sandbox: Split main() into separate file

Normally sandbox includes a main() function so that it can be started
correctly.

When fuzzing is enabled, main() is not required.

When sandbox is built as a library, the main program will be somewhere
else so must not be in the library.

Split the main() function out into a new main.c file. Split the fuzzing
code into a new fuzz.c file.

Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/cpu/Makefile

@@ -6,13 +6,18 @@
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
 obj-y	:= cache.o cpu.o mem.o state.o os.o
+ifdef CONFIG_FUZZ
+obj-y	+= fuzz.o
+else
+obj-y	+= main.o
+endif
 extra-y	:= start.o
 extra-$(CONFIG_SANDBOX_SDL)    += sdl.o
 obj-$(CONFIG_XPL_BUILD)	+= spl.o
 obj-$(CONFIG_ETH_SANDBOX_RAW)	+= eth-raw-os.o
 
 # Compile these files with system headers
-CFLAGS_USE_SYSHDRS := eth-raw-os.o os.o sdl.o
+CFLAGS_USE_SYSHDRS := eth-raw-os.o fuzz.o main.o os.o sdl.o
 
 # sdl.c fails to build with -fshort-wchar using musl
 cmd_cc_sdl.o = $(CC) $(filter-out -nostdinc -fshort-wchar, \

arch/sandbox/cpu/fuzz.c

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2022 Google, Inc.
+ * Written by Andrew Scull <ascull@google.com>
+ */
+
+#include <errno.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <os.h>
+#include <asm/fuzzing_engine.h>
+#include <asm/u-boot-sandbox.h>
+
+static void *fuzzer_thread(void *ptr)
+{
+	char cmd[64];
+	char *argv[5] = {"./u-boot", "-T", "-c", cmd, NULL};
+	const char *fuzz_test;
+
+	/* Find which test to run from an environment variable. */
+	fuzz_test = getenv("UBOOT_SB_FUZZ_TEST");
+	if (!fuzz_test)
+		os_abort();
+
+	snprintf(cmd, sizeof(cmd), "fuzz %s", fuzz_test);
+
+	sandbox_main(4, argv);
+	os_abort();
+	return NULL;
+}
+
+static bool fuzzer_initialized;
+static pthread_mutex_t fuzzer_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t fuzzer_cond = PTHREAD_COND_INITIALIZER;
+static const uint8_t *fuzzer_data;
+static size_t fuzzer_size;
+
+int sandbox_fuzzing_engine_get_input(const uint8_t **data, size_t *size)
+{
+	if (!fuzzer_initialized)
+		return -ENOSYS;
+
+	/* Tell the main thread we need new inputs then wait for them. */
+	pthread_mutex_lock(&fuzzer_mutex);
+	pthread_cond_signal(&fuzzer_cond);
+	pthread_cond_wait(&fuzzer_cond, &fuzzer_mutex);
+	*data = fuzzer_data;
+	*size = fuzzer_size;
+	pthread_mutex_unlock(&fuzzer_mutex);
+	return 0;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+	static pthread_t tid;
+
+	pthread_mutex_lock(&fuzzer_mutex);
+
+	/* Initialize the sandbox on another thread. */
+	if (!fuzzer_initialized) {
+		fuzzer_initialized = true;
+		if (pthread_create(&tid, NULL, fuzzer_thread, NULL))
+			os_abort();
+		pthread_cond_wait(&fuzzer_cond, &fuzzer_mutex);
+	}
+
+	/* Hand over the input. */
+	fuzzer_data = data;
+	fuzzer_size = size;
+	pthread_cond_signal(&fuzzer_cond);
+
+	/* Wait for the inputs to be finished with. */
+	pthread_cond_wait(&fuzzer_cond, &fuzzer_mutex);
+	pthread_mutex_unlock(&fuzzer_mutex);
+
+	return 0;
+}

arch/sandbox/cpu/main.c

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ */
+
+#include <asm/u-boot-sandbox.h>
+
+int main(int argc, char *argv[])
+{
+	return sandbox_main(argc, argv);
+}

arch/sandbox/cpu/os.c

@@ -10,7 +10,6 @@
 #include <fcntl.h>
 #include <pthread.h>
 #include <getopt.h>
-#include <setjmp.h>
 #include <signal.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -28,7 +27,6 @@
 #include <linux/compiler_attributes.h>
 #include <linux/types.h>
 
