Adjust populate_record_field() to handle errors softly

This adds a Node *escontext parameter to it and a bunch of functions
downstream to it, replacing any ereport()s in that path by either
errsave() or ereturn() as appropriate.  This also adds code to those
functions where necessary to return early upon encountering a soft
error.

The changes here are mainly intended to suppress errors in the
functions of jsonfuncs.c.  Functions in any external modules, such as
arrayfuncs.c, that those functions may in turn call are not changed
here based on the assumption that the various checks in jsonfuncs.c
functions should ensure that only values that are structurally valid
get passed to the functions in those external modules.  An exception
is made for domain_check() to allow handling domain constraint
violation errors softly.

For testing, this adds a function jsonb_populate_record_valid(),
which returns true if jsonb_populate_record() would finish without
causing an error for the provided JSON object, false otherwise.  Note
that jsonb_populate_record() internally calls populate_record(),
which in turn uses populate_record_field().

Extracted from a much larger patch to add SQL/JSON query functions.

Author: Nikita Glukhov <[email protected]>
Author: Teodor Sigaev <[email protected]>
Author: Oleg Bartunov <[email protected]>
Author: Alexander Korotkov <[email protected]>
Author: Andrew Dunstan <[email protected]>
Author: Amit Langote <[email protected]>

Reviewers have included (in no particular order) Andres Freund,
Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers,
Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby,
Álvaro Herrera, Jian He, Peter Eisentraut

Discussion: https://postgr.es/m/[email protected]
Discussion: https://postgr.es/m/[email protected]
Discussion: https://postgr.es/m/abd9b83b-aa66-f230-3d6d-734817f0995d%40postgresql.org
Discussion: https://postgr.es/m/CA+HiwqHROpf9e644D8BRqYvaAPmgBZVup-xKMDPk-nd4EpgzHw@mail.gmail.com
Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com

1 files changed, 32 insertions, 1 deletions

diff --git a/src/backend/utils/adt/domains.c b/src/backend/utils/adt/domains.c
index 9f6e1a15adb..21791105da8 100644
--- a/src/backend/utils/adt/domains.c
+++ b/src/backend/utils/adt/domains.c
@@ -40,6 +40,9 @@
 #include "utils/syscache.h"
 #include "utils/typcache.h"
 
+static bool domain_check_internal(Datum value, bool isnull, Oid domainType,
+								  void **extra, MemoryContext mcxt,
+								  Node *escontext);
 
 /*
  * structure to cache state across multiple calls
@@ -343,6 +346,32 @@ void
 domain_check(Datum value, bool isnull, Oid domainType,
 			 void **extra, MemoryContext mcxt)
 {
+	(void) domain_check_internal(value, isnull, domainType, extra, mcxt,
+								 NULL);
+}
+
+/* Error-safe variant of domain_check(). */
+bool
+domain_check_safe(Datum value, bool isnull, Oid domainType,
+				  void **extra, MemoryContext mcxt,
+				  Node *escontext)
+{
+	return domain_check_internal(value, isnull, domainType, extra, mcxt,
+								 escontext);
+}
+
+/*
+ * domain_check_internal
+ * 		Workhorse for domain_check() and domain_check_safe()
+ *
+ * Returns false if an error occurred in domain_check_input() and 'escontext'
+ * points to an ErrorSaveContext, true otherwise.
+ */
+static bool
+domain_check_internal(Datum value, bool isnull, Oid domainType,
+					  void **extra, MemoryContext mcxt,
+					  Node *escontext)
+{
 	DomainIOData *my_extra = NULL;
 
 	if (mcxt == NULL)
@@ -365,7 +394,9 @@ domain_check(Datum value, bool isnull, Oid domainType,
 	/*
 	 * Do the necessary checks to ensure it's a valid domain value.
 	 */
-	domain_check_input(value, isnull, my_extra, NULL);
+	domain_check_input(value, isnull, my_extra, escontext);
+
+	return !SOFT_ERROR_OCCURRED(escontext);
 }
 
 /*