Unpack jbvBinary objects passed to pushJsonbValue

pushJsonbValue was accepting jbvBinary objects passed as WJB_ELEM or
WJB_VALUE data. While this succeeded, when those objects were later
encountered in attempting to convert the result to Jsonb, errors
occurred. With this change we ghuarantee that a JSonbValue constructed
from calls to pushJsonbValue does not contain any jbvBinary objects.
This cures a problem observed with jsonb_delete.

This means callers of pushJsonbValue no longer need to perform this
unpacking themselves. A subsequent patch will perform some cleanup in
that area.

The error was not triggered by any 9.4 code, but this is a publicly
visible routine, and so the error could be exercised by third party
code, therefore backpatch to 9.4.

Bug report from Peter Geoghegan, fix by me.

2 files changed, 40 insertions, 6 deletions

diff --git a/src/backend/utils/adt/jsonb_util.c b/src/backend/utils/adt/jsonb_util.c
index 5cd9140896b..974e3865249 100644
--- a/src/backend/utils/adt/jsonb_util.c
+++ b/src/backend/utils/adt/jsonb_util.c
@@ -57,6 +57,9 @@ static void appendElement(JsonbParseState *pstate, JsonbValue *scalarVal);
 static int	lengthCompareJsonbStringValue(const void *a, const void *b);
 static int	lengthCompareJsonbPair(const void *a, const void *b, void *arg);
 static void uniqueifyJsonbObject(JsonbValue *object);
+static JsonbValue *pushJsonbValueScalar(JsonbParseState **pstate,
+										JsonbIteratorToken seq,
+										JsonbValue *scalarVal);
 
 /*
  * Turn an in-memory JsonbValue into a Jsonb for on-disk storage.
@@ -503,10 +506,43 @@ fillJsonbValue(JsonbContainer *container, int index,
  *
  * Only sequential tokens pertaining to non-container types should pass a
  * JsonbValue.  There is one exception -- WJB_BEGIN_ARRAY callers may pass a
- * "raw scalar" pseudo array to append that.
+ * "raw scalar" pseudo array to append it - the actual scalar should be passed
+ * next and it will be added as the only member of the array.
+ *
+ * Values of type jvbBinary, which are rolled up arrays and objects,
+ * are unpacked before being added to the result.
  */
 JsonbValue *
 pushJsonbValue(JsonbParseState **pstate, JsonbIteratorToken seq,
+			   JsonbValue *jbval)
+{
+	JsonbIterator *it;
+	JsonbValue *res = NULL;
+	JsonbValue v;
+	JsonbIteratorToken tok;
+
+	if (!jbval || (seq != WJB_ELEM && seq != WJB_VALUE) ||
+		jbval->type != jbvBinary)
+	{
+		/* drop through */
+		return pushJsonbValueScalar(pstate, seq, jbval);
+	}
+
+	/* unpack the binary and add each piece to the pstate */
+	it = JsonbIteratorInit(jbval->val.binary.data);
+	while ((tok = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
+		res = pushJsonbValueScalar(pstate, tok,
+								   tok < WJB_BEGIN_ARRAY ? &v : NULL);
+
+	return res;
+}
+
+/*
+ * Do the actual pushing, with only scalar or pseudo-scalar-array values
+ * accepted.
+ */
+static JsonbValue *
+pushJsonbValueScalar(JsonbParseState **pstate, JsonbIteratorToken seq,
 			   JsonbValue *scalarVal)
 {
 	JsonbValue *result = NULL;
@@ -549,13 +585,11 @@ pushJsonbValue(JsonbParseState **pstate, JsonbIteratorToken seq,
 			appendKey(*pstate, scalarVal);
 			break;
 		case WJB_VALUE:
-			Assert(IsAJsonbScalar(scalarVal) ||
-				   scalarVal->type == jbvBinary);
+			Assert(IsAJsonbScalar(scalarVal));
 			appendValue(*pstate, scalarVal);
 			break;
 		case WJB_ELEM:
-			Assert(IsAJsonbScalar(scalarVal) ||
-				   scalarVal->type == jbvBinary);
+			Assert(IsAJsonbScalar(scalarVal));
 			appendElement(*pstate, scalarVal);
 			break;
 		case WJB_END_OBJECT:
diff --git a/src/include/utils/jsonb.h b/src/include/utils/jsonb.h
index 7b561759f7f..b02934a1aef 100644
--- a/src/include/utils/jsonb.h
+++ b/src/include/utils/jsonb.h
@@ -418,7 +418,7 @@ extern JsonbValue *findJsonbValueFromContainer(JsonbContainer *sheader,
 extern JsonbValue *getIthJsonbValueFromContainer(JsonbContainer *sheader,
 							  uint32 i);
 extern JsonbValue *pushJsonbValue(JsonbParseState **pstate,
-			   JsonbIteratorToken seq, JsonbValue *scalarVal);
+			   JsonbIteratorToken seq, JsonbValue *jbVal);
 extern JsonbIterator *JsonbIteratorInit(JsonbContainer *container);
 extern JsonbIteratorToken JsonbIteratorNext(JsonbIterator **it, JsonbValue *val,
 				  bool skipNested);