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From: Nathan Bossart <nathandbossart@gmail.com>
Subject: [PATCH v4 1/2] Properly handle NULL short descriptions for custom variables.
Date: Fri, 27 May 2022 09:48:51 -0700

If a NULL short description is specified in one of the
DefineCustomXXXVariable functions, SHOW ALL will segfault.  This
change teaches SHOW ALL to properly handle NULL short descriptions.

Back-patch to all supported versions.

Reported by: Steve Chavez
Author: Steve Chavez
Reviewed by: Nathan Bossart, Michael Paquier, Andred Freund, Tom Lane
Discussion: https://postgr.es/m/CAGRrpzY6hO-Kmykna_XvsTv8P2DshGiU6G3j8yGao4mk0CqjHA%40mail.gmail.com
---
 src/backend/utils/misc/guc.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 8e9b71375c..55d41ae7d6 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -9780,7 +9780,16 @@ ShowAllGUCConfig(DestReceiver *dest)
 			isnull[1] = true;
 		}
 
-		values[2] = PointerGetDatum(cstring_to_text(conf->short_desc));
+		if (conf->short_desc)
+		{
+			values[2] = PointerGetDatum(cstring_to_text(conf->short_desc));
+			isnull[2] = false;
+		}
+		else
+		{
+			values[2] = PointerGetDatum(NULL);
+			isnull[2] = true;
+		}
 
 		/* send it to dest */
 		do_tup_output(tstate, values, isnull);
@@ -9792,7 +9801,8 @@ ShowAllGUCConfig(DestReceiver *dest)
 			pfree(setting);
 			pfree(DatumGetPointer(values[1]));
 		}
-		pfree(DatumGetPointer(values[2]));
+		if (conf->short_desc)
+			pfree(DatumGetPointer(values[2]));
 	}
 
 	end_tup_output(tstate);
@@ -10002,7 +10012,7 @@ GetConfigOptionByNum(int varnum, const char **values, bool *noshow)
 	values[3] = _(config_group_names[conf->group]);
 
 	/* short_desc */
-	values[4] = _(conf->short_desc);
+	values[4] = conf->short_desc != NULL ? _(conf->short_desc) : NULL;
 
 	/* extra_desc */
 	values[5] = conf->long_desc != NULL ? _(conf->long_desc) : NULL;
-- 
2.25.1


--IJpNTDwzlM2Ie8A6
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Introduce-pg_attribute_nonnull-and-use-it-for-Def.patch"



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