Improved debug messages (of the the preload library)

- when debugging is enabled, detects and prints nested use of lua_instance
  structures.
- from now on, lua_instance pointers returned by get_lua() must be released
  with release_lua().

3 files changed, 78 insertions, 5 deletions

diff --git a/luaif/argvenvp.c b/luaif/argvenvp.c
index 28b079b..c4eda50 100644
--- a/luaif/argvenvp.c
+++ b/luaif/argvenvp.c
@@ -65,7 +65,10 @@ void sb_push_string_to_lua_stack(char *str)
 {
 	struct lua_instance *luaif = get_lua();
 
-	if (luaif) lua_pushstring(luaif->lua, str);
+	if (luaif) {
+		lua_pushstring(luaif->lua, str);
+		release_lua(luaif);
+	}
 }
 
 /* Exec preprocessor:
@@ -81,11 +84,13 @@ int sb_execve_preprocess(char **file, char ***argv, char ***envp)
 	if (!argv || !envp) {
 		SB_LOG(SB_LOGLEVEL_ERROR,
 			"ERROR: sb_argvenvp: (argv || envp) == NULL");
+		release_lua(luaif);
 		return -1;
 	}
 
 	if (getenv("SBOX_DISABLE_ARGVENVP")) {
 		SB_LOG(SB_LOGLEVEL_DEBUG, "sb_argvenvp disabled(E):");
+		release_lua(luaif);
 		return 0;
 	}
 
@@ -119,6 +124,7 @@ int sb_execve_preprocess(char **file, char ***argv, char ***envp)
 
 	SB_LOG(SB_LOGLEVEL_NOISE,
 		"sb_execve_preprocess: at exit, gettop=%d", lua_gettop(luaif->lua));
+	release_lua(luaif);
 	return res;
 }
 
@@ -141,6 +147,7 @@ int sb_execve_postprocess(char *exec_type,
 	if (!argv || !envp) {
 		SB_LOG(SB_LOGLEVEL_ERROR,
 			"ERROR: sb_argvenvp: (argv || envp) == NULL");
+		release_lua(luaif);
 		return -1;
 	}
 
@@ -208,6 +215,7 @@ int sb_execve_postprocess(char *exec_type,
 
 	SB_LOG(SB_LOGLEVEL_NOISE,
 		"sb_execve_postprocess: at exit, gettop=%d", lua_gettop(luaif->lua));
+	release_lua(luaif);
 	return res;
 }
 
@@ -260,5 +268,6 @@ char *sb_query_exec_policy(const char *field_name, const char *binary_name,
 	/* normalize lua stack */
 	lua_pop(luaif->lua, 2);
 
+	release_lua(luaif);
 	return (result);
 }
diff --git a/luaif/luaif.c b/luaif/luaif.c
index 8841dfa..bfb849e 100644
--- a/luaif/luaif.c
+++ b/luaif/luaif.c
@@ -272,6 +272,48 @@ static struct lua_instance *alloc_lua(void)
 	return(tmp);
 }
 
+static void increment_luaif_usage_counter(volatile struct lua_instance *ptr)
+{
+	if (SB_LOG_IS_ACTIVE(SB_LOGLEVEL_DEBUG)) {
+		/* Well, to make this bullet-proof the luaif structure
+		 * should be locked, but since this code is now used only for
+		 * producing debugging information and the pointer is marked
+		 * "volatile", the results are good enough. No need to slow 
+		 * down anything with additional locks - this function is 
+		 * called frequently. */
+		if (ptr->lua_instance_in_use > 0) SB_LOG(SB_LOGLEVEL_DEBUG,
+			"Lua instance already in use! (%d)",
+			ptr->lua_instance_in_use);
+
+		(ptr->lua_instance_in_use)++;
+	}
+}
+
+void release_lua(struct lua_instance *luaif)
+{
+	if (SB_LOG_IS_ACTIVE(SB_LOGLEVEL_DEBUG)) {
+		int	i;
+		volatile struct lua_instance *ptr = luaif;
+
+		SB_LOG(SB_LOGLEVEL_NOISE, "release_lua()");
+
+		if (!ptr) {
+			SB_LOG(SB_LOGLEVEL_DEBUG,
+				"release_lua(): ptr is NULL ");
+			return;
+		}
+
+		i = ptr->lua_instance_in_use;
+		if (i > 1) SB_LOG(SB_LOGLEVEL_DEBUG,
+			"Lua instance usage counter was %d", i);
+
+		(ptr->lua_instance_in_use)--;
+	}
+}
+
+/* get access to lua context. Remember to call release_lua() after the
+ * pointer is not needed anymore.
+*/
 struct lua_instance *get_lua(void)
 {
 	struct lua_instance *ptr = NULL;
@@ -280,6 +322,8 @@ struct lua_instance *get_lua(void)
 
 	if (!SB_LOG_INITIALIZED()) sblog_init();
 
