4 files changed, 122 insertions, 0 deletions
diff --git a/src/include/fmgr.h b/src/include/fmgr.h
index 380a82b9de..b7832d0aa2 100644
--- a/src/include/fmgr.h
+++ b/src/include/fmgr.h
@@ -700,6 +700,10 @@ extern Datum OidFunctionCall9Coll(Oid functionId, Oid collation,
 /* Special cases for convenient invocation of datatype I/O functions. */
 extern Datum InputFunctionCall(FmgrInfo *flinfo, char *str,
 							   Oid typioparam, int32 typmod);
+extern bool InputFunctionCallSafe(FmgrInfo *flinfo, char *str,
+								  Oid typioparam, int32 typmod,
+								  fmNodePtr escontext,
+								  Datum *result);
 extern Datum OidInputFunctionCall(Oid functionId, char *str,
 								  Oid typioparam, int32 typmod);
 extern char *OutputFunctionCall(FmgrInfo *flinfo, Datum val);
diff --git a/src/include/nodes/meson.build b/src/include/nodes/meson.build
index e63881086e..f0e60935b6 100644
--- a/src/include/nodes/meson.build
+++ b/src/include/nodes/meson.build
@@ -16,6 +16,7 @@ node_support_input_i = [
   'nodes/bitmapset.h',
   'nodes/extensible.h',
   'nodes/lockoptions.h',
+  'nodes/miscnodes.h',
   'nodes/replnodes.h',
   'nodes/supportnodes.h',
   'nodes/value.h',
diff --git a/src/include/nodes/miscnodes.h b/src/include/nodes/miscnodes.h
new file mode 100644
index 0000000000..b50ee60352
--- /dev/null
+++ b/src/include/nodes/miscnodes.h
@@ -0,0 +1,56 @@
+/*-------------------------------------------------------------------------
+ *
+ * miscnodes.h
+ *	  Definitions for hard-to-classify node types.
+ *
+ * Node types declared here are not part of parse trees, plan trees,
+ * or execution state trees.  We only assign them NodeTag values because
+ * IsA() tests provide a convenient way to disambiguate what kind of
+ * structure is being passed through assorted APIs, such as function
+ * "context" pointers.
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/nodes/miscnodes.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef MISCNODES_H
+#define MISCNODES_H
+
+#include "nodes/nodes.h"
+
+/*
+ * ErrorSaveContext -
+ *		function call context node for handling of "soft" errors
+ *
+ * A caller wishing to trap soft errors must initialize a struct like this
+ * with all fields zero/NULL except for the NodeTag.  Optionally, set
+ * details_wanted = true if more than the bare knowledge that a soft error
+ * occurred is required.  The struct is then passed to a SQL-callable function
+ * via the FunctionCallInfo.context field; or below the level of SQL calls,
+ * it could be passed to a subroutine directly.
+ *
+ * After calling code that might report an error this way, check
+ * error_occurred to see if an error happened.  If so, and if details_wanted
+ * is true, error_data has been filled with error details (stored in the
+ * callee's memory context!).  FreeErrorData() can be called to release
+ * error_data, although that step is typically not necessary if the called
+ * code was run in a short-lived context.
+ */
+typedef struct ErrorSaveContext
+{
+	NodeTag		type;
+	bool		error_occurred; /* set to true if we detect a soft error */
+	bool		details_wanted; /* does caller want more info than that? */
+	ErrorData  *error_data;		/* details of error, if so */
+} ErrorSaveContext;
+
+/* Often-useful macro for checking if a soft error was reported */
+#define SOFT_ERROR_OCCURRED(escontext) \
+	((escontext) != NULL && IsA(escontext, ErrorSaveContext) && \
+	 ((ErrorSaveContext *) (escontext))->error_occurred)
+
+#endif							/* MISCNODES_H */
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index f107a818e8..8025dce335 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -18,6 +18,10 @@
 
 #include "lib/stringinfo.h"
 
+/* We cannot include nodes.h yet, so forward-declare struct Node */
+struct Node;
+
+
 /* Error level codes */
 #define DEBUG5		10			/* Debugging messages, in categories of
 								 * decreasing detail. */
@@ -235,6 +239,63 @@ extern int	getinternalerrposition(void);
 	ereport(elevel, errmsg_internal(__VA_ARGS__))
 
 
+/*----------
+ * Support for reporting "soft" errors that don't require a full transaction
+ * abort to clean up.  This is to be used in this way:
+ *		errsave(context,
+ *				errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
+ *				errmsg("invalid input syntax for type %s: \"%s\"",
+ *					   "boolean", in_str),
+ *				... other errxxx() fields as needed ...);
+ *
+ * "context" is a node pointer or NULL, and the remaining auxiliary calls
+ * provide the same error details as in ereport().  If context is not a
+ * pointer to an ErrorSaveContext node, then errsave(context, ...)
+ * behaves identically to ereport(ERROR, ...).  If context is a pointer
+ * to an ErrorSaveContext node, then the information provided by the
+ * auxiliary calls is stored in the context node and control returns
+ * normally.  The caller of errsave() must then do any required cleanup
+ * and return control back to its caller.  That caller must check the
+ * ErrorSaveContext node to see whether an error occurred before
+ * it can trust the function's result to be meaningful.
+ *
+ * errsave_domain() allows a message domain to be specified; it is
+ * precisely analogous to ereport_domain().
+ *----------
+ */
+#define errsave_domain(context, domain, ...)	\
+	do { \
+		struct Node *context_ = (context); \
+		pg_prevent_errno_in_scope(); \
+		if (errsave_start(context_, domain)) \
+			__VA_ARGS__, errsave_finish(context_, __FILE__, __LINE__, __func__); \
+	} while(0)
+
+#define errsave(context, ...)	\
+	errsave_domain(context, TEXTDOMAIN, __VA_ARGS__)
+
+/*
+ * "ereturn(context, dummy_value, ...);" is exactly the same as
+ * "errsave(context, ...); return dummy_value;".  This saves a bit
+ * of typing in the common case where a function has no cleanup
+ * actions to take after reporting a soft error.  "dummy_value"
+ * can be empty if the function returns void.
+ */
+#define ereturn_domain(context, dummy_value, domain, ...)	\
+	do { \
+		errsave_domain(context, domain, __VA_ARGS__); \
+		return dummy_value; \
+	} while(0)
+
+#define ereturn(context, dummy_value, ...)	\
+	ereturn_domain(context, dummy_value, TEXTDOMAIN, __VA_ARGS__)
+
+extern bool errsave_start(struct Node *context, const char *domain);
+extern void errsave_finish(struct Node *context,
+						   const char *filename, int lineno,
+						   const char *funcname);
+
+
 /* Support for constructing error strings separately from ereport() calls */
 
 extern void pre_format_elog_string(int errnumber, const char *domain);