Code to manage the list of subsystems.

1 files changed, 130 insertions, 0 deletions

diff --git a/src/app/main/subsysmgr.c b/src/app/main/subsysmgr.c
new file mode 100644
index 0000000000..7974f2d238
--- /dev/null
+++ b/src/app/main/subsysmgr.c
@@ -0,0 +1,130 @@
+/* Copyright (c) 2003-2004, Roger Dingledine
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "orconfig.h"
+#include "app/main/subsysmgr.h"
+#include "lib/err/torerr.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/**
+ * True iff we have checked tor_subsystems for consistency.
+ **/
+static bool subsystem_array_validated = false;
+
+/**
+ * True if a given subsystem is initialized.  Expand this array if there
+ * are more than this number of subsystems.  (We'd rather not
+ * dynamically allocate in this module.)
+ **/
+static bool sys_initialized[128];
+
+/**
+ * Exit with a raw assertion if the subsystems list is inconsistent;
+ * initialize the subsystem_initialized array.
+ **/
+static void
+check_and_setup(void)
+{
+  if (subsystem_array_validated)
+    return;
+
+  raw_assert(ARRAY_LENGTH(sys_initialized) >= n_tor_subsystems);
+  memset(sys_initialized, 0, sizeof(sys_initialized));
+
+  int last_level = MIN_SUBSYS_LEVEL;
+
+  for (unsigned i = 0; i < n_tor_subsystems; ++i) {
+    const subsys_fns_t *sys = tor_subsystems[i];
+    if (sys->level < MIN_SUBSYS_LEVEL || sys->level > MAX_SUBSYS_LEVEL) {
+      fprintf(stderr, "BUG: Subsystem %s (at %u) has an invalid level %d. "
+              "It is supposed to be between %d and %d (inclusive).\n",
+              sys->name, i, sys->level, MIN_SUBSYS_LEVEL, MAX_SUBSYS_LEVEL);
+      raw_assert_unreached_msg("There is a bug in subsystem_list.c");
+    }
+    if (sys->level < last_level) {
+      fprintf(stderr, "BUG: Subsystem %s (at #%u) is in the wrong position. "
+              "Its level is %d; but the previous subsystem's level was %d.\n",
+              sys->name, i, sys->level, last_level);
+      raw_assert_unreached_msg("There is a bug in subsystem_list.c");
+    }
+    last_level = sys->level;
+  }
+
+  subsystem_array_validated = true;
+}
+
+/**
+ * Initialize all the subsystems; exit on failure.
+ **/
+int
+subsystems_init(void)
+{
+  return subsystems_init_upto(MAX_SUBSYS_LEVEL);
+}
+
+/**
+ * Initialize all the subsystems whose level is less than or equal to
+ * <b>target_level</b>; exit on failure.
+ **/
+int
+subsystems_init_upto(int target_level)
+{
+  check_and_setup();
+
+  for (unsigned i = 0; i < n_tor_subsystems; ++i) {
+    const subsys_fns_t *sys = tor_subsystems[i];
+    if (!sys->supported)
+      continue;
+    if (sys->level > target_level)
+      break;
+    if (sys_initialized[i])
+      continue;
+    int r = 0;
+    if (sys->initialize)
+      r = sys->initialize();
+    if (r < 0) {
+      fprintf(stderr, "BUG: subsystem %s (at %u) initialization failed.\n",
+              sys->name, i);
+      raw_assert_unreached_msg("A subsystem couldn't be initialized.");
+    }
+    sys_initialized[i] = true;
+  }
+
+  return 0;
+}
+
+/**
+ * Shut down all the subsystems.
+ **/
+void
+subsystems_shutdown(void)
+{
+  subsystems_shutdown_downto(MIN_SUBSYS_LEVEL - 1);
+}
+
+/**
+ * Shut down all the subsystems whose level is above <b>target_level</b>.
+ **/
+void
+subsystems_shutdown_downto(int target_level)
+{
+  check_and_setup();
+
+  for (int i = (int)n_tor_subsystems - 1; i >= 0; --i) {
+    const subsys_fns_t *sys = tor_subsystems[i];
+    if (!sys->supported)
+      continue;
+    if (sys->level <= target_level)
+      break;
+    if (! sys_initialized[i])
+      continue;
+    if (sys->shutdown)
+      sys->shutdown();
+    sys_initialized[i] = false;
+  }
+}