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authorColin Walters <walters@verbum.org>2009-02-25 11:10:15 -0500
committerColin Walters <walters@verbum.org>2009-05-06 12:51:17 -0400
commit15f518301605ed748fbcecdf5e38d0a5ef982c3b (patch)
tree696948b35333656cd9da0bcc4103c13639cbcef4
parenta709566edd8358ba431b7427a1530a7db0d1832d (diff)
downloaddbus-15f518301605ed748fbcecdf5e38d0a5ef982c3b.tar.gz
Bug 20137 - Fix alignment usage when demarshaling basics
We can't safely type-pun from e.g. char * to DBusBasicValue *, because the latter has higher alignment requirements. Instead, create an explicit pointer for each case. Also, we mark each one volatile to sidestep strict aliasing issues, for the future when we turn on strict aliasing support. Original patch and review from Jay Estabrook <jay.estabrook@hp.com>.
-rw-r--r--dbus/dbus-marshal-basic.c40
1 files changed, 28 insertions, 12 deletions
diff --git a/dbus/dbus-marshal-basic.c b/dbus/dbus-marshal-basic.c
index 724d94b8..38fbe2d6 100644
--- a/dbus/dbus-marshal-basic.c
+++ b/dbus/dbus-marshal-basic.c
@@ -508,59 +508,74 @@ _dbus_marshal_read_basic (const DBusString *str,
int *new_pos)
{
const char *str_data;
- DBusBasicValue *vp;
_dbus_assert (dbus_type_is_basic (type));
str_data = _dbus_string_get_const_data (str);
- vp = value;
+ /* Below we volatile types to avoid aliasing issues;
+ * see http://bugs.freedesktop.org/show_bug.cgi?id=20137
+ */
+
switch (type)
{
case DBUS_TYPE_BYTE:
- vp->byt = _dbus_string_get_byte (str, pos);
+ {
+ volatile unsigned char *vp = value;
+ *vp = (unsigned char) _dbus_string_get_byte (str, pos);
(pos)++;
+ }
break;
case DBUS_TYPE_INT16:
case DBUS_TYPE_UINT16:
+ {
+ volatile dbus_uint16_t *vp = value;
pos = _DBUS_ALIGN_VALUE (pos, 2);
- vp->u16 = *(dbus_uint16_t *)(str_data + pos);
+ *vp = *(dbus_uint16_t *)(str_data + pos);
if (byte_order != DBUS_COMPILER_BYTE_ORDER)
- vp->u16 = DBUS_UINT16_SWAP_LE_BE (vp->u16);
+ *vp = DBUS_UINT16_SWAP_LE_BE (*vp);
pos += 2;
+ }
break;
case DBUS_TYPE_INT32:
case DBUS_TYPE_UINT32:
case DBUS_TYPE_BOOLEAN:
+ {
+ volatile dbus_uint32_t *vp = value;
pos = _DBUS_ALIGN_VALUE (pos, 4);
- vp->u32 = *(dbus_uint32_t *)(str_data + pos);
+ *vp = *(dbus_uint32_t *)(str_data + pos);
if (byte_order != DBUS_COMPILER_BYTE_ORDER)
- vp->u32 = DBUS_UINT32_SWAP_LE_BE (vp->u32);
+ *vp = DBUS_UINT32_SWAP_LE_BE (*vp);
pos += 4;
+ }
break;
case DBUS_TYPE_INT64:
case DBUS_TYPE_UINT64:
case DBUS_TYPE_DOUBLE:
+ {
+ volatile dbus_uint64_t *vp = value;
pos = _DBUS_ALIGN_VALUE (pos, 8);
#ifdef DBUS_HAVE_INT64
if (byte_order != DBUS_COMPILER_BYTE_ORDER)
- vp->u64 = DBUS_UINT64_SWAP_LE_BE (*(dbus_uint64_t*)(str_data + pos));
+ *vp = DBUS_UINT64_SWAP_LE_BE (*(dbus_uint64_t*)(str_data + pos));
else
- vp->u64 = *(dbus_uint64_t*)(str_data + pos);
+ *vp = *(dbus_uint64_t*)(str_data + pos);
#else
- vp->u64 = *(DBus8ByteStruct*) (str_data + pos);
+ *vp = *(DBus8ByteStruct*) (str_data + pos);
swap_8_octets (vp, byte_order);
#endif
pos += 8;
+ }
break;
case DBUS_TYPE_STRING:
case DBUS_TYPE_OBJECT_PATH:
{
int len;
+ volatile char **vp = value;
len = _dbus_marshal_read_uint32 (str, pos, byte_order, &pos);
- vp->str = (char*) str_data + pos;
+ *vp = (char*) str_data + pos;
pos += len + 1; /* length plus nul */
}
@@ -568,11 +583,12 @@ _dbus_marshal_read_basic (const DBusString *str,
case DBUS_TYPE_SIGNATURE:
{
int len;
+ volatile char **vp = value;
len = _dbus_string_get_byte (str, pos);
pos += 1;
- vp->str = (char*) str_data + pos;
+ *vp = (char*) str_data + pos;
pos += len + 1; /* length plus nul */
}