vm: maintain export symbol tables per program

Instead of having one global export table per VM instance maintain one table
per program instance. This is required to avoid clobbering the export list
in case `import` using code is loaded at runtime through `require()`,
`loadfile()` etc.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 10 insertions, 12 deletions

diff --git a/vm.c b/vm.c
index d8f0074..3bf9836 100644
--- a/vm.c
+++ b/vm.c
@@ -184,9 +184,6 @@ void uc_vm_free(uc_vm_t *vm)
 	for (i = 0; i < vm->restypes.count; i++)
 		ucv_put(vm->restypes.entries[i]->proto);
 
-	for (i = 0; i < vm->exports.count; i++)
-		ucv_put(&vm->exports.entries[i]->header);
-
 	uc_vm_reset_callframes(vm);
 	uc_vm_reset_stack(vm);
 	uc_vector_clear(&vm->stack);
@@ -200,7 +197,6 @@ void uc_vm_free(uc_vm_t *vm)
 		free(vm->restypes.entries[i]);
 
 	uc_vector_clear(&vm->restypes);
-	uc_vector_clear(&vm->exports);
 }
 
 static uc_chunk_t *
@@ -2362,6 +2358,7 @@ static void
 uc_vm_insn_import(uc_vm_t *vm, uc_vm_insn_t insn)
 {
 	uc_callframe_t *frame = uc_vm_current_frame(vm);
+	uc_program_t *prog = uc_vm_current_program(vm);
 	uint16_t from = vm->arg.u32 & 0xffff;
 	uint16_t to = vm->arg.u32 >> 16;
 	uc_value_t *name, *modobj;
@@ -2376,8 +2373,8 @@ uc_vm_insn_import(uc_vm_t *vm, uc_vm_insn_t insn)
 		 * first module export and `from` times u32 values containing
 		 * the constant indexes of the names */
 		for (from = frame->ip[0] * 0x100 + frame->ip[1], frame->ip += 2;
-		     from < to && from < vm->exports.count;
-		     from++) {
+		     from < prog->exports.count && to > 0;
+		     from++, to--) {
 
 			cidx = (
 				frame->ip[0] * 0x1000000UL +
@@ -2390,9 +2387,9 @@ uc_vm_insn_import(uc_vm_t *vm, uc_vm_insn_t insn)
 
 			name = uc_program_get_constant(uc_vm_current_program(vm), cidx);
 
-			if (ucv_type(name) == UC_STRING && vm->exports.entries[from])
+			if (ucv_type(name) == UC_STRING && prog->exports.entries[from])
 				ucv_object_add(modobj, ucv_string_get(name),
-					ucv_get(&vm->exports.entries[from]->header));
+					ucv_get(&prog->exports.entries[from]->header));
 
 			ucv_put(name);
 		}
@@ -2403,9 +2400,9 @@ uc_vm_insn_import(uc_vm_t *vm, uc_vm_insn_t insn)
 	}
 
 	/* module export available, patch into upvalue */
-	else if (from < vm->exports.count && vm->exports.entries[from]) {
-		frame->closure->upvals[to] = vm->exports.entries[from];
-		ucv_get(&vm->exports.entries[from]->header);
+	else if (from <= prog->exports.count && prog->exports.entries[from]) {
+		frame->closure->upvals[to] = prog->exports.entries[from];
+		ucv_get(&prog->exports.entries[from]->header);
 	}
 
 	/* module export missing, e.g. due to premature return in module,
@@ -2420,9 +2417,10 @@ static void
 uc_vm_insn_export(uc_vm_t *vm, uc_vm_insn_t insn)
 {
 	uc_callframe_t *frame = uc_vm_current_frame(vm);
+	uc_program_t *prog = uc_vm_current_program(vm);
 	uc_upvalref_t *ref = uc_vm_capture_upval(vm, frame->stackframe + vm->arg.u32);
 
-	uc_vector_push(&vm->exports, ref);
+	uc_vector_push(&prog->exports, ref);
 	ucv_get(&ref->header);
 }