Signal error on field values that cannot be safely represented as strings instead of crashing.

This fixes bug 2845.

svn path=/trunk/; revision=26749

3 files changed, 14 insertions, 3 deletions

diff --git a/epan/ftypes/ftype-tvbuff.c b/epan/ftypes/ftype-tvbuff.c
index c4449a12d1..135de1d0be 100644
--- a/epan/ftypes/ftype-tvbuff.c
+++ b/epan/ftypes/ftype-tvbuff.c
@@ -130,7 +130,7 @@ val_repr_len(fvalue_t *fv, ftrepr_t rtype)
 {
 	guint length;
 
-	g_assert(rtype == FTREPR_DFILTER);
+	if (rtype != FTREPR_DFILTER) return -1;
 	length = tvb_length(fv->value.tvb);
 	/* 3 bytes for each byte of the byte "NN:" minus 1 byte
 	 * as there's no trailing ":". */
diff --git a/epan/ftypes/ftypes.c b/epan/ftypes/ftypes.c
index 25084237a9..49b1a20f27 100644
--- a/epan/ftypes/ftypes.c
+++ b/epan/ftypes/ftypes.c
@@ -303,7 +303,13 @@ fvalue_to_string_repr(fvalue_t *fv, ftrepr_t rtype, char *buf)
 {
 	g_assert(fv->ftype->val_to_string_repr);
 	if (!buf) {
-		buf = g_malloc0(fvalue_string_repr_len(fv, rtype) + 1);
+		int len;
+		if ((len = fvalue_string_repr_len(fv, rtype)) >= 0) {
+			buf = g_malloc0(len + 1);
+		} else {
+			/* the value cannot be represented in the given representation type (rtype) */
+			return NULL;
+		}
 	}
 	fv->ftype->val_to_string_repr(fv, rtype, buf);
 	return buf;
diff --git a/epan/ftypes/ftypes.h b/epan/ftypes/ftypes.h
index c2f52186ae..edfdc92bb0 100644
--- a/epan/ftypes/ftypes.h
+++ b/epan/ftypes/ftypes.h
@@ -280,6 +280,9 @@ fvalue_from_string(ftenum_t ftype, char *s, LogFunc logfunc);
 
 /* Returns the length of the string required to hold the
  * string representation of the the field value.
+ *
+ * Returns -1 if the string cannot be represented in the given rtype.
+ *
  * The length DOES NOT include the terminating NUL. */
 int
 fvalue_string_repr_len(fvalue_t *fv, ftrepr_t rtype);
@@ -291,7 +294,9 @@ fvalue_string_repr_len(fvalue_t *fv, ftrepr_t rtype);
  * The pointer to the beginning of the string representation is
  * returned. If 'buf' was NULL, this points to the newly-allocated
  * memory. if 'buf' was non-NULL, then the return value will be
- * 'buf'. */
+ * 'buf'. 
+ *
+ * Returns NULL if the string cannot be represented in the given rtype.*/
 extern char *
 fvalue_to_string_repr(fvalue_t *fv, ftrepr_t rtype, char *buf);