4 files changed, 65 insertions, 10 deletions

diff --git a/src/lisp/ao_lisp.h b/src/lisp/ao_lisp.h
index 44838a34..ea3d2a09 100644
--- a/src/lisp/ao_lisp.h
+++ b/src/lisp/ao_lisp.h
@@ -26,16 +26,22 @@ typedef int16_t		ao_signed_poly;
 #ifdef AO_LISP_SAVE
 
 struct ao_lisp_os_save {
-	ao_poly	ao_lisp_atoms;
-	ao_poly	ao_lisp_globals;
+	ao_poly		atoms;
+	ao_poly		globals;
+	uint16_t	const_checksum;
+	uint16_t	const_checksum_inv;
 };
 
-#define AO_LISP_POOL	(AO_LISP_POOL_TOTAL - sizeof (struct ao_lisp_os_save))
+#define AO_LISP_POOL_EXTRA	(sizeof(struct ao_lisp_os_save))
+#define AO_LISP_POOL	((int) (AO_LISP_POOL_TOTAL - AO_LISP_POOL_EXTRA))
 
 int
 ao_lisp_os_save(void);
 
 int
+ao_lisp_os_restore_save(struct ao_lisp_os_save *save, int offset);
+
+int
 ao_lisp_os_restore(void);
 
 #endif
@@ -67,12 +73,14 @@ extern uint8_t ao_lisp_const[AO_LISP_POOL_CONST];
 #define _ao_lisp_atom_eval	_atom("eval")
 #define _ao_lisp_atom_read	_atom("read")
 #define _ao_lisp_atom_eof	_atom("eof")
+#define _ao_lisp_atom_save	_atom("save")
+#define _ao_lisp_atom_restore	_atom("restore")
 #else
 #include "ao_lisp_const.h"
 #ifndef AO_LISP_POOL
-#define AO_LISP_POOL	16384
+#define AO_LISP_POOL	3072
 #endif
-extern uint8_t		ao_lisp_pool[AO_LISP_POOL];
+extern uint8_t		ao_lisp_pool[AO_LISP_POOL + AO_LISP_POOL_EXTRA];
 #endif
 
 /* Primitive types */
diff --git a/src/lisp/ao_lisp_make_const.c b/src/lisp/ao_lisp_make_const.c
index 0a8c9d07..6a29f402 100644
--- a/src/lisp/ao_lisp_make_const.c
+++ b/src/lisp/ao_lisp_make_const.c
@@ -86,6 +86,33 @@ is_atom(int offset)
 	return 0;
 }
 
+#define AO_FEC_CRC_INIT	0xffff
+
+static inline uint16_t
+ao_fec_crc_byte(uint8_t byte, uint16_t crc)
+{
+	uint8_t	bit;
+
+	for (bit = 0; bit < 8; bit++) {
+		if (((crc & 0x8000) >> 8) ^ (byte & 0x80))
+			crc = (crc << 1) ^ 0x8005;
+		else
+			crc = (crc << 1);
+		byte <<= 1;
+	}
+	return crc;
+}
+
+uint16_t
+ao_fec_crc(const uint8_t *bytes, uint8_t len)
+{
+	uint16_t	crc = AO_FEC_CRC_INIT;
+
+	while (len--)
+		crc = ao_fec_crc_byte(*bytes++, crc);
+	return crc;
+}
+
 int
 main(int argc, char **argv)
 {
@@ -126,6 +153,7 @@ main(int argc, char **argv)
 	printf("extern const uint8_t ao_lisp_const[AO_LISP_POOL_CONST] __attribute__((aligned(4)));\n");
 	printf("#define ao_builtin_atoms 0x%04x\n", ao_lisp_atom_poly(ao_lisp_atoms));
 	printf("#define ao_builtin_frame 0x%04x\n", ao_lisp_frame_poly(ao_lisp_frame_global));
+	printf("#define ao_lisp_const_checksum ((uint16_t) 0x%04x)\n", ao_fec_crc(ao_lisp_const, ao_lisp_top));
 
