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cmd/cc: reject unions containing pointers 

If a union contains a pointer, it will mess up the garbage collector, causing memory corruption.

R=golang-dev, dave, nightlyone, adg, dvyukov, bradfitz, minux.ma, r, iant
CC=golang-dev
https://golang.org/cl/8469043
This commit is contained in:
Daniel Morsing 2013-05-22 21:13:30 +02:00
parent 72c4ee1a9d
commit dbee8ad0f9
1 changed files with 25 additions and 0 deletions
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25
src/cmd/cc/dcl.c
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@ -554,6 +554,28 @@ newlist(Node *l, Node *r)
return new(OLIST, l, r);
}
static int
haspointers(Type *t)
{
Type *fld;
switch(t->etype) {
case TSTRUCT:
for(fld = t->link; fld != T; fld = fld->down) {
if(haspointers(fld))
return 1;
}
return 0;
case TARRAY:
return haspointers(t->link);
case TFUNC:
case TIND:
return 1;
default:
return 0;
}
}
void
sualign(Type *t)
{
@ -608,6 +630,9 @@ sualign(Type *t)
diag(Z, "incomplete union element");
l->offset = 0;
l->shift = 0;
if((debug['q'] || debug['Q']) && haspointers(l))
diag(Z, "precise garbage collector cannot handle unions with pointers");
o = align(align(0, l, Ael1, &maxal), l, Ael2, &maxal);
if(o > w)
w = o;