From 8fd7a384e2facd4517b200ec8cc79966b3774684 Mon Sep 17 00:00:00 2001
From: herman ten brugge <hermantenbrugge@home.nl>
Date: Fri, 25 Sep 2020 12:23:48 +0200
Subject: [PATCH] Fix bitfields init : tiny solution

tccgen.c: Check struct/union size for bitfield.
tests/tcctest.c: Add test code.
---
 tccgen.c        | 9 ++++++---
 tests/tcctest.c | 3 +++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/tccgen.c b/tccgen.c
index 52f2462..61ef787 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -7339,7 +7339,7 @@ static void init_putz(Section *sec, unsigned long c, int size)
    'al' contains the already initialized length of the
    current container (starting at c).  This returns the new length of that.  */
 static int decl_designator(CType *type, Section *sec, unsigned long c,
-                           Sym **cur_field, int flags, int al)
+                           Sym **cur_field, int flags, int al, int size)
 {
     Sym *s, *f;
     int index, index_last, align, l, nb_elems, elem_size;
@@ -7428,8 +7428,11 @@ static int decl_designator(CType *type, Section *sec, unsigned long c,
        ensures that it even works with designators) */
     if (!(flags & DIF_SIZE_ONLY)) {
         int zlen = c - (corig + al);
-        if (type->t & VT_BITFIELD) /* must include current field too */
+        if (type->t & VT_BITFIELD) { /* must include current field too */
             zlen += type_size(type, &align);
+            if (al + zlen > size)
+                zlen = size - al;
+        }
         if (zlen > 0)
 	    init_putz(sec, corig + al, zlen);
     }
@@ -7783,7 +7786,7 @@ static void decl_initializer(CType *type, Section *sec, unsigned long c,
           do_init_list:
 	    len = 0;
 	    while (tok != '}' || (flags & DIF_HAVE_ELEM)) {
-		len = decl_designator(type, sec, c, &f, flags, len);
+		len = decl_designator(type, sec, c, &f, flags, len, n*size1);
 		flags &= ~DIF_HAVE_ELEM;
 		if (type->t & VT_ARRAY) {
 		    ++indexsym.c;
diff --git a/tests/tcctest.c b/tests/tcctest.c
index 48b20b9..71089b5 100644
--- a/tests/tcctest.c
+++ b/tests/tcctest.c
@@ -1746,6 +1746,8 @@ struct bfa_SS {int a,b; struct bf_SS c[3]; int d,e; };
 struct bfa_SS bfa_init = { .c[1].bit = 1 };
 struct bf_SS bfaa_init[3] = { [1].bit = 1 };
 struct bf_SS bfaa_vinit[] = { [2].bit = 1 };
+struct b2_SS {long long int field : 52; long long int pad : 12; };
+struct b2_SS bf_init2 = {0xFFF000FFF000FLL, 0x123};
 
 extern int external_inited = 42;
 
@@ -1771,6 +1773,7 @@ void init_test(void)
     struct bfa_SS bfa_finit = { .c[1].bit = 1 };
     struct bf_SS bfaa_finit[3] = { [1].bit = 1 };
     struct bf_SS bfaa_fvinit[] = { [2].bit = 1 };
+    struct b2_SS bf_finit2 = {0xFFF000FFF000FLL, 0x123};
     
     printf("sinit1=%d\n", sinit1);
     printf("sinit2=%d\n", sinit2);