Re: [PATCH 2/2] Avoid potentially dereferencing a NULL pointer

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+Date: Sat, 22 Sep 2012 12:19:08 -0400\r
+From: Austin Clements <amdragon@MIT.EDU>\r
+To: Justus Winter <4winter@informatik.uni-hamburg.de>\r
+Subject: Re: [PATCH 2/2] Avoid potentially dereferencing a NULL pointer\r
+Message-ID: <20120922161908.GF26662@mit.edu>\r
+References:\r
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+Quoth Justus Winter on Sep 21 at  2:50 pm:\r
+> GMIME_IS_MULTIPART and GMIME_IS_MESSAGE both handle NULL pointers\r
+> gracefully, but the G_OBJECT_TYPE used in the error handling block\r
+> dereferences it without checking it first.\r
+> \r
+> Fix this by checking whether parent->part is valid.\r
+> \r
+> Found using the clang static analyzer.\r
+\r
+Neat.\r
+\r
+Can this actually happen, though?  If so, I think this point is too\r
+late to be checking for a NULL part field.  It should probably be\r
+checked when the mime_node_t is created so that mime_node_t never has\r
+a NULL part field.\r
+\r
+> Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>\r
+> ---\r
+>  mime-node.c |    2 +-\r
+>  1 file changed, 1 insertion(+), 1 deletion(-)\r
+> \r
+> diff --git a/mime-node.c b/mime-node.c\r
+> index 97e8b48..839737a 100644\r
+> --- a/mime-node.c\r
+> +++ b/mime-node.c\r
+> @@ -291,7 +291,7 @@ mime_node_child (mime_node_t *parent, int child)\r
+>      GMimeObject *sub;\r
+>      mime_node_t *node;\r
+>  \r
+> -    if (!parent || child < 0 || child >= parent->nchildren)\r
+> +    if (!parent || !parent->part || child < 0 || child >= parent->nchildren)\r
+>      return NULL;\r
+>  \r
+>      if (GMIME_IS_MULTIPART (parent->part)) {\r