Embed fixed ESP32 firmware identity

src/MeshCoreImageIdentity.cpp

@@ -0,0 +1,49 @@
+#if defined(ESP32_PLATFORM)
+
+#include <stdint.h>
+
+#ifndef MESHCORE_BUILD_ENV
+#define MESHCORE_BUILD_ENV "unknown"
+#endif
+
+#ifndef OTA_VARIANT
+#define OTA_VARIANT MESHCORE_BUILD_ENV
+#endif
+
+#ifndef FIRMWARE_VERSION
+#define FIRMWARE_VERSION MESHCORE_DEFAULT_FIRMWARE_VERSION
+#endif
+
+namespace {
+
+constexpr uint16_t MESHCORE_IMAGE_IDENTITY_SCHEMA = 1;
+constexpr uint32_t MESHCORE_IMAGE_IDENTITY_END_MAGIC = 0x3144494dUL;  // "MID1"
+
+struct MeshCoreImageIdentity {
+  char magic[8];
+  uint16_t schema;
+  uint16_t size;
+  char environment[96];
+  char firmware_version[96];
+  uint32_t end_magic;
+};
+
+static_assert(sizeof(MeshCoreImageIdentity) == 208,
+              "MeshCore image identity layout changed");
+
+}  // namespace
+
+// ESP-IDF places .rodata_custom_desc immediately after esp_app_desc_t. The
+// record therefore starts at byte 0x120 relative to every ESP32 app image,
+// independent of the app partition's absolute flash address.
+extern "C" __attribute__((section(".rodata_custom_desc"), used))
+const MeshCoreImageIdentity meshcore_image_identity = {
+    {'M', 'C', 'F', 'W', 'I', 'D', '0', '1'},
+    MESHCORE_IMAGE_IDENTITY_SCHEMA,
+    sizeof(MeshCoreImageIdentity),
+    OTA_VARIANT,
+    FIRMWARE_VERSION,
+    MESHCORE_IMAGE_IDENTITY_END_MAGIC,
+};
+
+#endif