 	for (a = ao_lisp_atoms; a; a = ao_lisp_poly_atom(a->next)) {
 		char	*n = a->name, c;
diff --git a/src/lisp/ao_lisp_mem.c b/src/lisp/ao_lisp_mem.c
index 31ee9e1e..0373f015 100644
--- a/src/lisp/ao_lisp_mem.c
+++ b/src/lisp/ao_lisp_mem.c
@@ -24,7 +24,7 @@ uint8_t ao_lisp_const[AO_LISP_POOL_CONST] __attribute__((aligned(4)));
 #undef AO_LISP_POOL
 #define AO_LISP_POOL AO_LISP_POOL_CONST
 #else
-uint8_t	ao_lisp_pool[AO_LISP_POOL] __attribute__((aligned(4)));
+uint8_t	ao_lisp_pool[AO_LISP_POOL + AO_LISP_POOL_EXTRA] __attribute__((aligned(4)));
 #endif
 
 #if 0
diff --git a/src/lisp/ao_lisp_save.c b/src/lisp/ao_lisp_save.c
index 2b19fdcb..030846b7 100644
--- a/src/lisp/ao_lisp_save.c
+++ b/src/lisp/ao_lisp_save.c
@@ -17,12 +17,18 @@
 ao_poly
 ao_lisp_save(struct ao_lisp_cons *cons)
 {
+	if (!ao_lisp_check_argc(_ao_lisp_atom_save, cons, 0, 0))
+		return AO_LISP_NIL;
+
 #ifdef AO_LISP_SAVE
 	struct ao_lisp_os_save *os = (struct ao_lisp_os_save *) &ao_lisp_pool[AO_LISP_POOL];
 
 	ao_lisp_collect();
-	os->ao_lisp_atoms = ao_lisp_atom_poly(ao_lisp_atoms);
-	os->ao_lisp_globals = ao_lisp_frame_poly(ao_lisp_frame_global);
+	os->atoms = ao_lisp_atom_poly(ao_lisp_atoms);
+	os->globals = ao_lisp_frame_poly(ao_lisp_frame_global);
+	os->const_checksum = ao_lisp_const_checksum;
+	os->const_checksum_inv = ~ao_lisp_const_checksum;
+
 	if (ao_lisp_os_save())
 		return _ao_lisp_atom_t;
 #endif
@@ -32,13 +38,26 @@ ao_lisp_save(struct ao_lisp_cons *cons)
 ao_poly
 ao_lisp_restore(struct ao_lisp_cons *cons)
 {
+	if (!ao_lisp_check_argc(_ao_lisp_atom_save, cons, 0, 0))
+		return AO_LISP_NIL;
+
 #ifdef AO_LISP_SAVE
+	struct ao_lisp_os_save save;
 	struct ao_lisp_os_save *os = (struct ao_lisp_os_save *) &ao_lisp_pool[AO_LISP_POOL];
 
+	if (!ao_lisp_os_restore_save(&save, AO_LISP_POOL))
+		return ao_lisp_error(AO_LISP_INVALID, "header restore failed");
+
+	if (save.const_checksum != ao_lisp_const_checksum ||
+	    save.const_checksum_inv != (uint16_t) ~ao_lisp_const_checksum)
+	{
+		return ao_lisp_error(AO_LISP_INVALID, "image is corrupted or stale");
+	}
+
 	if (ao_lisp_os_restore()) {
 
-		ao_lisp_atoms = ao_lisp_poly_atom(os->ao_lisp_atoms);
-		ao_lisp_frame_global = ao_lisp_poly_frame(os->ao_lisp_globals);
+		ao_lisp_atoms = ao_lisp_poly_atom(os->atoms);
+		ao_lisp_frame_global = ao_lisp_poly_frame(os->globals);
 
 		/* Clear the eval global variabls */
 		ao_lisp_eval_clear_globals();