From f51fc836c5b690f5448e76196dd40bdb55957a11 Mon Sep 17 00:00:00 2001
From: Flavio Cruz <flaviocruz@gmail.com>
Date: Mon, 14 Nov 2022 00:40:07 -0500
Subject: Initialize basic types once and print errors for duplicate
 definitions

For kernel server or user subsystems we would initialize basic types
twice, once in main() and again for the subsystem declaration. Instead,
initialize basic types when the subsystem is declared and then throw
errors when types are defined multiple times.
Message-Id: <Y3HUt/YAKaqMMTi3@viriathus>
---
 migcom.c |  1 -
 parser.y |  5 ++---
 type.c   | 16 ++++++++++++++++
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/migcom.c b/migcom.c
index c07e84d..e61c79b 100644
--- a/migcom.c
+++ b/migcom.c
@@ -213,7 +213,6 @@ main(int argc, char **argv)
     set_program_name("mig");
     parseArgs(argc, argv);
     init_global();
-    init_type();
 
     LookNormal();
     (void) yyparse();
diff --git a/parser.y b/parser.y
index 104f604..23294bf 100644
--- a/parser.y
+++ b/parser.y
@@ -212,6 +212,7 @@ Subsystem		:	SubsystemStart SubsystemMods
 	       IsKernelUser ? ", KernelUser" : "",
 	       IsKernelServer ? ", KernelServer" : "");
     }
+    init_type();
 }
 			;
 
@@ -238,7 +239,6 @@ SubsystemMod		:	syKernelUser
     IsKernelUser = TRUE;
     port_size = vm_offset_size;
     port_size_in_bits = vm_offset_size_in_bits;
-    init_type();
 }
 			|	syKernelServer
 {
@@ -247,7 +247,6 @@ SubsystemMod		:	syKernelUser
     IsKernelServer = TRUE;
     port_size = vm_offset_size;
     port_size_in_bits = vm_offset_size_in_bits;
-    init_type();
 }
 			;
 
@@ -351,7 +350,7 @@ TypeDecl		:	syType NamedTypeSpec
     identifier_t name = $2->itName;
 
     if (itLookUp(name) != itNULL)
-	warn("overriding previous definition of %s", name);
+		error("overriding previous definition of %s", name);
     itInsert(name, $2);
 }
 			;
diff --git a/type.c b/type.c
index 66944d9..3846746 100644
--- a/type.c
+++ b/type.c
@@ -57,6 +57,7 @@ ipc_type_t *itWaitTimeType;	/* used for dummy WaitTime args */
 ipc_type_t *itMsgOptionType;	/* used for dummy MsgOption args */
 ipc_type_t *itShortType;        /* used for the short type */
 ipc_type_t *itIntType;          /* used for the int type */
+static boolean_t types_initialized = FALSE;
 
 static ipc_type_t *list = itNULL;
 
@@ -67,6 +68,13 @@ static ipc_type_t *list = itNULL;
 ipc_type_t *
 itLookUp(identifier_t name)
 {
+    if (!types_initialized)
+    {
+        error("Basic types not initialized when looking up type %s. Did you "
+              "forget to define the subsystem?", name);
+        return NULL;
+    }
+
     ipc_type_t *it, **last;
 
     for (it = *(last = &list); it != itNULL; it = *(last = &it->itNext))
@@ -875,6 +883,14 @@ itMakeDeallocType(void)
 void
 init_type(void)
 {
+    if (types_initialized)
+    {
+        error("Basic types were already initialized");
+        exit(EXIT_FAILURE);
+    }
+    /* Mark initialization here since itInsert below will require it. */
+    types_initialized = TRUE;
+
     itByteType = itAlloc();
     itByteType->itName = "unsigned char";
     itByteType->itInName = MACH_MSG_TYPE_BYTE;
-- 
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