+	SB_LOG(SB_LOGLEVEL_NOISE, "get_lua()");
+
 	if (pthread_detection_done == 0) check_pthread_library();
 
 	if (pthread_library_is_available) {
@@ -312,6 +356,10 @@ struct lua_instance *get_lua(void)
 			exit(1);
 		}
 	}
+
+	if (SB_LOG_IS_ACTIVE(SB_LOGLEVEL_DEBUG)) {
+		increment_luaif_usage_counter(ptr);
+	}
 	return(ptr);
 }
 
@@ -336,9 +384,12 @@ void sb2_preload_library_constructor(void)
 char *sb2__read_string_variable_from_lua__(const char *name)
 {
 	struct lua_instance *luaif;
+	char *cp;
 
 	luaif = get_lua();
-	return(read_string_variable_from_lua(luaif, name));
+	cp = read_string_variable_from_lua(luaif, name);
+	release_lua(luaif);
+	return(cp);
 }
 
 /* Read and execute an lua file. Used from sb2-show, useful
@@ -352,6 +403,7 @@ void sb2__load_and_execute_lua_file__(const char *filename)
 
 	luaif = get_lua();
 	load_and_execute_lua_file(luaif, filename);
+	release_lua(luaif);
 }
 
 #if 0 /* DISABLED 2008-10-23/LTA: sb_decolonize_path() is not currently available*/
diff --git a/luaif/paths.c b/luaif/paths.c
index 08e8cf8..dfaf5bb 100644
--- a/luaif/paths.c
+++ b/luaif/paths.c
@@ -935,7 +935,7 @@ static char *scratchbox_path_internal(
 	int dont_resolve_final_symlink,
 	int process_path_for_exec)
 {
-	struct lua_instance *luaif;
+	struct lua_instance *luaif = NULL;
 	char *mapping_result;
 
 	SB_LOG(SB_LOGLEVEL_DEBUG, "scratchbox_path_internal: %s(%s)", func_name, path);
@@ -966,6 +966,7 @@ static char *scratchbox_path_internal(
 		SB_LOG(SB_LOGLEVEL_ERROR,
 			"ERROR: scratchbox_path_internal: path==NULL [%s]",
 			func_name);
+		release_lua(luaif);
 		return NULL;
 	}
 
@@ -976,6 +977,7 @@ static char *scratchbox_path_internal(
 		*/
 		SB_LOG(SB_LOGLEVEL_INFO, "disabled(E): %s '%s'",
 			func_name, path);
+		release_lua(luaif);
 		return strdup(path);
 	}
 	if (luaif->mapping_disabled) {
@@ -985,6 +987,7 @@ static char *scratchbox_path_internal(
 		*/
 		SB_LOG(SB_LOGLEVEL_INFO, "disabled(%d): %s '%s'",
 			luaif->mapping_disabled, func_name, path);
+		release_lua(luaif);
 		return strdup(path);
 	}
 
@@ -994,6 +997,11 @@ static char *scratchbox_path_internal(
 		char *decolon_path = NULL;
 		char *full_path_for_rule_selection = NULL;
 
+
+		/* FIXME: following call to sb_decolonize_path() will lead to
+		 * another call to get_lua()...it would be more efficient to just
+		 * pass luaif pointer from here.
+		*/
 		full_path_for_rule_selection = sb_decolonize_path(func_name, path);
 
 		if (*full_path_for_rule_selection != '/') {
@@ -1107,6 +1115,7 @@ static char *scratchbox_path_internal(
 
 	SB_LOG(SB_LOGLEVEL_NOISE, "scratchbox_path_internal: mapping_result='%s'",
 		mapping_result ? mapping_result : "<No result>");
+	release_lua(luaif);
 	return(mapping_result);
 }
 
@@ -1207,9 +1216,12 @@ char *scratchbox_reverse_path(
 	const char *full_path)
 {
 	struct lua_instance *luaif = get_lua();
+	char *result;
 
-	return (call_lua_function_sbox_reverse_path(luaif,
+	result = call_lua_function_sbox_reverse_path(luaif,
 		(sbox_binary_name ? sbox_binary_name : "UNKNOWN"),
-		func_name, full_path));
+		func_name, full_path);
+	release_lua(luaif);
+	return(result);
 }