILESIZE=614384
   fi
   if [[ ${ENV} == *"esp32"* ]]; then
     MAX_FILESIZE=1310720

src/ESPEasy-Globals.h

@@ -161,7 +161,7 @@ extern NotificationStruct Notification[NPLUGIN_MAX];
     #include <ESP8266mDNS.h>
   #endif
   #define SMALLEST_OTA_IMAGE 276848 // smallest known 2-step OTA image
-  #define MAX_SKETCH_SIZE 1044464
+  #define MAX_SKETCH_SIZE 1044464   // 1020 kB - 16 bytes
   #define PIN_D_MAX        16
 #endif
 #if defined(ESP32)

src/Misc.ino

@@ -2676,13 +2676,20 @@ void play_rtttl(uint8_t _pin, const char *p )
 
 bool OTA_possible(uint32_t& maxSketchSize, bool& use2step) {
 #if defined(ESP8266)
-  maxSketchSize = (ESP.getFreeSketchSpace() - 0x1000) & 0xFFFFF000;
-  const bool otaPossible = maxSketchSize > SMALLEST_OTA_IMAGE;
-  use2step = maxSketchSize < ESP.getSketchSize();
+  // Compute the current free space and sketch size, rounded to 4k blocks.
+  // These block bounaries are needed for erasing a full block on flash.
+  const uint32_t freeSketchSpace = (ESP.getFreeSketchSpace() - 0x1000) & 0xFFFFF000;
+  const uint32_t currentSketchSize = (ESP.getSketchSize() + 0x1000) & 0xFFFFF000;
+  const uint32_t smallestOtaImageSizeNeeded = (((SMALLEST_OTA_IMAGE + 16) + 0x1000) & 0xFFFFF000);
+  const bool otaPossible = freeSketchSpace >= smallestOtaImageSizeNeeded;
+  use2step = freeSketchSpace < currentSketchSize; // Assume the new image has the same size.
   if (use2step) {
-    const uint32_t totalSketchSpace = ESP.getFreeSketchSpace() + ESP.getSketchSize();
-    maxSketchSize = totalSketchSpace - SMALLEST_OTA_IMAGE;
+    const uint32_t totalSketchSpace = freeSketchSpace + currentSketchSize;
+    maxSketchSize = totalSketchSpace - smallestOtaImageSizeNeeded;
+  } else {
+    maxSketchSize = freeSketchSpace;
   }
+  maxSketchSize -= 16; // Must leave 16 bytes at the end.
   if (maxSketchSize > MAX_SKETCH_SIZE) maxSketchSize = MAX_SKETCH_SIZE;
   return otaPossible;
 #else

src/StringProvider.ino

@@ -91,6 +91,9 @@ String getLabel(LabelType::Enum label) {
     case LabelType::SKETCH_FREE:            return F("Sketch Free");
     case LabelType::SPIFFS_SIZE:            return F("SPIFFS Size");
     case LabelType::SPIFFS_FREE:            return F("SPIFFS Free");
+    case LabelType::MAX_OTA_SKETCH_SIZE:    return F("Max. OTA Sketch Size");
+    case LabelType::OTA_2STEP:              return F("OTA 2-step Needed");
+    case LabelType::OTA_POSSIBLE:           return F("OTA possible");
 
   }
   return F("MissingString");
@@ -189,6 +192,9 @@ String getValue(LabelType::Enum label) {
     case LabelType::SKETCH_FREE:            break;
     case LabelType::SPIFFS_SIZE:            break;
     case LabelType::SPIFFS_FREE:            break;
+    case LabelType::MAX_OTA_SKETCH_SIZE:    break;
+    case LabelType::OTA_2STEP:              break;
+    case LabelType::OTA_POSSIBLE:           break;
 
   }
   return F("MissingString");

src/StringProviderTypes.h

@@ -91,6 +91,9 @@ enum Enum : short {
   SKETCH_FREE,
   SPIFFS_SIZE,
   SPIFFS_FREE,
+  MAX_OTA_SKETCH_SIZE,
+  OTA_2STEP,
+  OTA_POSSIBLE,
 
 
 };

src/WebServer_SysInfoPage.ino

@@ -529,6 +529,24 @@ void handle_sysinfo_Storage() {
   TXBuffer += F(" kB free)");
   # endif // if defined(ESP8266)
 
+  {
+    uint32_t maxSketchSize;
+    bool     use2step;
+    bool     otaEnabled = OTA_possible(maxSketchSize, use2step);
+
+    addRowLabel(getLabel(LabelType::MAX_OTA_SKETCH_SIZE));
+    TXBuffer += maxSketchSize / 1024;
+    TXBuffer += F(" kB (");
+    TXBuffer += maxSketchSize;
+    TXBuffer += F(" bytes)");
+
+    addRowLabel(getLabel(LabelType::OTA_POSSIBLE));
+    TXBuffer += boolToString(otaEnabled);
+
+    addRowLabel(getLabel(LabelType::OTA_2STEP));
+    TXBuffer += boolToString(use2step);
+  }
+
   addRowLabel(getLabel(LabelType::SPIFFS_SIZE));
   TXBuffer += SpiffsTotalBytes() / 1024;
   TXBuffer += F(" kB (");
@@ -597,4 +615,4 @@ void handle_sysinfo_Storage() {
   # endif // ifdef ESP32
 }
 
-#endif // ifdef WEBSERVER_SYSINFO
+#endif    // ifdef WEBSERVER_SYSINFO

src/WebServer_ToolsPage.ino

@@ -136,7 +136,9 @@ void handle_tools() {
       }
       TXBuffer += F(" Max sketch size: ");
       TXBuffer += maxSketchSize / 1024;
-      TXBuffer += F(" kB");
+      TXBuffer += F(" kB (");
+      TXBuffer += maxSketchSize;
+      TXBuffer += F(" bytes)");
     }
     #  endif // ifndef NO_HTTP_UPDATER
   }