Fix Switch OTA launcher self-update via a bootstrap NRO.

A running launcher cannot replace its own NRO on sdmc/FAT; stage the new
binary and chainload a tiny helper from romfs to swap it in before loading
the game.

native/switch-ota-bootstrap/Makefile

@@ -0,0 +1,72 @@
+#---------------------------------------------------------------------------------
+# One-shot OTA bootstrap NRO (copied into the main launcher's romfs).
+#---------------------------------------------------------------------------------
+.SUFFIXES:
+
+ifeq ($(strip $(DEVKITPRO)),)
+
+.PHONY: all
+all:
+	@echo "DEVKITPRO not set — bootstrap builds with the launcher only."
+	@false
+
+else
+
+TOPDIR ?= $(CURDIR)
+include $(DEVKITPRO)/libnx/switch_rules
+
+TARGET		:=	ota-bootstrap
+BUILD		:=	build
+SOURCES		:=	.
+INCLUDES	:=	include
+ROMFS		:=
+
+APP_TITLE	:=	gen1recomp OTA
+APP_AUTHOR	:=	bryanthaboi, port by andrewqsantos
+APP_VERSION	:=	0.0.0
+
+ARCH	:=	-march=armv8-a+crc+crypto -mtune=cortex-a57 -mtp=soft -fPIE
+CFLAGS	:=	-g -Wall -O2 -ffunction-sections $(ARCH) $(DEFINES)
+CFLAGS	+=	$(INCLUDE) -D__SWITCH__
+ASFLAGS	:=	-g $(ARCH)
+LDFLAGS	=	-specs=$(DEVKITPRO)/libnx/switch.specs -g $(ARCH) -Wl,-Map,$(notdir $*.map)
+LIBS	:=	-lnx
+LIBDIRS	:= $(LIBNX)
+
+ifneq ($(BUILD),$(notdir $(CURDIR)))
+export OUTPUT	:=	$(CURDIR)/$(TARGET)
+export TOPDIR	:=	$(CURDIR)
+export VPATH	:=	$(foreach dir,$(SOURCES),$(CURDIR)/$(dir))
+export DEPSDIR	:=	$(CURDIR)/$(BUILD)
+CFILES		:=	$(foreach dir,$(SOURCES),$(notdir $(wildcard $(dir)/*.c)))
+export LD	:=	$(CC)
+export OFILES	:=	$(CFILES:.c=.o)
+export INCLUDE	:=	$(foreach dir,$(INCLUDES),-I$(CURDIR)/$(dir)) \
+			$(foreach dir,$(LIBDIRS),-I$(dir)/include) \
+			-I$(CURDIR)/$(BUILD)
+export LIBPATHS	:=	$(foreach dir,$(LIBDIRS),-L$(dir)/lib)
+export APP_ICON := $(LIBNX)/default_icon.jpg
+export NROFLAGS += --icon=$(APP_ICON)
+export NROFLAGS += --nacp=$(CURDIR)/$(TARGET).nacp
+
+.PHONY: $(BUILD) clean all
+
+all: $(BUILD)
+
+$(BUILD):
+	@[ -d $@ ] || mkdir -p $@
+	@$(MAKE) --no-print-directory -C $(BUILD) -f $(CURDIR)/Makefile
+
+clean:
+	@echo clean ...
+	@rm -fr $(BUILD) $(TARGET).nro $(TARGET).nacp $(TARGET).elf
+
+else
+.PHONY: all
+DEPENDS	:=	$(OFILES:.o=.d)
+all: $(OUTPUT).nro
+$(OUTPUT).nro: $(OUTPUT).elf $(OUTPUT).nacp
+$(OUTPUT).elf: $(OFILES)
+-include $(DEPENDS)
+endif
+endif

native/switch-ota-bootstrap/main.c

@@ -0,0 +1,36 @@
+/*
+ * Tiny one-shot helper: swap a staged launcher NRO into place, then load the game.
+ * The main OTA launcher chainloads here because a running NRO cannot replace itself
+ * on sdmc/FAT.
+ */
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#if defined(__SWITCH__)
+#include <switch.h>
+#endif
+
+#define INSTALL_DIR "sdmc:/switch/gen1recomp"
+#define STAGED INSTALL_DIR "/gen1recomp.nro.staged"
+#define LAUNCHER INSTALL_DIR "/gen1recomp.nro"
+#define GAME INSTALL_DIR "/gen1recomp-game.nro"
+
+int main(int argc, char **argv) {
+  (void)argc;
+  (void)argv;
+
+#if defined(__SWITCH__)
+  remove(LAUNCHER);
+  if (rename(STAGED, LAUNCHER) != 0) {
+    return 1;
+  }
+  Result rc = envSetNextLoad(GAME, GAME);
+  if (R_FAILED(rc)) return 1;
+  return 0;
+#else
+  fprintf(stderr, "ota-bootstrap: host stub (would rename %s -> %s, load %s)\n", STAGED, LAUNCHER,
+          GAME);
+  return 0;
+#endif
+}