vm: add API to control trace mode

Add a public getter and setter to read and set the VM trace level
respectively. Use the new API to control the trace mode with a newly
introduced `-t` command line switch.

Drop support for honouring the `TRACE` environment variable as
host programs embedding ucode might want to prevent that behaviour
or handle it differently.

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

4 files changed, 31 insertions, 13 deletions

diff --git a/main.c b/main.c
index b420051..a71e053 100644
--- a/main.c
+++ b/main.c
@@ -40,11 +40,11 @@ print_usage(const char *app)
 {
 	printf(
 	"== Usage ==\n\n"
-	"  # %s [-d] [-l] [-r] [-S] [-R] [-e '[prefix=]{\"var\": ...}'] [-E [prefix=]env.json] {-i <file> | -s \"ucode script...\"}\n"
+	"  # %s [-t] [-l] [-r] [-S] [-R] [-e '[prefix=]{\"var\": ...}'] [-E [prefix=]env.json] {-i <file> | -s \"ucode script...\"}\n"
 	"  -h, --help	Print this help\n"
 	"  -i file	Specify an ucode script to parse\n"
 	"  -s \"ucode script...\"	Specify an ucode fragment to parse\n"
-	"  -d Instead of executing the script, dump the resulting AST as dot\n"
+	"  -t Enable VM execution tracing\n"
 	"  -l Do not strip leading block whitespace\n"
 	"  -r Do not trim trailing block newlines\n"
 	"  -S Enable strict mode\n"
@@ -76,7 +76,7 @@ register_variable(uc_value_t *scope, const char *key, uc_value_t *val)
 static int
 parse(uc_parse_config *config, uc_source *src,
       uc_value_t *env, uc_value_t *modules,
-      int argc, char **argv)
+      int argc, char **argv, int trace)
 {
 	uc_value_t *globals = NULL, *res = NULL, *arr, *name, *mod;
 	uc_function_t *entry;
@@ -87,6 +87,8 @@ parse(uc_parse_config *config, uc_source *src,
 
 	uc_vm_init(&vm, config);
 
+	uc_vm_trace_set(&vm, trace);
+
 	entry = uc_compile(config, src, &err);
 
 	if (!entry) {
@@ -224,8 +226,8 @@ main(int argc, char **argv)
 {
 	uc_value_t *env = NULL, *modules = NULL, *o, *p;
 	uc_source *source = NULL, *envfile = NULL;
+	int opt, rv = 0, trace = 0;
 	char *stdin = NULL, *c;
-	int opt, rv = 0;
 
 	uc_parse_config config = {
 		.strict_declarations = false,
@@ -239,7 +241,7 @@ main(int argc, char **argv)
 		goto out;
 	}
 
-	while ((opt = getopt(argc, argv, "hlrSRe:E:i:s:m:")) != -1)
+	while ((opt = getopt(argc, argv, "hlrtSRe:E:i:s:m:")) != -1)
 	{
 		switch (opt) {
 		case 'h':
@@ -358,6 +360,10 @@ main(int argc, char **argv)
 			ucv_array_push(modules, ucv_string_new(optarg));
 
 			break;
+
+		case 't':
+			trace = 1;
+			break;
 		}
 	}
 
@@ -377,7 +383,7 @@ main(int argc, char **argv)
 		goto out;
 	}
 
-	rv = parse(&config, source, env, modules, argc, argv);
+	rv = parse(&config, source, env, modules, argc, argv, trace);
 
 out:
 	ucv_put(modules);
diff --git a/tests/cram/test_basic.t b/tests/cram/test_basic.t
index d866c49..940f1d1 100644
--- a/tests/cram/test_basic.t
+++ b/tests/cram/test_basic.t
@@ -12,11 +12,11 @@ check that ucode provides exepected help:
   $ ucode | sed 's/ucode-san/ucode/'
   == Usage ==
   
-    # ucode [-d] [-l] [-r] [-S] [-R] [-e '[prefix=]{"var": ...}'] [-E [prefix=]env.json] {-i <file> | -s "ucode script..."}
+    # ucode [-t] [-l] [-r] [-S] [-R] [-e '[prefix=]{"var": ...}'] [-E [prefix=]env.json] {-i <file> | -s "ucode script..."}
     -h, --help\tPrint this help (esc)
     -i file\tSpecify an ucode script to parse (esc)
     -s "ucode script..."\tSpecify an ucode fragment to parse (esc)
-    -d Instead of executing the script, dump the resulting AST as dot
+    -t Enable VM execution tracing
     -l Do not strip leading block whitespace
     -r Do not trim trailing block newlines
     -S Enable strict mode
diff --git a/vm.c b/vm.c
index 99e07bb..82d2f1c 100644
--- a/vm.c
+++ b/vm.c
@@ -14,7 +14,6 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
 #include <assert.h>
@@ -137,13 +136,9 @@ uc_vm_output_exception(uc_vm *vm, uc_exception *ex);
 
 void uc_vm_init(uc_vm *vm, uc_parse_config *config)
 {
-	char *s = getenv("TRACE");
-
 	vm->exception.type = EXCEPTION_NONE;
 	vm->exception.message = NULL;
 
-	vm->trace = s ? strtoul(s, NULL, 0) : 0;
-
 	vm->config = config;
 
 	vm->open_upvals = NULL;
@@ -160,6 +155,8 @@ void uc_vm_init(uc_vm *vm, uc_parse_config *config)
 	uc_vm_alloc_global_scope(vm);
 
 	uc_vm_exception_handler_set(vm, uc_vm_output_exception);
+
+	uc_vm_trace_set(vm, 0);
 }
 
 void uc_vm_free(uc_vm *vm)
@@ -2409,3 +2406,15 @@ uc_vm_exception_handler_set(uc_vm *vm, uc_exception_handler_t *exhandler)
 {
 	vm->exhandler = exhandler;
 }
+
+uint32_t
+uc_vm_trace_get(uc_vm *vm)
+{
+	return vm->trace;
+}
+
+void
+uc_vm_trace_set(uc_vm *vm, uint32_t level)
+{
+	vm->trace = level;
+}
diff --git a/vm.h b/vm.h
index 84b42fe..3d22105 100644
--- a/vm.h
+++ b/vm.h
@@ -123,6 +123,9 @@ uc_value_t *uc_vm_stack_peek(uc_vm *vm, size_t offset);
 uc_exception_handler_t *uc_vm_exception_handler_get(uc_vm *vm);
 void uc_vm_exception_handler_set(uc_vm *vm, uc_exception_handler_t *exhandler);
 
+uint32_t uc_vm_trace_get(uc_vm *vm);
+void uc_vm_trace_set(uc_vm *vm, uint32_t level);
+
 uc_exception_type_t uc_vm_call(uc_vm *vm, bool mcall, size_t nargs);
 
 void __attribute__((format(printf, 3, 0)))