From 5d57d7b755c3a23ca94bf922581a417844249044 Mon Sep 17 00:00:00 2001
From: Sandro Santilli <strk@kbt.io>
Date: Wed, 14 Sep 2022 11:10:10 +0200
Subject: [PATCH v2] Allow wildcard (%) in extension upgrade paths

A wildcard character "%" will be accepted in the
"source" side of the upgrade script and be considered
usable to upgrade any version to the "target" side.

Using wildcards needs to be explicitly requested by
extensions via a "wildcard_upgrades" setting in their
control file.
---
 src/backend/commands/extension.c | 58 ++++++++++++++++++++++++++++----
 1 file changed, 52 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index 6b6720c690..e36a79ae75 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -86,6 +86,7 @@ typedef struct ExtensionControlFile
 	bool		relocatable;	/* is ALTER EXTENSION SET SCHEMA supported? */
 	bool		superuser;		/* must be superuser to install? */
 	bool		trusted;		/* allow becoming superuser on the fly? */
+	bool		wildcard_upgrades;  /* allow using wildcards in upgrade scripts */
 	int			encoding;		/* encoding of the script file, or -1 */
 	List	   *requires;		/* names of prerequisite extensions */
 } ExtensionControlFile;
@@ -128,6 +129,7 @@ static void ApplyExtensionUpdates(Oid extensionOid,
 								  bool cascade,
 								  bool is_create);
 static char *read_whole_file(const char *filename, int *length);
+static bool file_exists(const char *name);
 
 
 /*
@@ -579,6 +581,14 @@ parse_extension_control_file(ExtensionControlFile *control,
 						 errmsg("parameter \"%s\" requires a Boolean value",
 								item->name)));
 		}
+		else if (strcmp(item->name, "wildcard_upgrades") == 0)
+		{
+			if (!parse_bool(item->value, &control->wildcard_upgrades))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("parameter \"%s\" requires a Boolean value",
+								item->name)));
+		}
 		else if (strcmp(item->name, "encoding") == 0)
 		{
 			control->encoding = pg_valid_server_encoding(item->value);
@@ -636,6 +646,7 @@ read_extension_control_file(const char *extname)
 	control->relocatable = false;
 	control->superuser = true;
 	control->trusted = false;
+	control->wildcard_upgrades = false;
 	control->encoding = -1;
 
 	/*
@@ -890,7 +901,15 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 	if (from_version == NULL)
 		elog(DEBUG1, "executing extension script for \"%s\" version '%s'", control->name, version);
 	else
+	{
+		if ( control->wildcard_upgrades && ! file_exists(filename) )
+		{
+			elog(DEBUG1, "extension upgrade script \"%s\" does not exist, will try wildcard", filename);
+			/* if filename does not exist, try wildcard */
+			filename = get_extension_script_filename(control, "%", version);
+		}
 		elog(DEBUG1, "executing extension script for \"%s\" update from version '%s' to '%s'", control->name, from_version, version);
+	}
 
 	/*
 	 * If installing a trusted extension on behalf of a non-superuser, become
@@ -1215,13 +1234,23 @@ identify_update_path(ExtensionControlFile *control,
 	/* Find shortest path */
 	result = find_update_path(evi_list, evi_start, evi_target, false, false);
 
-	if (result == NIL)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("extension \"%s\" has no update path from version \"%s\" to version \"%s\"",
-						control->name, oldVersion, newVersion)));
+	if (result != NIL)
+		return result;
 
-	return result;
+	/* Find wildcard path, if allowed by control file */
+	if ( control->wildcard_upgrades )
+	{
+		evi_start = get_ext_ver_info("%", &evi_list);
+		result = find_update_path(evi_list, evi_start, evi_target, false, false);
+
+		if (result != NIL)
+			return result;
+	}
+
+	ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			 errmsg("extension \"%s\" has no update path from version \"%s\" to version \"%s\"",
+					control->name, oldVersion, newVersion)));
 }
 
 /*
@@ -3392,3 +3421,20 @@ read_whole_file(const char *filename, int *length)
 	buf[*length] = '\0';
 	return buf;
 }
+
+static bool
+file_exists(const char *name)
+{
+	struct stat st;
+
+	AssertArg(name != NULL);
+
+	if (stat(name, &st) == 0)
+		return !S_ISDIR(st.st_mode);
+	else if (!(errno == ENOENT || errno == ENOTDIR || errno == EACCES))
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not access file \"%s\": %m", name)));
+
+	return false;
+}
-- 
2.34.1