-#include <asm/fuzzing_engine.h>
 #include <asm/getopt.h>
 #include <asm/sections.h>
 #include <asm/state.h>
@@ -1151,75 +1149,3 @@ void os_relaunch(char *argv[])
 	execv(argv[0], argv);
 	os_exit(1);
 }
-
-#ifdef CONFIG_FUZZ
-static void *fuzzer_thread(void * ptr)
-{
-	char cmd[64];
-	char *argv[5] = {"./u-boot", "-T", "-c", cmd, NULL};
-	const char *fuzz_test;
-
-	/* Find which test to run from an environment variable. */
-	fuzz_test = getenv("UBOOT_SB_FUZZ_TEST");
-	if (!fuzz_test)
-		os_abort();
-
-	snprintf(cmd, sizeof(cmd), "fuzz %s", fuzz_test);
-
-	sandbox_main(4, argv);
-	os_abort();
-	return NULL;
-}
-
-static bool fuzzer_initialized = false;
-static pthread_mutex_t fuzzer_mutex = PTHREAD_MUTEX_INITIALIZER;
-static pthread_cond_t fuzzer_cond = PTHREAD_COND_INITIALIZER;
-static const uint8_t *fuzzer_data;
-static size_t fuzzer_size;
-
-int sandbox_fuzzing_engine_get_input(const uint8_t **data, size_t *size)
-{
-	if (!fuzzer_initialized)
-		return -ENOSYS;
-
-	/* Tell the main thread we need new inputs then wait for them. */
-	pthread_mutex_lock(&fuzzer_mutex);
-	pthread_cond_signal(&fuzzer_cond);
-	pthread_cond_wait(&fuzzer_cond, &fuzzer_mutex);
-	*data = fuzzer_data;
-	*size = fuzzer_size;
-	pthread_mutex_unlock(&fuzzer_mutex);
-	return 0;
-}
-
-int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
-{
-	static pthread_t tid;
-
-	pthread_mutex_lock(&fuzzer_mutex);
-
-	/* Initialize the sandbox on another thread. */
-	if (!fuzzer_initialized) {
-		fuzzer_initialized = true;
-		if (pthread_create(&tid, NULL, fuzzer_thread, NULL))
-			os_abort();
-		pthread_cond_wait(&fuzzer_cond, &fuzzer_mutex);
-	}
-
-	/* Hand over the input. */
-	fuzzer_data = data;
-	fuzzer_size = size;
-	pthread_cond_signal(&fuzzer_cond);
-
-	/* Wait for the inputs to be finished with. */
-	pthread_cond_wait(&fuzzer_cond, &fuzzer_mutex);
-	pthread_mutex_unlock(&fuzzer_mutex);
-
-	return 0;
-}
-#else
-int main(int argc, char *argv[])
-{
-	return sandbox_main(argc, argv);
-}
-#endif

arch/sandbox/cpu/start.c

@@ -22,6 +22,7 @@
 #include <asm/malloc.h>
 #include <asm/sections.h>
 #include <asm/state.h>
+#include <asm/u-boot-sandbox.h>
 #include <dm/root.h>
 #include <linux/ctype.h>
 #include <linux/log2.h>

arch/sandbox/include/asm/u-boot-sandbox.h

@@ -46,8 +46,9 @@ void __noreturn sandbox_exit(void);
  *
  * @argc:	the number of arguments passed to the program
  * @argv:	array of argc+1 pointers, of which the last one is null
-
- * This starts sandbox. It does not return unless something goes wrong.
+ *
+ * This calls sandbox_init(), then board_init_f/r(). It does not return unless
+ * something goes wrong.
  *
  * Return: 1 on error
  */